bluuebunny/crossref_metadata_2025 huggingface dataset:
Managing change through employee empowerment
Authors: Rothermel Rick , LaMarsh Jeanenne
Published: December 2011

Discouraged by the challenges inherent in making organizational changes, many business leaders seek to overcome these obstacles by establishing a change management program. To ensure timely and effective results, such a program needs to involve not only the organization's leaders as sponsors of change and the project team members as change agents, but also the employees who will be affected by the alterations to the work environment. As one hospital that took this approach discovered, empowering those individuals as partners in the change process does far more than increase the probability of a successful change. It also teaches the employees a new way of dealing with it. © 2012 Wiley Periodicals, Inc.
Bacterial Adhesion‐Resistant Poly(2‐hydroxyethyl methacrylate) Derivative for Mammalian Cell Cultures
Authors: Sohn Eun‐Ho , Ahn Jooyeon , Bhang Suk Ho , Kang Junil , Yoon Jeyong , Kim Byung‐Soo , Lee Jong‐Chan
Published: December 2011

In an attempting to find new biomaterials for mammalian cell culture, PHEMA derivatives with ester side groups are synthesized by one‐step polymer‐analogous reaction. These polymers show excellent antifouling properties against S. epidermidis and P. aeruginosa while their cytotoxicity and proliferation activity for HDF cell are on a similar level as commercially available TCPS. The interesting bioadhesion property is systematically correlated with surface properties of the PHEMA derivatives.

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Thermally Modulated Retention of Lymphoctytes on Polymer‐Brush‐Grafted Glass Beads
Authors: Nagase Kenichi , Mukae Naoto , Kikuchi Akihiko , Okano Teruo
Published: December 2011

Thermoresponsive PIPAAm‐brush‐grafted glass beads are prepared through siATRP and their physicochemical properties are characterized by micro‐nitrogen analysis, XPS, and contact angle measurements. The amount of grafted PIPAAm on glass bead surfaces can be controlled by varying the ATRP reaction time, leading to a modulation of the temperature‐dependent wettability of the prepared surfaces. To evaluate a possible use of the beads as cell separation matrices, loading with rat lymphocytes from mesenteric lymph nodes is studied. The results show that the interaction between PIPAAm brushes and lymphocytes can be controlled by modulating PIPAAm brush length and temperature. The PIPAAm‐brush‐grafted beads might therefore be useful as effective cell separation matrices.

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Correction of systematic errors in quantitative proton density mapping
Authors: Volz Steffen , Nöth Ulrike , Deichmann Ralf
Published: December 2011

Interest in techniques yielding quantitative information about brain tissue proton densities is increasing. In general, all parameters influencing the signal amplitude are mapped in several acquisitions and then eliminated from the image data to obtain pure proton density weighting. Particularly, the measurement of the receiver coil sensitivity profile is problematic. Several methods published so far are based on the reciprocity theorem, assuming that receive and transmit sensitivities are identical. Goals of this study were (1) to determine quantitative proton density maps using an optimized variable flip angle method for T1 mapping at 3 T, (2) to investigate if systematic errors can arise from insufficient spoiling of transverse magnetization, and (3) to compare two methods for mapping the receiver coil sensitivity, based on either the reciprocity theorem or bias field correction. Results show that insufficient spoiling yields systematic errors in absolute proton density of about 3–4 pu. A correction algorithm is proposed. It is shown that receiver coil sensitivity mapping based on the reciprocity theorem yields erroneous proton density values, whereas reliable data are obtained with bias field correction. Absolute proton density values in different brain areas, evaluated on six healthy subjects, are in excellent agreement with recent literature results. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Dielectric studies of tetraaryl and triaryl polycarbonates and comparisons with bisphenol A‐polycarbonate
Authors: Fontanella J. J. , Boyles D. A. , Filipova T. S. , Awwad S. , Edmondson C. A. , Bendler J. T. , Wintersgill M. C. , Lomax J. F. , Schroeder M. J.
Published: December 2011

The relative permittivity, loss, and breakdown strength are reported for a commercial sample of bisphenol A‐polycarbonate (comm‐BPA‐PC) and a purified sample of the same polymer (rp‐BPA‐PC) as well as for two new polycarbonates having low molecular cross‐sectional areas, namely a copolymer of tetraaryl polycarbonate and BPA‐PC (TABPA‐BPA‐PC) and a triaryl polycarbonate homopolymer (TriBPA‐PC). The glass transition temperatures of the new polymers are higher than the Tg of BPA‐PC (187 and 191 °C vs. 148 °C). Relative permittivity and loss measurements were carried out from 10 to 105 Hz over a wide temperature range, and results for the α‐ and γ‐relaxation regions are discussed in detail. For the α‐relaxation, the isochronal peak position, Tα, scales approximately with Tg. On the other hand, the peak temperature for the γ‐relaxation is approximately constant, independent of Tg. Also, in contrast to what is observed for α, γ exhibits a strong increase in peak height as temperature/frequency increases and a significant difference is found between Arrhenius plots determined from isochronal and isothermal data analyses. Next, the γ‐relaxation region for comm‐BPA‐PC and associated activation parameters show strong history/purity effects. The activation parameters also depend on the method of data analysis. The results shed light on discrepancies that exist in the literature for BPA‐PC. The shapes of the γ loss peaks and hence glassy‐state motions for all the polymers are very similar. However, the intensities of the TriBPA‐PC and TABPA‐BPA‐PC γ peaks are reduced by an amount that closely matches the reduced volume fraction of carbonate units in the two new polymers. Finally, for comm‐BPA‐PC, the breakdown strength is strongly affected by sample history and this is assumed to be related to volatile components in the material. It is found that the breakdown strengths for TriBPA‐PC and TABPA‐BPA‐PC are relatively close to that for rp‐BPA‐PC with the value for TriBPA‐PC being slightly larger than that for rp‐BPA‐PC or the value usually reported for typical capacitor grade polycarbonate. Finally, it is shown that the real part of the relative permittivity remains relatively constant from low temperatures to Tg. Consequently, based on the dielectric properties, TriBPA‐PC and TABPA‐BPA‐PC should be usable in capacitors to at least 50 °C higher than BPA‐PC. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Optical Characterization of Large Caliber Muzzle Blast Waves
Authors: Steward Bryan J. , Gross Kevin C. , Perram Glen P.
Published: December 2011

