bluuebunny/crossref_metadata_2025 huggingface dataset:
Early fetal growth, PAPP‐A and free β‐hCG in relation to risk of delivering a small‐for‐gestational age infant
Authors: Kirkegaard I. , Henriksen T. B. , Uldbjerg N.
Published: August 2010

Objectives

To examine early fetal growth, pregnancy‐associated plasma protein‐A (PAPP‐A) and free β‐human chorionic gonadotropin (β‐hCG) in relation to the risk of delivering a small‐for‐gestational age (SGA) infant.

Methods

Included in the study were 9450 singleton pregnant women who attended the prenatal screening program at Aarhus University Hospital, Denmark, between January 2005 and December 2007. Maternal serum levels of PAPP‐A and free β‐hCG were measured between gestational weeks 8 and 13. Two ultrasound examinations were performed, the first at 11–13 weeks and the second at 18–22 weeks, from which gestational age was estimated based on crown–rump length and biparietal diameter, respectively. Early fetal growth was expressed as an index: the ratio between the estimated number of days from the first to the second scan and the actual calendar time elapsed in days. SGA was defined as birth weight < 5th centile for gestational age, and the risk of SGA was evaluated according to different cut‐offs of the early fetal growth index and the serum markers.

Results

PAPP‐A < 0.4 MoM combined with an early fetal growth index < 10th centile resulted in an increased risk of SGA (odds ratio (OR), 5.8; 95% CI, 2.7–12.7). Low PAPP‐A, low free β‐hCG and slow early fetal growth were statistically, independently associated with SGA, and the association between free β‐hCG < 0.3 MoM and SGA was as strong as that between PAPP‐A < 0.3 MoM and SGA (OR, 3.1 and 3.0, respectively).

Conclusion

The combination of slow early fetal growth and low PAPP‐A resulted in a nearly six‐fold increased risk of delivery of an SGA infant. These findings might improve our chances of early identification of fetuses at increased risk of growth restriction. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Using adaptation tipping points to prepare for climate change and sea level rise: a case study in the Netherlands
Authors: Kwadijk Jaap C. J. , Haasnoot Marjolijn , Mulder Jan P. M. , Hoogvliet Marco M. C. , Jeuken Ad B. M. , van der Krogt Rob A. A. , van Oostrom Niels G. C. , Schelfhout Harry A. , van Velzen Emiel H. , van Waveren Harold , de Wit Marcel J. M.
Published: August 2010

Studies on the impact of climate change and sea level rise usually take climate scenarios as their starting point. To support long‐term water management planning in the Netherlands, we carried out a study that started at the opposite end of the effect chain. In the study we refer to three aspects of water management, flood defense, drinking water supply, and protection of the Rotterdam Harbour. We examined whether, and for how long, current water management strategies will continue to be effective under different climate change scenarios. We did this by applying the concept of ‘adaptation tipping points’, and reached it if the magnitude of change is such that the current management strategy can no longer meet its objectives. Beyond the tipping points, an alternative adaptive strategy is needed. By applying this approach, the following basic questions of decision makers are answered:whatare the first issues that we will face as a result of climate change andwhencan we expect this. The results show, for instance, that climate change and the rise in sea level are more likely to cause a threat to the fresh water supply in the west of the Netherlands than flooding. Expressing uncertainty in terms of the period that the existing strategy is effective (when will a critical point be reached) was found to be useful for the policy makers. © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

Vulnerability and Adaptation to Climate Change > Learning from Cases and Analogies
Climate projections and their impact on policy and practice
Authors: Lemos Maria Carmen , Rood Richard B.
Published: August 2010

This article examines the relationship between projections of climate change and the responses to those projections. First, it discusses uncertainty and its role in shaping not only the production of climate projections but also the use of these projections by decision makers. We find that uncertainty critically affects the way climate projections move from useful to usable, where usefulness is defined by scientists' perception of users' needs, and usability is defined by users' perception of what knowledge can be readily applied to their decision. From the point of view of the natural scientist, we pose that there is an uncertainty fallacy, that is, a belief that the systematic reduction of uncertainty in climate projections is required in order for the projections to be used by decision makers. Second, we explore the implications of climate projections for policy and decision making, using examples from the seasonal climate forecast applications literature as an analog. We examine constraints and opportunities for their application in policy and practice and find that over‐reliance on science and technical solutions might crowd out the moral imperative to do what is needed to improve livelihoods and to guarantee ecosystems' long‐term sustainability. We conclude that, in the context of high uncertainty, decision makers should not look for ‘perfect’ forecasts, but seek to implement knowledge systems that integrate climate projections with other kinds of knowledge and that consider the multiple stressors that shape their decision environment. Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

Social Status of Climate Change Knowledge > Climate Science and Decision Making

Social Status of Climate Change Knowledge > Knowledge and Practice
DCLRRA: Distributed cross‐layer routing and resource allocation techniques for OFDMA‐based broadband wireless networks
Authors: Hayajneh Mohammad , Gadallah Yasser
Published: August 2010

In this study, we develop a fully distributed routing protocol for OFDMA‐based multihop broadband wireless access (BWA) networks such as those of IEEE 802.16j. We refer to this protocol as the DCLRRA protocol. DCLRRA is based on autonomous resource allocation schemes that we also derive in this paper. The routing protocol's selection of the proper resource allocation scheme is based on whether the relay stations (RSs) are nomadic or stationary. While we develop the autonomous resource allocation schemes, we exploit the multi‐user capabilities of the OFDMA physical layer. This allows simultaneous data transmission sessions within the same neighborhood while offering a total elimination of interference between transmitting nodes. The direct result of this strategy is increased throughput with high utilization of the communication channel. We examine our routing technique to show its performance merits through extensive simulations. Copyright © 2010 John Wiley & Sons, Ltd.
Dynamic region‐based mobile multicast
Authors: Wang Shengling , Cui Yong , Das Sajal K. , Wu Jianping
Published: August 2010

