bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte carlo simulation of bacterial disinfection: Nonlinear and time‐explicit intensity of transition
Authors: Argoti Andres , Fan L. T. , Chou S. T.
Published: April 2010

Bacteria being disinfected in fluid media are discrete entities and mesoscopic in size; moreover, they are incessantly as well as irregularly in motion and in collision among themselves or with the surrounding solid surfaces. As such, it is highly likely that some of the attributes of the bacterial population, for example, their number concentration, will fluctuate randomly. This is especially the case at the tail‐end of disinfection when the population of bacteria is sparse. It might be effectual, therefore, to explore the resultant random fluctuations via a stochastic paradigm. Proposed herein is a Markovian stochastic model for the rate of bacterial disinfection, whose intensity of transition takes into account the contact time of the bacteria with the disinfecting agent to eliminate any given percentage of the bacteria in terms of a nonlinear function of time. The model's master equation has been simulated by resorting to the Monte Carlo method to circumvent the undue complexities in solving it analytically or numerically via conventional numerical techniques. For illustration, the mean, the variance (standard deviation), and the coefficient of variation of the number concentration of bacteria during disinfection have been estimated through Monte Carlo simulation. The results of simulation compare favorably with the available experimental data as well as with those computed from the corresponding deterministic model. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Diffusion properties of bacteriophages through agarose gel membrane
Authors: Hu Jun , Miyanaga Kazuhiko , Tanji Yasunori
Published: April 2010

A simple two‐chamber diffusion method was developed to study the diffusion properties of bacteriophages (phages). The apparent diffusion coefficients (Dapp) of Myoviridae phage T4 and filamentous phage fNEL were investigated, and the diffusion of the phages was found to be much slower than the diffusion of three antibiotics, ciprofloxacin, penicillin G, and tetracycline. Dapp of T4 and fNEL in water through filter paper were calculated to be 2.8 × 10−11 m2/s and 6.8 × 10−12 m2/s, respectively, and Dapp of fNEL through agarose gel membrane, an artificial biofilm, was also calculated to be smaller than that of T4. In addition, Dapp of phages through agarose gel was dependent on agarose concentration due to the similar size of phage and agarose gel mesh. We concluded that Dapp of phages through an artificial biofilm is dependent on both phage morphology and biofilm density, and suggest the use of this method to study diffusion properties through real biofilms. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Metabolic flux analysis of embryonic stem cells using three distinct differentiation protocols and comparison to gene expression patterns
Authors: Sepúlveda Darío E. , Andrews Barbara A. , Papoutsakis Eleftherios Terry , Asenjo Juan A.
Published: April 2010

Metabolic flux analysis (MFA) was performed on mouse embryonic stem cells cultured under three distinct differentiation conditions: classical embryoid body formation (EB), and on surfaces coated with either gelatin (GEL) or matrigel (MAT). MFA was based on 15 metabolic reactions and eight transport steps, and was carried out based on measurements of four substrates and/or metabolites: glucose, lactate, glutamine, and glutamate. Fluxes representing biomass production remained fairly constant for all three culture conditions with at most a 40% variation. In contrast, major temporal variations, up to 500%, were observed for all other major central metabolic fluxes across all culture conditions. Fluxes were compared to gene‐expression patterns measured by microarray analysis. Particularly interesting is the correlation between the metabolic fluxes with expression patterns of the corresponding genes of the pyruvate to lactate reaction, whereby the genes for several isoforms of the lactate dehydrogenase enzyme were examined. The patterns of this flux were notably different in the EB cultures compared to the GEL and MAT cultures and reflected differences in oxygen and nutrient transport in EB vs. the GEL and MAT cultures. Another novel finding of this study is an event occurring between Days 4 and 5 of differentiation, which was identified by a notable change in both the metabolic fluxes and gene‐expression patterns. This suggests that metabolic patterns can be used as effective beacons of changes in differentiating stem cells. Overall, and qualitatively, core metabolic fluxes, under the three culture conditions examined, correlated well with gene‐expression patterns. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Findings of unique small muscle fibers at the superficial portion of the orbicularis oculi in the lateral canthal region of Japanese adult cadavers
Authors: Tamatsu Yuichi , Tsukahara Kazue , Shimada Kazuyuki
Published: April 2010

This study reports the existence of previously unknown muscle fascicles in Japanese adult cadavers. A bundle of these muscle fascicles diverged from the pretarsal portion of the orbicularis oculi muscle and coursed in a lateral direction superficial to this muscle. When observed with the naked eye, the bundle seemed to originate at the medial canthus and run along or near the edge of the upper eyelid. However, its boundary with the orbicularis oculi muscle was indistinguishable until it crossed superficial to this muscle. Throughout our observations, the thin muscle bundle was identified with high frequency (94%, 49 of 52 individual cadavers), and is thus unlikely to be an artifact. Light microscopy revealed that, in sagittal sections, the thin muscle bundle was located on the superficial side of the lateral portion of the orbicularis oculi muscle, while in horizontal sections, it ran in a superficial plane to the orbicularis oculi muscle in a medial to lateral direction. Despite having some similarity to a muscular raphe, the lateral canthal band, and to one of the previously known inferior muscles of the orbicularis oculi muscle, the results of our anatomical study suggest that the bundle is none of these. Rather, it is a previously unreported muscle that likely contributes to the surface morphology at the lateral canthus. Clin. Anat. 23:637–641, 2010. © 2010 Wiley‐Liss, Inc.
Direct measurement of tibial cortical bone surface area
Authors: Cattrysse E. , Scafoglieri A. , Louis O. , De Mey J. , Clarys J.P.
Published: April 2010