High‐speed, 1,600 Hz, visible imagery of the blast wave from 147 firings of a 152 mm howitzer were observed for three different propellant charges. Blast wave trajectories were determined at 0.5–13 m from the muzzle exit, yielding initial velocities of Mach 3–4 that decayed to near acoustic within the imager field of view. A piecewise treatment of the Taylor‐Sedov point blast model was sufficient to describe the trajectories with an average error of 0.1 m. The trajectories were consistent with a three‐dimensional expansion and constant rate of energy release. A Constant Breech Pressure gun model was used to estimate total energy of the muzzle flow, and the efficiency of depositing energy into the blast wave was 18–24 %. Plume temperatures of approximately 980–1,210 K were estimated by partitioning energy and were correlated with likelihood of plume combustion. Classification of charge type based on energy deposition rate was modest, characterized by a ratio of between‐class to within‐class variance of 1.3, for the very similar events.
Implications of intra‐family and external ownership transfer of family firms: short‐term and long‐term performance differences
Authors: Wennberg Karl , Wiklund Johan , Hellerstedt Karin , Nordqvist Mattias
Published: December 2011

We contrast the performance consequences of intra‐family versus external ownership transfers. Investigating a sample of all private family firms in Sweden that went through ownership transfers during 10 years, we find that firms transferred to external owners outperform those transferred within the family, but that survival is higher among intra‐family transfers. We attribute these performance differences to the long‐term orientation of family firms passed on to the next generation and to the entrepreneurial willingness of acquirers to bear uncertainty. Based on distinct ownership transition routes and theoretical mechanisms explaining performance differences, we outline implications for family business and entrepreneurship research. Copyright © 2011 Strategic Management Society.
Resource orchestration in family firms: investigating how entrepreneurial orientation, generational involvement, and participative strategy affect performance
Authors: Chirico Francesco , Sirmon David G. , Sciascia Salvatore , Mazzola Pietro
Published: December 2011

Drawing on the process of resource orchestration, we argue a co‐alignment of multiple factors is needed for family firms to increase performance through entrepreneurship. Specifically, we posit that entrepreneurial orientation provides the mobilizing vision to use the heterogeneous yet complementary knowledge and experiences offered by increased generational involvement toward entrepreneurship. However, without a coordinating mechanism, generational involvement leads to conflict and negative outcomes. When, instead, it is also coordinated via a participative strategy, performance gains are achieved. In sum, results suggest that realizing the benefits from entrepreneurship in family firms is a complicated matter affected by the synchronization of entrepreneurial orientation, generational involvement, and participative strategy. Copyright © 2011 Strategic Management Society.
European guidance–a project of the European Psychiatric Association
Authors: Gaebel W. , Möller H.-J.
Published: December 2011

Evidence based medicine is a cornerstone of modern medicine including psychiatry. Treatment practice guidelines are nowadays available for guiding mental health care mainly with a focus on specific disorders. Many important clinical situations or problems beyond treatment, however, are lacking proper guidance. It is in this scope that a European Psychiatry Association (EPA) has developed its own program, the European Guidance Project. The present special issue presents six topics out of these series of guidance documents.
Tristetraprolin down‐regulates IL‐17 through mRNA destabilization
Authors: Lee Hyun Hee , Yoon Nal Ae , Vo Mai-Tram , Kim Chae Won , Woo Je Moon , Cha Hee Jeong , Cho Young Woo , Lee Byung Ju , Cho Wha Ja , Park Jeong Woo
Published: December 2011

An excess of interleukin 17 (IL‐17) may contribute to chronic inflammatory disorders, but mechanisms that regulate IL‐17 in immune cells are unclear. Here we report that tristetraprolin (TTP) inhibits IL‐17 production in human T cell lines. Overexpression of TTP decreased the expression of IL‐17. Conversely, TTP inhibition by siRNA increased IL‐17 production. IL‐17 mRNA contains eight AREs within its 3′UTR. TTP bound directly to the IL‐17 mRNA 3′UTR at a location between the fourth and seventh AREs and enhanced decay of IL‐17 transcripts. These results suggest that TTP could control IL‐17‐mediated inflammation.
The protein chaperone Ssa1 affects mRNA localization to the mitochondria
Authors: Eliyahu Erez , Lesnik Chen , Arava Yoav
Published: December 2011

