bluuebunny/crossref_metadata_2025 huggingface dataset:
Landslide impact on organic carbon cycling in a temperate montane forest
Authors: Hilton Robert G. , Meunier Patrick , Hovius Niels , Bellingham Peter J. , Galy Albert
Published: June 2011

In humid, forested mountain belts, bedrock landslides can harvest organic carbon from above ground biomass and soil (OCmodern) while acting to refresh the landscape surface and turnover forest ecosystems. Here the impact of landslides on organic carbon cycling in 13 river catchments spanning the length of the western Southern Alps, New Zealand is assessed over four decades. Spatial and temporal landslide maps are combined with the observed distribution and measured variability of hillslope OCmodern stocks. On average, it is estimated that landslides mobilized 7.6 ± 2.9 tC km−2 yr−1 of OCmodern, ~30% of which was delivered to river channels. Comparison with published estimates of OCmodern export in river suspended load suggests additional erosion of OCmodern by small, shallow landslides or overland flow in catchments. The exported OCmodern may contribute to geological carbon sequestration if buried in sedimentary deposits. Landslides may have also contributed to carbon sequestration over shorter timescales (<100 years). 5.4 ± 3.0 tC km−2 yr−1 of the eroded OCmodern was retained on hillslopes, representing a net‐carbon sink following re‐vegetation of scar surfaces. In addition, it was found that landslides caused rapid turnover of the landscape, with rates of 0.3% of the surface area per decade. High rates of net ecosystem productivity were measured in this forest of 94 ± 11 tC km−2 yr−1, which is consistent with rapid landscape turnover suppressing ecosystem retrogression. Landslide‐OCmodern yields and rates of turnover vary between river catchments and appear to be controlled by gradients in climate (precipitation) and geomorphology (rock exhumation rate, topographic slope). Copyright © 2011 John Wiley & Sons, Ltd.
The strange blood: Natural hybridization in primates
Authors: Zinner Dietmar , Arnold Michael L. , Roos Christian
Published: June 2011

Hybridization between two closely related species is a natural evolutionary process that results in an admixture of previously isolated gene pools. The exchange of genes between species may accelerate adaptation and lead to the formation of new lineages. Hybridization can be regarded as one important evolutionary mechanism driving speciation processes. Although recent studies have highlighted the taxonomic breadth of natural hybridization in the primate order, information about primate hybridization is still limited compared to that about the hybridization of fish, birds, or other mammals. In primates, hybridization has occurred mainly between subspecies and species, but has also been detected between genera and even in the human lineage. Here we provide an overview of cases of natural hybridization in all major primate radiations. Our review emphasizes a phylogenetic approach. We use the data presented to discuss the impact of hybridization on taxonomy and conservation.
Inter‐individual variability in aroma release during sweet mint consumption
Authors: Repoux Marie , Sémon Etienne , Feron Gilles , Guichard Elisabeth , Labouré Hélène
Published: June 2011

Inter‐individual variations of in vivo aroma release kinetics have been observed widely in the literature. However, the corresponding causes are yet to be clearly identified. For this purpose, 68 subjects in whom salivary flow rates (at rest and Parafilm™‐stimulated) had been determined were recruited for the study. The release of menthone was measured using atmospheric pressure ionisation–mass spectrometry during the consumption of a sweet mint tablet. The subjects complied with an imposed protocol of oral movements. Inter‐individual variability was investigated through a qualitative analysis of the oral movements inducing menthone release, and through quantitative analysis. Swallowing events were the main contributors to menthone release. Tongue and jaw movements did not induce menthone release in all the subjects, thus explaining inter‐individual differences in menthone release curve profiles. Inter‐individual differences in term of the quantity of menthone released partly arose from the percentage of sweet mint tablet degradation. The greater the degree of degradation, the more menthone was released. Although protein concentrations in the saliva gave a first indication of differences in mint tablet degradation between subjects, other factors such as the content of specific proteins, and particularly enzymes, still need to be explored. Copyright © 2011 John Wiley & Sons, Ltd.
Solution of flow around complex‐shaped surfaces by an immersed boundary‐body conformal enrichment method
Authors: Ilinca F. , Hétu J.‐F.
Published: June 2011

Solving the flow around objects with complex shapes may involve extensive meshing work that has to be repeated each time a change in the geometry is needed. Time consuming meshing can be avoided when the solution algorithm can tackle grids that do not fit the shape of immersed objects. This work presents applications of a recently proposed immersed boundary—body conformal enrichment method to the solution of the flow around complex shaped surfaces such as those of a metallic foam matrix. The method produces solutions of the flow satisfying accurately Dirichlet boundary conditions imposed on the immersed fluid/solid interface. The boundary of immersed objects is defined using a level‐set function, and the finite element discretization of interface elements is enriched with additional degrees of freedom, which are eliminated at element level. The method is first validated in the case of flow problems for which reference solutions on body‐conformal grids can be obtained: flow around an array of spheres and flow around periodic arrays of cylinders. Then, solutions are shown for the more complex flow inside a metallic foam matrix. A multiscale approach combining the solution at the pore level by the immersed boundary method and the macro‐scale solution with simulated permeability is used to solve actual experimental configurations. The computed pressure drop as a function of the flow rate on the macro scale configuration replicating two experimental setups is compared with the experimental data for various foam thicknesses. Copyright © 2011 National Research Council Canada
Geotechnical performance of a novel gravity base type shallow foundation for offshore wind turbines
Authors: Sturm Hendrik
Published: June 2011

This paper presents a novel foundation solution specially developed for offshore wind turbines installed on sandy or stiff soils. It is a pre‐fabricated cross‐shaped structure which rests on the seabed through four skirted plates. The geotechnical performance of the foundation has been analysed numerically with respect to both capacity and displacement during extreme loading and normal operation. The effects of different geometrical aspects such as skirt length and structural stiffness have been studied by means of 2D and 3D Finite Element simulations. Fully coupled stress equilibrium and pore water flow simulations have been performed in order to analyse the influence of accumulated excess pore pressure due to cyclic loading. The long‐term behaviour of the foundation is discussed based on stability and failure considerations. The results of the numerical study show that the proposed foundation solution offers a viable alternative as a safe foundation for offshore wind turbines. This has been demonstrated representatively for a 5 MW wind turbine installed in a water depth of 35 m on homogeneous ground subjected to the governing design load cases.