Cortical bone surface area estimation is generally performed by analysis of medical images but its accuracy has not yet been verified by direct bone measurements. This study was performed to evaluate the reproducibility of direct ex vivo estimations of cross sectional tibial cortical bone surface area. Ten tibiae were evaluated by two observers using direct 3D‐digitization at 38 and 66% of total tibial length using a ‘critical’ and a ‘general’ criterion for differentiation between cortical and cancellous bone. The results of the analysis using the more severe ‘critical’ differentiation criterion yielded high intra and interobserver agreement. Mean intraobserver reliability was demonstrated by R = 0.98 (Spearman rank correlation between 0.98 and 0.97; P < 0.01) and inter observer reliability by R = 0.91 (Spearman rank correlation between 0.95 and 0.88; P < 0.01). When using strict criteria to differentiate between cortical and cancellous bone, intra and interobserver reliability of the presented method of direct cortical bone surface area estimation is very high. The results indicate that cross‐sectional cortical bone surface estimation by direct 3D‐digitization can serve as a gold standard for validation of other estimations methods. Clin. Anat. 23:720–725, 2010. © 2010 Wiley‐Liss, Inc.
Stereoselection in the binding of Ln DOTA to γ‐cyclodextrin: A near infrared circular dichroism study
Authors: Di Bari Lorenzo , Pintacuda Guido , Salvadori Piero
Published: April 2010

The formation of an inclusion complex between γ‐cyclodextrin and Ln DOTA has been reported in the literature. All Ln DOTA complexes in solution give rise to a network of equilibria between different stereoisomers, which are pairs of enantiomers. By means of near infrared circular dichroism of the Yb derivative, we demonstrate that upon the formation of the host–guest complex, there is a complete stereoselection and that only the Λ(δδδδ) binds. Chirality 2010. © 2010 Wiley‐Liss, Inc.
Trennung von Enantiomeren mittels Mikroemulsionen
Authors: Dimitrova P. , Bart H.‐J.
Published: April 2010

Unter dem Gesichtspunk der Prozessintensivierung werden Öl/Wasser‐Mikroemulsionen als reaktives Medium für enantioselektive Trennungen eingesetzt. Für die Mikroemulsion wurden das nichtionische Tensid Igepal CO‐630 und Cylohexan verwendet. Dabei wurden die chiralen Selektoren N‐Heptyl‐L‐hydroxyprolin und N‐Decyl‐L‐hydroxyprolin in den Öltröpfchen immobilisiert und ein chirales Umfeld erzeugt, mit dessen Hilfe sich die Enantiomerenpaare DL‐Leucin und DL‐Methionin trennen lassen. Für die Kreislaufführung der Tenside wurde ein Vergleich zwischen Trübungspunktextraktion und mizellarer Extraktion durchgeführt.
Rendering Conventional Molecular Fingerprints for Virtual Screening Independent of Molecular Complexity and Size Effects
Authors: Nisius Britta , Bajorath Jürgen
Published: April 2010

Molecular complexity and size effects represent a known complication of fingerprint similarity searching and virtual screening that often leads to an increase in false‐positive rates and a decrease in hit rates. In standard fingerprints, differences in the complexity of reference and database molecules lead to different fingerprint bit densities, which negatively affects similarity search calculations, in particular, when fingerprints of reference molecules have higher bit density than corresponding fingerprints of database compounds. In pharmaceutical research, this is the case in many practical virtual screening applications when chemically optimized reference molecules are used. Herein we introduce an intuitive computational method to make standard fingerprints such as structural keys or pharmacophore feature fingerprints independent of molecular complexity and size effects. This is achieved by applying the concept of 'balanced codes' originating in computer science. Following this approach, binary fingerprints are transformed by incorporating the complement of their bit patterns. This straightforward transformation produces fingerprint representations with characteristic bit patterns that have exactly half of their bit positions set on, corresponding to a constant bit density of 50 % for all test compounds, regardless of their complexity and size. In similarity search calculations in the presence of complexity effects of increasing magnitude, transformed structural key and pharmacophore fingerprints display consistently better performance than their unmodified counterparts and recover active compounds in cases where the original fingerprints fail.
SPECT/CT hybrid imaging; with which CT?
Authors: Bach‐Gansmo Tore , Schwarzlmüller Thomas , Jøraholmen Vivi , Salbu Jan , Biermann Martin , Naum Alexandru , Kleven‐Madsen Nina
Published: April 2010

Aim

The aim of this study is to show the practical use of, and to discuss the rationale for, high‐end computed tomography (CT) integrated with intrinsic low‐resolution single‐photon emission tomography (SPECT).

Materials and methods

All examinations performed on three new SPECT/CT systems with diagnostic CT capabilities were recorded retrospectively. The use of CT was classified as low‐dose, using the CT with restraint as to the tube current and radiation dose, or diagnostic, with an optimum use of the CT, using CT protocols as used in ordinary radiological practice. The number of low‐dose CT was compared with the number of diagnostic CT examinations. The report is based on 436 patient examinations from three hospitals in Norway with recently installed SPECT/CT systems, the time of use varying from 6 months to 2 years. The examinations performed were myocardial perfusion (45%), various tumors (thyroid, parathyroid, neuroendocrine 37%), malignant skeletal disease (12%), brain perfusion (4%), sentinel nodes in breast cancer (1%) and gastrointestinal bleeding (1%).

