bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrostatics dominate quadruplex stability
Authors: Smirnov Ivan V. , Shafer Richard H.
Published: September 2006

Stabilization of nucleic acid structures results from a balance of multiple interactions, including electrostatics, base stacking, hydrophobic interactions, hydrogen bonding, van der Waals forces, etc. Nucleic acid quadruplexes are unusual structures in that their formation is driven by specific binding of metal ions. This unique mode of metal binding, which is tightly coupled to oligonucleotide folding, can engender correspondingly unique solution behavior. In particular, we show that addition of many cosolvents, such as primary aliphatic alcohols, increases the thermal stability of quadruplexes, as determined by melting temperature, Tm, in direct contrast to the response of duplexes to the same admixture of solvents. Thermal stability is observed to increase as the dielectric constant of the composite solvent decreases. This behavior suggests a dominant role for electrostatics in quadruplex formation and stability. Additional studies done with other cosolvents and solutes suggest that, in some cases, other forces may come into play, including the possibility of direct interaction with the quadruplex structure. Nonetheless, many cosolvents and small molecules, such as ethanol, dimethylformamide, and betaine, stabilize the quadruplex conformation in sharp distinction to their destabilization of DNA duplexes. © 2006 Wiley Periodicals, Inc. Biopolymers 85: 91–101, 2007.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Bio‐reductive dechlorination of 1,1,1‐trichloroethane and chloroform using a hydrogen‐based membrane biofilm reactor
Authors: Chung Jinwook , Rittmann Bruce E.
Published: September 2006

A H2‐based, denitrifying and sulfate‐reducing membrane biofilm reactor (MBfR) was effective for removing 1,1,1‐trichloroethane (TCA) and chloroform (CF) by reductive dechlorination. When either TCA or CF was first added to the MBfR, reductive dechlorination took place immediately and then increased over 3 weeks, suggesting enrichment for TCA‐ or CF‐dechlorinating bacteria. Increasing the H2 pressure increased the dechlorination rates of TCA or CF, and it also increased the rate of sulfate reduction. Increased sulfate loading allowed more sulfate reduction, and this competed with reductive dechlorination, particularly the second steps. The acceptor flux normalized by effluent concentration can be an efficient indicator to gauge the intrinsic kinetics of the MBfR biofilms for the different reduction reactions. The analysis of normalized rates showed that the kinetics for reductive‐dechlorination reactions were slowed by reduced H2 bio‐availability caused by a low H2 pressure or competition from sulfate reduction. Biotechnol. Bioeng. 2007;97:52–60. © 2006 Wiley Periodicals, Inc.
Redox‐stratification controlled biofilm (ReSCoBi) for completely autotrophic nitrogen removal: The effect of co‐ versus counter‐diffusion on reactor performance
Authors: Terada Akihiko , Lackner Susanne , Tsuneda Satoshi , Smets Barth F.
Published: September 2006

A multi‐population biofilm model for completely autotrophic nitrogen removal was developed and implemented in the simulation program AQUASIM to corroborate the concept of a redox‐stratification controlled biofilm (ReSCoBi). The model considers both counter‐ and co‐diffusion biofilm geometries. In the counter‐diffusion biofilm, oxygen is supplied through a gas‐permeable membrane that supports the biofilm while ammonia (NH) is supplied from the bulk liquid. On the contrary, in the co‐diffusion biofilm, both oxygen and NH are supplied from the bulk liquid. Results of the model revealed a clear stratification of microbial activities in both of the biofilms, the resulting chemical profiles, and the obvious effect of the relative surface loadings of oxygen and NH (J/J) on the reactor performances. Steady‐state biofilm thickness had a significant but different effect on T‐N removal for co‐ and counter‐diffusion biofilms: the removal efficiency in the counter‐diffusion biofilm geometry was superior to that in the co‐diffusion counterpart, within the range of 450–1,400 µm; however, the efficiency deteriorated with a further increase in biofilm thickness, probably because of diffusion limitation of NH. Under conditions of oxygen excess (J/J > 3.98), almost all NH was consumed by aerobic ammonia oxidation in the co‐diffusion biofilm, leading to poor performance, while in the counter‐diffusion biofilm, T‐N removal efficiency was maintained because of the physical location of anaerobic ammonium oxidizers near the bulk liquid. These results clearly reveal that counter‐diffusion biofilms have a wider application range for autotrophic T‐N removal than co‐diffusion biofilms. Biotechnol. Bioeng. 2007;97:40–51. © 2006 Wiley Periodicals, Inc.
On the Lack of Ring‐Current Aromaticity of (Heteroatom) [N]Radialenes and their Dianions
Authors: Domene Carmen , Fowler Patrick W. , Jenneskens Leonardus W. , Steiner Erich
Published: September 2006

Current‐density maps, calculated at the ab initio RHF//6–31G**/CTOCD‐DZ level, show no significant π ring current in planar equilateral geometries of neutral and dianionic [N]radialenes, oxocarbons and thiocarbons CNYNq− (Y=CH2, O, S; N=4, 5, 6; q=0 (1 a–12 a), 2 (1 b–12 b)). Only the N=3 deltate dianions C3Y32− (Y=CH2, O, S (1 b, 5 b and 9 b)) have discernible π ring current, and then with at most 20–25 % of the strength of the standard benzene current. On the magnetic criterion, lack of current is definitive evidence against aromaticity. Pictorial molecular‐orbital analysis within the ipsocentric approach shows this to be an inevitable consequence of the nodal structure of the π and π* orbitals of [N]radialene‐like systems. On grounds of angular‐momentum symmetry, spatial distribution, or both, the HOMO–LUMO excitation does not contribute a significant central diamagnetic ring current.
Highly Luminescent Gold(I)–Silver(I) and Gold(I)–Copper(I) Chalcogenide Clusters
Authors: Crespo Olga , Gimeno M. Concepción , Laguna Antonio , Larraz Carmen , Villacampa M. Dolores
Published: September 2006

