bluuebunny/crossref_metadata_2025 huggingface dataset:
One‐Pot Solvothermal Synthesis of Highly Water‐Dispersible Size‐Tunable Functionalized Magnetite Nanocrystal Clusters for Lipase Immobilization
Authors: Zhu Hao , Hou Chen , Li Yijing , Zhao Guanghui , Liu Xiao , Hou Ke , Li Yanfeng
Published: April 2013

A facile one‐pot synthesis of highly water‐dispersible size‐tunable magnetite (Fe3O4) nanocrystal clusters (MNCs) end‐functionalized with amino or carboxyl groups by a modified solvothermal reduction reaction has been developed. Dopamine and 3,4‐dihydroxyhydroxycinnamic acid were used for the first time as both a surfactant and interparticle linker in a polylol process for economical and environment‐friendly purposes. Morphology, chemical composition, and magnetic properties of the prepared particles were investigated by several methods, including FESEM, TEM, XRD, XPS, Raman, FTIR, TGA, zeta potential, and VSM. The sizes of the particles could be easily tuned over a wide range from 175 to 500 nm by varying the surfactant concentration. Moreover, ethylene glycol/diethylene glycol (EG/DEG) solvent mixtures with different ratios could be used as reductants to obtain the particles with smaller sizes. The XRD data demonstrated that the surfactants restrained the crystal growth of the grains. The nanoparticles showed superior magnetic properties and high colloidal stability in water. The cytotoxicity results indicated the feasibility of using the synthesized nanocrystals in biology‐related fields. To estimate the applicability of the obtained MNCs in biotechnology, Candida rugosa lipase was selected for the enzyme immobilization process. The immobilized lipase exhibited excellent thermal stability and reusability in comparison with the free enzyme. This novel strategy would simplify the reaction protocol and improve the efficiency of materials functionalization, thus offering new potential applications in biotechnology and organocatalysis.
Faster than their prey: New insights into the rapid movements of active carnivorous plants traps
Authors: Poppinga Simon , Masselter Tom , Speck Thomas
Published: April 2013

Plants move in very different ways and for different reasons, but some active carnivorous plants perform extraordinary motion: Their snap‐, catapult‐ and suction traps perform very fast and spectacular motions to catch their prey after receiving mechanical stimuli. Numerous investigations have led to deeper insights into the physiology and biomechanics of these trapping devices, but they are far from being fully understood. We review concisely how plant movements are classified and how they follow principles that bring together speed, actuation and architecture of the moving organ. In particular, we describe and discuss how carnivorous plants manage to execute fast motion. We address open questions and assess the prospects for future studies investigating potential universal mechanisms that could be the basis of key characteristic features in plant movement such as stimulus transduction, post‐stimulatory mechanical answers, and organ formation.
Genome‐scale modeling of human metabolism – a systems biology approach
Authors: Mardinoglu Adil , Gatto Francesco , Nielsen Jens
Published: April 2013

Altered metabolism is linked to the appearance of various human diseases and a better understanding of disease‐associated metabolic changes may lead to the identification of novel prognostic biomarkers and the development of new therapies. Genome‐scale metabolic models (GEMs) have been employed for studying human metabolism in a systematic manner, as well as for understanding complex human diseases. In the past decade, such metabolic models – one of the fundamental aspects of systems biology – have started contributing to the understanding of the mechanistic relationship between genotype and phenotype. In this review, we focus on the construction of the Human Metabolic Reaction database, the generation of healthy cell type‐ and cancer‐specific GEMs using different procedures, and the potential applications of these developments in the study of human metabolism and in the identification of metabolic changes associated with various disorders. We further examine how in silico genome‐scale reconstructions can be employed to simulate metabolic flux distributions and how high‐throughput omics data can be analyzed in a context‐dependent fashion. Insights yielded from this mechanistic modeling approach can be used for identifying new therapeutic agents and drug targets as well as for the discovery of novel biomarkers. Finally, recent advancements in genome‐scale modeling and the future challenge of developing a model of whole‐body metabolism are presented. The emergent contribution of GEMs to personalized and translational medicine is also discussed.
A potential new enriching trial design for selecting non‐small‐cell lung cancer patients with no predictive biomarker for trials based on both histology and early tumor response: further analysis of a thalidomide trial
Authors: Lee Siow Ming , Hackshaw Allan
Published: April 2013

There are few predictive biomarkers for antiangiogenic trials in lung cancer. We examine a potential treatment strategy in which a patient group is enriched using both histology and an early assessment of response during standard chemotherapy, and where a new agent is given for the remainder of chemotherapy and as maintenance. We performed a retrospective analysis of 722 stage IIIB/IV non‐small‐cell lung cancer patients from a double‐blind placebo‐controlled trial of thalidomide or placebo 100–200 mg/day, combined with gemcitabine/carboplatin (for up to four cycles), then given as single agent maintenance therapy. There was a significant statistical interaction between treatment and histology, with a possible benefit among squamous cell cancer (SCC) patients. We examined 150 SCC patients who were “nonprogressors” (stable disease or complete/partial response) after completing the second chemotherapy cycle. Endpoints were progression‐free survival (PFS) and overall survival (OS). Among the 150 patients nonprogressors after cycle 2 (thalidomide, n = 72; placebo, n = 78; baseline characteristics were similar), the hazard ratios (HRs) were: OS = 0.76 (95% CI: 0.54–1.07) and PFS = 0.69 (95% CI: 0.50–0.97). In 57 patients who had a complete/partial response, the HRs were: OS = 0.63 (95% CI: 0.34–1.15) and PFS = 0.50 (95% CI: 0.28–0.88). SCC patients who were nonprogressors after 2 cycles of standard chemotherapy showed evidence of a benefit from thalidomide when taken for the remainder of chemotherapy and as maintenance. This strategy based on histology and, importantly, early assessment of tumor response, as a means of patient enrichment, could be examined in other lung cancer studies. Such an approach might be suitable for trials where there are no predictive biomarkers.
Transcatheter aortic valve implantation in patients of small body size
Authors: Watanabe Yusuke , Hayashida Kentaro , Lefèvre Thierry , Chevalier Bernard , Hovasse Thomas , Romano Mauro , Garot Philippe , Farge Arnaud , Donzeau‐Gouge Patrick , Bouvier Erik , Cormier Bertrand , Morice Marie‐Claude
Published: April 2013