Results

Of the 436 patients, 431 had a low‐dose CT for attenuation correction, anatomic localisation and, also for diagnosis, whereas five patients had a diagnostic CT. In these series, as was found in recent literature, the diagnostic potential of the CT was seldom used to its capacity and always in predetermined diagnostic situations.

Conclusion

There is a low degree of utilization of the diagnostic capabilities of the CT in the SPECT/CT context, for a number of reasons. This raises questions about the cost–benefit of investing in high‐end CT for SPECT/CT applications. Copyright © 2010 John Wiley & Sons, Ltd.
Assessment of tumor angiogenesis: dynamic contrast‐enhanced MRI with paramagnetic nanoparticles compared with Gd‐DTPA in a rabbit Vx‐2 tumor model
Authors: Kassner Andrea , Thornhill Rebecca E. , Liu Fang , Winter Patrick M. , Caruthers Shelton D. , Wickline Samuel A. , Lanza Gregory M.
Published: April 2010

The purpose of this study was to evaluate the suitability of a macromolecular MRI contrast agent (paramagnetic nanoparticles, PNs) for the characterization of tumor angiogenesis. Our aim was to estimate the permeability of PNs in developing tumor vasculature and compare it with that of a low molecular weight contrast agent (Gd‐DTPA) using dynamic contrast‐enhanced MRI (DCE). Male New Zealand white rabbits (n = 5) underwent DCE MRI 12–14 days after Vx‐2 tumor fragments were implanted into the left hind limb. Each contrast agent (PNs followed by Gd‐DTPA) was evaluated using a DCE protocol and transendothelial transfer coefficient (Ki) maps were calculated using a two‐compartment model. Two regions of interest (ROIs) were located within the tumor core and hindlimb muscle and five ROIs were placed within the tumor rim. Comparisons were performed using repeated measures analysis of variance (ANOVA). The Ki values estimated using PNs were significantly lower than those obtained for Gd‐DTPA (p = 0.018). When PNs and Gd‐DTPA data were analyzed separately, significant differences were identified among tumor rim ROIs for PNs (p < 0.0001), but not for Gd‐DTPA data (p = 0.34). The mean Ki for the tumor rim was significantly greater than that of either the core or the hindlimb muscle for both contrast agents (p < 0.05 for each comparison). In summary, the extravasation of Gd‐DTPA was far greater than that of PNs, suggesting that PNs can reveal regional differences in tumor vascular permeability that are not otherwise apparent with clinical contrast agents such as Gd‐DTPA. These results suggest that PNs show potential for the noninvasive delineation of tumor angiogenesis. Copyright © 2010 John Wiley & Sons, Ltd.
The mediation effect of experiential avoidance between coping and psychopathology in chronic pain
Authors: Costa Joana , Pinto‐Gouveia José
Published: April 2010

This study explores experiential avoidance as a mediator in the relationship between coping (rational coping, avoidant coping and detached/ emotional coping) and psychopathology (depression, anxiety and stress). A battery of self‐report questionnaires was used to assess coping, experiential avoidance and depression, anxiety and stress in 70 participants with a chronic pain from Portuguese primary health care units.

Regression analyses were performed and showed preliminary evidence supporting the mediation role of experiential avoidance in a Portuguese sample with chronic pain. Results show that experiential avoidance partially or fully mediate the effects of rational coping and detached/emotional coping on depression and stress. Implications for clinical practice were discussed and suggest that psychopathology is not necessary direct product of coping and other processes, such as experiential avoidance, are likely involved. Copyright © 2010 John Wiley & Sons, Ltd.

Key Practitioner Message:

• Low use of adaptive coping was associated with more psychopathology via differences in psychological (in)flexibility as a general characteristic.

• Findings suggest that psychopathology is not necessary direct product of coping and other processes, such as experiential avoidance, are likely involved.

• Patients with chronic pain may achieve better psychosocial outcomes they reduce their avoidance and other attempts to control pain, accept it, and direct their efforts toward valued goal.
Guidelines for the diagnosis and monitoring of paroxysmal nocturnal hemoglobinuria and related disorders by flow cytometry
Authors: Borowitz Michael J. , Craig Fiona E. , DiGiuseppe Joseph A. , Illingworth Andrea J. , Rosse Wendell , Sutherland D. Robert , Wittwer Carl T. , Richards Stephen J.
Published: April 2010

Background:

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematopoietic stem cell disorder characterized by a somatic mutation in the PIGA gene, leading to a deficiency of proteins linked to the cell membrane via glycophosphatidylinositol (GPI) anchors. While flow cytometry is the method of choice for identifying cells deficient in GPI‐linked proteins and is, therefore, necessary for the diagnosis of PNH, to date there has not been an attempt to standardize the methodology used to identify these cells.

Methods:

In this document, we present a consensus effort that describes flow cytometric procedures for detecting PNH cells.