Many nuclear‐transcribed mRNAs encoding mitochondrial proteins are localized near the mitochondrial outer membrane. A yet unresolved question is whether protein synthesis is important for transport of these mRNAs to their destination. Herein we present a connection between mRNA localization in yeast and the protein chaperone Ssa1. Ssa1 depletion lowered mRNA association with mitochondria while its overexpression increased it. A genome‐wide analysis revealed that Ssa proteins preferentially affect mRNAs encoding hydrophobic proteins, which are expected targets for these protein chaperones. Importantly, deletion of the mitochondrial receptor Tom70 abolished the impact of Ssa1 overexpression on mRNAs encoding Tom70 targets. Taken together, our results suggest a role for Ssa1 in mediating localization of nascent peptide‐ribosome‐mRNA complexes to the mitochondria, consistent with a co‐translational transport process.
Nonlinear interactions between deep-water waves and currents
Authors: Moreira R. M. , Peregrine D. H.
Published: December 2011

The effects of nonlinearity on a train of linear water waves in deep water interacting with underlying currents are investigated numerically via a boundary-integral method. The current is assumed to be two-dimensional and stationary, being induced by a distribution of singularities located beneath the free surface, which impose sharp and gentle surface velocity gradients. For ‘slowly’ varying currents, the fully nonlinear results confirm that opposing currents induce wave steepening and breaking within the region where a high convergence of rays occurs. For ‘rapidly’ varying currents, wave blocking and breaking are more prominent. In this case reflection was observed when sufficiently strong adverse currents are imposed, confirming that at least part of the wave energy that builds up within the caustic can be released in the form of partial reflection and wave breaking. For bichromatic waves, the fully nonlinear results show that partial wave blocking occurs at the individual wave components in the wave groups and that waves become almost monochromatic upstream of the blocking region.
Amphipods (Crustacea: Amphipoda) associated with red algae (Rhodophyta) in Kandalaksha Bay (the White Sea, Russia)
Authors: Uryupova Ekaterina F. , Spiridonov Vassily A. , Zhadan Dmitry G.
Published: December 2011

Amphipods' assemblages living in the red algae communities were studied in Velikaya Salma Strait (Kandalaksha Bay, north-western White Sea) in the depth range of 3–11 m. Sampling sites were located along the depth and shore exposure gradients in the areas with a significant number of rhodophytes. In total 12 species of amphipods were found withAmpithoe rubricataandCrassicorophium bonelliibeing most common and abundant.Gammaropsis melanopsandPleusymtes glaberwere revealed as subdominant species. As an algal grazerA. rubricataappeared to be the species most closely associated with various algal assemblages.Crassicorophium bonelliiwere found on substrates being a deposit feeder predominantly inhabiting mixed assemblages of red algae where deposition and accumulation of seston most likely took place.Gammaropsis melanopsandP. glaberare known as grazers but they preferred the habitats with both red algae and sponges. None of the species can be considered as obligate inhabitants of red algae hosts.Ampithoe rubricataandC. bonelliioccurred in red algae communities in the shallow area (about 4 m). The most diverse and quantitatively rich amphipod assemblages were found at depths of 8–9 m in the area protected from waves and surf by the islands. Three of the most common and abundant speciesA. rubricata, C. bonelliiandP. glaberare considered as amphiboreal while most of the species associated with rhodophytes belong to the Arctic-boreal ones. Amphiboreal species are presumably adapted to a broader temperature-range, in particular to higher summer temperature, than the Arctic-boreal species; they most likely have an advantage when occupying biotopes at shallow subtidal depth with local conditions in the White Sea.
The neuropsychology of prefrontal function in antisocial personality disordered offenders with varying degrees of psychopathy
Authors: Dolan M.
Published: December 2011

Background

Despite methodological differences between studies, it has been suggested that psychopathy may be associated with a ventromedial prefrontal cortex (VMPFC) deficit and antisocial personality disorder (ASPD), as classified in the DSM-IV, with a broader range of deficits in dorsolateral prefrontal cortex (DLPFC) and VMPFC function.

Method

Ninety-six male offenders with ASPD who were assessed using the Psychopathy Checklist: Screening Version (PCL:SV) and 49 male right-handed healthy controls (HCs), matched for age and IQ, completed a neuropsychological test battery.

Results

Offenders with ASPD displayed subtle impairments on executive function tasks of planning ability and set shifting and behavioural inhibition compared to HCs. However, among the offenders with ASPD there was no significant association between executive function impairment and scores on the measure of psychopathy.

Conclusions

Psychopathic traits in offenders with ASPD are not associated with greater executive function impairment.
Active Citizenship: An Empirical Investigation
Authors: Onyx Jenny , Kenny Sue , Brown Kevin
Published: December 2011

This paper reports on a study of what active citizenship means from the perspective of citizens who are active within third sector organisations. It is based on an empirical study involving 1,610 respondents across 11 towns in six countries. The study explored how active citizenship is manifested, by gathering data on attitudes towards social changes and the forms and practices of active citizenship. There are two major, and apparently contradictory themes emerging in the data. The first theme provides a portrait of active engagement, proactively, and sometimes oppositionally working for a better world. On the other hand, citizens by and large avoid active oppositional engagement in the political process. They prefer to work collaboratively with government and to work at the local level. This second theme can be understood as social maintenance, support for existing structures that facilitates community cohesion, while providing relief for the disadvantaged, often with a conservative charity or welfare orientation. Following the work of Touraine, the study revealed how citizens act at the local rather than the national level, and focus on concrete issues and interpersonal relations rather than political action aimed at wider policy change. While this form of citizenship action can reflect a conservative form of maintenance, it is equally a creative new form of association and mutual support.
Wet surface and dense atmosphere on early Mars suggested by the bomb sag at Home Plate, Mars
Authors: Manga Michael , Patel Ameeta , Dufek Josef , Kite Edwin S.
Published: December 2011