Aims

The aim of this study was to evaluate the efficacy and safety of transcatheter aortic valve implantation (TAVI) in patients of small body size (SB).

Methods and Results

Between October 2006 and November 2011, 424 patients undergoing TAVI were evaluated. Patients with a small body surface area (BSA; <1.75 m2) were defined as the “SB group” (n = 215) and the remaining large BSA patients as the “LB group” (n = 209). In the SB group, mean annulus diameter measured by CT and minimal femoral artery diameter were significantly smaller (23.1 ± 1.92 vs. 24.3 ± 1.91 mm, P < 0.01; 7.59 ± 1.06 vs. 8.29 ± 1.34 mm, P < 0.01, respectively). The logistic EuroSCORE was similar between groups (22.5 ± 10.4 vs. 23.4 ± 12.0; P = 0.43). Equivalent device success (91.2% vs. 91.4%; P = 0.94) and 30‐day survival rates (85.1% vs. 87.6%; P = 0.46) were achieved in both groups. Vascular complications and the 30‐day combined safety end point rate were significantly higher in the SB group (13.0% vs. 4.3%, P < 0.01; 27.4% vs. 18.3%, P = 0.03, respectively). Similar post‐procedural mean pressure gradient was achieved in both groups (10.2 ± 4.3 vs. 11.0 ± 4.6 mmHg; P = 0.12). Multivariate analysis showed that BSA was one of the independent predictors of 30‐day combined safety end point (Odds ratio: 0.20; 95% confidence interval (CI): 0.05–0.88; P = 0.03). However, Kaplan–Meier analysis revealed no significant difference in mid‐term survival rate between groups (log‐rank P = 0.64).

Conclusions

TAVI in SB patients resulted in similar clinical outcomes with effective post‐procedural hemodynamics compared with LB patients. Care should be taken to avoid vascular complications in SB patients. © 2013 Wiley Periodicals, Inc.
Mitral paravalvular leak closure by antegrade percutaneous approach: Three‐dimensional transesophageal echocardiographic guided multiple amplatzer implantation by a modified sequential anchoring‐based technique
Authors: Tarantini Giuseppe , Mojoli Marco , Napodano Massimo
Published: April 2013

We describe the technical aspects and the possible advantages of a modified anchoring‐based technique for the implantation of multiple Amplatzer devices, in a case of large anteroseptal mitral paravalvular leak causing massive regurgitation, which was manaed by antegrade transseptal, single‐stage, percutaneous approach. Real‐time three‐dimensional transesophageal echocardiographic guidance was crucial to ensure successful recrossings of the target defect and the optimal anatomical closure. © 2013 Wiley Periodicals, Inc.
Left main dissection conservatively managed with optical coherence tomography guidance
Authors: Binder Ronald K. , Boone Robert H. , Webb John G.
Published: April 2013

Left main dissection (LMD) is a rare but feared complication of cardiac catheterization. It is usually managed by bailout stent implantation or coronary artery bypass surgery. We describe a case of iatrogenic, retrograde LMD during percutaneous coronary intervention. After covering the retrograde entry of the dissection in the ostial left anterior descending artery (LAD), optical coherence tomography (OCT) showed, that there was no antegrade entry in the left main and that the minimal true lumen area in the left main was 7.2 mm2. It was therefore decided to treat the LMD conservatively and reassess the results by angiography 6 months later. At follow‐up angiography, no stenosis or residual dissection in the left main were noted. The patient was doing fine at 1‐year follow‐up. OCT is a valuable tool for assessing coronary artery dissections and may guide the decision, whether to stent or not to stent a dissection. In selected cases LMD may be managed conservatively. © 2013 Wiley Periodicals, Inc.
Synthesis of 2,5‐Diarylpyrroles by Ligand‐Free Palladium‐Catalyzed CH Activation of Pyrroles in Ionic Liquids
Authors: Ehlers Peter , Petrosyan Andranik , Baumgard Jens , Jopp Stefan , Steinfeld Norbert , Ghochikyan Tariel V. , Saghyan Ashot S. , Fischer Christine , Langer Peter
Published: April 2013

The palladium‐catalyzed CH activation and arylation of N‐methylpyrrole and N‐phenylpyrrole allowed a convenient synthesis of diarylpyrroles. The reactions were performed by using tetrabutylammonium acetate as an ionic solvent, which allowed for the application of a ligand‐free catalytic system by using simple palladium salts or polyvinylpyrrolidone‐stabilized palladium nanoparticles as the catalyst.
Hydrodynamics and Transport Processes during Centrifugal Short‐Path Distillation
Authors: Chen L.‐J. , Dong H.‐B. , Li Q. , Niu C.‐C. , Zeng A.‐W.
Published: April 2013