Traditional mobile multicast schemes have higher multicast tree reconfiguration cost or multicast packet delivery cost. Two costs are very critical because the former affects the service disruption time during handoff while the latter affects the packet delivery delay. Although the range‐based mobile multicast (RBMoM) scheme and its similar schemes offer the trade‐off between two costs to some extent, most of them do not determine the size of service region, which is critical to the network performance. Hence, we propose a dynamic region‐based mobile multicast (DRBMoM) to dynamically determine the optimal service region for reducing the multicast tree reconfiguration and multicast packet delivery costs. DRBMoM provides two versions: (i) the per‐user version, named DRBMoM‐U, and (ii) the aggregate‐users version, named DRBMoM‐A. Two versions have different applicability, which are the complementary technologies for pursuing efficient mobile multicast. Though having different data information and operations, two versions have the same method for finding the optimal service region. To that aim, DRBMoM models the users' mobility with arbitrary movement directional probabilities in 2‐D mesh network using Markov Chain, and predicts the behaviors of foreign agents' (FAs') joining in a multicast group. DRBMoM derives a cost function to formulate the average multicast tree reconfiguration cost and the average multicast packet delivery cost, which is a function of service region. DRBMoM finds the optimal service region that can minimize the cost function. The simulation tests some key parameters of DRBMoM. In addition, the simulation and numerical analyses show the cost in DRBMoM is about 22∼50% of that in RBMoM. At last, the applicability and computational complexity of DRBMoM and its similar scheme are analyzed. Copyright © 2010 John Wiley & Sons, Ltd.
Bounds on Delaunay tessellations
Authors: Shores Roger W. , Wegman Edward J.
Published: August 2010

Motivated by applications in density estimation and data compression, this article considers the bounds on the number of tiles in a Delaunay tessellation as a function of both the number of tessellating points and the dimension. Results can also be interpreted for the dual of the Delaunay tessellation, the Voronoi diagram. Several theoretical lower and upper bounds are found in the combinatorics and computational geometry literatures and are brought together in this article. We make a comparison of these bounds with several empirically derived curves based on multivariate uniform and Gaussian generated random tessellating points. The upper bounds are found to be very conservative when compared with the empirically derived number of tiles, often off by many orders of magnitude. Copyright © 2010 John Wiley & Sons, Inc.

This article is categorized under:

Applications of Computational Statistics > Computational Mathematics
Natural homogeneous coordinates
Authors: Wegman Edward J. , Said Yasmin H.
Published: August 2010

The natural homogeneous coordinate system is the analog of the Cartesian coordinate system for projective geometry. Roughly speaking a projective geometry adds an axiom that parallel lines meet at a point at infinity. This removes the impediment to line‐point duality that is found in traditional Euclidean geometry. The natural homogeneous coordinate system is surprisingly useful in a number of applications including computer graphics and statistical data visualization. In this article, we describe the axioms of projective geometry, introduce the formalism of natural homogeneous coordinates, and illustrate their use with four applications. WIREs Comp Stat 2010 2 678–685 DOI: 10.1002/wics.122

This article is categorized under:

Applications of Computational Statistics > Computational Mathematics
Challenges in assessing nanomaterial toxicology: a personal perspective
Authors: Geraci Charles L. , Castranova Vincent
Published: August 2010

Nanotechnology exploits the fact that nanoparticles exhibit unique physicochemical properties, which are distinct from fine‐sized particles of the same composition. It follows that nanoparticles may also express distinct bioactivity and unique interactions with biological systems. Therefore, it is essential to assess the potential health risks of exposure to nanoparticles to allow development and implementation of prevention measures. Risk assessment requires data concerning hazard and exposure. Several challenges face the field of nanotoxicology in obtaining the necessary data for assessment of the bioactivity of nanoparticles. They include: (1) the vast number of nanoparticle types to be evaluated, (2) the need to use nanoparticle doses and structure sizes in cellular and animal test systems which are relevant to anticipated workplace exposures, and (3) artifactual in vitro results due to absorption of nutrients or assay indicator compounds from the culture media. This ‘opinion’ reviews the progress made in the field of nanotoxicology in recent years to overcome these challenges. WIREs Nanomed Nanobiotechnol 2010 2 569–577

This article is categorized under:

Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials
A central role for RNA in the induction and biological activities of type 1 interferons
Authors: Li Xiao‐Ling , Ezelle Heather J. , Hsi Teresa Y. , Hassel Bret A.
Published: August 2010