Geotechnisches Verhalten eines neuartigen Flachfundaments zur Gründung von Offshore Windenergieanlagen In diesem Beitrag wird ein neuartiges Gründungskonzept für Offshore Windenergieanlagen vorgestellt, das besonders für sandige und steife Böden geeignet ist. Es handelt sich um eine vorgefertigte kreuzförmige Hohlkastenkonstruktion, die mittels vier Platten mit Schürzen auf dem Meeresboden ruht. Sowohl das Tragverhalten für ein Extremlastereignis als auch die Gebrauchstauglichkeit für eine repräsentative zyklische Belastung wurden mithilfe numerischer Berechnungen untersucht. In 2D und 3D Finite Element Berechnungen wurde der Einfluss der Schürzenlänge, der Struktursteifigkeit und anderer Eigenschaften analysiert. Neben voll dränierten Berechnungen wurden auch gekoppelte Spannungsgleichgewichts‐ und Porenwasserfluss‐Berechnungen durchgeführt, um den Einfluss der Porenwasserdruckakkumulation aus quasi‐statisch zyklischer Belastung aus Wind und Wellen zu erfassen. Eine Abschätzung des Langzeitverhaltens der Gründung wird auf Basis von Stabilitäts‐ bzw. Versagensbetrachtungen gegeben. Die Ergebnisse der numerischen Berechnungen zeigen, dass das vorgestellte Fundament eine geeignete Alternativlösung zur sicheren Gründung von Offshore Windenergieanlagen darstellt. Dies wird beispielhaft für eine 5 MW Anlage gezeigt, die in 35 m Wassertiefe auf homogenem Grund installiert ist und mit typischen Einwirkungen aus Wind und Wellen belastet wird.
Bohrtechnische und baubetriebliche Auswirkungen von Bohrlochinstabilitäten auf die Bohr‐ und Sprengarbeiten beim Bau des Flusskraftwerks Rheinfelden/Baden
Authors: Plinninger Ralf J. , Warning Nils , Krämer Manfred
Published: June 2011

Seit 2003 wird in Rheinfelden/Baden‐Württemberg der Ersatz des aus dem späten 19. Jahrhundert stammenden bestehenden Rheinkraftwerks Rheinfelden realisiert. Das neue Kraftwerk mit einer projektierten Leistung von 100 MW besteht im Wesentlichen aus einem quer zur Fließrichtung errichteten Stauwehr und einem neuen Maschinenhaus. Zur Errichtung des Maschinenhauses sowie zur Erhöhung des nutzbaren Gefälles wurden in der Felssohle des Rheinbetts umfangreiche Lockerungssprengungen erforderlich. Im Zuge der Bauausführung zeigte sich, dass die Bohr‐ und Sprengarbeiten in vielfältiger Weise durch Bohrlochinstabilitäten beeinflusst wurden. Um auch in Lockergestein und gestörtem Fels eine definierte Ladesäule aufbauen und den Sprengerfolg sicherstellen zu können, wurden umfangreiche bohr‐ und sprengtechnische Anpassungen vorgenommen, mit denen das Projekt schließlich erfolgreich realisiert werden konnte. Der vorliegende Beitrag fasst die Rahmenumstände des Projekts, die technischen Grundlagen der Bohr‐ und Sprengarbeiten und die im Zuge der baubegleitenden Dokumentation gewonnenen Erfahrungen zur Interaktion von Geologie, Bohr‐ und Sprengtechnik und Baubetrieb zusammen.

Technical and operational aspects of borehole instability on drill and blast works at the Rheinfelden Hydroelectric Power Plant. Since 2003, a new Hydroelectric Power Plant has been under construction in the river Rhine near the city of Rheinfelden/Germany. The new Rheinfelden power plant with a projected power capacity of 100 MW mainly consists of a new concrete dam and a new powerhouse as a replacement for the old facilities constructed in the late 19th century. The construction of the powerhouse and the increase of the available river gradient required extensive loosening blasts in the riverbed, which is formed by Triassic limestone and alluvial river deposits. In the course of the drill and blast works, it was observed that unstable rock mass sections and borehole instabilities influenced the drilling, loading and blasting of the rock in many ways. In order to ensure a defined loading in loose alluvial deposits and faulted rock, extensive changes were made to the drilling and blasting methods, for instance insertion of plastic casings or the use of the RBS cased drilling method. The implementation of these measures enabled the works to be completed successfully. This paper gives the basic outlines of the project and the techniques used, and summarises some of the findings on the interaction of geology on the one hand and technical and operational aspects of drilling and blasting on the other hand.
Linear mixed modelling of snow distribution in the central Yukon
Authors: Kasurak Andrew , Kelly Richard , Brenning Alexander
Published: June 2011

Remote sensing estimates of snow water equivalent (SWE) in mountainous areas are subject to large uncertainties. As a prerequisite for testing passive microwave algorithm estimations of SWE, this study aims to collect snow depth (SD) data and provide an understanding of its complex spatial structure as part of the Canadian International Polar Year observations theme. Snow accumulation, redistribution and ablation are controlled by processes that depend on a variety of topographic factors as well as land surface characteristics, which leads us to modelling SD as a function of proxy variables derived from digital elevation model and Landsat data. Field measurements were performed at 3924 locations compromising 184 sites in 50 transects over 2 years. These measurements were used to predict SD over the study area using a spatial linear mixed‐effects model, a model type capable of handling the hierarchical structure of the field data.