To simulate the centrifugal short‐path distillation process, both two phases and interfacial transport are taken into account simultaneously for the first time. A new computational fluid dynamics model based on the volume‐of‐fluid and species transport methods is built up to analyze the detailed flow and transfer characteristics. A binary system with dibutyl phthalate‐dibutyl sebacate (DBP‐DBS) is used as an example for the investigation with both numerical and experimental methods. The residence time and the effects of operating parameters such as evaporator temperature and feed flow rate are explored comparatively. The simulation result for the liquid‐film thickness shows a satisfactory agreement with literature data. On the basis of the simulation results, we may also obtain detailed characteristics of the heat and mass transfer such as gradients in temperature and concentration and the liquid overall mass transfer coefficient.
Design and Control of Extraction Distillation for Dehydration of Tetrahydrofuran
Authors: Fan Z. , Zhang X. , Cai W. , Wang F.
Published: April 2013

Design and control of an extractive distillation system for tetrahydrofuran (THF) dehydration with ethylene glycol as entrainer is investigated. The main module is a two‐column system containing an extractive distillation column, whose top stream is the desired product THF, and an entrainer recovery column. Economic analysis with total annual cost as the objective function is developed. Two kinds of control strategies are explored for THF dehydration. The responses reveal that the control structure with fixed reflux ratio cannot maintain the bottom liquid level of the entrainer recovery column, while the control scheme with fixed reboiler heat duty/feed flow ratio exhibits good control performance in spite of large deviations in feed flow rate and feed composition.
Redox‐Controlled Helical Self‐Assembly of a Polyoxometalate Complex
Authors: Zhang Jing , Li Wen , Wu Che , Li Bao , Zhang Jiao , Wu Lixin
Published: April 2013

Polyoxometalate (POM) complex (DODA)2[Mo6O19] with a symmetrical linear structure was prepared conveniently by replacing the tetrabutylammonium (TBA) counterions of Lindquist‐type cluster (TBA)2[Mo6O19] with cationic surfactant dioctadecyldimethylammonium (DODA). A helical self‐assembled structure of the complex was formed in dichloromethane/propanol. The dynamically reversible transformation between helical and spherical assemblies on alternate UV irradiation and H2O2 oxidation was characterized by SEM, TEM, and UV/Vis studies. The redox‐controlled morphology change is modulated by variation of the electrostatic interactions between the inorganic polyanion and the organic cation DODA through controlling the redox properties of the POM component, as shown by the XRD, X‐ray photoelectron spectroscopic, and 1H NMR measurements. The strategy applied herein is a unique example of targeted smart and helical assembly of POM complexes.
Visible‐Light‐Induced Photodimerization of a Photoactive Yellow Protein (PYP) Chromophore Model in a Single Crystal
Authors: Nath Naba K. , Manoj Kochunnoonny , Gâz Andrei Şerban , Naumov Panče
Published: April 2013

The chromophore of the photoactive yellow protein (PYP), the photoreceptor in the photomotility of the bacterium Halorhodospira halophila, is a deprotonated para‐coumaric thioester linked to the side residue of a cysteine residue. The photophysics of the PYP chromophore is conveniently modeled with para‐hydroxycinnamic thiophenyl esters. Herein, we report the first direct evidence, obtained with X‐ray diffraction, of photodimerization of a para‐hydroxycinnamic thiophenyl ester in single crystalline state. This result represents the first direct observation of [2+2] dimerization of a model PYP chromophore, and demonstrates that even very weak light in the visible region is capable of inducing parallel radical reactions in PYP from the excited state of the chromophore, in addition to the main reaction pathway (trans–cis isomerization). This PYP model system adds an interesting example to the known solid‐state photodimerizations, because unlike the anhydrous crystal (which is not capable of sustaining the stress and disintegrates in the course of photodimerization), a single water molecule “dilutes” the structure to the extent sufficient for single‐crystal‐to‐single‐crystal reaction.
Optical imaging detection of microscopic mammary cancer in ErbB‐2 transgenic mice through the DA364 probe binding αvβ3 integrins
Authors: Conti Laura , Lanzardo Stefania , Iezzi Manuela , Montone Monica , Bolli Elisabetta , Brioschi Chiara , Maiocchi Alessandro , Forni Guido , Cavallo Federica
Published: April 2013

Despite spontaneous tumor growth in genetically engineered mice being one of the most recognized tools for the in vivo evaluation of novel diagnostic and therapeutic anticancer compounds, monitoring early stage lesions in live animals is a goal that has yet to be achieved. A large number of targets for the molecular imaging of various diseases have been identified and many imaging technologies, including optical techniques are emerging. One of the most commonly exploited targets in tumor imaging is αvβ3 integrin, which plays an important role in the expansion, invasiveness and metastatic capability of a number of cancers, including breast cancer. The aim of this study was to set up an optical imaging method for the early detection of autochthonous mammary cancer in female BALB/c mice transgenic for the rat‐ErbB‐2 oncogene (BALB‐neuT). We show that DA364, a near‐infrared fluorescence arginine–glycine–aspartic acid cyclic probe, was taken up by neoplastic mammary glands and that its uptake increased with cancer progression. By contrast, the nonaccumulation of DA364 in the healthy mammary glands of virgin and lactating wild‐type mice suggests that the probe specifically targets breast cancers. Comparisons of optical imaging with whole‐mount and histological findings showed that DA364 allows the noninvasive visualization of atypical hyperplasia and microscopic foci of in situ carcinoma 2 months before mammary lesions become detectable by palpation. Moreover, DA364 was successfully used to monitor the outcome of anticancer vaccination. Therefore, it can be considered a promising early detection tool in near‐infrared noninvasive optical imaging for the early diagnosis of breast cancer. Copyright © 2013 John Wiley & Sons, Ltd.
Assessment of the biodistribution of an [18F]FDG‐loaded perfluorocarbon double emulsion using dynamic micro‐PET in rats
Authors: Fabiilli Mario L. , Piert Morand R. , Koeppe Robert A. , Sherman Phillip S. , Quesada Carole A. , Kripfgans Oliver D.
Published: April 2013