We use the Mars Exploration Rover Spirit observation of a bomb sag produced by an explosive volcanic eruption to infer the atmospheric density at the time of eruption. We performed analogue experiments to determine the relationship between the wetness of the substrate and the velocity and density of impacting clasts and 1) the formation (or not) of bomb sags, 2) the morphology of the impact crater, and 3) the penetration depth of the clast. The downward deflection of beds seen on Mars is consistent with water‐saturated sediment in the laboratory experiments. Collision angles <20 degrees from vertical are needed to produce bomb sags. From the experiments we infer an impact velocity up to 4 × 101 m/s, lower than ejection velocities during phreatic and phreatomagmatic eruptions on Earth. If this velocity represents the terminal subaerial impact velocity, atmospheric density exceeded 0.4 kg/m3 at the time of eruption, much higher than at present.
Estimating labile particulate iron concentrations in coastal waters from remote sensing data
Authors: McGaraghan Anna R. , Kudela Raphael M.
Published: December 2011

Owing to the difficulties inherent in measuring trace metals and the importance of iron as a limiting nutrient for biological systems, the ability to monitor particulate iron concentration remotely is desirable. This study examines the relationship between labile particulate iron, described here as weak acid leachable particulate iron or total dissolvable iron, and easily obtained bio‐optical measurements. We develop a bio‐optical proxy that can be used to estimate large‐scale patterns of labile iron concentrations in surface waters, and we extend this by including other environmental variables in a multiple linear regression statistical model. By utilizing a ratio of optical backscatter and fluorescence obtained by satellite, we identify patterns in iron concentrations confirmed by traditional shipboard sampling. This basic relationship is improved with the addition of other environmental parameters in the statistical linear regression model. The optical proxy detects known temporal and spatial trends in average surface iron concentrations in Monterey Bay. The proxy is robust in that similar performance was obtained using two independent particulate iron data sets, but it exhibits weaker correlations than the full statistical model. This proxy will be a valuable tool for oceanographers seeking to monitor iron concentrations in coastal regions and allows for better understanding of the variability of labile particulate iron in surface waters to complement direct measurement of leachable particulate or total dissolvable iron.
The sensitivity of turbidity currents to mass and momentum exchanges between these underflows and their surroundings
Authors: Traer M. M. , Hilley G. E. , Fildani A. , McHargue T.
Published: December 2011

This study examines sensitivity of the layer‐averaged equations of motion for turbidity currents to changes in the parameters that describe how mass, momentum, and turbulent kinetic energy (TKE) are transferred between the flow and its surroundings in a channelized environment. This analysis shows that one‐dimensional flows traversing a constant slope are sensitive to small changes in the sediment and clear‐water entrainment parameters that describe mass transfer relationships. Uncertainties within these proposed relationships were quantified by applying a Bayesian sampler to available laboratory data. Sampled entrainment parameter values show a strong preference to values differing from those previously determined. The uncertainties within the entrainment relationships were then propagated into the dynamics of a reference flow (described by flow velocity, sediment flux, and height) to assess the degree to which uncertainty within the mass transfer functions affects predictions of flow behavior down‐slope. Given the range of sampled values, flow parameters were found difficult to predict beyond 200–500 meters. The entrainment relationships largely control the spatial and temporal patterns of erosion and deposition and thus the channel architectures. A wide range of entrainment parameters might be necessary to accurately predict the range of plausible flow dynamics and resulting channel morphologies.
Chromogens, Fluorogens, Trojan Horses and their Use in Culture Media
Authors: Druggan Patrick
Published: December 2011

Synthetic enzyme substrates were first used to identify lac mutants in Escherichia coli in the late 1940s, but this technology was not used in food microbiology until the late 1980s. Owing to the increased specificity afforded by chromogens and fluorogens in the detection of pathogens, their use has steadily increased. A major obstacle to greater understanding and use of chromogenic and fluorogenic substrates by food microbiologists is a lack of understanding of chemical nomenclature and molecular biology. Details of the relationship between natural sugars and synthetic analogues are given, together with a description of the molecular biology involved in the induction of operons, transportation and hydrolysis of substrates. The nature of a variety of fluorogens, chromogens and Trojan horses is discussed, together with the benefits this technology can bring in food analysis.
Harvesting Solar Energy through Natural or Artificial Photosynthesis: Scientific, Social, Political and Economic Implications
Authors: Larkum* A. W. D.
Published: December 2011

Natural photosynthesis is an inherently inefficient process that developed millions or even billions of years ago. Thus present systems for harvesting solar energy in the form of organic carbon are inefficient compared with solar photovoltaic cells. The highest productivities are about 1% compared with ∼10% for solar cells. Somewhat higher rates can be envisaged in the future but only through the use of a high solar footprint (the area of the Earth's surface needed to sustain a certain energy output), i.e. by using extra energy, which in a long-term sustainable world can come only from solar energy. While bioenergy production from algae may be lead to even greater efficiencies in the future it seems that this will only come about by an even higher solar footprint. Additionally, while bioenergy production may seem to be favourable in terms of carbon footprint, in practice there are several unfavourable outcomes. Further, bioenergy production immediately conflicts with use of the Earth's surface for food production and/or the need to maintain biodiversity. Thus artificial photosynthesis with very much higher expected efficiencies than natural photosynthesis is a worthwhile goal, in that it could potentially compete in efficiency with energy production by photovoltaic cells.
Photophysics of Photosynthetic Reaction Centres
Authors: Renger Thomas
Published: December 2011