The model, built using stepwise variable selection, uses as predictor variables transformed elevation, slope, the logarithm of slope, potential incoming solar radiation and its transform; the normalized difference vegetation index, and a transformed tasseled cap brightness from Landsat imagery. A second, simpler model links SD with density giving SWE. The cross‐validated root mean squared error of the SD distribution model was 14 cm around an overall mean of 80 cm over a domain of 250 × 250 km.

This instantaneous end‐of‐season peak‐accumulation snow map will enable the validation of satellite remote sensing over a generally inaccessible area. Copyright © 2011 John Wiley & Sons, Ltd.
Structural basis of thrombin–protease‐activated receptor interactions
Authors: Gandhi Prafull S. , Chen Zhiwei , Appelbaum Eric , Zapata Fatima , Di Cera Enrico
Published: June 2011

Aggregation of platelets is an essential step in the formation of a stable blood clot during vascular injury. The trypsin‐like protease thrombin acts as the dominant agonist of platelet activation on engagement of protease‐activated receptors (PARs). Important details on the molecular aspects of thrombin–PAR interactions have been revealed recently by structural biology. In the case of human platelets, PAR1 engages thrombin via an extended surface of recognition encompassing the active site and exosite I. In the case of murine platelets, PAR4 binds to the active site in a conformation that leaves exosite I free for interaction with cofactors like PAR3. Human PAR4 mimics the murine receptor binding mechanism for residues upstream of the scissile bond. This information is consistent with existing functional data and provides a solid background for future structural and mutagenesis studies of PAR interaction with thrombin and related proteases. © 2011 IUBMB IUBMB Life, 63(6): 375–382, 2011
Muscle‐type 6‐phosphofructo‐1‐kinase and aldolase associate conferring catalytic advantages for both enzymes
Authors: Marcondes Mariah Celestino , Sola‐Penna Mauro , Torres Renan da Silva Gianoti , Zancan Patricia
Published: June 2011

6‐Phosphofructo‐1‐kinase (PFK) and aldolase are two sequential glycolytic enzymes that associate forming heterotetramers containing a dimer of each enzyme. Although free PFK dimers present a negligible activity, once associated to aldolase these dimers are as active as the fully active tetrameric conformation of the enzyme. Here we show that aldolase‐associated PFK dimers are not inhibited by clotrimazole, an antifulgal azole derivative proposed as an antineoplastic drug due to its inhibitory effects on PFK. In the presence of aldolase, PFK is not modulated by its allosteric activators, ADP and fructose‐2,6‐bisphosphate, but is still inhibited by citrate and lactate. The association between the two enzymes also results on the twofold stimulation of aldolase maximal velocity and affinity for its substrate. These results suggest that the association between PFK and aldolase confers catalytic advantage for both enzymes and may contribute to the channeling of the glycolytic metabolism. © 2011 IUBMB IUBMB Life, 63(6): 435–445, 2011
Brief update on different roles of tau in neurodegeneration
Authors: Ittner Arne , Ke Yazi D. , Eersel Janet van , Gladbach Amadeus , Götz Jürgen , Ittner Lars M.
Published: June 2011

Both Alzheimer's disease (AD) and almost every second case of frontotemporal lobar degeneration (FTLD) are characterized by the deposition of hyperphosphorylated forms of the microtubule‐associated protein tau in neurons and/or glia. This unifying pathology led to coining the umbrella term “tauopathies” for these conditions. While the deposition of tau ultimately results in the formation of typical histopathological lesions, such as the neurofibrillary tangles (NFTs) in AD, it is now well accepted that tau interferes with normal functions in neurons already before its deposition. Together with the identification of pathogenic mutations in the tau‐encoding gene MAPT in FTLD and evidence from a rising number of in vivo animal models a central role of tau in neurodegeneration has emerged. Here, we review the role of pathological tau in axonal transport, mitochondrial respiration, and in mediating amyloid‐β toxicity in AD. Furthermore, we review recent findings regarding the spreading of tau pathology throughout the brain as disease progresses. © 2011 IUBMB IUBMB Life, 63(7): 495–502, 2011
Moonlighting characteristics of G protein‐coupled receptors: Focus on receptor heteromers and relevance for neurodegeneration
Authors: Borroto‐Escuela Dasiel O. , Tarakanov Alexander O. , Guidolin Diego , Ciruela Francisco , Agnati Luigi F. , Fuxe Kjell
Published: June 2011