Perfluorocarbon (PFC) double emulsions loaded with a water‐soluble, therapeutic agent can be triggered by ultrasound in a process known as acoustic droplet vaporization. Elucidating the stability and biodistribution of these sonosensitive vehicles and encapsulated agents is critical in developing targeted drug delivery strategies using ultrasound. [18F]fluorodeoxyglucose (FDG) was encapsulated in a PFC double emulsion and the in vitro diffusion of FDG was assessed using a Franz diffusion cell. Using dynamic micro‐positron emission tomography and direct tissue sampling, the biodistribution of FDG administered as a solution (i.e. non‐emulsified) or as an emulsion was studied in Fisher 344 rats (n = 6) bearing subcutaneous 9L gliosarcoma. Standardized uptake values (SUVs) and area under the curve of the SUV (AUCSUV) of FDG were calculated for various tissues. The FDG flux from the emulsion decreased by up to a factor of 6.9 compared with the FDG solution. FDG uptake, calculated from the AUCSUV, decreased by 36% and 44% for brain and tumor, respectively, when comparing FDG solution vs FDG emulsion (p < 0.01). Decreases in AUCSUV in highly metabolic tissues such as brain and tumor demonstrated retention of FDG within the double emulsion. No statistically significant differences in lung AUCSUV were observed, suggesting minimal accumulation of the emulsion in the pulmonary capillary bed. The liver AUCSUV increased by 356% for the FDG emulsion, thus indicating significant hepatic retention of the emulsion. Copyright © 2013 John Wiley & Sons, Ltd.
Reconstruction of Coefficients in Scalar Second‐Order Elliptic Equations from Knowledge of Their Solutions
Authors: Bal Guillaume , Uhlmann Gunther
Published: April 2013

This paper concerns the reconstruction of possibly complex‐valued coefficients in a second‐order scalar elliptic equation that is posed on a bounded domain from knowledge of several solutions of that equation. We show that for a sufficiently large number of solutions and for an open set of corresponding boundary conditions, all coefficients can be uniquely and stably reconstructed up to a well‐characterized gauge transformation. We also show that in some specific situations, a minimum number of such available solutions equal to
$I_n = {1 \over 2}n(n + 3)$
is sufficient to uniquely and globally reconstruct the unknown coefficients. This theory finds applications in several coupled‐physics medical imaging modalities including photo‐acoustic tomography, transient elastography, and magnetic resonance elastography. © 2013 Wiley Periodicals, Inc.
Computational Studies on Non‐covalent Interactions of Carbon and Boron Fullerenes with Graphene
Authors: Manna Arun K. , Pati Swapan K.
Published: April 2013

First‐principles DFT calculations are carried out to study the changes in structures and electronic properties of two‐dimensional single‐layer graphene in the presence of non‐covalent interactions induced by carbon and boron fullerenes (C60, C70, C80 and B80). Our study shows that larger carbon fullerene interacts more strongly than the smaller fullerene, and boron fullerene interacts more strongly than that of its carbon analogue with the same nuclearity. We find that van der Waals interactions play a major role in governing non‐covalent interactions between the adsorbed fullerenes and graphene. Moreover, a greater extent of van der Waals interactions found for the larger fullerenes, C80 and B80, relative to smaller C60, and consequently, results in higher stabilisation. We find a small amount of electron transfer from graphene to fullerene, which gives rise to a hole‐doped material. We also find changes in the graphene electronic band structures in the presence of these surface‐decorated fullerenes. The Dirac cone picture, such as that found in pristine graphene, is significantly modified due to the re‐hybridisation of graphene carbon orbitals with fullerenes orbitals near the Fermi energy. However, all of the composites exhibit perfect conducting behaviour. The simulated absorption spectra for all of the graphene–fullerene hybrids do not exhibit a significant change in the absorption peak positions with respect to the pristine graphene absorption spectrum. Additionally, we find that the hole‐transfer integral between graphene and C60 is larger than the electron‐transfer integrals and the extent of these transfer integrals can be significantly tuned by graphene edge functionalisation with carboxylic acid groups. Our understanding of the non‐covalent functionalisation of graphene with various fullerenes would promote experimentalists to explore these systems, for their possible applications in electronic and opto‐electronic devices.
Failure of centrosome migration causes a loss of motile cilia in talpid3 mutants
Authors: Stephen Louise A. , Davis Gemma M. , Mcteir Katie E. , James John , Mcteir Lynn , Kierans Martin , Bain Andrew , Davey Megan G.
Published: April 2013