The reactions of [AuClL] with Ag2O, where L represents the heterofunctional ligands PPh2py and PPh2CH2CH2py, give the trigoldoxonium complexes [O(AuL)3]BF4. Treatment of these compounds with thio‐ or selenourea affords the triply bridging sulfide or selenide derivatives [E(AuL)3]BF4 (E=S, Se). These trinuclear species react with Ag(OTf) or [Cu(NCMe)4]PF6 to give different results, depending on the phosphine and the metal. The reactions of [E(AuPPh2py)3]BF4 with silver or copper salts give [E(AuPPh2py)3M]2+ (E=O, S, Se; M=Ag, Cu) clusters that are highly luminescent. The silver complexes consist of tetrahedral Au3Ag clusters further bonded to another unit through aurophilic interactions, whereas in the copper species two coordination isomers with different metallophilic interactions were found. The first is analogous to the silver complexes and in the second, two [S(AuPPh2py)3]+ units bridge two copper atoms through one pyridine group in each unit. The reactions of [E(AuPPh2CH2CH2py)3]BF4 with silver and copper salts give complexes with [E(AuPPh2CH2CH2py)3M]2+ stoichiometry (E=O, S, Se; M=Ag, Cu) with the metal bonded to the three nitrogen atoms in the absence of Au⋅⋅⋅M interactions. The luminescence of these clusters has been studied by varying the chalcogenide, the heterofunctional ligand, and the metal.
Scope and Mechanistic Insights into the Use of Tetradecyl(trihexyl)phosphonium Bistriflimide: A Remarkably Selective Ionic Liquid Solvent for Substitution Reactions
Authors: McNulty James , Nair Jerald J. , Cheekoori Sreedhar , Larichev Vladimir , Capretta Alfredo , Robertson Al J.
Published: September 2006

A survey of substitution reactions conducted in a phosphonium bistriflimide ionic liquid is presented. The results demonstrate high selectivity favoring substitution over typically competitive elimination and solvolytic processes even when challenging secondary and tertiary electrophiles are employed. The first reports of Kornblum substitution reactions in an ionic liquid are described that proceed with very high chemoselectivity in favor of nitro over nitroso products and elimination side products. The structure–reactivity study indicates that these reactions proceed through a narrow spectrum of pathways ranging from straight SN2 to a preassociation pathway along a saddle point that approaches the SN1 limit. The barrier to the formation of dissociated carbocations is attributed to the structural features of this ionic liquid that favor intervention of the associated nucleophile over dissociation, also preventing cross over to E1 processes. The lack of any basic entity in the phosphonium bistriflimide ionic liquid appears to prevent any potential base‐mediated elimination reactions, which makes this a highly selective medium for use in general substitution reactions.
Studies of a Molecular Hourglass: Synthesis and Magnetic Characterisation of a Cyclic Dodecanuclear {Cr10Cu2} Complex
Authors: Shanmugam Muralidharan , Engelhardt Larry P. , Larsen Finn K. , Luban Marshall , McInnes Eric J. L. , Muryn Christopher A. , Overgaard Jacob , Rentschler Eva , Timco Grigore A. , Winpenny Richard E. P.
Published: September 2006

The synthesis, structure, EPR, and magnetic studies of two dodecanuclear heterometallic cyclic clusters are reported. The compounds have the general formula [R2NH2]2[Cr10Cu2F14(O2CCMe3)22] (R=Me, 1 or iPr, 2). Both structures contain an array of metal centers which describe an approximate “hourglass”, with an ammonium cation in the center of each half of the figure. The chromium sites are all six‐coordinate, with the two copper sites five‐coordinate. The majority of metal–metal edges are bridged by a single fluoride and two pivalate ligands, while two CrCu edges are bridged by a single fluoride and a single pivalate. Magnetic studies show that 1 and 2 exhibit similar (but not identical) behavior, which can be attributed to ten antiferromagnetic and two ferromagnetic exchange interactions around the ring which gives an S=0 ground state. Quantum Monte Carlo calculations have been used to quantify the exchange interactions by successfully simulating the susceptibility for the full temperature range and thus clarifying the distinction between 1 and 2. EPR spectroscopy shows signals due to excited states, and a variable‐temperature study has provided an estimate of the energy gap between the first excited state (S=1) and second excited state (S=2) for 1 that is consistent with the value obtained using the QMC method.
Mo15S20: First Evidence of a New Molybdenum Cluster Type in a Metastable Solid‐State Compound
Authors: Salloum Dialla , Gautier Régis , Potel Michel , Gougeon Patrick
Published: September 2006

The Mo15S20 compound was obtained by thermal decomposition of the metastable binary Mo15S19 in sealed silica tube at temperatures above 500 °C. Its crystal structure was solved and refined from a two‐component composite crystal by X‐ray diffraction in the hexagonal space group P63/m and consists of an equal mixture of the original Mo9S27 cluster unit and the classical one Mo6S8S6 interconnected through MoS bonds. The Mo core of the Mo9S27 unit is totally new and formed a tricapped trigonal prism. Quantum chemical calculations carried out in order to understand these trends as well as magnetic susceptibility measurements are also reported. The title compound becomes superconducting below 5 K.
Cultured endothelial cells display endogenous activation of the canonical Wnt signaling pathway and express multiple ligands, receptors, and secreted modulators of Wnt signaling
Authors: Goodwin Anne M. , Sullivan Kaitlyn M. , D'Amore Patricia A.
Published: September 2006