It is proposed that the moonlighting concept can be applied to G protein coupled receptors (GPCRs) as, obviously, they can carry out different types of functions. The same motifs in, for example, the third intracellular loop, can moonlight by switching between receptor–receptor interactions and interactions with signaling proteins such as G proteins or calmodulin. A “guide‐and‐clasp” manner of receptor–receptor interactions has been proposed where the “adhesive guides” may be the triplet homologies. As an example, the triplets AAR (or RAA) and AAE (or EAA) homologies in A2AR‐D2R heteromers may guide‐and‐clasp binding not only of the two protomers but also of calmodulin and Gi. A beautiful moonlighting phenomenon in the A2AR‐D2R heteromer is that the positively charged D2R N‐terminal third intracellular loop epitope (VLRRRRKRVN) may switch between bindings to the negatively charged A2AR epitope (SAQEpSQGNT), localized in the medium segment of the C terminus of the A2A receptor to several negative epitopes of calmodulin. Furthermore, overlapping motifs may favor moonlighting to Gi/o via inter alia electrostatic interaction between triplets AAR(in D2R third intracellular loop) and AAE (Gi/alpha1) (and/or their symmetric variants) contributing to guide‐and‐clasp D2R‐Gi interactions Thus, moonlighting in GPCR heteromers can take place via allosteric receptor–receptor interactions and is also described in D1R‐D2R, D2R‐5‐HT2R,and A1R‐P2Y1 heteromers. Allosteric receptor–receptor interactions in GPCR‐receptor tyrosine kinases (RTKs) heteromers and postulated ion channel receptor‐RTK heteromers‐like, for example, AMPA‐NMDA‐TrkB heteromers may lead to moonlighting of the participating GPCR and RTK protomers altering, for example, the pattern of the five major signaling pathways of the RTKs favoring MAPK and/or mTOR signaling with high relevance for neurodegenerative processes and depression induced atrophy of neurons. Moonlighting may also develop in the intracellular loops and C‐terminal of the GPCRs as a result of dynamic allosteric interactions between different types of G proteins and other receptor interacting proteins in these domains of the receptor. ©2011 IUBMB IUBMB Life, 63(7): 463‐472, 2011
How a neutral evolutionary ratchet can build cellular complexity
Authors: Lukeš Julius , Archibald John M. , Keeling Patrick J. , Doolittle W. Ford , Gray Michael W.
Published: June 2011

Complex cellular machines and processes are commonly believed to be products of selection, and it is typically understood to be the job of evolutionary biologists to show how selective advantage can account for each step in their origin and subsequent growth in complexity. Here, we describe how complex machines might instead evolve in the absence of positive selection through a process of “presuppression,” first termed constructive neutral evolution (CNE) more than a decade ago. If an autonomously functioning cellular component acquires mutations that make it dependent for function on another, pre‐existing component or process, and if there are multiple ways in which such dependence may arise, then dependence inevitably will arise and reversal to independence is unlikely. Thus, CNE is a unidirectional evolutionary ratchet leading to complexity, if complexity is equated with the number of components or steps necessary to carry out a cellular process. CNE can explain “functions” that seem to make little sense in terms of cellular economy, like RNA editing or splicing, but it may also contribute to the complexity of machines with clear benefit to the cell, like the ribosome, and to organismal complexity overall. We suggest that CNE‐based evolutionary scenarios are in these and other cases less forced than the selectionist or adaptationist narratives that are generally told. © 2011 IUBMB IUBMB Life, 63(7): 528–537, 2011
Ligand‐ and proton‐linked conformational changes of the ferrous 2/2 hemoglobin of Pseudoalteromonas haloplanktis TAC125
Authors: Giordano Daniela , Russo Roberta , Ciaccio Chiara , Howes Barry D. , di Prisco Guido , Marden Michael C. , Hui Bon Hoa Gaston , Smulevich Giulietta , Coletta Massimo , Verde Cinzia
Published: June 2011

The spectroscopic and ligand‐binding properties of a 2/2 globin from the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 have been studied in the ferrous state. It displays two major conformations characterized by CO‐association rates that differ by a factor of 20, with relative fractions that depend on pH. A dynamic equilibrium is found between the two conformations, as indicated by an enhanced slower phase when lower CO levels were used to allow a longer time to facilitate the transition. The deoxy form, in the absence of external ligands, is a mixture of a predominant six‐coordinate low spin form and a five‐coordinate high‐spin state; the proportion of low spin increasing at alkaline pH. In addition, at temperatures above the physiological temperature of 1 °C, an enhanced tendency of the protein to oxidize is observed. © 2011 IUBMB IUBMB Life, 63(7): 566–573, 2011
Tyr306 near the C‐terminus of protein phosphatase‐1 affects enzyme stability and inhibitor binding
Authors: Wang Bai J. , Tang Wei , Zhang Peng , Wei Qun
Published: June 2011

Previous deletion studies have suggested that Tyr306 has an important influence on the properties of protein phosphatase‐1 (PP1). To test this inference, we constructed three site‐directed mutants, PP1Y306A, PP1Y306K, and PP1Y306E. The specific activity of PP1Y306A was 3.5‐fold higher than that of PP1wt, especially with K‐R‐Tp‐I‐R‐R as substrate, and it also had a 13‐fold higher Kcat and a 43‐fold higher Kcat/Km. PP1Y306K and PP1Y306E, in that order, and were next in terms of increased activity. Use of the denaturant guanidine hydrochloride (GdnHCl) demonstrated that mutation of this site decreased enzyme stability. PP1Y306A and PP1Y306E lost all activity when incubated for 24 h in 0.6 M GdnHCl, and their fluorescence spectra confirmed the loss of stability. Because all three substitutions had a similar effect, we infer that the aromatic group of Tyr plays a crucial role in maintaining enzyme stability. Our results show that Tyr306 does affect the spatial conformation of the catalytic subunit of PP1 molecule. The IC50 of PP1Y306A for the inhibitor microcystin‐LR was threefold higher than that of PP1wt, whereas those of PP1Y306E for tautomycin and norcantharidin were 15‐fold and 10‐fold higher, respectively. We conclude that Tyr306 plays an important role in enzyme stability and inhibitor binding. © 2011 IUBMB IUBMB Life, 63(7): 574–581, 2011
Intrinsically unstructured proteins and neurodegenerative diseases: Conformational promiscuity at its best
Authors: Das Samir , Mukhopadhyay Debashis
Published: June 2011