Background: Loss of function mutations in the centrosomal protein TALPID3 (KIAA0586) cause a failure of primary cilia formation in animal models and are associated with defective Hedgehog signalling. It is unclear, however, if TALPID3 is required only for primary cilia formation or if it is essential for all ciliogenesis, including that of motile cilia in multiciliate cells. Results: FOXJ1, a key regulator of multiciliate cell fate, is expressed in the dorsal neuroectoderm of the chicken forebrain and hindbrain at stage 20HH, in areas that will give rise to choroid plexuses in both wt and talpid3 embryos. Wt ependymal cells of the prosencephalic choroid plexuses subsequently transition from exhibiting single short cilia to multiple long motile cilia at 29HH (E8). Primary cilia and long motile cilia were only rarely observed on talpid3 ependymal cells. Electron microscopy determined that talpid3 ependymal cells do develop multiple centrosomes in accordance with FOXJ1 expression, but these fail to migrate to the apical surface of ependymal cells although axoneme formation was sometimes observed. Conclusions: TALPID3, which normally localises to the proximal centrosome, is essential for centrosomal migration prior to ciliogenesis but is not directly required for de novo centriologenesis, multiciliated fate, or axoneme formation. Developmental Dynamics 242:923–931, 2013. © 2013 Wiley Periodicals, Inc.
Estimation of in‐service quality of experience for peer‐to‐peer live video streaming systems using a user‐centric and context‐aware approach based on Bayesian networks
Authors: Mian Ahmad Umair , Hu Zheng , Tian Hui
Published: April 2013

In this paper, a modified and improved quality of experience (QoE) estimation approach has been presented on the basis of the user‐behavior modelling and context‐aware modelling. We have implemented this proposed approach for peer‐to‐peer live video streaming systems because of the dynamically adaptive and distributed nature of these systems. The problem of estimating QoE is formulated as a Bayesian network model using user‐behavior and context‐related variables as nodes. The relationship between these nodes are established to find out estimated QoE, which is based on the user‐behavior data and context data, and dynamically adapt to any change in their values. This relationship is further explored to provide the basis for more user‐centric, context‐aware and dynamically adaptive services and network systems as this in‐service QoE is important for network optimization and service provisioning. Copyright © 2013 John Wiley & Sons, Ltd.
Limited plastic potential of the left ventral premotor cortex in speech articulation: Evidence From intraoperative awake mapping in glioma patients
Authors: van Geemen Kim , Herbet Guillaume , Moritz‐Gasser Sylvie , Duffau Hugues
Published: April 2013

Objectives: Despite previous lesional and functional neuroimaging studies, the actual role of the left ventral premotor cortex (vPMC), i.e., the lateral part of the precentral gyrus, is still poorly known. Experimental design:We report a series of eight patients with a glioma involving the left vPMC, who underwent awake surgery with intraoperative cortical and subcortical language mapping. The function of the vPMC, its subcortical connections, and its reorganization potential are investigated in the light of surgical findings and language outcome after resection. Principal observations: Electrostimulation of both the vPMC and subcortical white matter tract underneath the vPMC, that is, the anterior segment of the lateral part of the superior longitudinal fascicle (SLF), induced speech production disturbances with anarthria in all cases. Moreover, although some degrees of redistribution of the vPMC have been found in four patients, allowing its partial resection with no permanent speech disorders, this area was nonetheless still detected more medially in the precentral gyrus in the eight patients, despite its invasion by the glioma. Moreover, a direct connection of the vPMC with the SLF was preserved in all cases. Conclusions: Our original data suggest that the vPMC plays a crucial role in the speech production network and that its plastic potential is limited. We propose that this limitation is due to an anatomical constraint, namely the necessity for the left vPMC to remain connected to the lateral SLF. Beyond fundamental implications, such knowledge may have clinical applications, especially in surgery for tumors involving this cortico‐subcortical circuit. Hum Brain Mapp 35:1587–1596, 2014. © 2013 Wiley Periodicals, Inc.
Association between white matter fiber structure and reward‐related reactivity of the ventral striatum
Authors: Koch Kathrin , Wagner Gerd , Schachtzabel Claudia , Schultz C. Christoph , Güllmar Daniel , Reichenbach Jürgen R. , Sauer Heinrich , Zimmer Claus , Schlösser Ralf G.M.
Published: April 2013

Individual responsiveness to rewards or rewarding stimuli may affect various domains of normal as well as pathological behavior. The ventral striatum/nucleus accumbens (NAcc) constitutes a key brain structure in the regulation of reward‐appetitive behavior. It remains unclear, however, to which extent individual reward‐related BOLD response in the NAcc is dependent on individual characteristics of connecting white matter fiber tracts. Using tract‐based spatial statistics (TBSS) and statistical parametric mapping (SPM) this combined DTI ‐ fMRI study investigated this question by correlating NAcc BOLD signal upon receipt of a monetary reward with different white matter characteristics (FA, axial diffusivity, radial diffusivity). The results show that increased integrity of white matter as assessed by FA in the cingulate and corpus callosum, the inferior fronto‐occipital fasciculus, the anterior thalamic radiation and the anterior limb of the internal capsule was positively correlated with reward‐related activation in the NAcc. There were no negative correlations as well as no significant results regarding axial and radial diffusivity. These findings indicate that microstructural properties of fiber tracts connecting, amongst others, the cortex with the striatum may influence intensity of reward‐related responsiveness of the ventral striatum by constraining or increasing efficiency in information transfer within relevant circuitries involved in processing of reward. Hum Brain Mapp 35:1469–1476, 2014. © 2013 Wiley Periodicals, Inc.
The chronology and the hydrometeorology of catastrophic floods on Dartmoor, South West England
Authors: Foulds S. A. , Macklin M. G. , Brewer P. A.
Published: April 2013