Results:

We discuss clinical indications and offer recommendations on data interpretation and reporting but mostly focus on analytical procedures important for analysis. We distinguish between routine analysis (defined as identifying an abnormal population of 1% or more) and high‐sensitivity analysis (in which as few as 0.01% PNH cells are detected). Antibody panels and gating strategies necessary for both procedures are presented in detail. We discuss methods for assessing PNH populations in both white blood cells and red blood cells and the relative advantages of measuring each. We present steps needed to validate the more elaborate high‐sensitivity techniques, including the need for careful titration of reagents and determination of background rates in normal populations, and discuss technical pitfalls that might affect interpretation.

Conclusions:

This document should both enable laboratories interested in beginning PNH testing to establish a valid procedure and allow experienced laboratories to improve their techniques. © 2010 Clinical Cytometry Society
Characterization of indoor time reversal UWB communication systems: Spatial, temporal and frequency properties
Authors: Abbasi‐Moghadam Dariush , Vakili Vahid Tabataba
Published: April 2010

In this paper, an indoor UWB communications system that applies time reversal (TR) for transmitting the desired signal is proposed. First we define equivalent channel model of TR‐UWB, which is the convolution of channel impulse response and its complex conjugate time‐reversed version. Then spatial, temporal and frequency characteristics of equivalent channel are analyzed and the analytical or semi‐analytical results are validated by comparing measurements with simulation. (Semi) analytical expression of equivalent channel transfer function, TR UWB power delay profile (PDP), focusing gain, spatial correlation and power azimuth spectrum (PAS) is performed. Also probability density function (PDF) of TR‐UWB amplitude and path‐gain is derived.

Analysis and simulation results of different distributions, such as uniform, Laplacian and Gaussian for PAS, are considered and presented. It is shown that uniform and truncated Laplacian distributions are appropriate fits to the measurement results for power azimuth spectrum of TR‐UWB. It is seen that for distances greater than λ/2 from the authorized receiver, received signal decreases 10 dB, where λ is the wavelength of the central frequency. Finally, PDF of TR‐UWB path‐gain is described. Measurement results show that for small time windows, the densities of the path‐gain are highly non‐Gaussian. But for starting time of 10Tw or more, and window size of 2Tw or more the densities are nearly Gaussian, where Tw is the transmitted pulse duration. Copyright © 2010 John Wiley & Sons, Ltd.
CD137 ligand signaling induces human monocyte to dendritic cell differentiation
Authors: Kwajah M. M. Shaqireen , Schwarz Herbert
Published: April 2010

The ligand for CD137 (4‐1BB) is expressed on peripheral human monocytes and delivers a potent activating signal via reverse signaling. Here we show that treatment of monocytes with a recombinant CD137 protein that induces reverse signaling through CD137 ligand reduces typical macrophage characteristics such as phagocytosis, oxidative burst and CD14 expression; however, typical DC characteristics including endocytosis, costimulatory molecule expression and the ability to stimulate proliferation of naïve T cells are induced. CD137‐generated DC do not express DC‐SIGN, CD1a or IL‐12 and secrete less IL‐10 than classical DC. CD137‐generated DC are mature, and addition of LPS+IFN‐γ does not enhance their T‐cell‐stimulatory capacity. This indicates that CD137 as a sole factor is sufficient to induce development to mature DC, making stimulation of CD137 ligand the most simple protocol to generate mature DC. CD137‐generated DC are more potent in inducing T‐cell proliferation than classical DC. They inhibit development of Treg cells but induce T‐cell expression of perforin, IFN‐γ, IL‐13 and IL‐17. These data demonstrate that CD137 as a single factor is sufficient to induce differentiation of peripheral monocytes to mature inflammatory DC that have a more potent T‐cell‐stimulatory capacity than classical DC.
Epidermis‐to‐dermis migration of immature Langerhans cells upon topical irritant exposure is dependent on CCL2 and CCL5
Authors: Ouwehand Krista , Scheper Rik J. , de Gruijl Tanja D. , Gibbs Susan
Published: April 2010

Skin irritation is generally not considered to be an immunological event; however, alterations in the density of Langerhans cells (LC) in the epidermis do occur, which is indicative of LC migration. In this study, we investigated the migration of LC out of the epidermis after skin exposure to contact irritants and identified the chemokines involved. With the aid of ex vivo‐intact human skin and epidermal sheets we show that dermal fibroblasts play a role in mediating LC migration towards the dermis. Exposure of ex vivo‐intact human skin to a panel of seven irritants (SDS, salicylic acid, phenol, isopropanol, DMSO, TritonX, or benzalkonium chloride) resulted in decreased numbers of CD1a+ cells in the epidermis and the accumulation of CD1a+ cells in the dermis. In contrast to allergen exposure, neutralizing antibodies to either CXCL12 or CCL19/CCL21 did not inhibit LC migration out of the epidermis. Exposure of epidermal sheets to the prototypical irritant SDS resulted in a TNF‐α‐dependent LC migration towards dermal fibroblasts. This was a result of CCL2/MCP‐1 and CCL5/RANTES chemokine secretion by fibroblasts: injection of CCL2‐ and CCL5‐neutralizing antibodies into intact human skin totally inhibited LC migration into the dermis. We have thus identified a novel role for TNF‐α‐inducible dermis‐derived CCL2 and CCL5 in initiating migration of irritant‐exposed human LC out of the epidermis.
Ligand dimensions are important in controlling NK‐cell responses
Authors: Brzostek Joanna , Chai Jian‐Guo , Gebhardt Friedemann , Busch Dirk H. , Zhao Rui , van der Merwe P. Anton , Gould Keith G.
Published: April 2010