Neurodegenerative diseases are complex, multifactorial disorders where misfolding of proteins cause aberrant protein–protein interactions. They are not usually characterized by specific mutations especially for nonfamilial disease types. Most of the causative proteins, however, are intrinsically unstructured (IUP), loss of whose fine balance could play pivotal role in these processes. Very fast conformational switch of these IUPs between different functional forms, so as to choose different interaction partners and different functional niches within the cell, is the basic premise on which these proteins maintain their interaction network. We are working on the hypothesis that even small perturbations in conformation leads to disruption of the network and to the disease phenotype. Based on a comprehensive data search, the evidence was obtained for the role of IUPs in neurodegenerative disorders, and their mode of action through conformational promiscuity is elaborated through three case studies. © 2011 IUBMB IUBMB Life, 63(7): 478–488, 2011
Moonlighting cytochrome P450 monooxygenases
Authors: Zhao Bin , Waterman Michael R.
Published: June 2011

Recently, cytochrome P450 170A1 (CYP170A1) has been found to be a bifunctional protein, which catalyzes both monooxygenase activity and terpene synthase activity by two distinct active sites in the well‐established P450 protein structure. Therefore, CYP170A1 is identified clearly as a moonlighting protein. The known activities of a small number of the 13,000 members of the P450 superfamily fall into two general classes: promiscuous enzymes that are not considered as moonlighting and forms that participate in biosynthesis of endogenous compounds, such as steroids, vitamins and play different roles in different tissues, sometimes being moonlighting enzymes. Here, we review examples of moonlighting P450, which add to our understanding of the large CYP superfamily. © 2011 IUBMB IUBMB Life, 63(7): 473–477, 2011
Titania–hydroxyapatite nanocomposite coatings support human mesenchymal stem cells osteogenic differentiation
Authors: Dimitrievska Sashka , Bureau Martin N. , Antoniou John , Mwale Fackson , Petit Alain , Lima Rogerio S. , Marple Basil R.
Published: June 2011

In addition to mechanical and chemical stability, the third design goal of the ideal bone‐implant coating is the ability to support osteogenic differentiation of mesenchymal stem cells (MSCs). Plasma‐sprayed TiO2‐based bone‐implant coatings exhibit excellent long‐term mechanical properties, but their applications in bone implants are limited by their bioinertness. We have successfully produced a TiO2 nanostructured (grain size <50 nm) based coating charged with 10% wt hydroxyapatite (TiO2–HA) sprayed by high‐velocity oxy‐fuel. On Ti64 substrates, the novel TiO2–HA coating bond 153× stronger and has a cohesive strength 4× higher than HA coatings. The HA micro‐ and nano‐sized particles covering the TiO2–HA coating surface are chemically bound to the TiO2 coating matrix, producing chemically stable coatings under high mechanical solicitations. In this study, we elucidated the TiO2–HA nanocomposite coating surface chemistry, and in vitro osteoinductive potential by culturing human MSCs (hMSCs) in basal and in osteogenic medium (hMSC‐ob). We assessed the following hMSCs and hMSC‐ob parameters over a 3‐week period: (i) proliferation; (ii) cytoskeleton organization and cell–substrate adhesion; (iii) coating–cellular interaction morphology and growth; and (iv) cellular mineralization. The TiO2–HA nanocomposite coatings demonstrated 3× higher hydrophilicity than HA coatings, a TiO2‐nanostructured surface in addition to the chemically bound HA micron‐ and nano‐sized rod to the surface. hMSCs and hMSC‐ob demonstrated increased proliferation and osteoblastic differentiation on the nanostructured TiO2–HA coatings, suggesting the TiO2–HA coatings nanostructure surface properties induce osteogenic differentiation of hMSC and support hMSC‐ob osteogenic potential better than our current golden standard HA coating. Published 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
A generalized strategy for designing 19F/1H dual‐frequency MRI coil for small animal imaging at 4.7 Tesla
Authors: Hu Lingzhi , Hockett Frank D. , Chen Junjie , Zhang Lei , Caruthers Shelton D. , Lanza Gregory M. , Wickline Samuel A.
Published: June 2011

Purpose:

To propose and test a universal strategy for building 19F/1H dual‐frequency RF coil that permits multiple coil geometries.

Materials and Methods:

The feasibility to design 19F/1H dual‐frequency RF coil based on coupled resonator model was investigated. A series capacitive matching network enables robust impedance matching for both harmonic oscillating modes of the coupled resonator. Two typical designs of 19F/1H volume coils (birdcage and saddle) at 4.7T were implemented and evaluated with electrical bench test and in vivo 19F/1H dual‐nuclei imaging.

Results:

For various combinations of internal resistances of the sample coil and secondary resonator, numerical solutions for the tunable capacitors to optimize impedance matching were obtained using a root‐seeking program. Identical and homogeneous B1 field distribution at 19F and 1H frequencies were observed in bench test and phantom image. Finally, in vivo mouse imaging confirmed the sensitivity and homogeneity of the 19F/1H dual‐frequency coil design.