In mammals the type 1 interferon (IFN) system functions as the primary innate antiviral defense and more broadly as a stress response and regulator of diverse homeostatic mechanisms. RNA plays a central role in the induction of IFN and in its biologic activities. Cellular toll‐like receptors (TLR), RIG‐I‐like receptors (RLR), and nucleotide organization domain‐like receptors (NLR) sense pathogen‐ and danger‐associated RNAs as nonself based on structural features and subcellular location that distinguish them from ubiquitous host RNAs. Detection of nonself RNAs activates signaling pathways to induce IFN transcription and secretion. In turn, IFN binds cell surface receptors to initiate signaling that results in the induction of IFN‐stimulated genes (ISGs) that mediate its biologic activities. RNA also plays a critical role in this effector phase of the IFN system, serving as an activator of enzyme activity for protein kinase RNA‐dependent (PKR) and oligoadenylate synthetase (OAS), and as a substrate for 2′, 5′‐linked oligoadenylate dependant‐endoribonuclease (RNase‐L). In contrast to the transcriptional response induced by RNA receptors, these key ISGs mediate their activities primarily through post transcriptional mechanisms to regulate the translation and stability of host and microbial RNAs. Together RNA‐sensing and RNA‐effector molecules comprise a network of coordinately regulated proteins with integrated feedback and feed‐forward loops that tightly regulate the cellular response to RNA. This stringent regulation is essential to prevent deleterious effects of uncontrolled IFN expression and effector activation. In light of this extensive crosstalk, targeting key mediators of the cellular response to RNA represents a viable strategy for therapeutic modulation of immune function and treatment of diseases in which this response is dysregulated (e.g., cancer). WIREs RNA 2011 2 58–78 DOI: 10.1002/wrna.32

This article is categorized under:

RNA Interactions with Proteins and Other Molecules > Protein–RNA Recognition

RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications

RNA Turnover and Surveillance > Regulation of RNA Stability

RNA in Disease and Development > RNA in Disease
In silico models of bone remodeling from macro to nano—from organ to cell
Authors: Webster Duncan , Müller Ralph
Published: August 2010

Computational modeling is a tool through which researchers can achieve a greater understanding of the mechanisms governing biological systems. In the field of bone biology, a plethora of models exist which attempt to replicate and investigate bone's dynamic behavior at different scales. At organ level, models are continuum based and describe the variation of bone's apparent density as a function of both biological and external mechanical stimuli. At tissue level, models include bone microarchitecture and more descriptive parameters such as trabecular thickness, osteoclast resorption depth, and activation frequency. Finally, at cell level, models employ partial differential equations to describe complex cellular interactions in the temporal domain. Although informative, these models exist in isolation. Consequently, their interpretation is limited. In this review, we present an overview of the organ‐, tissue‐, and cell‐level models and assess their ability to reflect bone's metabolic processes reliably. Existing interscale synergies are then presented along with a computational framework which could be exploited to achieve a fully integrated, multiscale modeling approach. WIREs Syst Biol Med 2011 3 241–251 DOI: 10.1002/wsbm.115

This article is categorized under:

Analytical and Computational Methods > Computational Methods

Models of Systems Properties and Processes > Organ, Tissue, and Physiological Models
Improving the performance of industrial ethanol‐producing yeast by expressing the aspartyl protease on the cell surface
Authors: Guo Zhong‐peng , Zhang Liang , Ding Zhong‐yang , Wang Zheng‐Xiang , Shi Gui‐Yang
Published: August 2010

The yeasts used in fuel ethanol manufacture are unable to metabolize soluble proteins. The PEP4 gene, encoding a vacuolar aspartyl protease in Saccharomyces cerevisiae, was either secretively or cell‐surface anchored expressed in industrial ethanol‐producing S. cerevisiae. The obtained recombinant strains APA (expressing the protease secretively) and APB (expressing the protease on the cell wall) were studied under ethanol fermentation conditions in feed barley cultures. The effects of expression of the protease on product formation, growth and cell protein content were measured. The biomass yield of the wild‐type was clearly lower than that of the recombinant strains (0.578 ± 0.12 g biomass/g glucose for APA and 0.582 ± 0.08 g biomass/g glucose for APB). In addition, nearly 98–99% of the theoretical maximum level of ethanol yield was achieved (relative to the amount of substrate consumed) for the recombinant strains, while limiting the nitrogen source resulted in dissatisfactory fermentation for the wild‐type and more than 30 g/l residual sugar was detected at the end of fermentation. In addition, higher growth rate, viability and lower yields of byproducts such as glycerol and pyruvic acid for recombinant strains were observed. Expressing acid protease can be expected to lead to a significant increase in ethanol productivity. Copyright © 2010 John Wiley & Sons, Ltd.
Transformation of Candida albicans with a synthetic hygromycin B resistance gene
Authors: Basso Luiz R. , Bartiss Ann , Mao Yuxin , Gast Charles E. , Coelho Paulo S. R. , Snyder Michael , Wong Brian
Published: August 2010

Synthetic genes that confer resistance to the antibiotic nourseothricin in the pathogenic fungus Candida albicans are available, but genes conferring resistance to other antibiotics are not. We found that multiple C. albicans strains were inhibited by hygromycin B, so we designed a 1026 bp gene (CaHygB) that encodes Escherichia coli hygromycin B phosphotransferase with C. albicans codons. CaHygB conferred hygromycin B resistance in C. albicans transformed with ars2‐containing plasmids or single‐copy integrating vectors. Since CaHygB did not confer nourseothricin resistance and since the nourseothricin resistance marker SAT‐1 did not confer hygromycin B resistance, we reasoned that these two markers could be used for homologous gene disruptions in wild‐type C. albicans. We used PCR to fuse CaHygB or SAT‐1 to approximately 1 kb of 5′ and 3′ noncoding DNA from C. albicans ARG4, HIS1 and LEU2, and introduced the resulting amplicons into six wild‐type C. albicans strains. Homologous targeting frequencies were approximately 50–70%, and disruption of ARG4, HIS1 and LEU2 alleles was verified by the respective transformants' inabilities to grow without arginine, histidine and leucine. CaHygB should be a useful tool for genetic manipulation of different C. albicans strains, including clinical isolates. Copyright © 2010 John Wiley & Sons, Ltd.
Hairpin dsRNA does not trigger RNA interference in Candida albicans cells
Authors: Staab Janet F. , White Theodore C. , Marr Kieren A.
Published: August 2010