A growing body of evidence implicates Wnt signaling in the control of angiogenesis. To better understand the role of the Wnt/β‐catenin pathway in endothelial cells (EC), we examined endogenous signaling activity and signaling component expression in vascular cells. We observed stabilization of cytosolic β‐catenin and activation of a T‐cell factor (TCF) ‐luciferase promoter, hallmarks of canonical Wnt signaling activity, in cultured EC. This activity was increased in subconfluent EC, which are known to display characteristics of angiogenic EC, compared with confluent EC, which have a more differentiated phenotype. Endogenous TCF activity was inhibited by transfection with a secreted inhibitor of canonical Wnt signaling. A systematic analysis of Wnt, Fzd, SFRP, and Dkk gene expression in human EC (cultured and freshly isolated), smooth muscle cells (cultured), and aorta demonstrated that numerous Wnt signaling components are expressed by vascular cells. We conclude that Wnt signaling components are expressed and active in cultured EC. Developmental Dynamics 235:3110–3120, 2006. © 2006 Wiley‐Liss, Inc.
The RNA binding protein Zfp36l1 is required for normal vascularisation and post‐transcriptionally regulates VEGF expression
Authors: Bell Sarah E. , Sanchez Maria Jose , Spasic‐Boskovic Olivera , Santalucia Tomas , Gambardella Laure , Burton Graham J. , Murphy John J. , Norton John D. , Clark Andrew R. , Turner Martin
Published: September 2006

The Zfp36l1 gene encodes a zinc finger‐containing mRNA binding protein implicated in the posttranscriptional control of gene expression. Mouse embryos homozygous for a targeted mutation in the Zfp36l1 locus died mid‐gestation and exhibited extraembryonic and intraembryonic vascular abnormalities and heart defects. In the developing placenta, there was a failure of the extraembryonic mesoderm to invaginate the trophoblast layer. The phenotype was associated with an elevated expression of vascular endothelial growth factor (VEGF)‐A in the embryos and in embryonic fibroblasts cultured under conditions of both normoxia and hypoxia. VEGF‐A overproduction by embryonic fibroblasts was not a consequence of changes in Vegf‐a mRNA stability; instead, we observed enhanced association with polyribosomes, suggesting Zfp36l1 influences translational regulation. These data implicate Zfp36l1as a negative regulator of Vegf‐a gene activity during development. Developmental Dynamics 235:3144–3155, 2006. © 2006 Wiley‐Liss, Inc.
Quantitative volumetric analysis of cardiac morphogenesis assessed through micro‐computed tomography
Authors: Butcher Jonathan T. , Sedmera David , Guldberg Robert E. , Markwald Roger R.
Published: September 2006

We present a method to generate quantitative embryonic cardiovascular volumes at extremely high resolution without tissue shrinkage using micro‐computed tomography (Micro‐CT). A CT dense polymer (Microfil, Flow Tech, Inc.) was used to perfuse avian embryonic hearts from Hamburger and Hamilton stage (HH) 15 through HH36, which solidified to create a cast within the luminal space. Hearts were then scanned at 10.5 μm3 voxel resolution using a VivaCT scanner, digital slices were contoured for regions of interest, and computational analysis was conducted to quantify morphogenetic parameters. The three‐dimensional morphology was compared with that of scanning electron microscopy (SEM) images and serial section reconstruction of similarly staged hearts. We report that Microfil‐perfused hearts swelled to maximum end‐diastolic volume with negligible shrinking after polymerization. Comparison to SEM revealed good agreement of cardiac chamber proportions and intracardiac tissue structures (i.e., valves and septa) at the stages of development assessed. Quantification of changes in chamber volume over development revealed several notable results that confirm earlier hypotheses. Heart chamber volumes grow over two orders of magnitude during the 1‐week developmental period analyzed. The atrioventricular canal comprised a significant proportion of the early heart volume. While left atrium/left ventricular volume ratios approached 1 in later development, right atrium/right ventricle ratios increase to over 2.5. Quantification of trabeculation patterns confirmed that the right and left ventricles are similarly trabeculated before HH27, after which the right ventricle became quantitatively coarser than that of the left ventricle. These results demonstrate that Micro‐CT can be used to image and quantify cardiovascular structures during development. Developmental Dynamics 236:802–809, 2007. © 2006 Wiley‐Liss, Inc.
Dact1 presomitic mesoderm expression oscillates in phase with Axin2 in the somitogenesis clock of mice
Authors: Suriben Rowena , Fisher Daniel A. , Cheyette Benjamin N.R.
Published: September 2006

During segmentation (somitogenesis) in vertebrate embryos, somites form in a rostral‐to‐caudal sequence according to a species‐specific rhythm called the somitogenesis clock. The expression of genes participating in somitogenesis oscillates in the presomitic mesoderm (PSM) in time with this clock. We previously reported that the Dact1 gene (aka Dpr1/Frd1/ThyEx3), which encodes a Dishevelled‐binding intracellular regulator of Wnt signaling, is prominently expressed in the PSM as well as in a caudal‐rostral gradient across the somites of mouse embryos. This observation led us to examine whether Dact1 expression oscillates in the PSM. We have found that Dact1 PSM expression does indeed oscillate in time with the somitogenesis clock. Consistent with its known signaling functions and with the “clock and wavefront” model of signal regulation during somitogenesis, the oscillation of Dact1 occurs in phase with the Wnt signaling component Axin2, and out of phase with the Notch signaling component Lfng. Developmental Dynamics 235:3177–3183, 2006. © 2006 Wiley‐Liss, Inc.
Expression of the AmphiTcf gene in amphioxus: Insights into the evolution of the TCF/LEF gene family during vertebrate evolution
Authors: Lin Hsiu‐Chin , Holland Linda Z. , Holland Nicholas D.
Published: September 2006