Conclusion:

A generalized strategy for designing 19F/1H dual‐frequency coils based on the coupled resonator approach was developed and validated. A unique feature of this design is that it preserves the B1 field homogeneity of the RF coil at both resonant frequencies. Thus it minimizes the susceptibility effect on image co‐registration. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Intracranial arterial wall imaging using three‐dimensional high isotropic resolution black blood MRI at 3.0 Tesla
Authors: Qiao Ye , Steinman David A. , Qin Qin , Etesami Maryam , Schär Michael , Astor Brad C. , Wasserman Bruce A.
Published: June 2011

Purpose:

To develop a high isotropic‐resolution sequence to evaluate intracranial vessels at 3.0 Tesla (T).

Materials and Methods:

Thirteen healthy volunteers and 4 patients with intracranial stenosis were imaged at 3.0T using 0.5‐mm isotropic‐resolution three‐dimensional (3D) Volumetric ISotropic TSE Acquisition (VISTA; TSE, turbo spin echo), with conventional 2D‐TSE for comparison. VISTA was repeated for 6 volunteers and 4 patients at 0.4‐mm isotropic‐resolution to explore the trade‐off between SNR and voxel volume. Wall signal‐to‐noise‐ratio (SNRwall), wall‐lumen contrast‐to‐noise‐ratio (CNRwall‐lumen), lumen area (LA), wall area (WA), mean wall thickness (MWT), and maximum wall thickness (maxWT) were compared between 3D‐VISTA and 2D‐TSE sequences, as well as 3D images acquired at both resolutions. Reliability was assessed by intraclass correlations (ICC).

Results:

Compared with 2D‐TSE measurements, 3D‐VISTA provided 58% and 74% improvement in SNRwall and CNRwall‐lumen, respectively. LA, WA, MWT and maxWT from 3D and 2D techniques highly correlated (ICCs of 0.96, 0.95, 0.96, and 0.91, respectively). CNRwall‐lumen using 0.4‐mm resolution VISTA decreased by 27%, compared with 0.5‐mm VISTA but with reduced partial‐volume‐based overestimation of wall thickness. Reliability for 3D measurements was good to excellent.

Conclusion:

The 3D‐VISTA provides SNR‐efficient, highly reliable measurements of intracranial vessels at high isotropic‐resolution, enabling broad coverage in a clinically acceptable time. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Dynamic late gadolinium enhancement simply quantified using myocardium to lumen signal ratio: Normal range of ratio and diffuse abnormal enhancement of cardiac amyloidosis
Authors: Kono Atsushi K. , Yamada Naoaki , Higashi Masahiro , Kanzaki Suzu , Hashimura Hiromi , Morita Yoshiaki , Sakuma Toshiharu , Noguchi Teruo , Naito Hiroaki , Sugimura Kazuro
Published: June 2011

Purpose:

To detect abnormal myocardial tissue in patients with diffuse myocardial disease, we propose a simple technique of late gadolinium enhancement (LGE) using routine myocardial imaging modalities.

Materials and Methods:

We retrospectively reviewed LGE images from 51 patients with normal myocardium and 10 patients with pathologically proven cardiac amyloidosis (CA). We obtained sequential LGE images from patients at 2, 5, 10, and 20 minutes after injection of Gd‐DTPA (0.15 mmol/kg) with a fixed inversion time of 300 msec. We evaluated the signal intensity ratio of the myocardium to the left ventricular lumen (M/L) in one long and two short axial sections within 463 and 120 segments of normal myocardium and CA, respectively. Visually unenhanced and enhanced regions of myocardium were evaluated in each segment of patients with CA.

Results:

Among normal myocardium, M/L (means ± standard deviation; SD) was stable with time (2, 5, 10, and 20 min: 0.34 ± 0.03, 0.31 ± 0.05, 0.34 ± 0.07, and 0.42 ± 0.11, respectively). The calculated M/L of unenhanced (0.60 ± 0.20, 0.68 ± 0.19, 0.76 ± 0.20, and 1.09 ± 0.25, respectively) and enhanced myocardium (0.77 ± 0.27, 0.99 ± 0.29, 1.20 ± 0.40, and 1.45 ± 0.54, respectively) in patients with CA was significantly greater than that seen for the normal myocardium at each time and increased over time.

Conclusion:

In patients with CA, diffuse myocardial abnormalities can be demonstrated using M/L, and this technique may be useful for the characterization of other myocardial diseases. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
The relationships among spatiotemporal collagen gene expression, histology, and biomechanics following full‐length injury in the murine patellar tendon
Authors: Dyment Nathaniel A. , Kazemi Namdar , Aschbacher‐Smith Lindsey E. , Barthelery Nicolas J. , Kenter Keith , Gooch Cynthia , Shearn Jason T. , Wylie Christopher , Butler David L.
Published: June 2011

Tendon injuries are major orthopedic problems that worsen as the population ages. Type‐I (Col1) and type‐II (Col2) collagens play important roles in tendon midsubstance and tendon‐to‐bone insertion healing, respectively. Using double transgenic mice, this study aims to spatiotemporally monitor Col1 and Col2 gene expression, histology, and biomechanics up to 8 weeks following a full‐length patellar tendon injury. Gene expression and histology were analyzed weekly for up to 5 weeks while mechanical properties were measured at 1, 2, 5, and 8 weeks. At week 1, the healing region displayed loose granulation tissue with little Col1 expression. Col1 expression peaked at 2 weeks, but the ECM was highly disorganized and hypercellular. By 3 weeks, Col1 expression had reduced and by 5 weeks, the ECM was generally aligned along the tendon axis. Col2 expression was not seen in the healing midsubstance or insertion at any time point. The biomechanics of the healing tissue was inadequate at all time points, achieving ultimate loads and stiffnesses of 48% and 63% of normal values by 8 weeks. Future studies will further characterize the cells within the healing midsubstance and insertion using tenogenic markers and compare these results to those of tendon cells during normal development. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:28–36, 2012
Mid‐scale free‐flow electrophoresis with gravity‐induced uniform flow of background buffer in chamber for the separation of cells and proteins
Authors: Dong Yu‐Chao , Shao Jing , Yin Xiao‐Yang , Fan Liu‐yin , Cao Cheng‐Xi
Published: June 2011