Size‐dependent protein segregation at the cell–cell contact interface has been suggested to be critical for regulation of lymphocyte function. We investigated the role of ligand dimensions in regulation of mouse NK‐cell activation and inhibition. Elongated forms of H60a, a mouse NKG2D ligand, were generated and expressed stably in the RMA cell line. RMA cells expressing the normal size H60a were lysed efficiently by both freshly isolated and IL‐2 stimulated C57BL/6 mouse‐derived NK cells; however the level of lysis decreased as the H60a ligand size increased. Importantly, H60a elongation did not affect NKG2D binding, as determined by soluble NKG2D tetramer staining, and by examining NK‐cell target cell conjugate formation. CHO cells are efficient at activating NK cells from C57BL/6 mice, and expression of a single chain form of H‐2Kb, a ligand for the mouse inhibitory receptor Ly49C, strongly inhibited such activation of Ly49C/I positive NK cells. Elongation of H‐2Kb resulted in decreased inhibition of both lysis and IFN‐γ production by NK cells. These results establish that small ligand dimensions are important for both NK‐cell activation and inhibition, and suggest that there are shared features between the mechanisms of receptor triggering on different types of lymphocytes.
The Role of C–H···H–B Interactions in Establishing Rotamer Configurations in Metallabis(dicarbollide) Systems
Authors: Juárez‐Pérez Emilio José , Núñez Rosario , Viñas Clara , Sillanpää Reijo , Teixidor Francesc
Published: April 2010

The aim of this work is to explore the self‐interaction capability of the anion [3,3′‐Co(1,2‐C2B9H11)2]–throughCcluster–H···H–B (Cc–H···H–B) dihydrogen bonds. A set of theoretical and empirical data aiming to establish the main rules that account for the binding mode between the negatively charged borane framework made by [3,3′‐Co(1,2‐C2B9H11)2]–and the [NMe4]+ions have been compiled. The interaction between cation and anion is mainly electrostatic but the covalent contribution is also proven and quantified. The existing intermolecular H···H short contacts have been studied and are compared with available data from the Cambridge Structural Database. The results show that the electronic configuration of the transition metal atom in the sandwich complex is not enough to define the preferred rotamer due to the influence of the anion environment and the H···H interactions present in the solid state. We present a methodology with widely used theoretical tools to study cation···cobaltabisdicarbollide interactions in the solid state.
Facile Synthesis of Lanthanidocenes by the “Borohydride/Alkyl Route” and Their Application in Isoprene Polymerization
Authors: Visseaux Marc , Terrier Michael , Mortreux André , Roussel Pascal
Published: April 2010

Several borohydridolanthanidocenes were synthesized by means of a straightforward approach starting from equimolar amounts of Ln(BH4)3(thf)3 (Ln = Nd, Sm) and n‐butylethylmagnesium (BEM) in the presence of 2 equiv. of a cyclopentadiene derivative. Depending on the nature of the cyclopentadiene, monometallic Cp*2Nd(BH4)(thf) (Cp* = C5Me5) (1), heterodimetallic [Cp2Nd(BH4)(μ‐BH4)]2Mg(thf)4 (Cp = C5H5) (2), [(CMe2C5H4)2Ln(BH4)(μ‐BH4)]2Mg(thf)3 (Ln = Nd, 3a; Ln = Sm, 3b), and monometallic anilidocyclopentadienyl compounds (C5Me4CH2SiMe2NPh)Ln(BH4)(thf)2 (Ln = Nd, 4a; Ln = Sm, 4b) were isolated. The complexes were characterized by 1H NMR spectroscopy, elemental analysis, and X‐ray structural analysis. Mg(BH4)2(thf)3 (5) was isolated as a byproduct and structurally characterized, revealing an unprecedented structural arrangement. In combination with BEM, complexes 2a, 3a, and 4a were found to be efficient in isoprene polymerization to afford highly stereoregular trans‐polyisoprene. Similar results were obtained by an “all in situ” approach starting from Nd(BH4)3(thf)3/BEM mixtures in the presence of 2 equiv. of cyclopentadiene derivative.
Electron‐Withdrawing, Biphenyl‐2,2′‐diol‐Based Compounds for Asymmetric Catalysis
Authors: Gutierrez Elisa G. , Moorhead Eric J. , Smith Eva H. , Lin Vivian , Ackerman Laura K. G. , Knezevic Claire E. , Sun Victoria , Grant Sharday , Wenzel Anna G.
Published: April 2010

Facile synthetic routes to a chiral chloro‐substituted biphenyl‐2,2′‐diyl hydrogen phosphate and a chiral O,O‐biphenyl‐2,2′‐diyl phosphoramidothioate are described. The performance of these compounds as catalysts for the hydrophosphonylation of imines and the Friedel–Crafts alkylation of indole was investigated. In the latter reaction, the chloro‐substituted phosphoric acid derivative was found to rival the best Brønsted acid catalysts reported to date.
Acid‐Induced Rearrangement of Epoxygermacra‐8,12‐olides: Synthesis and Absolute Configuration of Guaiane and Eudesmane Derivatives from Artemisiifolin
Authors: Rosselli Sergio , Maggio Antonella , Raccuglia Rosa Angela , Bruno Maurizio
Published: April 2010