T‐cell factor (TCF) and lymphoid enhancer factors (LEF) genes encode proteins that are transcription factors mediating β‐catenin/Wnt signaling. Whereas mammals have four such genes, the Florida amphioxus (Branchiostoma floridae) apparently has only one such gene (AmphiTcf). From cleavage through early gastrula, cytoplasmic maternal transcripts of this gene are localized toward the animal pole. In gastrulae, AmphiTcf expression begins in the mesendoderm. In neurulae, there is expression in the pharynx, hindgut, anterior notochord, somites, and at the anterior end of the neural plate. In early larvae, expression is detectable in the floor of the diencephalon, notochord, tail bud, forming somites, pharynx, and ciliated pit (a presumed homolog of the vertebrate adenohypophysis). Phylogenetic analysis of TCF/LEF proteins placed AmphiTcf as the sister group of a clade comprising vertebrate Tcf1, Lef1, Tcf3, and Tcf4. Comparison of developmental expression for amphioxus AmphiTcf and vertebrate TCF/LEF genes indicates that this gene family has undergone extensive subfunctionalization and neofunctionalization during vertebrate evolution. Developmental Dynamics 235:3396–3403, 2006. © 2006 Wiley‐Liss, Inc.
Transgenic mice for Cre‐inducible overexpression of the oncogenes c‐MYC and Pim‐1 in multiple tissues
Authors: Roh Meejeon , Kim Jongchan , Song Chisu , Wills Marcia , Abdulkadir Sarki A.
Published: September 2006

The transcription factor c‐MYC and the serine‐threonine kinase Pim‐1 have multiple roles in development and cancer, including in lymphomagenesis and prostate tumorigenesis. In some cancers, MYC and Pim‐1 oncogenes are co‐expressed and show marked cooperativity. To facilitate the analysis of the pathological roles of MYC and Pim‐1 in specific cell types and developmental stages, we generated mice carrying Cre‐inducible MYC/Pim‐1 transgenes. The mice carry a constitutively expressed lacZ marker and silent MYC/Pim‐1 genes. Cre‐mediated recombination results in deletion of the lacZ marker and concurrent activation of the MYC/Pim‐1 transgene. In addition, the Pim‐1 mice harbor an alkaline phosphatase gene as a positive marker for recombination. Mouse lines for each gene were established, which show distinct patterns of expression in multiple tissues. In vivo recombination was confirmed for all lines by breeding to Cre transgenic mice. These mice provide a valuable resource for investigating the significance of MYC and Pim‐1 overexpression in various tissues. genesis 44:447–453, 2006. © 2006 Wiley‐Liss, Inc.
Summary of ‘Interventions for promoting booster seat use in four to eight year olds traveling in motor vehicles’
Authors: Milne Andrea
Published: September 2006

This is a summary of a Cochrane review, published in this issue of EBCH, first published as: Ehiri JE, Ejere HOD, Magnussen L, Emusu D, King W, Osberg JS. Interventions for promoting booster seat use in four to eight year olds traveling in motor vehicles. Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD004334. DOI: 10.1002/14651858.CD004334.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Expert Commentary and Characteristics and Key Findings Tables articles. Copyright © 2006 John Wiley & Sons, Ltd.
Commentary on ‘EMLA and Amethocaine for reduction of children's pain associated with needle insertion’
Authors: van Dijk Monique
Published: September 2006

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Lander JA, Weltman BJ, So SS. EMLA and Amethocaine for reduction of children's pain associated with needle insertion. Cochrane Database of Systematic Reviews 2006, Issue 3. Art. No.: CD004236. DOI: 10.1002/14651858.CD004236.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Characteristics and Key Findings Tables articles. Copyright © 2006 John Wiley & Sons, Ltd.
Characteristics and key findings for ‘Interventions for promoting booster seat use in four to eight year olds traveling in motor vehicles’
Authors: van Dalen Elvira , Offringa Martin , Kremer Leontien
Published: September 2006

These are the characteristics and key findings for a Cochrane review, published in this issue of EBCH, first published as: Ehiri JE, Ejere HOD, Magnussen L, Emusu D, King W, Osberg JS. Interventions for promoting booster seat use in four to eight year olds traveling in motor vehicles. Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD004334. DOI: 10.1002/14651858.CD004334.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Expert Commentary articles. Copyright © 2006 John Wiley & Sons, Ltd.
Informational intra‐group influence: the effects of time pressure and group size
Authors: Bonner Bryan L. , Baumann Michael R.
Published: September 2006

The judgments of groups have immense impact on our daily lives. This paper theorizes that three families of intra‐group influence affect the collective estimation process. These different forms of influence map to different levels of task demonstrability, or the extent to which correct answers are transparent to problem‐solvers. When demonstrability is low, group estimates are disproportionately influenced by proposals closer to the intra‐group mean (centrality). When demonstrability is high and groups are small, group decisions are disproportionately influenced by proposals closer to the correct answer (accuracy). Finally, when demonstrability is high and groups are larger, group decisions are disproportionately influenced by proposals offered by generally more accurate individuals across a set of judgments (expertise). Three laboratory studies support our predictions with regard to informational influence in cooperative groups. Copyright © 2006 John Wiley & Sons, Ltd.
Der Beitrag deutscher Botaniker an der Erforschung von Flora und Vegetation in der Mongolei
Authors: Hilbig Werner
Published: September 2006

In der Arbeit wird ein Überblick über die Forschungen deutscher Botaniker in der Mongolei gegeben. Beginnend mit Hinweisen auf deutsche Naturforscher in russischen Diensten im 18. und 19. Jahrhundert wird vor allem über die intensiven Forschungen während der letzten 40 Jahre und ihre Ergebnisse berichtet.