This chapter relates the structural features of photosynthetic reaction centres, discussed in the previous chapter, to their function, i.e., the capture of excitation energy, primary charge separation and charge stabilization. Special attention is paid to the question of what the common building principles are that have led to a very similar pigment organization in all known reaction centres of photosynthetic organisms, and how subtle differences in the structure are related to an optimization of photochemical efficiency. As an important example of such optimization we compare the type II reaction centres of purple bacteria and higher plants. Despite the very similar arrangement of chlorin pigments in the two reaction centres, there are important differences in the optical properties and of some mechanistic details of the primary photophysical reactions. For example, the sink for triplet and singlet excitation energy in the reaction centre of photosystem II of higher plants, and thereby the primary electron donor, is not the central chlorophyll dimer (the special pair) as in purple bacteria, but a special chlorophyll monomer. We argue that evolution had to incorporate these changes in order to allow photosystem II to use water as an electron source.
Photosynthetic O2 Evolution
Authors: Messinger Johannes , Noguchi Takumi , Yano Junko
Published: December 2011

Oxygen evolution by photosynthetic water oxidation has shaped life on planet Earth. This unique biological reaction may provide important clues for developing artificial devices (‘artificial leaves’) for splitting water into O2 and H2 by visible light. In this chapter, we summarize the latest structural and mechanistic information on photosystem II, its water-oxidizing complex (WOC), and O2 formation from water at its Mn4CaO5 cluster. Structural information on the WOC derived by X-ray crystallography, X-ray spectroscopy, EPR/ENDOR, and theoretical approaches are compared and discussed in detail. After a description of the basic mechanism of water-oxidation (Kok model), our knowledge about the storage of oxidizing equivalents, substrate water-binding, the release of the products O2 and H+, and the energetics of water-oxidation is described. The near electroneutrality of the water-splitting process via coupling of electron and proton transfer steps and the stabilization of the initial light-driven charge separation by spatial separation and heat dissipation are emphasized as important design principles for coupling fast photochemistry with comparatively slow chemical reactions. The chapter concludes with a discussion of recent DFT-based mechanistic proposals for photosynthetic water oxidation, and with an attempt to identify lessons for the design of artificial systems.
Energy from Photosystem II: Manganese Water Oxidation Catalysts
Authors: Brimblecombe Robin , Dismukes G. Charles , Swiegers Gerhard F. , Spiccia Leone
Published: December 2011

Photosystem II is a blueprint for the design of water oxidation catalysts for incorporation into photoelectrochemical devices capable of efficient solar hydrogen production. In this chapter, we review ongoing efforts to develop manganese water oxidation catalysts. These catalytic systems embody one or more of the key features observed in the PSII water oxidizing complex – the concentration of high energy oxidation states of multiple manganese centres, the ability to facilitate di-oxygen bridge formation, a dynamic supporting environment that prevents dissociation of the complex, assists in electron and proton removal, and aids coupling to a photoactive charge separation centre – with the most successful examples incorporating most or all of these key features. Promising advances have been made towards achieving solar water oxidation, ranging from the direct coupling of Mn complexes to Ru dyes or TiO2 to demonstrate successful oxidation of Mn centers, to achieving direct light driven water oxidation by coupling a Nafion supported Mn catalysts to a Ru-dye sensitized TiO2 electrode, which should stimulate further interesting developments.
Structure and Function of Hydrogenase Enzymes
Authors: Lubitz Wolfgang , Ogata Hideaki , Reijerse Eduard , Higuchi Yoshiki
Published: December 2011

The understanding of the basic principles of hydrogen production and utilization by the enzyme hydrogenase is a goal of major importance both for basic research and possible applications in our society. Hydrogenases are enzymes that facilitate the uptake and release of molecular hydrogen using a heterolytic reaction mechanism: H2⇌H++H−⇌2H++2e−. The acidity of H2, which is extremely low, is dramatically increased by binding to a metal. Many of the currently used catalysts for anthropogenic utilization of hydrogen involve precious metals such as platinum, while Nature's catalysts are based on cheap and abundant first row transition metals. Three phylogenetically distinct classes of hydrogenase are known; these are the [NiFe], the [FeFe] and the [Fe] hydrogenases. The first two classes have active sites containing binuclear metal cores with an unusual ligand sphere, whereas the third class harbors a mononuclear iron next to a special organic cofactor. In all these hydrogenases, the protein plays an important role for tuning the active site properties, but also by providing pathways for protons, electrons as well as dihydrogen. An important feature of the native systems is the very high turnover frequency (up to ∼104 s−1). Hydrogenases from (hyper)thermophilic organisms show a remarkable stability at high temperatures (up to ∼100°C) and several [NiFe] hydrogenases (e.g. from Knallgas bacteria) are active even in the presence of ambient levels of molecular oxygen. As discussed in this chapter, a combination of X-ray crystallography, spectroscopy, electrochemistry and quantum chemistry was instrumental in characterizing the hydrogenases with respect to their structure and function. Furthermore, mechanisms for the enzymatic reactions are proposed and guidelines for the construction of biomimetic hydrogenase model systems are provided.
Lactococcus lactis HemW (HemN) is a haem-binding protein with a putative role in haem trafficking
Authors: Abicht Helge K. , Martinez Jacobo , Layer Gunhild , Jahn Dieter , Solioz Marc
Published: December 2011