A study on the acid‐induced rearrangement of 4,5‐epoxy‐ and 1,10‐epoxygermacra‐8,12‐olides was carried out. From a 4,5‐epoxy derivative, guaianes were obtained, whereas 1,10‐epoxy derivatives furnished, depending on the stereochemistry of the C‐1/C‐10 epoxy ring, trans‐5β,10α‐ or trans‐5α,10β‐eudesmanolides.
Time‐course of micronucleated erythrocytes in response to whole‐body gamma irradiation in a model mammalian species, the bank vole (Clethrionomys glareolus, Schreber)
Authors: Smolich Igor I. , Savina Natalya V. , Ryabokon Nadezhda I.
Published: April 2010

The time course of the formation of micronucleated polychromatic (MNPCEs) and normochromatic erythrocytes (MNNCEs) in the bone marrow of the bank vole (Clethrionomys glareolus, Schreber), a model mouse‐like species, was studied using the standard micronucleus test at 0, 6, 12, 18, 24, 30, 36 and 48 hr following whole‐body acute γ‐irradiation at a dose of 0.5 Gy. Based on the existing literature on laboratory mice, it was suggested that such a dose will not have significant effect on erythroid cell proliferation in the bank vole and hence on the time course of the rise of micronucleated cells. In total, ∼905,000 polychromatic (PCEs) and normochromatic erythrocytes (NCEs) from 82 adult bank voles were analyzed. Although the mean frequencies of MNNCEs were too low to allow for the correct assessment of their time course, an analysis of PCEs showed an increasing rate of MNPCE appearance at 6 hr that reached a maximum at 18–24 hr after irradiation and subsequently decreased. Because the kinetics of MNPCEs reflects the process of erythropoiesis, the current results regarding the time points of appearance of radiation‐induced MNPCEs provide the first information on the prolongation of one of the terminal stages of erythrocyte formation in bank vole specimens, namely the stage of maturation of PCEs from erythroblasts. Moreover, the observed time‐course data, as well as the low‐background frequencies of MNPCEs and characteristic level of PCEs response to radiation, showed similarities between the two model species: bank vole (this study) and laboratory mice (literature data). Environ. Mol. Mutagen. 52:50–57, 2011. © 2010 Wiley‐Liss, Inc.
Reflections on the origins and evolution of genetic toxicology and the environmental mutagen society
Authors: Wassom John S. , Malling Heinrich V. , Sankaranarayanan K. , Lu Po‐Yung
Published: April 2010

This article traces the development of the field of mutagenesis and its metamorphosis into the research area we now call genetic toxicology. In 1969, this transitional event led to the founding of the Environmental Mutagen Society (EMS). The charter of this new Society was to “encourage interest in and study of mutagens in the human environment, particularly as these may be of concern to public health.” As the mutagenesis field unfolded and expanded, new wording appeared to better describe this evolving area of research. The term “genetic toxicology” was coined and became an important subspecialty of the broad area of toxicology. Genetic toxicology is now set for a thorough reappraisal of its methods, goals, and priorities to meet the challenges of the 21st Century. To better understand these challenges, we have revisited the primary goal that the EMS founders had in mind for the Society's main mission and objective, namely, the quantitative assessment of genetic (hereditary) risks to human populations exposed to environmental agents. We also have reflected upon some of the seminal events over the last 40 years that have influenced the advancement of the genetic toxicology discipline and the extent to which the Society's major goal and allied objectives have been achieved. Additionally, we have provided suggestions on how EMS can further advance the science of genetic toxicology in the postgenome era. Any oversight or failure to make proper acknowledgment of individuals, events, or the citation of relevant references in this article is unintentional. Environ. Mol. Mutagen., 2010. © 2010 Wiley‐Liss, Inc.
Modelling mid‐channel bars in meandering channels
Authors: Luchi Rossella , Zolezzi Guido , Tubino Marco
Published: April 2010

An analytical modelling framework is proposed to reproduce the frequently observed but poorly studied occurrence of mid‐channel bars in meandering channels. Mid‐channel bars occur in meanders and may characterize transitional morphologies between pure meandering and braided rivers. Based on existing field and experimental observations, we propose that two different mechanisms can generate central topographical patterns in meanders. A former mechanism (‘width‐forced’) is related to spatial width oscillations which determine a laterally symmetrical bed shear stress pattern that promotes mid‐channel bars. A second mechanism (‘curvature‐forced’) can take place also in curvilinear equiwidth streams since also longitudinal variations of channel curvature can produce laterally symmetrical alterations of the sediment transport capacity. A perturbation approach is employed to model both mechanisms within a common framework, allowing reproduction, at least qualitatively, of several observed features. While width‐forced mid‐channel bars are a symmetric linear altimetric response, to reproduce curvature‐forced mid‐channel bars requires modelling nonlinear flow‐bed topography interactions at the second order of the perturbation expansion. Hypotheses on how these mechanisms operate are further discussed through an application to field cases. The amplitude of the nonlinear response can be relevant compared to that of the point bar in equiwidth meanders and the location of mid‐channel bars seldom coincides with bend apexes, mainly depending upon the intrinsic meander wavelength. Central bars tend to symmetrically divert the flow against the two banks, a process which is proposed as a possible cause of cross‐sectional overwidening, along with the asymmetry between the rates of bank erosion and of the opposite bank accretion. The outcomes of this first modelling step on the subject allow discussion of the mutual feedback processes that characterize interactions between mid‐channel bars and width variations in river meanders. Copyright © 2010 John Wiley & Sons, Ltd.
Long‐term river meandering as a part of chaotic dynamics? A contribution from mathematical modelling
Authors: Frascati Alessandro , Lanzoni Stefano
Published: April 2010