Seit den 1960‐er Jahren führten vor allem Biologen der Akademie der Wissenschaften der DDR und der Martin‐Luther‐Universität Halle‐Wittenberg in Zusammenarbeit mit mongolischen Kollegen zahlreiche Untersuchungen in verschiedenen Teilen der Mongolei durch. Seit 1990 sind nunmehr Vertreter weiterer deutscher Universitäten an den Forschungen beteiligt. Die Forschungen auf Expeditionen und in Forschungsstationen führten zu internationalen Tagungen, zu zahlreichen Publikationen und zu Qualifizierungsarbeiten deutscher und mongolischer Expeditionsteilnehmer. Die vielen Publikationen werden zitiert.

Die floristischen Untersuchungen erbrachten zahlreiche Neufunde von höheren Pflanzen, Moosen, Flechten und Pilzen sowie Neubeschreibungen von Arten. Am Institut für Biochemie der Pflanzen Halle der Akademie der Wissenschaften wurden viele Pflanzenarten chemisch analysiert. In den Herbarien der Universität Halle (HAL) und des Instituts für Pflanzengenetik und Kulturpflanzenforschung Gatersleben (GAT) wurden umfangreiche Mongolei‐Sammlungen aufgebaut.

Die vegetationskundlichen und ökologischen Untersuchungen erbrachten detaillierte Vegetationsbeschreibungen von Teilgebieten der Mongolei und einen Überblick über die Vegetationseinheiten des Landes und ihre Standortsverhältnisse. Für die Naturschutzarbeit der Mongolei konnten Hinweise, speziell zur Schutzgebietsplanung, gegeben werden. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vegetationskundliche Untersuchungen in der Borzongijn‐ und Galbyn‐Gobi (Ömnögov Aimak, Mongolei)
Authors: Hilbig W. , Tungalag R.
Published: September 2006

Während der im August 2005 von Zoologen der Georg‐August‐Universität Göttingen durchgeführten 4. “Gobi Desert Vertebrates”‐Expedition in den Ömnögov Aimak der Mongolei, an der wir teilnehmen konnten, wurden von uns Vegetationsuntersuchungen in den pflanzengeographischen Bezirken Ost‐Gobi und Alašan‐Gobi durchgeführt. Dabei widmeten wir uns im Wesentlichen den weitverbreiteten zonalen Pflanzengesellschaften der Wüsten und Halbwüsten. Aber auch der Vegetation der grundwassernahen Standorte und der anthropogenen Vegetation wurde Beachtung geschenkt. Einige floristische Neunachweise für die genannten Bezirke konnten erbracht werden. Solanum physalifolium wurde in der Mongolei neu gefunden. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The identity of the three earliest binomials in BomareaMirb. (Alstroemeriaceae)
Authors: Hofreiter A.
Published: September 2006

The identity of the three Bomarea ‐species (B. multiflora, B. ovata and B. salsilla) used by Mirbel (1804) to set up the genus, is clarified. All synonyms and the variability and distribution of the species are discussed. The types are illustrated and epitype is chosen for B. salsilla. The type of B. ovata is identified. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Novel combination therapy against metastatic and androgen‐independent prostate cancer by using gefitinib, tamoxifen and etoposide
Authors: Mimeault Murielle , Venkatraman Ganesh , Johansson Sonny L. , Moore Erik , Henichart Jean‐Pierre , Depreux Patrick , Lin Ming‐Fong , Batra Surinder K.
Published: September 2006

In this study, we evaluated, for the first time, the antiproliferative and cytotoxic effects induced by a combination of a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, gefitinib, with other chemotherapeutic drugs including estrogen receptor‐beta (ER‐β) antagonist (tamoxifen) and topoisomerase II inhibitor (etoposide) on some metastatic prostate cancer (PC) cell lines. Immunohistochemial analyses revealed that EGFR expression was enhanced in 38% of primary prostatic adenocarcinomas (Gleason scores 4–10) as compared to the corresponding normal tissues of the same prostate gland from 32 PC patients. The RT‐PCR and Western blot data have also indicated the higher expression levels of EGFR and ER‐β transcripts and proteins in metastatic LNCaP, DU145 and PC3 cells relative to nonmalignant normal prostate cells. Moreover, the results from MTT and FACS analyses revealed that the drugs, alone or in combination at lower concentrations, inhibited the growth of 17β‐estradiol (E2) plus EGF and serum‐stimulated androgen‐responsive LNCaP‐C33 and androgen‐independent LNCaP‐C81, DU145 and PC3 cells. Importantly, the combined gefitinib, tamoxifen and etoposide also caused a higher rate of apoptotic death of PC cells as compared to single agents. The cytotoxic effects induced by these drugs in PC3 cells appear to be mediated through the accumulation of cellular ceramide and activation of caspase cascades via a mitochondrial pathway. These findings indicate that the combined use of inhibitors of EGF‐EGFR and E2‐ER‐β signaling with etoposide, which act by increasing the cellular ceramide levels and caspase activity, represents a promising strategy for a more effective treatment of metastatic PC forms. © 2006 Wiley‐Liss, Inc.
Correlation between hypermethylation of the RASSF2A promoter and K‐ras/BRAF mutations in microsatellite‐stable colorectal cancers
Authors: Park Hye‐Won , Kang Hio Chung , Kim Il‐Jin , Jang Sang‐Geun , Kim Kun , Yoon Hyun‐Ju , Jeong Seung‐Yong , Park Jae‐Gahb
Published: September 2006