Extreme floods are the most widespread and often the most fatal type of natural hazard experienced in Europe, particularly in upland and mountainous areas. These ‘flash flood’ type events are particularly dangerous because extreme rainfall totals in a short space of time can lead to very high flow velocities and little or no time for flood warning. Given the danger posed by extreme floods, there are concerns that catastrophic hydrometeorological events could become more frequent in a warming world. However, analysis of longer term flood frequency is often limited by the use of short instrumental flow records (last 30–40 years) that do not adequately cover alternating flood‐rich and flood‐poor periods over the last 2 to 3 centuries. In contrast, this research extends the upland flood series of South West England (Dartmoor) back to ca AD 1800 using lichenometry. Results show that the period 1820 to mid‐1940s was characterized by widespread flooding, with particularly large and frequent events in the mid‐to‐late 19th and early 20th centuries. Since ca 1850 to 1900, there has been a general decline in flood magnitude that was particularly marked after the 1930s/mid‐1940s. Local meteorological records show that: (1) historical flood‐rich periods on Dartmoor were associated with high annual, seasonal and daily rainfall totals in the last quarter of the 19th century and between 1910 and 1946, related to sub‐decadal variability of the North Atlantic Oscillation and receipt of cyclonic and southerly weather types over the southwest peninsula; and (2) the incidence of heavy daily rainfall declined notably after 1946, similar to sedimentary archives of flooding. The peak period of flooding on Dartmoor predates the beginning of gauged flow records, which has practical implications for understanding and managing flood risk on rivers that drain Dartmoor. Copyright © 2013 John Wiley & Sons, Ltd.
Screening for occult malignancy with FDG‐PET/CT in patients with unprovoked venous thromboembolism
Authors: Alfonso Ana , Redondo Margarita , Rubio Tomás , Del Olmo Beatriz , Rodríguez‐Wilhelmi Pablo , García‐Velloso María J. , Richter José A. , Páramo José A. , Lecumberri Ramón
Published: April 2013

Extensive screening strategies to detect occult cancer in patients with unprovoked venous thromboembolism (VTE) are complex and no benefit in terms of survival has been reported. FDG‐PET/CT (2‐[F‐18] fluoro‐2‐deoxy‐D‐glucose positron emission tomography combined with computed tomography), a noninvasive technique for the diagnosis and staging of malignancies, could be useful in this setting. Consecutive patients ≥ 50 years with a first unprovoked VTE episode were prospectively included. Screening with FDG‐PET/CT was performed 3–4 weeks after the index event. If positive, appropriate diagnostic work‐up was programmed. Clinical follow‐up continued for 2 years. Blood samples were collected to assess coagulation biomarkers. FDG‐PET/CT was negative in 68/99 patients (68.7%), while suspicious FDG uptake was detected in 31/99 patients (31.3%). Additional diagnostic work‐up confirmed a malignancy in 7/31 patients (22.6%), with six of them at early stage. During follow‐up, two patients with negative FDG‐PET/CT were diagnosed with cancer. Sensitivity (S), positive (PPV) and negative predictive values (NPV) of FDG‐PET/CT as single tool for the detection of occult malignancy were 77.8% (95% CI: 0.51–1), 22.6% (95% CI: 0.08–0.37) and 97.1% (95% CI: 0.93–1), respectively. Median tissue factor (TF) activity in patients with occult cancer was 5.38 pM vs. 2.40 pM in those without cancer (p = 0.03). Limitation of FDG‐PET/CT screening to patients with TF activity > 2.8 pM would improve the PPV to 37.5% and reduce the costs of a single cancer diagnosis from 20,711€ to 11,670€. FDG‐PET/CT is feasible for the screening of occult cancer in patients with unprovoked VTE, showing high S and NPV. The addition of TF activity determination may be useful for patient selection.
Hematotoxicological analysis of surface‐modified and ‐unmodified chitosan nanoparticles
Authors: Nadesh Ragima , Narayanan Dhanya , P.R. Sreerekha , Vadakumpully Sajini , Mony Ullas , Koyakkutty Manzoor , Nair Shantikumar V. , Menon Deepthy
Published: April 2013

The increasing interest in using chitosan nanoparticles for controlled drug delivery is hampered by its blood incompatibility, especially for intravenous applications. This study investigated the effects of processing solvents (acetic acid/lactic acid), dispersing media (acidic medium/saline), and surface modifiers (polyethylene glycol, polyvinyl alcohol, and ethylenediaminetetraacetatic acid) on the hemocompatibility of chitosan. Blood compatibility of chitosan nanoparticles prepared by ionotropic gelation with altered surface chemistry was evaluated by assessing their hemolytic activity, platelet aggregation, coagulation, and cytokine induction. It was observed that nanoparticles prepared in lactic acid and dispersed in saline did not show hemolysis, platelet aggregation, or coagulation, whereas nanoparticles prepared in acetic acid showed strong hemolysis. Surface modifiers were not observed to significantly affect blood compatibility, with the exception of EDTA, which delayed blood clotting times. Thus, chitosan nanoparticles prepared in lactic acid and dispersed in saline may be an ideal nanocarrier for parenteral applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A:2957–2966, 2013.
Cell toxicity of methacrylate monomers—The role of glutathione adduct formation
Authors: Ansteinsson V. , Kopperud H. B. , Morisbak E. , Samuelsen J. T.
Published: April 2013