RNA interference/silencing mechanisms triggered by double‐stranded RNA (dsRNA) have been described in many eukaryotes, including fungi. These mechanisms have in common small RNA molecules (siRNAs or microRNAs) originating from dsRNAs that, together with the effector protein Argonaute, mediate silencing. The genome of the fungal pathogen Candida albicans harbours a well‐conserved Argonaute and a non‐canonical Dicer, essential members of silencing pathways. Prototypical siRNAs are detected as members of the C. albicans transcriptome, which is potential evidence of RNA interference/silencing pathways in this organism. Surprisingly, expression of a dsRNA a hairpin ADE2 dsRNA molecule to interfere with the endogenous ADE2 mRNA did not result in down‐regulation of the message or produce adenine auxotrophic strains. Cell free assays showed that the hairpin dsRNA was a substrate for the putative C. albicans Dicer, discounting the possibility that the nature of the dsRNA trigger affects silencing functionality. Our results suggested that unknown cellular events govern the functionality of siRNAs originating from transgenes in RNA interference/silencing pathways in C. albicans. Copyright © 2010 John Wiley & Sons, Ltd.
Novel episomal vectors and a highly efficient transformation procedure for the fission yeast Schizosaccharomyces japonicus
Authors: Aoki Keita , Nakajima Reiko , Furuya Kanji , Niki Hironori
Published: August 2010

Schizosaccharomyces japonicus is a fission yeast for which new genetic tools have recently been developed. Here, we report novel plasmid vectors with high transformation efficiency and an electroporation method for Sz. japonicus. We isolated 44 replicating segments from 12 166 transformants of Sz. japonicus genomic fragments and found a chromosomal fragment, RS1, as a new replicating sequence that conferred high transformation activity to Sz. japonicus cells. This sequence was cloned into a pUC19 vector with ura4+ of Sz. pombe (pSJU11) or the kan gene on the kanMX6 module (pSJK11) as selection markers. These plasmids transformed Sz. japonicus cells in the early‐log phase by electroporation at a frequency of 123 cfu/µg for pSJK11 and 301 cfu/µg for pSJU11, which were higher than previously reported autonomously replicating sequences. Although a portion of plasmids remained in host cells by integration into the chromosome via RS1 segment, the plasmids could be recovered from transformants. The plasmid copy number was estimated to be 1.88 copies per cell by Southern blot analysis using a Sz. pombe ura4+ probe. The plasmid containing ade6+ suppressed the auxotrophic growth of the ade6‐domE mutant, indicating that the plasmid would be useful for suppressor screening and complementation assays in Sz. japonicus. Furthermore, pSJU11 transformed Sz. pombe cells with the same frequency as the pREP2 plasmid. This study is a report to demonstrate practical use of episomal plasmid vectors for genetic research in Sz. japonicus. RS1 has been submitted to the DDBJ/EMBL/GenBank database (Accession No. AB547343). Copyright © 2010 John Wiley & Sons, Ltd.
Slt2 MAPK pathway is essential for cell integrity in the presence of arsenate
Authors: Matia‐González Ana M. , Rodríguez‐Gabriel Miguel A.
Published: August 2010

Arsenate is a common toxic metalloid found in drinking water worldwide that causes several human diseases. The biochemical action underlying cellular response to arsenate, however, is not yet completely understood. Here we used Saccharomyces cerevisiae as an eukaryotic model system to identify proteins essential for adaptation to arsenate treatment. Previous studies have demonstrated a function for Hog1 MAPK in modulating the cellular response to arsenite. Our results, however, showed that cells deficient in Hog1 did not show increased sensitivity to arsenate, suggesting that perhaps other MAPKs may be involved in the response to this particular arsenic species. Here, we found that Slt2 MAPK and several of its upstream regulators are essential in modulating the response to arsenate, and that Slt2 is phosphorylated after arsenate treatment. Furthermore, whole‐genome transcriptional analysis showed that Slt2 is required for the induction of several genes in response to arsenate exposure. Many of these genes are involved in the cellular response to heat, suggesting an overlap between these two stress response pathways, and pointing toward a common response to both arsenate and heat exposure in Saccharomyces cerevisiae. Furthermore, our results support the idea that cellular exposure to arsenate results in induction of cellular signalling pathways different from those induced under arsenite treatment. Copyright © 2010 John Wiley & Sons, Ltd.
Requirement of glutathione for Sod1 activation during lifespan extension
Authors: Mannarino Sérgio C. , Vilela Leonardo F. , Brasil Aline A. , Aranha Juliana N. , Moradas‐Ferreira Pedro , Pereira Marcos D. , Costa Vítor , Eleutherio Elis C. A.
Published: August 2010