Recently, RASSF2A was identified as a potential tumor suppressor epigenetically inactivated in human cancers. Here, we evaluated the methylation status of RASSF2A in colorectal cancer (CRC) and analyzed its correlation with K‐ras/BRAF mutations, microsatellite instability status and other clinicopathological features. Using methylation‐specific PCR and bisulfite sequencing, we analyzed the methylation status in primary CRC, adenomas and corresponding normal tissues and then compared it with the presence of K‐ras and BRAF mutations. We also examined the expression and methylation status of RASSF2A in CRC cell lines. We found that aberrant methylation of RASSF2A promoter regions is associated with gene silencing in CRC cell lines. In primary CRC, the frequency of RASSF2A methylation was 72.6%, and it was found in 16 of 16 (100%) adenomas. In addition, there was a positive correlation between K‐ras/BRAF mutations and RASSF2A methylation in primary CRC. Furthermore, a significant positive correlation between K‐ras/BRAF mutations and RASSF2A methylation was also observed in microsatellite‐stable (p = 0.033) and distal CRC (p = 0.025). These results show that RASSF2A methylation is a frequent event in colorectal tumorigenesis and positively correlates with K‐ras/BRAF mutation in microsatellite‐stable or distal CRC. © 2006 Wiley‐Liss, Inc.
Hypoxia leads to necrotic hepatocyte death
Authors: Smith Molly K. , Mooney David J.
Published: September 2006

Hepatocyte transplantation is being investigated as a therapy for liver disease; however, its success has been limited by rapid death of the cells following transplantation. This study was dedicated to elucidating the mode of death responsible for loss of transplanted hepatocytes in order to guide future strategies for promoting their survival. Using a tissue engineering model, it was found that the environment within polymer scaffolds containing transplanted cells was hypoxic after 5 daysin vivo, with (90 ± 3)% of hepatocytes existing at pO2< 10 mmHg. The primary mode of hepatocyte death in response to hypoxic conditions of 0 or 2 vol % oxygen was then determinedin vitro. Several assays for features of apoptosis and necrosis demonstrated that hepatocytes cultured in an anoxic environment died via necrosis, while culture at 2% oxygen inhibited proliferation. These results suggest it will not be possible to prevent hepatocyte death by interfering with the apoptotic process, and hypoxic conditions in the transplants must instead be addressed. The finding that the environment within cell transplantation scaffolds is hypoxic is likely applicable to many cell‐based therapies, and a similar analysis of the primary mode of death for other cell types in response to hypoxia may be valuable in guiding future strategies for their transplantation. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Conjugation of extracellular matrix proteins to basal lamina analogs enhances keratinocyte attachment
Authors: Bush Katie A. , Downing Brett R. , Walsh Sarah E. , Pins George D.
Published: September 2006

The dermal–epidermal junction of skin contains extracellular matrix proteins that are involved in initiating and controlling keratinocyte signaling events such as attachment, proliferation, and terminal differentiation. To characterize the relationship between extracellular matrix proteins and keratinocyte attachment, a biomimetic design approach was used to precisely tailor the surface of basal lamina analogs with biochemistries that emulate the native biochemical composition found at the dermal–epidermal junction. A high‐throughput screening device was developed by our laboratory that allows for the simultaneous investigation of the conjugation of individual extracellular matrix proteins (e.g. collagen type I, collagen type IV, laminin, or fibronectin) as well as their effect on keratinocyte attachment, on the surface of an implantable collagen membrane. Fluorescence microscopy coupled with quantitative digital image analyses indicated that the extracellular matrix proteins adsorbed to the collagen‐GAG membranes in a dose‐dependent manner. To determine the relationship between extracellular matrix protein signaling cues and keratinocyte attachment, cells were seeded on protein‐conjugated collagen‐GAG membranes and a tetrazolium‐based colorimetric assay was used to quantify viable keratinocyte attachment. Our results indicate that keratinocyte attachment was significantly enhanced on the surfaces of collagen membranes that were conjugated with fibronectin and type IV collagen. These findings define a set of design parameters that will enhance keratinocyte binding efficiency on the surface of collagen membranes and ultimately improve the rate of epithelialization for dermal equivalents. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
In vitro degradation of biodegradable blending materials based on poly(p‐dioxanone) and poly(vinyl alcohol)‐graft‐poly(p‐dioxanone) with high molecular weights
Authors: Chen Si‐Chong , Wang Xiu‐Li , Wang Yu‐Zhong , Yang Ke‐Ke , Zhou Zhi‐Xuan , Wu Gang
Published: September 2006

Amphiphilic biodegradable graft copolymer, poly(vinyl alcohol)‐graft‐poly(p‐dioxanone) (PVA‐g‐PPDO), was used to prepare a new biodegradable material by blending with poly(p‐dioxanone) (PPDO). The in vitro degradation properties of the copolymer and blends with different contents of PVA‐g‐PPDO were studied in phosphate buffer at 37°C. The degradation processes of the PVA‐g‐PPDO and its blends with the PPDO were monitored by weight loss, viscosimetry, water uptake, differential scanning calorimetry (DSC), and scanning electron microscopy. The results of inherent viscosity and weight loss reveal that the PVA‐g‐PPDO has a different in vitro degradation behavior from that of PPDO, and the introducing of copolymer into the blending system may enhance the degradability of PPDO when the contents of copolymer is higher than 5%. The change of the degree of crystallization (Dc) of copolymer and blends derived from the DSC also shows that the copolymer and blends have faster degradation rates than the neat PPDO during the testing period. A degradation mechanism of the blends was postulated based on the results of the weight retention, inherent viscosity measurement, and DSC. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Kitagawa‐Takahashi diagrams define the limiting conditions for cyclic fatigue failure in human dentin
Authors: Kruzic J.J. , Ritchie R.O.
Published: September 2006