Lactococcus lactis cannot synthesize haem, but when supplied with haem, expresses a cytochrome bd oxidase. Apart from the cydAB structural genes for this oxidase, L. lactis features two additional genes, hemH and hemW (hemN), with conjectured functions in haem metabolism. While it appears clear that hemH encodes a ferrochelatase, no function is known for hemW. HemW-like proteins occur in bacteria, plants and animals, and are usually annotated as CPDHs (coproporphyrinogen III dehydrogenases). However, such a function has never been demonstrated for a HemW-like protein. We here studied HemW of L. lactis and showed that it is devoid of CPDH activity in vivo and in vitro. Recombinantly produced, purified HemW contained an Fe–S (iron–sulfur) cluster and was dimeric; upon loss of the iron, the protein became monomeric. Both forms of the protein covalently bound haem b in vitro, with a stoichiometry of one haem per monomer and a KD of 8 μM. In vivo, HemW occurred as a haem-free cytosolic form, as well as a haem-containing membrane-associated form. Addition of L. lactis membranes to haem-containing HemW triggered the release of haem from HemW in vitro. On the basis of these findings, we propose a role of HemW in haem trafficking. HemW-like proteins form a distinct phylogenetic clade that has not previously been recognized.
Fighting the curse of dimensionality in first-principles semiclassical calculations: Non-local reference states for large number of dimensions
Authors: Ceotto Michele , Tantardini Gian Franco , Aspuru-Guzik Alán
Published: December 2011

Semiclassical methods face numerical challenges as the dimensionality of the system increases. In the general context of the theory of differential equations, this is known as the “curse of dimensionality.” In the present manuscript, we apply the recently-introduced multi-coherent states semiclassical initial value representation (MC-SC-IVR) approach to extend the applicability of first-principles semiclassical calculations. The proposed strategy involves the use of non-local coherent states with the goal of increasing accuracy in the Fourier transforms, and on the other hand, allows for the selection of peaks of different frequencies. The ability to filter desired peaks is important for analyzing the power spectra of complex systems. The MC-SC-IVR approach allows us to solve a 19-dimensional test system and to resolve on-the-fly the power spectra of the formaldehyde molecule with very few classical trajectories.
188 HUMAN FOLLICULAR FLUID IN EQUINE IN VITRO MATURATION MEDIUM SUPPORTS IN VITRO MATURATION AND VIABLE INTRACYTOPLASMIC SPERM INJECTION-BLASTOCYST PREGNANCIES
Authors: Makloski C. , Gotti R. , Harris K. , Bottger J. , Meintjes M.
Published: December 2011

The aim of this study was 2-fold: (1) To determine if altrenogest-treated mares will yield higher numbers of quality in vitro-matured (IVM) oocytes than early pregnant mares and cycling/control mares and (2) if the addition of human follicular fluid (HFF) to IVM medium can support IVM and viable pregnancies from in vitro-produced blastocysts. In this study, 18 mares were assigned to 3 equally sized treatment groups and each mare was subjected to follicle aspiration every 10 to 11 days without monitoring follicular growth. The 3 treatment groups were altrenogest-treated mares (0.044 mg kg–1 of PO daily), early pregnant mares (30–110 days) and control/cycling mares. Using transvaginal ultrasound guidance, all visible follicles were aspirated. Altrenogest-treated mares each yielded more follicles (8.75) per aspiration session when compared with the control mare group (5.75) and the pregnant mare group (3.72), but there was no difference in oocyte recovery rates among the groups (Table 1). A limited number of these oocytes were subjected to in vitro maturation. After heated (38.5°C) transport of oocytes to an off-site laboratory, the oocytes were placed in maturation medium containing 10% HFF obtained from preovulatory follicles after ovulation induction, 20% serum substitute supplement and no hormones for 36 h. This approach yielded a maturation rate of 61.8, 68.8 and 82.0% for the altrenogest, pregnant and control treatment groups, respectively (not significant). Mature oocytes (n = 65) were injected with frozen-thawed sperm using a standard intracytoplasmic sperm injection (ICSI) technique. Four expanding blastocysts (Table 1) were selectively transported back to the embryo transfer facility and transcervically transferred into recipient mares on Day 6 post-ICSI. These 4 transfers resulted in 2 viable, normally progressing pregnancies, ongoing beyond 60 days of gestation. Both pregnancies resulted from the altrenogest-treated aspiration group. In this study we concluded that (1) altrenogest-treated mares provide more follicles and may be a better source of viable immature oocytes for the production of ICSI embryos and foals, but their overall advantage is unclear; (2) addition of HFF to IVM media, in the absence of added gonadotropins, can support oocyte maturation, blastocyst production and viable pregnancies; (3) an aspiration schedule of every 10 to 11 days without ultrasonic monitoring can yield viable immature oocytes, capable of producing ICSI blastocysts, resulting in viable pregnancies.