It has been shown that the activation of cytosolic superoxide dismutase (Sod1) in Saccharomyces cerevisiae is only dependent on Ccs1, which is responsible for insertion of copper into the enzyme catalytic center, and that glutathione (GSH) is not necessary for this process. In this work, we addressed an important role of GSH in Sod1 activation by a Ccs1‐dependent mechanism during oxidative stress and its role in yeast lifespan. Exponential cells of Saccharomyces cerevisiae, treated or not with 0.5 mM menadione for 1 h, were used for evaluation of the effect of a mild oxidative stress pre‐treatment on chronological lifespan. The results showed that menadione induced a lifespan extension in the wild‐type (WT) strain but this adaptive response was repressed in gsh1 and in sod1 strains. Interestingly, menadione treatment increased SOD1 and CCS1 gene expression in both WT and gsh1 strains. However, while these strains showed the same Sod1 activity before treatment, only the WT presented an increase of Sod1 activity after menadione exposure. Glutathionylation seems to be essential for Sod1 activation since no increase in activity was observed after menadione treatment in grx1 and grx2 null mutants. Our results suggest that GSH and glutathionylation are fundamental to protect Sod1 sulfhydryl residues under mild oxidative stress, enabling Sod1 activation and lifespan extension. Copyright © 2010 John Wiley & Sons, Ltd.
2,4‐Dimethylpentadienyl‐Komplexe des Neodyms, Lanthans und Yttriums als Präkatalysatoren für die stereoselektive Butadienpolymerisation
Authors: Kunze Michael R. , Taube Rudolf
Published: August 2010

To extend the investigation of the applicability of 2,4‐dimethylpentadienyl rare earth metal complexes as precatalysts for stereoselective butadiene polymerization, a selection of new neodymium, lanthanum, and yttrium complexes were previously supplied with detailed structural characterization. We report herein our observations on the catalytically nature of 2,4‐dimethylpentadienyl rare earth metal complexes. Under standard conditions the complexes are catalytically inactive. In order to successfully activate the coordinatively saturated complexes, aluminium trialkyls AlMe3, AlEt3, and Al(iBu)3, aluminoxanes methylaluminoxane (MAO), hexaisobuthylaluminoxane (HiBAO), and modified methylaluminoxane with an Al(iBu)3 additive (MMAO) and diethylaluminium bromide were employed as cocatalysts. The actual catalyst is believed to be a soluble mono(2,4‐dimethylpentadienyl)neodymium(III) dianion complex, through which an insertion of 1,3‐butadiene in the pentadienyl‐neodymium(III) bond causes the catalysis of the chain growth to be initiated. From these investigations a substantial further insight into the chemistry of (2,4‐dimethylpentadienyl)lanthanide(III) complexes was gained and the special applicability of the neodymium complexes for the preparation of highly active catalyst for the 1,4‐cis‐polymerization of 1,3‐butadienes was demonstrated.
Synthesis, Crystal Structures, and Thermal Properties of New Zinc(II) Thiocyanato Coordination Compounds
Authors: Bhosekar Gaurav , Boeckmann Jan , Jeß Inke , Näther Christian
Published: August 2010

Reaction of zinc(II) thiocyanate with pyrazine, pyrimidine, pyridazine, and pyridine leads to the formation of new zinc(II) thiocyanato coordination compounds. In bis(isothiocyanato‐N)‐bis(μ2‐pyrazine‐N,N) zinc(II) (1) and bis(isothiocyanato‐N)‐bis(μ2‐pyrimidine‐N,N) zinc(II) (2) the zinc atoms are coordinated by four nitrogen atoms of the diazine ligands and two nitrogen atoms of the isothiocyanato anions within slightly distorted octahedra. The zinc atoms are connected by the diazine ligands into layers, which are further linked by weak intermolecular S···S interactions in 1 and by weak intermolecular C–H···S hydrogen bonding in 2. In bis(isothiocyanato‐N)‐bis(pyridazine‐N) (3) discrete complexes are found, in which the zinc atoms are coordinated by two nitrogen atoms of the isothiocyanato ligands and two nitrogen atoms of the pyridazine ligands. The crystal structure of bis(isothiocyanato‐N)‐tetrakis(pyridine‐N) (4) is known and consists of discrete complexes, in which the zinc atoms are octahedrally coordinated by two thiocyanato anions and four pyridine molecules. Investigations using simultaneous differential thermoanalysis and thermogravimetry, X‐ray powder diffraction and IR spectroscopy prove that on heating, the ligand‐rich compounds 1, 2, and 3 decompose without the formation of ligand‐deficient intermediate phases. In contrast, compound 4 looses the pyridine ligands in two different steps, leading to the formation of the literature known ligand‐deficient compound bis(isothiocyanato‐N)‐bis(pyridine‐N) (5) as an intermediate. The crystal structure of compound 5 consists of tetrahedrally coordinated zinc atoms which are surrounded by two isothiocyanato anions and two pyridine ligands. The structures and the thermal reactivity are discussed and compared with this of related transition metal isothiocyanates with pyrazine, pyrimidine, pyridazine, and pyridine.
Methane Storage in Prussian Blue Analogues and Related Porous Solids: Nature of the Involved Adsorption Forces
Authors: Zamora Blanca , Roque Jorge , Balmaseda Jorge , Reguera Edilso
Published: August 2010

Methane adsorption is possible through three types of interactions: (1) dispersive forces (van der Waals type); (2) polarization of its electron cloud by a positive charge center; (3) induced quadrupole moment by perturbation of the molecule electron cloud through the polarization interaction. This induced quadrupole moment is able to interact with the local electric field gradient. Porous Prussian blue analogues and related zeolite‐like zinc hexacyanometallates appear to have unique features for the evaluation of the relative importance of these adsorption forces for the methane storage in molecular porous materials. Methane adsorption isotherms for T3[Co(CN)6]2 (T = Mn, Co, Ni, Cu, Zn, Cd) and Zn3A2[Fe(CN)6]2 (A = Na, K, Rb, Cs) were recorded and interpreted. From the obtained adsorption data information on the relative contribution of both electrostatic and dispersive interactions to the adsorption forces was obtained.
Supramolecular Architectures of Four New Transition Metal Complexes with 3‐[4‐(Carboxymethoxy)phenyl]propanoic Acid and N‐[4‐(Carboxymethoxy)phenyl]iminodiacetic Acid
Authors: Liu Chong‐Bo , Wen Hui‐Liang , Gong Yun‐Nan , Liu Xiao‐Ming , Tan Sheng‐Shui
Published: August 2010