A large‐scale free‐flow electrophoresis (LS‐FFE) is often too large for cell separation of lab scale, whereas micro‐FFE (μFFE) has great difficulty in cell isolation due to easy blockage by cell accumulation in μFFE. In this study, a mid‐scale FFE (MS‐FFE) is developed for cell and protein separations. The volume of the separation chamber (70×40×0.1–0.8 mm) is from 280 μL to 2.24 mL, much lower than that in an LS‐FFE but higher than that in a μFFE. Gravity is used for uniform flow of the background buffer only via a single pump with 16 channels and the sample is injected via an adjuster originally used for clinical intravenous injection. The experiments reveal that the hydrodynamic and electrohydrodynamic flows are much stable, and the Joule heat can be effectively dispersed without obvious positive or negative deviation as shown by the omega plots. By the device, Escherichia coli and Staphylococcus aureus, which easily accumulate to block μFFE and are separated with difficulty due to their same negative charges carried, can be well isolated under the conditions of 4.5 mM pH 8.5 Tris‐boric buffer (4.5 mM Tris, 4.5 mM boric acid) with 0.10 mM ethylene diamine tetraacetic acid and 5% m/v sucrose, 200 μL/min, 800 V, and sample injection via inlet 4. The mid‐scale FFE device could also be used for the separation of three model proteins of horse heart cytochrome c, myoglobin and bovine serum albumin. The device has clear significance for mid‐scale separation of cells and proteins.
Quick Polymerization from Electrospun Macroinitiators for Making Thermoresponsive Nanofibers
Authors: Brandl Christian , Greiner Andreas , Agarwal Seema
Published: June 2011

Thermoresponsive nanofibers by very fast grafting of N,N‐isopropylacrylamide (NIPAAm) from electrospun atom transfer radical polymerization (ATRP) macroinitiator are presented in this work. The heterogenous grafting of NIPAAm onto macroinitiator fibers could be done in few minutes, i.e., in less than 5 min. The procedure involved electrospinning of an ATRP macroinitiator and subsequent PNIPAAm grafting using “grafting from” technique. The ATRP Macroinitiator was based on a copolymer of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA). The growth of the PNIPAAm layer on electrospun fibers was followed by IR‐spectroscopy and SEM analysis. The temperature‐dependent‐phase transition was proven by contact angle measurements and could be shown on the same surface for many cycles.

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Human brain iron mapping using atlas‐based T2 relaxometry
Authors: Hasan Khader M. , Walimuni Indika S. , Kramer Larry A. , Narayana Ponnada A.
Published: June 2011

Several in vivo quantitative MRI techniques have been proposed as surrogate measures to map iron content in the human brain. The majority of in vivo quantitative MRI iron mapping methods used the age‐dependent iron content data based on postmortem data. In this work, we fused atlas‐based human brain volumetry obtained on a large cohort of healthy adults using FreeSurfer with T2 relaxation time measurements. We provide a brain atlas‐based T2 relaxation time map, which was subsequently used along with published postmortem iron content data to obtain a map of iron content in subcortical and cortical gray matter. We have also investigated the sensitivity of the linear model relating transverse relaxation rate with published iron content to the number of regions used. Our work highlights the challenges encountered on using the simple model along with postmortem data to infer iron content in several brain regions where postmortem iron data are scant (e.g., corpus callosum, amygdale). Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Feasibility of an Exercise‐Based Rehabilitation Programme for Chronic Hip Pain
Authors: Bearne Lindsay M. , Walsh Nicola E. , Jessep Sally , Hurley Michael V.
Published: June 2011

Background

Chronic hip pain is prevalent and disabling and has considerable consequences for the individual, and health and social care. Evidence‐based guidelines recommend that patients with chronic hip pain benefit from exercise, but these guidelines are predominantly based on the efficacy of knee rehabilitation programmes. Studies investigating hip rehabilitation programmes suggest that these may not be feasible, citing issues with case identification. This study evaluated the feasibility of an exercise‐based rehabilitation programme in a primary care hospital.

Methods

Forty‐eight participants with chronic hip pain were randomly allocated to receive a five‐week exercise and self‐management programme or to continue under the management of their general practitioner (GP). Participants were assessed at baseline, six weeks and six months. Outcome measures included Western Ontario and McMaster Universities osteoarthritis index physical function subscale, pain, objective functional performance, self‐efficacy, anxiety and depression.

Results

This programme was feasible, well tolerated and easily implemented into a primary healthcare facility. Adherence to the programme was high (81% attendance). Immediately following rehabilitation, all outcomes measures improved (effect sizes 0.2–0.4), although these improvements diminished at six months. There were no differences between the groups (all p > 0.05).