Table 1.Altrenogest-treated mares compared to early pregnant mares and control mares
205 SELECTIVE ANTITUMOR THERAPEUTIC EFFECT OF 5-FLUOROCYTOSINE AND INTERFERON-BETA AGAINST BREAST AND ENDOMETRIAL CANCER CELLS BY ENGINEERED STEM CELLS EXPRESSING CYTOSINE DEAMINASE AND HUMAN INTERFERON-BETA
Authors: Yi B.-R. , Hwang K.-A. , Choi K.-C.
Published: December 2011

When genetically engineered with chemo- or immunotherapeutic genes, stem cells can exhibit a potent therapeutic efficacy combined with their strong tumour tropism. The stem cells were genetically engineered to express a bacterial cytosine deaminase (CD) gene and/or a human interferon-β (IFN-b) gene; thus, 2 stem cell lines, HB1.F3.CD and HB1.F3.CD.IFN-b, were generated, respectively. The CD gene, one of suicide gene, can convert the nontoxic prodrug 5-fluorocytosine (5-FC) to an active form, 5-fluorouracil (5-FU), which has a powerful cytotoxic effect on cancer cells. In addition, human IFN-b is a typical cytokine having an antitumour effect. Using reverse transcription-PCR (RT-PCR), we confirmed CD and/or IFN-b gene expression in HB1.F3 (maternal stem cells) and HB1.F3.CD and HB1.F3.CD.IFN-b cells and the expression of chemoattractant ligands and receptors including stem cell factor (SCF), CXCR4, c-kit, vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) in breast (MCF-7) and endometrial cancer (Ishikawa) cells. To determine the migratory capability of engineered stem cells, we performed a modified trans-well assay. In addition, to identify their therapeutic efficacy, we co-cultured HB1.F3.CD or HB1.F3.CD.IFN-b with breast and endometrial cancer cells and cell viability was measured by MTT assay. The engineered stem cells expressed CD and IFN-b genes and several chemoattractant molecules, SCF, CXCR4, VEGF/VEGFR2 and c-kit, were strongly expressed in breast and endometrial cancer cells. These stem cells were effectively migrated to breast and endometrial cancer cells due to chemoattractant molecules secreted by breast and endometrial cancer cells. In therapeutic efficacy, the viability of breast and endometrial cancer cells treated with 5-FC was reduced in the presence of the HB1.F3.CD and HB1.F3.CD.IFN-b cells. Cell viability was more reduced when co-cultured with HB1.F3.CD.IFN-b compared with HB1.F3.CD cells. In conclusion, the results from the present study suggest that genetically modified stem cells expressing CD and IFN-b can be used as a gene-based therapy for treating breast and endometrial cancer via their tumour tropism.
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2011-0005723).
213 TRANSCRIPTOMIC COMPARISON BETWEEN PORCINE ADIPOSE AND BONE MARROW MESENCHYMAL STEM CELLS DURING IN VITRO OSTEOGENIC AND ADIPOGENIC DIFFERENTIATION
Authors: Monaco E. , Bionaz M. , Lima A. , Hurley W. L. , Wheeler M. B.
Published: December 2011

Previous data support the use of adipose-derived stem cells (ASC) as an alternative to bone marrow as a source of adult stem cells for therapeutic purposes. The aims of the present study were to directly compare the transcriptome of ASC and bone marrow-derived mesenchymal stem cells (BMSC) in order to uncover potential functional differences between the two mesenchymal stem cells (MSC), to identify differentially expressed genes (DEG) and related functions that may drive MSC to become bone or adipose and to identify potential markers for adipogenic and osteogenic differentiation. ASC and BMSC, isolated from subcutaneous adipose tissue and femurs of 3 adult pigs were differentiated in vitro along the osteogenic and adipogenic lineage for up to 4 wk. At 0, 2, 7 and 21 days of differentiation, RNA was extracted for microarray analysis. Data were normalized by Lowess and statistical analysis run using ANOVA with Benjamini-Hochberg false discovery rate (FDR) correction. Data mining was carried out using Ingenuity Pathway Analysis and DAVID. Analysis of undifferentiated MSC for genes with the highest expression and DEG between MSC and fully differentiated tissues uncovered MSC being featured by low immunity and high angiogenic capacity. The direct comparison between differentiation lineages indicated that the expression of a limited number of genes has to change in order to determine cell fate. Functional analysis of the DEG between differentiation lineages indicated that osteogenesis is characterised by larger cell proliferation and cytoskeleton organisation with a crucial role of G-proteins compared to adipogenesis. On the other hand, adipogenesis is driven by PPAR signalling, has greater angiogenesis, lipid metabolism, migration and tumorigenesis capacity compared to osteogenesis. The direct comparison between ASC and BMSC during the same differentiation uncovered that ASC is featured by a greater lipid metabolism compared to BMSC, while BMSC has a more pronounced cell growth and proliferation than ASC. In addition, we uncovered 39 specific gene markers for adipogenesis and 65 for osteogenesis. NAD(P)H dehydrogenase quinone 1 (NQO1), aquaporin 3 (AQP3), stearoyl-CoA desaturase (SCD), fatty acid binding protein 3 and 5 (FABP3 and FABP5) and ferritin light polypeptide (FTL) were among the best adipogenic markers. Hemopexin (HPX), collagenase type 3α (COL3A1), annexin A8-like 1 (ANXA8L1), flotillin 2 (FLOT2) and periostin or osteoblast specific factor (POSTN) were among the best osteogenic markers. Overall, the data indicated that the transcriptome of the two MSC are similar across the conditions studied. In addition, despite the limited DEG between the two MSC, the enrichment of several functions/pathways might indicate differences in therapeutic application.
This work was support by the Illinois Regenerative Medicine Institute (IDPH # 63080017).
224 EFFECT OF LENGTHENING THE SUPERSTIMULATORY TREATMENT PROTOCOL ON THE OVARIAN RESPONSE AND NUMBERS OF TRANSFERABLE EMBRYOS IN BEEF COWS
Authors: Garcia Guerra A. , Tribulo A. , Yapura J. , Singh J. , Mapletoft R. J.
Published: December 2011