As cyclic fatigue is considered to be a major cause of clinical tooth fractures, achieving a comprehensive understanding of the fatigue behavior of dentin is of importance. In this note, the fatigue behavior of human dentin is examined in the context of the Kitagawa‐Takahashi diagram to define the limiting conditions for fatigue failure. Specifically, this approach incorporates two limiting threshold criteria for fatigue: (i) a threshold stress for fatigue failure, specifically the smooth‐bar (unnotched) fatigue endurance strength, at small crack sizes and (ii) a threshold stress‐intensity range for fatigue‐crack growth at larger crack sizes. The approach provides a “bridge” between the traditional fatigue life and fracture mechanics based damage‐tolerant approaches to fatigue‐life estimation, and as such defines a “failure envelope” of applied stresses and flaw sizes where fatigue failure is likely in dentin This approach may also be applied to fatigue failure in human cortical bone (i.e. clinical “stress fractures”), which exhibits similar fatigue behavior characteristics, and in principle may aid clinicians in making quantitative evaluations of the risk of fractures in mineralized tissues. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Time‐dependent effects of fatty acids on skeletal muscle metabolism
Authors: Hirabara Sandro M. , Silveira Leornardo R. , Abdulkader Fernando , Carvalho Carla R.O. , Procopio Joaquim , Curi Rui
Published: September 2006

Increased plasma levels of free fatty acids (FFA) occur in states of insulin resistance such as type 2 diabetes mellitus, obesity, and metabolic syndrome. These high levels of plasma FFA seem to play an important role for the development of insulin resistance but the mechanisms involved are not known. We demonstrated that acute exposure to FFA (1 h) in rat incubated skeletal muscle leads to an increase in the insulin‐stimulated glycogen synthesis and glucose oxidation. In conditions of prolonged exposure to FFA, however, the insulin‐stimulated glucose uptake and metabolism is impaired in skeletal muscle. In this review, we discuss the differences between the effects of acute and prolonged exposure to FFA on skeletal muscle glucose metabolism and the possible mechanisms involved in the FFA‐induced insulin resistance. J. Cell. Physiol. 210: 7–15, 2007. © 2006 Wiley‐Liss, Inc.
AF6/s‐afadin is a dual residency protein and localizes to a novel subnuclear compartment
Authors: Buchert Michael , Poon Carole , King James A.J. , Baechi Thomas , D'Abaco Giovanna , Hollande Frédéric , Hovens Christopher M.
Published: September 2006

The AF6/afadin protein is a component of cell membranes at specialized sites of cell–cell contact. Two main splice variants exist, known as l‐ and s‐afadin, respectively. L‐afadin is widely expressed in cells of epithelial origin, whilst s‐afadin expression is restricted to the brain. Here we demonstrate that the short form of AF6/s‐afadin is a dual residency protein able to localize to the plasma membrane or nucleus whilst the long form of AF6, l‐afadin is unable to localize to the nucleus. AF6/s‐afadin clusters in a distinctive speckled pattern in the nucleus, but is unable to do so when cell cycle progression is inhibited at the G1/S or G2/M checkpoints. The formation of AF6/s‐afadin nuclear bodies is also sensitive to the transcriptional activity of the cell with inhibition of RNA polymerase activity abolishing AF6/s‐afadin nuclear clustering. AF6/s‐afadin nuclear bodies localize to a novel subnuclear compartment, failing to colocalize with other known nuclear bodies. Formation of the AF6/s‐afadin nuclear foci can be regulated by specific growth factor receptor mediated signaling events and by cytoplasmic tyrosine kinases, but does not correlate with tyrosine phosphorylation of AF6/s‐afadin. AF6/s‐afadin is a candidate for mediating control of cellular growth processes by regulated translocation to the nucleus. J. Cell. Physiol. 210: 212–223, 2007. © 2006 Wiley‐Liss, Inc.
Characterization of linear and cyclic polylactic acids and their solvolysis products by electrospray ionization mass spectrometry
Authors: Osaka Issey , Watanabe Mikio , Takama Masashi , Murakami Masahiro , Arakawa Ryuichi
Published: September 2006

Linear and cyclic polylactic acids (PLAs) were characterized using electrospray ionization mass spectrometry (ESI‐MS) as part of our ongoing investigation of the hydrolysis mechanism of biodegradable polymers. The condensation oligomers of linear polylactic acid (LPLA) were synthesized by thermal dehydration of L‐lactic acid. The trimer and tetramer base polymers of cyclic polylactic acid (CPLA) were obtained by cyclization reactions of lactic acid trimers and tetramers, respectively. In the ESI‐MS/MS measurement, LPLA yielded three types of product ion series, while CPLA yielded only one type, from which the repeated units of CPLA were removed. The MS/MS spectrum of the NH4+ adduct ion for both cyclic and linear PLA showed loss of one ammonia molecule. The postsource decay (PSD) spectrum of CPLA by matrix‐assisted laser desorption ionization (MALDI) mass spectrometry was similar to the ESI‐MS/MS spectrum, while that of LPLA was different. In addition, the degradation of cyclic and linear PLAs by solvolysis was investigated. Solvolysis with anhydrous MeOH was quite feasible, but did not readily occur in the presence of even a small amount of water in the MeOH solvent. Copyright © 2006 John Wiley & Sons, Ltd.
Proliferation of anterior cruciate ligament cells in vitro by photo‐immobilized epidermal growth factor
Authors: Woo Young Kyun , Kwon Soon Yong , Lee Hwa Sung , Park Yong Soon
Published: September 2006