In the present contribution we focus our attention on the possible signatures of a chaotic behaviour or a self‐organized criticality state triggered in river meandering dynamics by repeated occurrence of cutoff processes. The analysis is carried out examining, through some robust nonlinear methodologies inferred from time series analysis, both the spatial series of local curvatures and the time series of long‐term channel sinuosity. Temporal distribution of cutoff inter‐arrivals is also investigated. The analyzed data have been obtained by using a suitable physics‐based simulation model for river meandering able to reproduce reasonably the features of real rivers. The results are consistent and show that, at least from a modelling point of view, no evidence of chaotic determinism or self‐organized criticality is detectable in the investigated meandering dynamics. Copyright © 2010 John Wiley & Sons, Ltd.
Effectiveness of grass strips in trapping suspended sediments from runoff
Authors: Pan Chengzhong , Ma Lan , Shangguan Zhouping
Published: April 2010

Little information is available concerning the performance of grass strips for erosion control from steep cropland. An experiment was conducted on 5‐m‐long grass strips with slopes of 3°∼15° that were subjected to silt laden runoff and simulated rainfall, to investigate the sediment trapping processes. The grass strips had three treatments including intact grass control (C), no litter (dead grass material covering the soil surface was removed) (NL), and no litter or leaves (only 2∼3 cm grass stems and roots were reserved) (NLL).

Generally the grass strips had a high effectiveness in trapping sediment from steep cropland runoff. Sediment trapping efficiency (STE) decreased with increasing slope gradient, and even for a 15° slope, STE was still more than 40%. Most sediment deposited in the backwater region before each grass strips. The removal of grass litter or/and leaves had no significant influence on STE. The sediment median size (D50) in inflow was greater than that in outflow, and the difference (ΔD50) decreased with increasing slope. A positive power relationship between STE and ΔD50 can be obtained. Grass strips were more effective in trapping sediments coarser than 10 or 25 µm, but sediments finer than 1 µm were more readily removed from runoff than particles in the range of 2 to approximately 10 µm.

Grass litter had less influence on flow velocity than leaves because the deposited sediment partially covered the litter layer. Mean flow velocity and its standard deviation were negatively correlated with STE, and they can help make good estimation of STE. Results from this study should be useful in planting and managing forage grass to effectively conserve soil loss by runoff from steep slopes on the Loess Plateau of China. Copyright © 2010 John Wiley & Sons, Ltd.
Transverse architecture of lahar terraces, inferred from radargrams: preliminary results from Semeru Volcano, Indonesia
Authors: Gomez C. , Lavigne F.
Published: April 2010

Semeru Volcano is the highest mountain of Java (Indonesia), and a vulcanian explosion occurs every 15 minutes on average, since 1967. Thus a constantly renewed stock of material and the heavy monsoon rainfall [3700 mm yr−1 at 1500 m above sea level (a.s.l.)] provide a perfect setting for the study of lahars and their deposits. Hence, we examined the architecture of lahars' terraces 9·5 km from the summit in the Curah Lengkong Valley. We first used ground penetrating radar (GPR) over vertical exposures of the lahars cut‐bank terraces. This allowed us to better understand transversal radargrams across terraces, which are not visually accessible in the field.

Preliminary results from a single radargram are very instructive, since (1) they prove that the lateral architecture does not correspond to that observed from banks only; (2) we could observe the presence of lenses and stratigraphic discontinuities; (3) the setting of the various units can also help reconstruct deposition processes and the chronology of different units. In order to finalize these preliminary results, we however need to perform multiple GPR radargrams and provide a complete set of results. Copyright © 2010 John Wiley & Sons, Ltd.
Rock slope instability assessment using spatially distributed structural orientation data in Darjeeling Himalaya (India)
Authors: Ghosh Saibal , Günther Andreas , Carranza Emmanuel John M. , van Westen Cees J. , Jetten Victor G.
Published: April 2010

We discuss a geographic information system (GIS)‐based methodology for rock slope instability assessment based on geometrical relationships between topographic slopes and structural discontinuities in rocks. The methodology involves (a) regionalization of point observations of orientations (azimuth and dip) of structural discontinuities in rocks in order to generate a digital structural model (DStM), (b) testing the kinematical possibility of specific modes of rock slope failures by integrating DStMs and digital elevation model (DEM)‐derived slope and aspect data and (c) computation of stability scenarios with respect to identified rock slope failure modes. We tested the methodology in an area of 90 km2 in Darjeeling Himalaya (India) and in a small portion (9 km2) within this area with higher density of field structural orientation data. The results of the study show better classification of rock slope instability in the smaller area with respect to known occurrences of deep‐seated rockslides than with respect to shallow translational rockslides, implying that structural control is more important for deep‐seated rockslides than for shallow translational rockslides. Results of scenario‐based analysis show that, in rock slopes classified to be unstable, stress‐induced rock slope instability tends to increase with increasing level of water saturation. The study demonstrates the usefulness of spatially distributed data of orientations of structural discontinuities in rocks for medium‐ to small‐scale classification of rock slope instability in mountainous terrains. Copyright © 2010 John Wiley & Sons, Ltd.
Modeling fluid saturated porous media under frost attack
Authors: Ricken Tim , Bluhm Joachim
Published: April 2010