The present study was designed to test the hypothesis that an increase in the length of exposure of ovulatory follicles to progesterone and FSH during ovarian superstimulation will increase the number of ovulations and viable embryos in cattle. Twenty-four beef cows were initially subjected to follicle ablation at random stages of the oestrous cycle to determine the number of follicles at wave emergence; cows with comparable numbers of follicles were randomly allocated to groups by replicate. A single dose of prostaglandin F2α (PGF; Estroplan, Vétoquinol, QC, Canada) was given IM 7 to 9 days after follicle ablation and daily ultrasound examinations were performed to detect ovulation. Follicular ablation of all follicles ≥5 mm was done 5 to 8 days after ovulation and a progesterone-releasing intravaginal device (PRID, Vétoquinol) was inserted. The Control group (n = 12) was treated with 4 days of FSH and cows in the Long group (n = 12) were given 7 days of FSH treatment. The FSH treatments were initiated 1.5 days after ablation (Day 0) with a total dose of 400 mg of NIH-FSH-P1 (Folltropin-V; Bioniche Animal Health, Belleville ON, Canada). The total dose of FSH was distributed equally over 8 (Control) or 14 (Long) IM injections at 12-h intervals. Prostaglandin F2α was administered twice (at 12-h intervals) on Day 2 (Control) or Day 5 (Long) and PRID were removed 12 h after the last PGF. Both groups received 25 mg of porcine LH (pLH) IM (Lutropin-V; Bioniche Animal Health) 24 h after PRID removal and AI with frozen–thawed semen of proven fertility was done 12 and 24 h later. A third AI was done 12 h later in cows with 2 or more follicles ≥9 mm (12/12 and 9/12 in Control and Long groups, respectively; P = 0.22). All animals were subjected to transrectal ultrasonography every other day and at the time of ova or embryo collection. Ova or embryos were collected nonsurgically 7 days after the pLH injection and evaluated following IETS guidelines. Embryos were defined as transferable (Grades 1, 2 and 3) and freezable (Grades 1 and 2). Procedure Genmod was used to compare variables between treatments and results are presented as means ± SEM (Table 1). There was no significant difference in the total numbers of ova/embryos recovered, but there were more ovulations, corpora lutea (CL), fertilized ova and transferable and freezable embryos in the Long group (P < 0.05). Collection efficiency (number of ova/embryos over the number of CL) was lower in the Long group (P < 0.05). In summary, lengthening of the superstimulatory treatment resulted in an increased number of ovulations without a decrease in oocyte or embryo competence. Data suggest that the traditional 4-day superstimulatory treatment protocol provides inadequate time to maximize ovulatory response.

Table 1.Superovulatory response (mean ± SEM) of cows subjected to a conventional 4-day (Control) or a 7-day (Long) treatment protocol
226 INCLUSION OF BOVINE SOMATOROPIN ON MULTIPLE-OVULATION EMBRYO TRANSFER TREATMENTS FOR LOW-RESPONDING BEEF DONOR COWS
Authors: Kmaid S. , Saldaña J. M. , Ramos Z. , Ungerfeld R.
Published: December 2011

An experiment was designed to determine if embryo production of Angus donors could be improved by including a single dose of bovine somatotropin (bST) before starting the superovulatory treatment (SPO). Thirty-three multiparous Angus cows (body condition = 4.6 ± 0.6, range = 1–8) were submitted to 2 SPO treatments at random stages of the oestrous cycle in a crossover design (60 days apart). On Day 0, cows were divided at random to receive either 500 mg of bST (n = 18; Lactotropin, Elanco Saude Animal, Brasil) or remain without bST (control, n = 15). At the same time, all cows received 2 mg of oestradiol benzoate, 50 mg of progesterone and a CIDR (Pfizer Animal Health, Uruguay). On Day 2, all cows received 200 IU of eCG (Inducel, Universal Laboratory, Uruguay) and on Day 4 were superstimulated with 425 IU of FSH (Pluset, Calier, Spain) in twice-daily decreasing doses over 4 days. On Day 6, all cows received 2 doses (a.m. and p.m.) of a PGF analogue (800 μg, Delprostenate, Glandinex, Universal Laboratory, Uruguay) and the CIDRs were removed in the morning of Day 7. Cows were injected with 10 μg of GnRH (Receptal, Intervet, the Netherlands) on Day 8 (a.m.) and were inseminated 12, 24 and 36 h later. On Day 15, ova/embryos were collected nonsurgically and evaluated in accordance to IETS guidelines. For statistical analysis, cows were categorized according to the number of transferable embryos obtained in control treatment (without bST) in terciles: low-responding cows (LR, ≤6; n = 11), middle-responding cows (7–9, n = 12), or high-responding cows (HR ≥ 10; n = 10). Data were analysed by a paired t-test. Treatment with bST increased the total ova and embryos and the number of transferable embryos in LR cows (Table 1). However, the number of transferable embryos and the percentage of transferable embryos werereduced in HR cows. The inclusion of a single bST dose 4 days before initiating SPO with FSH treatments may be a useful alternative to improve embryo production in low-responding cows.

Table 1.Response of low-responding and high-responding Angus cows to superovulatory treatments with or without bST (mean ± SD)