The purpose of this study was to explore the early treatment potential of anterior cruciate ligament (ACL) injuries using artificial juxtacrine stimulation by photo‐immobilization of a growth factor. A photo‐reactive epidermal growth factor complex (EGF‐Az) was synthesized by conjugating EGF with N‐(4‐azidobenzoyloxy) succinimide followed by immobilization onto polystyrene culture plates using UV irradiation. ACL cells from human tissues (1 × 105cells, 100 µl/well) were cultured as follows: control, no EGF; 50 µl native EGF; 50 µl EGF‐Az immobilized; and 100 µl EGF‐Az immobilized. The ACL cells were cultured long‐term and evaluated for possible differences in their responses to EGF. An in vitro wound closure assay was developed to enable examination of cellular proliferation and migration. ACL cell proliferation was most evident in the photo‐immobilized EGF culture group and was seen to increase in proportion to the amount of added EGF. In the in vitro wound closure assay, the lesioned area at 72 h after culture initiation was indistinguishable in the photo‐immobilized cultures, but remained clearly visible in the controls. We conclude that photo‐immobilized EGF induced rapid proliferation of ACL fibroblast cells by artificial juxtacrine stimulation and speculate that similar EGF immobilization onto bioabsorbable material (e.g., polyglycolic acid or polylactic acid) might contribute to a new therapy for the treatment of ACL injuries. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:73–80, 2007
An analysis of intertaxa differences in sulfur concentration in angiosperms
Authors: Willey Neil , Wilkins Janine
Published: September 2006

Understanding the behavior of sulfur (S) in the soil‐plant system is important for crop production, for predicting the movement of the radioisotope 35S in the environment, and for investigating the role of S in plant metabolism of xenobiotics. A database of relative mean S concentrations in 121 species of flowering plants was constructed using a Residual Maximum Likelihood (REML) procedure with new experimental data for 76 species and literature data for 57 species, there being 12 species in common. The relative mean S concentrations in plant species were normally distributed and their range greater than previously reported for S concentrations between plant species. There was a significant phylogenetic effect on S concentrations when they were analyzed using a nested ANOVA coded with a recent phylogeny of flowering plants. About 36% of the variance between species was associated with the rank of Order and above. At the rank of Order, S concentrations were Brassicales > Malphigiales > Lamiales > Rosales > Caryophyllales > Malvales > Poales > Fabales > Fagales > Asterales. Experiments to quantify intervarietal differences within Beta vulgaris, Triticum aestivum, and Cicer arietinum revealed that these reached a maximum in B. vulgaris at about 20% of those found at the species level and above. A comparison of relative mean S concentrations with previously reported relative mean concentrations for heavy metals suggested correlations between S and cadmium (Cd), and S and zinc (Zn). The frequency distributions and phylogenetic effects reported here are useful to understanding soil‐plant transfer of stable and radioactive S isotopes in agricultural and natural ecosystems and might aid investigations of plant response to xenobiotics.
Bodengefüge gegen Verdichtungen schützen – Lösungsansätze für den Schutz landwirtschaftlich genutzter Böden
Authors: Lebert Matthias , Brunotte Joachim , Sommer Claus , Böken Holger
Published: September 2006

Für den nachhaltigen Schutz des Bodens und seiner Funktionen fordert das deutsche Bundes‐Bodenschutzgesetz eine wirksame Vorsorge bei der Bodennutzung und – sofern die Gefahr des Eintretens einer schädlichen Bodenveränderung besteht – Maßnahmen zur Gefahrenabwehr. Die Ergebnisse eines Forschungsprojektes des Umweltbundesamtes haben gezeigt, dass ein Bodengefügeschaden durch Verdichtung anhand bodenkundlicher Kriterien ermittelt werden kann. Die so angezeigte Beeinträchtigung von Bodenfunktionen reicht zum Nachweis einer schädlichen Bodenveränderung im Sinne des Gesetzes jedoch alleine nicht aus, da die Erheblichkeit der Beeinträchtigungen und der Bezug zu Schutzgütern nicht hinreichend geklärt sind. Hierzu wäre eine weitere Sachverhaltsermittlung vor Ort notwendig.

Fachansätze aus der Landtechnik und der Bodenphysik schlagen Vorgehensweisen für den Schutz des Bodengefüges gegen Verdichtungen vor, die sich an den Grundsätzen der Vorsorge orientieren. Die einzelnen Ansätze haben unterschiedliche Zielsetzungen und Einsatzbereiche und stellen deshalb jeweils Lösungen für Teilbereiche des Verdichtungsschutzes dar. Das landtechnische Bewertungskonzept der „Befahrbarkeit anhand der Spurtiefe”︁ gibt Aufschluss über die Verdichtung des Gesamtbodens unter Praxisbedingungen, ohne eine Differenzierung zwischen den betroffenen Bodenschichten. Das bodenphysikalische Konzept „Schadverdichtungsgefährdungsklassen”︁ ist auf eine Beurteilung der Krumenverdichtung nach Ertragsgesichtspunkten ausgerichtet. Die bodenphysikalischen Konzepte „Vorbelastung”︁ und „Belastungsquotient”︁ liefern für den Risikofeuchtebereich der Feldkapazität Prognosen für die Unterbodenverdichtung und die Veränderung von Bodenfunktionen in Krume und Unterboden.

Für eine abschließende Bewertung der Prognosen der einzelnen Fachansätze ist eine weitere Validierung anhand zusätzlicher regionalisierter Daten zum Bodengefüge nötig. Für eine bundesweite Beurteilung der Gefahr von Gefügeschäden durch Bodenverdichtungen liegen gegenwärtig noch nicht genügend Erfahrungen in der Anwendung vor.