Polymer‐based dental restorative materials are designed to polymerize in situ. However, the conversion of methacrylate monomer to polymer is never complete, and leakage of the monomer occurs. It has been shown that these monomers are toxic in vitro; hence concerns regarding exposure of patients and dental personnel have been raised. Different monomer methacrylates are thought to cause toxicity through similar mechanisms, and the sequestration of cellular glutathione (GSH) may be a key event. In this study we examined the commonly used monomer methacrylates, 2‐hydroxyethylmethacrylate (HEMA), triethylenglycol‐dimethacrylate (TEGDMA), bisphenol‐A‐glycidyl‐dimethacrylate (BisGMA), glycerol‐dimethacrylate (GDMA) and methyl‐methacrylate (MMA). The study aimed to establish monomers' ability to complex with GSH, and relate this to cellular toxicity endpoints. Except for BisGMA, all the monomer methacrylates decreased the GSH levels both in cells and in a cell‐free system. The spontaneous formation of methacrylate‐GSH adducts were observed for all methacrylate monomers except BisGMA. However, we were not able to correlate GSH depletion and toxic response measured as SDH activity and changes in cell growth pattern. Together, the current study indicates mechanisms other than GSH‐binding to be involved in the toxicity of methacrylate monomers. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 3504–3510, 2013.
Synthesis and Evaluation of Activity‐Based Probes Carrying a 5′‐Fluorosulfonylbenzoyl Adenosine Moiety for Protein Kinases
Authors: Hsu Yu‐Ling , Yang Chun‐Chieh , Lan Chao‐Ying , Lin Jing‐Jer , Lo Lee‐Chiang
Published: April 2013

Protein kinases are involved in many important cellular signaling pathways. Development of activitybased probes targeting this enzyme family would be of great contemporary values. In this study, we established a synthetic route that allows parallel synthesis for the preparation of a 2 × 2 probe library. The probes feature a reactive fluorosulfonylbenzoyl moiety on an adenosine framework to investigate the effect of two structural variables on the labeling performance toward kinases. Preliminary labeling results indicated that probe 3, which is the best candidate in the probe library, is indeed an activity‐based probe for kinases. The results also revealed that the ester linkage between the fluorosulfonylbenzoyl moiety and the sugar plays an important role in the labeling ability of the probes, and the meta‐substituted sulfonyl fluoride could help improving the target specificity. The valuable information obtained in this study could be applied for probe improvement in the future.
Daytime altitude variations of the equatorial, topside magnetic field‐aligned ion transport at solar minimum
Authors: Burrell A. G. , Heelis R. A. , Ridley A.
Published: April 2013

Above the ion density peak, the interhemispheric transport of plasma plays an important role in shaping the spatial density distribution of the ionosphere. This study uses daytime observations of the ion drift, density, and composition near the geomagnetic equator from the Coupled Ion‐Neutral Dynamics Investigation on board the Communication/Navigation Outage Forecasting System satellite, for the period of extremely low solar activity present in 2008 and 2009, to explore the altitude variation in interhemispheric transport at heights reaching up to the O+/H+ transition height. These observations revealed that the physical processes leading to interhemispheric transport do not change with altitude. These processes include forcing from the lower thermosphere, E×B drift, and chemical processes. Their longitudinal variations combine with the structure of the geomagnetic field to cause the differences in interhemispheric transport seen in different longitude regions. At all longitudes, the quantity of plasma crossing the geomagnetic equator depends strongly on ion density, which causes large changes to the altitude variations of the field‐aligned plasma drift speed.
The propagation of compaction bands in porous rocks based on breakage mechanics
Authors: Das Arghya , Nguyen Giang D. , Einav Itai
Published: April 2013

We analyze the propagation of compaction bands in high porosity sandstones using a constitutive model based on breakage mechanics theory. This analysis follows the work by Das et al. [] on the initiation of compaction bands employing the same theory. In both studies, the theory exploits the links between the stresses and strains, and the micromechanics of grain crushing and pore collapse, giving the derived constitutive models advantages over previous models. In the current post localization analysis, the bifurcation instability of the continuum model is suppressed by the use of a rate‐dependent regularization. This allows us to perform a series of finite element analyses of drained triaxial tests on porous sandstone specimens. The obtained numerical results compare well with experimental counterparts, in terms of both the initiation and propagation of compaction bands, besides the macroscopic stress‐strain responses. On this basis, a parametric study is carried out to explore the effects of loading rate, degree of structural imperfections, and confining pressure on the propagation of compaction bands.
Numerical modeling of the formation and structure of the Orientale impact basin
Authors: Potter Ross W. K. , Kring David A. , Collins Gareth S. , Kiefer Walter S. , McGovern Patrick J.
Published: April 2013

The Orientale impact basin is the youngest and best‐preserved lunar multi‐ring basin and has, thus, been the focus of studies investigating basin‐forming processes and final structures. A consensus about how multi‐ring basins form, however, remains elusive. Here we numerically model the Orientale basin‐forming impact with the aim of resolving some of the uncertainties associated with this basin. By using two thermal profiles estimating lunar conditions at the time of Orientale's formation and constraining the numerical models with crustal structures inferred from gravity data, we provide estimates for Orientale's impact energy (2–9  × 1025 J), impactor size (50–80 km diameter), transient crater size (∼320–480 km), excavation depth (40–55 km), and impact melt volume (∼106 km3). We also analyze the distribution and deformation of target material and compare our model results and Orientale observations with the Chicxulub crater to investigate similarities between these two impact structures.
Riparian hydraulic gradient and stream‐groundwater exchange dynamics in steep headwater valleys
Authors: Voltz Thomas , Gooseff Michael , Ward Adam S. , Singha Kamini , Fitzgerald Michael , Wagener Thorsten
Published: April 2013