Freezing and thawing are important processes in civil engineering. On the one hand frost damage of porous building materials like road pavements and concrete in regions with periodical freezing is well known. On the other hand, artificial freezing techniques are widely used, e.g. for tunneling in non‐cohesive soils and other underground constructions as well as for the protection of excavation and compartmentalization of contaminated tracts. Ice formation in porous media results from a coupled heat and mass transport and is accompanied by the ice expansion. The volume increase in space and time is assigned to the moving freezing front inside the porous solid. In this paper, a macroscopic ternary model is presented within the framework of the Theory of Porous Media (TPM) in view of the description of phase transition. For the mass exchange between ice and water an evolution equation based on the local balance of the heat flux vector is used. Examples illustrate the application of the model for saturated porous solids under thermal loading (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solving geometrically exact micromorphic elasticity with a staggered algorithm
Authors: Klawonn Axel , Neff Patrizio , Rheinbach Oliver , Vanis Stefanie
Published: April 2010

A minimization problem modeling geometrically exact generalized continua of micromorphic type is considered. The solution consists of two fields, the elastic deformation φ of a given body and a tensorial field P which can model different additional features needed for a more reliable description of solids. For the solution of this minimization problem, a staggered algorithm is introduced which decouples the original problem into two separate problems. In each of these subproblems, one of the variables, φ or P, respectively, is kept fixed and the subproblem is solved for the remaining variables, i.e., P or φ, respectively. Each of the problems is discretized with finite elements. Numerical results are presented for a cubic and a cylindrical geometry (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parallel simulation of an infinitesimal elasto‐plastic Cosserat model
Authors: Neff Patrizio , Müller Wolfgang , Wieners Christian
Published: April 2010

We review the continuous and fully‐discrete problem setting of an elasto‐plastic Cosserat model, which is an enhanced continuum model with independent rotational degrees of freedom. The continuous model is defined by a variational inequality, and for the discrete model a corresponding non‐smooth nonlinear variational problem is derived which can be solved with a generalized Newton method. We present numerical results for two representative geometries, where we test the convergence for different finite element discretizations, we study the parameter dependency, and we demonstrate the efficiency of the parallel solution method for very large problem sizes (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ferroportin1 and hephaestin overexpression attenuate iron‐induced oxidative stress in MES23.5 dopaminergic cells
Authors: Song Ning , Wang Jun , Jiang Hong , Xie Junxia
Published: April 2010

Elevated iron was found in the substantia nigra (SN) of patients with Parkinson's disease (PD). Our previous in vivo experiments suggested that decreased ferroportin1 (FPN1) and hephaestin (HP) expression might account for the cellular iron accumulation and resulting dopaminergic neurons loss in the SN of PD animal models. In the present study, we investigated whether increased FPN1 and/or HP expression could attenuate iron‐induced oxidative stress in the dopaminergic MES23.5 cell line. We generated MES23.5 cells with stable overexpression of FPN1 and/or HP. Our study showed that overexpression of FPN1 and/or HP increased iron efflux, lowered cellular iron level, suppressed reactive oxygen species production, and restored mitochondrial transmembrane potential, similar to the effects seen for the iron chelator deferoxamine. These results suggest that FPN1 and/or HP might directly contribute to iron efflux process from neurons in conditions of overexpression, thus prevent cellular iron accumulation and eventually protect cells from iron‐induced oxidative stress. J. Cell. Biochem. 110: 1063–1072, 2010. Published 2010 Wiley‐Liss, Inc.
Interferon regulatory factor‐1 acts as a powerful adjuvant in tat DNA based vaccination
Authors: Castaldello Arianna , Sgarbanti Marco , Marsili Giulia , Brocca‐Cofano Egidio , Remoli Anna Lisa , Caputo Antonella , Battistini Angela
Published: April 2010

Genetic vaccines are safe cost‐effective approaches to immunization but DNA immunization is an inefficient process. There is, therefore, a pressing need for adjuvants capable of enhancing the immunogenicity and effectiveness of these vaccines. This is particularly important for diseases for which successful vaccines are still lacking, such as cancer and infectious diseases including HIV‐1/AIDS. Here we report an approach to enhance the immunogenicity of DNA vaccines involving the use of transcription factors of the Interferon regulatory factor (IRF) family, specifically IRF‐1, IRF‐3, and IRF‐7 using the tat gene as model antigen. Balb/c mice were immunized by three intramuscular inoculations, using a DNA prime‐protein boost protocol, with a DNA encoding tat of HIV‐1 and the indicated IRFs and immune responses were compared to those induced by vaccination with tat DNA alone. In vivo administration of plasmid DNA encoding IRF‐1, or a mutated version of IRF‐1 deleted of the DNA‐binding domain, enhanced Tat‐specific immune responses and shifted them towards a predominant T helper 1‐type immune response with increased IFN‐γ production and cytotoxic T lymphocytes responses. Conversely, the use of IRF‐3 or IRF‐7 did not affect the tat‐induced responses. These findings define IRF‐1 and its mutated form as efficacious T helper 1‐inducing adjuvants in the context of tat‐based vaccination and also providing a new promising candidate for genetic vaccine development. J. Cell. Physiol. 224: 702–709, 2010. © 2010 Wiley‐Liss, Inc.