Four new transition metal complexes: [Cu(Hcppa)2(H2O)2] (1), [Co2(cppa)2(H2O)10] (2), [Co3(cpia)2(H2O)8]·2H2O (3) and [Ni3(cpia)2(H2O)12]·6H2O (4) {H2cppa = 3‐(4‐(carboxymethoxy)phenyl]propanoic acid; H3cpia = N‐[4‐(carboxymethoxy)phenyl]iminodiacetic acid} were synthesized and characterized. Complexes 1 and 2 show mononuclear structures, complexes 3 and 4 exhibit dinuclear structures. All complexes extend to 3D supramolecular networks through hydrogen bonds, of which complexes 3 and 4 display microporous structures. In complexes 2–4 the water clusters are trapped by the cooperative association of coordinate interactions as well as hydrogen bonds, forming different 1D metal‐water chain structures. Thermal stabilities of complexes 1–4 were discussed.
Stannocene as Cyclopentadienyl Transfer Agent in Transmetalation Reactions with Lanthanide Metals for the Synthesis of Tris(cyclopentadienyl)lanthanides
Authors: Janiak Christoph
Published: August 2010

Transmetalation of the lanthanide metals samarium and ytterbium with bis(cyclopentadienyl)tin(II), stannocene, (η5‐C5H5)2Sn as cyclopentadienyl transfer agent yields the tris(cyclopentadienyl)lanthanides (η5‐C5H5)3Ln (in toluene), (η5‐C5H5)3Ln·THF (Ln = Sm, Yb) and bis(cyclopentadienyl)ytterbium, (η5‐C5H5)2Yb·THF in a direct, facile, high‐yield and halide‐free route. In toluene the base‐free forms (η5‐C5H5)3Ln are isolated directly. In THF the adducts (η5‐C5H5)3Ln·THF are obtained in crystalline form. At a 1:1 molar ratio of Yb:Sn the ytterbium metal reduces the initially formed (η5‐C5H5)3Yb·THF to (η5‐C5H5)2Yb·THF.
Manganese‐σ‐Borane Complexes from Dihaloboranes
Authors: Braunschweig Holger , Kraft Katharina , Kupfer Thomas , Siedler Eva
Published: August 2010

The hydride complex K[(η5‐C5H5)Mn(CO)2H] reacted with a range of dihalo(organyl)boranes X2BR (X = Cl, Br; R = tBu,Mes, Ferrocenyl) to give the corresponding borane complexes[(η5‐C5H5)Mn(CO)2(HB(X)R)]., The presence of a hydride in bridging position between manganese and boron was deduced from 11B decoupled 1H NMR spectra. Additionally, the structure of the tert‐butyl borane complex was confirmed by single‐crystal X‐ray diffraction.
Solvothermal Synthesis of New Luminescent Zinc(II) Coordination Polymers with One‐Dimensional Homochiral Structures
Authors: Duan Yulai , Lin Zhien , Stips Tobias , Dehnen Stefanie
Published: August 2010

By using a dual‐ligand approach, two new homochiral zinc(II) coordination polymers, Zn2(phen)2(H2O)2(cam)2·ethanol (1) and Zn(bipy)(cam) (2) [phen = 1,10‐phenanthroline, bipy = 2,2′‐bipyridine, H2cam = (1R,3S)‐(+)‐camphoric acid] have been synthesized under solvothermal conditions. Compound 1 has a zigzag chain‐like structure and compound 2 has a linear chain‐like structure. The two compounds exhibit intense photoluminescence upon photoexcitation at 280 and 290 nm, respectively.
Effect of the Length of Fatty Acid Ligands on Lead(II) Complexes Based on a 1,10‐Phenanthroline Derivative
Authors: Wang Xiu‐Li , Gao Qiang , Chen Yong‐Qiang , Liu Guo‐Cheng , Tian Ai‐Xiang , Kang Zhen‐Hui
Published: August 2010

Two new PbII metal‐organic coordination polymers [Pb(3‐pdip)(glu)]·H2O (1) and [Pb(3‐pdip)2(odc)]·2H2O (2) [3‐pdip = 2‐(3‐pyridine)imidazo[4,5‐f]1,10‐ phenanthroline, H2glu = glutaric acid, H2odc = octanedioic acid], were synthesized by hydrothermal reactions of varying fatty acid ligands, and structurally characterized by single‐crystal X‐ray diffraction. Complex 1 exhibits a one dimensional (1D) chain structure, in which 3‐pdip ligands are attached to one side of the 1D chain. Complex 2 exhibits also a 1D chain structure, in which some paired 3‐pdip ligands are affiliated on both sides of the 1D chain. In the title complexes, the π–π stacking and hydrogen‐bonding interactions extend the 1D chain into a 3D supramolecular framework, respectively. The structural differences between the title complexes indicate the importance of fatty acid length for the creation of molecular architectures. Moreover, the thermal and fluorescence properties of title complexes are also reported.
Progress in the Compilation of an Oxovanada‐Silsesquioxane Portfolio and Catalytic Activity of Organometallic Representatives in Ethylene Polymerisation
Authors: Ohde Christian , Limberg Christian , Schmidt Dennis , Enders Markus , Demeshko Serhiy , Knispel Christina
Published: August 2010