Patterns of riparian hydraulic gradients and stream‐groundwater exchange in headwater catchments provide the hydrologic context for important ecological processes. Although the controls are relatively well understood, their dynamics during periods of hydrologic change is not. We investigate riparian hydraulic gradients over three different time scales in two steep, forested, headwater catchments in Oregon (WS01 and WS03) to determine the potential controls of reach‐scale valley slope and cross‐sectional valley geometry. Groundwater and stream stage data collected at high spatial and temporal resolutions over a period encompassing a 1.25 year storm and subsequent seasonal baseflow recession indicate that hydraulic gradients in both riparian aquifers exhibit strong persistence of down‐valley dominance. Responses to rainfall do not support the simple conceptual models of increased riparian hydraulic gradient toward streams. Hydraulic gradient response in WS01 to both the seasonal baseflow recession and the storm suggested the potential for increased stream‐groundwater exchange, but there was less evidence for this in WS03. Results from four constant‐rate tracer injections in each stream showed a high baseline level of exchange overall, and both a slight seasonal increase (WS01) and slight decrease (WS03) in the riparian intrusion of tracer‐labeled stream water as stream discharge receded. These results indicate that steep headwater valley floors host extensive stream water exchange and very little change in the water table gradients over 3 orders of magnitude of stream discharge.
Suspension of bed material over sand bars in the Lower Mississippi River and its implications for Mississippi delta environmental restoration
Authors: Ramirez Michael T. , Allison Mead A.
Published: April 2013

Understanding specific pathways for sand transport in the lower reaches of large rivers, including the Mississippi, is a key for addressing multiple significant geologic problems, such as delta building and discharge to the oceans, and for environmental restoration efforts in deltaic environments threatened by rising sea levels. Field studies were performed in the Mississippi River 75–100 km upstream of the Gulf of Mexico outlet in 2010–2011 to examine sand transport phenomena in the tidally affected river channel over a range of discharges. Methods included mapping bottom morphology (multibeam sonar), cross‐sectional and longitudinal measurements of water column velocity and acoustic backscatter, suspended sediment sampling, and channel‐bed sampling. Substantial interaction was observed between the flow conditions in the river (boundary shear stress), channel‐bed morphology (size and extent of sandy bedforms), and bed material sand transport (quantity, transport mode, and spatial distribution). A lateral shift was observed in the region of maximum bed material transport from deep to shallow areas of subaqueous sand bars with increasing water discharge. Bed material was transported both in traction and in suspension at these water discharges, and we posit that the downriver flux of sand grains is composed of both locally‐ and drainage basin‐sourced material, with distinct transport pathways and relations to flow conditions. We provide suggestions for the optimal design and operation of planned river diversion projects.
Radiosynthesis of carbon‐11 and fluorine‐18 labelled radiotracers to image the ionotropic and metabotropic glutamate receptors
Authors: Sobrio Franck
Published: April 2013

l‐Glutamate is the major neurotransmitter in the central nervous system and activates both ionotropic and metabotropic receptors. Here the radiosynthesis of radiotracers developed for both types of receptors are reviewed with a highlight on the radiopharmaceuticals used or evaluated in humans. At first, radiotracers were developed for ionotropic N‐methyl‐d‐aspartate receptors without any success to obtain radiopharmaceuticals useable for clinical or even preclinical positron emission tomography (PET) imaging purposes. Some compounds were radiolabelled and evaluated for α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptors without any successful results. The recent development of radiotracers for metabotropic glutamate receptors was more efficient because radiopharmaceuticals are currently evaluated or used in clinical trials to study the mGluR1, mGluR2 or mGluR5 receptors by PET. Although the majority of the radiotracers were classically labelled with carbon‐11 by O‐ or N‐[11C]‐methylation or with fluorine‐18 nucleophilic substitution of aromatic nitro or halogeno precursors using krypofix 2.2.2/potassium [18F]fluoride complex, some radiosyntheses were performed with recent radiolabelling reactions like the use of iodionium salt for [18F]‐labelling.
11C and 18F PET radioligands for the serotonin transporter (SERT)
Authors: Stehouwer Jeffrey S. , Goodman Mark M.
Published: April 2013

The serotonin transporter (SERT) has been implicated in a variety of neuropsychiatric disorders including depression, anxiety, and suicide, and is the target of the selective serotonin reuptake inhibitor (SSRI) class of antidepressants. The availability of SERT‐specific positron emission tomography (PET) radioligands will allow the SERT to be studied noninvasively in living subjects through PET imaging of the SERT and occupancy studies of SSRIs. Numerous diaryl sulfide and tropane derivatives have been developed and radiolabeled with 11C or 18F for imaging the SERT with PET.
Synthetic strategies for radioligands for in vivo imaging of brain cannabinoid type‐1 receptors
Authors: Ahamed Muneer , Verbruggen Alfons , Bormans Guy
Published: April 2013

Despite its abundant expression in the brain, the cannabinoid type‐1 (CB1) receptor was discovered only in 1988. During the last decade, efforts from several research groups have made it possible to visualize the CB1 receptor in vivo to unravel its role in the brain physiology and pathology.

This review discusses strategies for (radio)synthesis of radioligands for in vivo imaging of CB1 receptors.