Conclusions

An exercise‐based rehabilitation programme was found to be feasible and well tolerated by people with chronic hip pain. The moderate effects in all outcomes immediately following rehabilitation suggested that it warrants further investigation. Issues with diagnosis and adaptations to the programme were identified and will be addressed in a randomized controlled trial. Copyright © 2011 John Wiley & Sons, Ltd.
Slip flow and heat transfer in rectangular and circular microchannels using hybrid FE/FV method
Authors: Palle Sridhar , Aliabadi Shahrouz
Published: June 2011

Rarefied gas flows typically encountered in MEMS systems are numerically investigated in this study. Fluid flow and heat transfer in rectangular and circular microchannels within the slip flow regime are studied in detail by our recently developed implicit, incompressible, hybrid (finite element/finite volume) flow solver. The hybrid flow solver methodology is based on the pressure correction or projection method, which involves a fractional step approach to obtain an intermediate velocity field by solving the original momentum equations with the matrix‐free, implicit, cell‐centered finite volume method. The Poisson equation resulting from the fractional step approach is then solved by node based Galerkin finite element method for an auxiliary variable, which is closely related to pressure and is used to update the velocity field and pressure field. The hybrid flow solver has been extended for applications in MEMS by incorporating first order slip flow boundary conditions. Extended inlet boundary conditions are used for rectangular microchannels, whereas classical inlet boundary conditions are used for circular microchannels to emphasize on the entrance region singularity. In this study, rarefaction effects characterized by Knudsen number (Kn) in the range of 0 ⩽ Kn ⩽ 0.1 are numerically investigated for rectangular and circular microchannels with constant wall temperature. Extensive validations of our hybrid code are performed with available analytical solutions and experimental data for fully developed velocity profiles, friction factors, and Nusselt numbers. The influence of rarefaction on rectangular microchannels with aspect ratios between 0 and 1 is thoroughly investigated. Friction coefficients are found to be decreasing with increasing Knudsen number for both rectangular and circular microchannels. The reduction in the friction coefficients is more pronounced for rectangular microchannels with smaller aspect ratios. Effects of rarefaction and gas‐wall surface interaction parameter on heat transfer are analyzed for rectangular and circular microchannels. For most engineering applications, heat transfer is decreased with rarefaction. However, for fluids with very large Prandtl numbers, velocity slip dominates the temperature jump resulting in an increase in heat transfer with rarefaction. Depending on the gas‐wall surface interaction properties, extreme reductions in the Nusselt number can occur. Present results confirm the existence of a transition point below and above wherein heat transfer enhancement and reduction can occur. Copyright © 2011 John Wiley & Sons, Ltd.
Proteomics characterization of gastrokine 1‐induced growth inhibition of gastric cancer cells
Authors: Yan Guang‐Rong , Xu Song‐Hui , Tan Zi‐Lu , Yin Xin‐Feng , He Qing‐Yu
Published: June 2011

We previously used proteomics technology to globally identify gastric cancer‐associated proteins and found that gastrokine 1 (GKN1) was dramatically underexpressed in gastric cancer tissues. Here, we further showed that GKN1 could inhibit cell growth and induce cell cycle arrest in gastric cancer cells. The activity of protein kinase PKCδ/θ was inhibited by GKN1, whereas the activity of ERK1/2 and JNK1/2 was increased by GKN1, suggesting that GKN1 induced growth inhibition of gastric cancer cells by synergistically regulating the activity of these protein kinases. Seventy‐four proteins were found to be regulated by GKN1 by proteomics analysis, including α‐enolase (ENO1) and Cathepsin D. Interestingly, ENO1 is an important hub in the protein–protein interaction network of the 74 differential proteins. Silencing of ENO1 resulted in growth inhibition and cell cycle arrest of gastric cancer cells, similar to the effect of GKN1 overexpression in cells, whereas ENO1 overexpression blocked GKN1‐induced growth inhibition and cell cycle arrest. These observations suggested that ENO1 downregulation played an important role in GKN1‐induced growth inhibition of gastric cancer cells.
Synthesis of various end‐functionalized polyesters by controlled/living ring‐opening polymerization of lactones using pentafluorophenylbis(triflyl)methane
Authors: Makiguchi Kosuke , Satoh Toshifumi , Kakuchi Toyoji
Published: June 2011

The ring‐opening polymerizations (ROPs) of ε‐caprolactone (ε‐CL) and δ‐valerolactone (δ‐VL) with pentafluorophenylbis(triflyl)methane (C6F5CHTf2) as the organocatalyst and alcohol initiators were carried out. For the ROP using 3‐phenyl‐1‐propanol (PPA) as the initiator in CH2Cl2 at room temperature with the [ε‐CL or δ‐VL]0/[PPA]0/[C6F5CHTf2] ratio of 50/1/0.1, the polymerization homogeneously proceeded to afford poly(ε‐caprolactone) (PCL) and poly(δ‐valerolactone) (PVL) having narrow polydispersity indices. The molecular weights of the obtained polymers determined from 1H NMR spectra showed good agreement with those estimated from the initial ratio of [ε‐CL or δ‐VL]0/[PPA]0 and monomer conversions. The 1H NMR, size exclusion chromatography, and matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry measurements strongly indicated that PCL and PVL possessed the 3‐phenylpropoxy group as the α‐chain‐end and the hydroxy group as the ω‐chain‐end. In addition, the controlled/living nature for the C6F5CHTf2‐catalyzed ROP of lactones was confirmed by kinetic and chain‐extension experiments. The block copolymerization of PCL and PVL successfully proceeded to afford PCL‐b‐PVL and PVL‐b‐PCL. In addition, various end‐functionalized PCLs and PVLs with narrow molecular weight distributions were synthesized by the ROP of ε‐CL and δ‐VL using functional initiators, such as 6‐azido‐1‐hexanol, 2‐hydroxyethyl methacrylate, propargyl alcohol, N‐(2‐hydroxyethyl)maleimide, 4‐vinylbenzyl alcohol, 5‐hexen‐1‐ol, and 5‐norbornene‐2‐methanol. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011