Employing various incompletely condensed silsesquioxanes as ligand precursors in reactions with simple oxovanadates a variety of oxovanadium silsequioxanes could be synthesised, that might be regarded as models for oxovanadium units on silica surfaces. These include a tetranuclear vanadium(IV) compound as well as two complexes where O2V+ units are coordinated to two siloxide functions as part of a silsesquioxane framework. Moreover, compounds containing Cp*V(O)2+ moieties were prepared, whose activities as polymerisation procatalysts were examined: They turned out to be moderately active for the polymerisation of ethylene. All compounds were fully characterised, in case of the tetranuclear vanadium(IV) complex this also includes the investigation of the magnetic behaviour. Moreover, for two complexes also the molecular structures could be determined with sufficient quality by X‐ray diffraction.
Prolonged Antibiotic Treatment does not Prevent Intra‐Abdominal Abscesses in Perforated Appendicitis
Authors: van Wijck K. , de Jong J. R. , van Heurn L. W. E. , van der Zee D. C.
Published: August 2010

Background

Children with perforated appendicitis have a relatively high risk of intra‐abdominal abscesses. There is no evidence that prolonged antibiotic treatment after surgery reduces intra‐abdominal abscess formation. We compared two patient groups with perforated appendicitis with different postoperative antibiotic treatment protocols.

Methods

We retrospectively reviewed patients younger than age 18 years who underwent appendectomy for perforated appendicitis at two academic hospitals between January 1992 and December 2006. Perforation was diagnosed during surgery and confirmed during histopathological evaluation. Patients in hospital A received 5 days of antibiotics postoperatively, unless decided otherwise on clinical grounds. Patients in hospital B received antibiotics for 5 days, continued until serum C‐reactive protein

(CRP) was <20 mg/l. Univariate logistic regression analysis was performed on intention‐to‐treat basis. p < 0.05 was considered significant.

Results

A total of 149 children underwent appendectomy for perforated appendicitis: 68 in hospital A, and 81 in hospital B. As expected, the median (range) use of antibiotics was significantly different: 5 (range, 1–16) and 7 (range, 2–32) days, respectively (p < 0.0001). However, the incidence of postoperative intra‐abdominal abscesses was similar (p = 0.95). Regression analysis demonstrated that sex (female) was a risk factor for abscess formation, whereas surgical technique and young age were not.

Conclusions

Prolonged use of antibiotics after surgery for perforated appendicitis in children based on serum CRP does not reduce postoperative abscess formation.
The effects of serotiny and rainfall‐cued dispersal on fitness: bet‐hedging in the threatened cactus Mammillaria pectinifera
Authors: Peters Edward M. , Martorell Carlos , Ezcurra Exequiel
Published: August 2010

Serotiny—the retention of seeds in the mother plant for over a year—in unpredictable environments may increase the probability that at least some seeds are dispersed during favorable periods. Propagules may be expelled when environmental cues announcing favorable conditions occur, or be gradually released into the environment. This could be a bet‐hedging strategy increasing the long‐term fitness by reducing interannual variability in reproduction. However, the impact of seed retention on the population dynamics of serotinous species and its contribution to fitness has been barely explored under field conditions. We assessed these issues in the threatened Mammillaria pectinifera, a small globose cactus that gets established only in exceptionally rainy years. This species expels some seeds actively during unusually rainy periods, while dispersing others passively over several years. Dynamics of the seeds in the mother plant over two very contrasting years in terms of precipitation was incorporated into a stochastic matrix model. Seed retention was found to increase significantly the probability that some of the seeds retained in any given year are dispersed within a subsequent rainy period. Active seed‐expulsion raises this probability even further. As expected in bet hedgers, seed retention increased fitness in the presence of temporal variability. Active fruit expulsion did not affect fitness, but reduced demographic stochasticity. The incomplete serotiny and fruit expulsion observed is the evolutionary outcome expected for the environment and life‐history attributes of the species.
Compromized geranylgeranylation of RhoA and Rac1 in mevalonate kinase deficiency
Authors: Henneman L. , Schneiders M. S. , Turkenburg M. , Waterham H. R.
Published: September 2010

Mevalonate kinase deficiency (MKD) is an autoinflammatory disorder caused by mutations in the MVK gene resulting in decreased activity of the enzyme mevalonate kinase (MK). Although MK is required for biosynthesis of all isoprenoids, in MKD, in particular, the timely synthesis of geranylgeranyl pyrophosphate appears to be compromised. Because small guanosine triphosphatases (GTPases) depend on geranylgeranylation for their proper signaling function, we studied the effect of MK deficiency on geranylgeranylation and activation of the two small GTPases, RhoA and Rac1. We demonstrate that both geranylgeranylation and activation of the two GTPases are more easily disturbed in MKD cells than in control cells when the flux though the isoprenoid biosynthesis pathway is suppressed by low concentrations of simvastatin. The limited capacity of geranylgeranylation in MKD cells readily leads to markedly increased levels of nonisoprenylated and activated GTPases, which will affect proper signaling by these GTPases.
Multidimensional Latent Markov Models in a Developmental Study of Inhibitory Control and Attentional Flexibility in Early Childhood
Authors: Bartolucci Francesco , Solis-Trapala Ivonne L.
Published: September 2010

We demonstrate the use of a multidimensional extension of the latent Markov model to analyse data from studies with repeated binary responses in developmental psychology. In particular, we consider an experiment based on a battery of tests which was administered to pre-school children, at three time periods, in order to measure their inhibitory control (IC) and attentional flexibility (AF) abilities. Our model represents these abilities by two latent traits which are associated to each state of a latent Markov chain. The conditional distribution of the test outcomes given the latent process depends on these abilities through a multidimensional one-parameter or two-parameter logistic parameterisation. We outline an EM algorithm for likelihood inference on the model parameters; we also focus on likelihood ratio testing of hypotheses on the dimensionality of the model and on the transition matrices of the latent process. Through the approach based on the proposed model, we find evidence that supports that IC and AF can be conceptualised as distinct constructs. Furthermore, we outline developmental aspects of participants’ performance on these abilities based on inspection of the estimated transition matrices.
Progression of functional limitations in relation to physical activity: a life course approach
Authors: von Bonsdorff Mikaela B. , Rantanen Taina
Published: August 2010

In this minireview, we summarize the research results to date on the progression of functional limitations and the role of physical activity during the life course in preventing risk factor accumulation. In addition, socioeconomic and health disparities play a role in the development process of functional limitation throughout life. We discuss the potential role of physical activity in alleviating this process. Functional limitations usually develop gradually over an extended period of time while the level of physical functioning varies greatly already from midlife onwards. Current research strongly suggests that physical activity has a beneficial effect on functional limitations at different life stages on the population level. However, the potential impact of physical activity in alleviating the effects caused by socioeconomic disparities is inconsistent. Research findings are also conflicting on the extent of the effect of physical activity among certain subsets of the population, such as obese persons. Although the benefits of physical activity on physical impairments and functioning among the adult population have been confirmed, the number of adults who are physically active is too low and, for the majority, physical activity declines with older age. Thus, detailed research evidence is needed for designing effective preventive interventions starting from earlier ages and continuing throughout the lifespan across different subgroups in the population.
Reducing the Risks Associated With Loaner Instrumentation and Implants
Authors: Seavey Rose
Published: September 2010

Surgical facilities borrow specialty surgical instrumentation and implants from vendors and other facilities to provide needed inventory to perform scheduled procedures without the burden of purchasing these items. Borrowing has many advantages, including reduced costs and the ability to expand services offered, but borrowed items must be handled and processed in a consistent way to ensure safe patient care. Instruments and implants must be received in time to be properly reprocessed by the borrowing facility. Lack of planning on the part of a hospital or vendor, lack of communication, lack of appropriate policies to guide the processing of items, increasingly complex instrumentation, and increasing workloads are factors that can contribute to lapses in processing requirements and, ultimately, risk to patients and staff members. Improving communication and policies and procedures can improve the quality and safety of loaner instrumentation and implant use.
Gastrointestinal symptoms in type‐1 diabetes: Is it all about brain plasticity?
Authors: Frøkjærl Jens Brøndum , Egsgaardl Line Lindhardt , Graversenl Carina , Søftelandl Eirik , Dimcevskil Georg , Blauenfeldtl Rolf Ankerlund , Drewesl Asbjørn Mohr
Published: September 2010

Background and aims: Autonomic neuropathy seems to play a central role in the development of gastrointestinal symptoms in diabetes. In order to explore the neuronal mechanisms behind the symptoms we evaluated the brain processing of painful visceral stimuli.

Methods: Evoked brain potentials were recorded to assess the response to painful oesophageal electrical stimuli in 15 healthy volunteers and 14 type‐1 diabetes patients with autonomic neuropathy and related gastrointestinal symptoms. Source reconstruction analysis (fixed Multiple Signal Classification (MUSIC) algorithm) was applied to estimate the location of the evoked electrical activity in the brain.

Results: The patients had increased oesophageal sensory thresholds compared to the controls (P =0.004). The latencies of the evoked brain potentials at vertex (Cz) were increased (P =0.007) and amplitudes reduced (P =0.011) in diabetics. Compared with controls the patients had a posterior shift of the electrical sources in the anterior cingulate cortex at 54 ms, and additional sources close to the posterior insula at 95 ms and in medial frontal gyrus at 184 ms.

Conclusions: There is evidence of altered central processing to visceral stimulation, and both peripheral and central mechanisms seem involved. Central neuronal reorganisation may contribute to our understanding of the gastrointestinal symptoms in patients with diabetic autonomic neuropathy and this may guide development and evaluation of new treatment modalities.
Development of a cell‐free system reveals an oxygen‐labile step in the maturation of [NiFe]‐hydrogenase 2 of Escherichia coli
Authors: Soboh Basem , Krüger Sara , Kuhns Martin , Pinske Constanze , Lehmann Anne , Sawers R. Gary
Published: September 2010

By combining extracts from strains lacking genes encoding either the maturation enzymes or the large subunits of hydrogenases 1, 2 and 3 we could reconstitute in vitro under strictly anaerobic conditions 10–15% of the hydrogenase activity present in wild type Escherichia coli extracts. Purified, unprocessed Strep‐tagged variants of the hydrogenase 2 large subunit, HybC, isolated from either a ΔhybD (encoding the hydrogenase 2‐specific protease) mutant or a strain deficient in HypF could also be matured to active, processed enzyme using this system. These studies reveal that minimally one step early on the hydrogenase maturation pathway is oxygen‐labile.