bluuebunny/crossref_metadata_2025_split huggingface dataset:
RBE4 cells are highly resistant to paraquat‐induced cytotoxicity: studies on uptake and efflux mechanisms
Authors: Vilas‐Boas V. , Silva R. , Guedes‐de‐Pinho P. , Carvalho F. , Bastos M. L. , Remião F. 
Published: October 2013

ABSTRACTParaquat (PQ) is a widely used, highly toxic and non‐selective contact herbicide, which has been associated with central neurotoxic effects, namely the development of Parkinson's disease, but whose effects to the blood–brain barrier (BBB) itself have rarely been studied. This work studied the mechanisms of PQ uptake and efflux in a rat's BBB cell model, the RBE4 cells. PQ is believed to enter cells using the basic or neutral amino acid or polyamine transport systems or through the choline‐uptake system. In contrast, PQ efflux from cells is reported to be mediated by P‐glycoprotein. Therefore, we evaluated PQ‐induced cytotoxicity and the effect of some substrates/blockers of these transporters (such as arginine, L‐valine, putrescine, hemicholinium‐3 and GF120918) on such cytotoxicity. RBE4 cells were shown to be extremely resistant to PQ after 24 h of exposure; even at concentrations as high as 50 mM approximately 45% of the cells remained viable. Prolonging exposure until 48 h elicited significant cytotoxicity only for PQ concentrations above 5 mM. Although hemicholinium‐3, a choline‐uptake system inhibitor, significantly protected cells against PQ‐induced toxicity, none of the effects were observed for arginine, L‐valine or putrescine. Meanwhile, inhibiting the efflux pump P‐glycoprotein using GF120918 significantly enhanced PQ‐induced cytotoxicity. In conclusion, PQ used the choline‐uptake system, instead of the transporters for the basic or neutral amino acids or for the polyamines, to enter RBE4 cells. P‐glycoprotein extrudes PQ back to the extracellular medium. However, this efflux mechanism only partially explains the observed RBE4 resistance to PQ. Copyright © 2013 John Wiley & Sons, Ltd.
A novel copper/polydimethiylsiloxane nanocomposite for copper‐containing intrauterine contraceptive devices
Authors: Xu X. X. , Ding M. H. , Zhang J. X. , Zheng W. , Li L. , Zheng Y. F. 
Published: October 2013

AbstractIn this article, a novel composite of copper (Cu) nanoparticles and polydimethiylsiloxane (PDMS) has been prepared and investigated for the potential application in Cu‐containing intrauterine device. The Cu/PDMS composite with various mass fraction of Cu nanoparticles was fabricated via the hot vulcanizing process. The chemical structures and surface morphologies of the Cu/PDMS composites were characterized confirming the physical interaction between Cu nanoparticles and PDMS. The surface morphology observation using scanning electron microscope and atomic force microscope showed the agglomeration of Cu nanoparticles in PDMS matrix and the distribution of the agglomerations was more uniform with increased amount of Cu nanoparticles. The cupric ion release behaviors of the Cu/PDMS composites with different amounts of Cu nanoparticles were investigated in simulated uterine fluid at 37°C for 150 days. The corrosion morphologies of the Cu/PDMS composites were also characterized. Both the burst release rate of the cupric ion in the first few days and the steady release rate after 30‐day immersion were improved. The cytotoxicity test has been done for the Cu/PDMS composites. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 101B: 1428–1436, 2013.
Osteocyte density in the peri‐implant bone of implants retrieved after different time periods (4 weeks to 27 years)
Authors: Piattelli Adriano , Artese Luciano , Penitente Enrico , Iaculli Flavia , Degidi Marco , Mangano Carlo , Shibli Jamil Awad , Coelho Paulo G , Perrotti Vittoria , Iezzi Giovanna 
Published: October 2013

AbstractBone tissue is characterized by a constant turnover in response to mechanical stimuli, and osteocytes play an essential role in bone mechanical adaptation. However, little to no information has been published regarding osteocyte density as a function of implantation time in vivo. The aim of this retrospective histological study was to evaluate the osteocyte density of the peri‐implant bone in implants retrieved because of different reasons in a time period from 4 weeks to 27 years. A total of 18 samples were included in the present study. Specimens were divided into 3 groups depending on the loading history of the implants: loading between 4 weeks and 7 months (group 1); loading between 1 and 5 years (group 2); loading between 14 and 27 years (group 3). All the samples were histologically evaluated and osteocyte density was obtained using the ratio of the number of osteocytes to the bone‐area (mm2). The osteocyte density values significantly increased in the Group 2 (1–5 years) compared with Group 1 (4 weeks–7 months), and significantly decreased in the Group 3 (14–27 years) compared to Group 2. No significant differences were detected between Group 1 and Group 3. The decrease in osteocyte density observed in samples that were in vivo for long periods of time under loading is possibly because of the fact that once the bone structure is well aligned and biomechanically competent, a lower number of osteocytes are necessary to keep the tissue homeostasis under loading. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 239–243, 2014.
Injectable biphasic calcium phosphate cements as a potential bone substitute
Authors: Sariibrahimoglu Kemal , Wolke Joop G. C. , Leeuwenburgh Sander C. G. , Yubao Li , Jansen John A. 
Published: October 2013

AbstractApatitic calcium phosphate cements (CPCs) have been widely used as bone grafts due to their excellent osteoconductive properties, but the degradation properties are insufficient to stimulate bone healing in large bone defects. A novel approach to overcome the lack of degradability of apatitic CPC involves the development of biphasic CPCs (BCPC) based on tricalcium phosphate (TCP) in both α‐ and β‐polymorphs. The aim of the current study was to prepare and analyze the physicochemical properties of BCPCs based on dual phase α/β‐TCP as obtained by heat treatment of pure α‐TCP. The handling and mechanical characteristics of the samples as well as the degradation behavior under in vitro condition were investigated and compared with a standard monophasic α‐TCP‐based CPC. The results showed that different heat treatments of commercially available α‐TCP allowed the formation of biphasic calcium phosphate powder with a variety of α/β‐TCP ratios. The use of biphasic powder particles as a reactant for CPCs resulted into increased setting and injectability times of the final BCPCs. During hardening of the cements, the amount of apatite formation decreased with increasing β‐TCP content in the biphasic precursor powders. The morphology of the monophasic CPC consisted of plate‐like crystals, whereas needle‐like crystals were observed for BCPCs. In vitro degradation tests demonstrated that dissolution rate and corresponding calcium release from the set cements increased considerably with increasing β‐TCP content, suggesting that apatitic CPCs can be rendered degradable by using biphasic α/β‐TCP as powder precursor phase. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 415–422, 2014.
The in vivo effect of P‐15 coating on early osseointegration
Authors: Coelho Paulo G. , Teixeira Hellen S. , Marin Charles , Witek Lukasz , Tovar Nick , Janal Malvin N. , Jimbo Ryo 
Published: October 2013

AbstractThe aim of this study was to evaluate mechanically and morphologically the effect of a specific peptide sequence P‐15, when incorporated into implant surfaces. Three types of implants were used for the study: Group A: commercially pure titanium implant (blasted and acid etched) + electrochemical thin calcium phosphate deposition, Group B: commercially pure titanium implant (blasted and acid etched) + electrochemical thin calcium phosphate deposition + P‐15 incorporation, and as control, Group C: commercially pure titanium implant (blasted and acid etched). After a topographical characterization, transcortical osteotomies were made, and all implant groups (102 implants per group) were randomly placed bilaterally in the tibiae of adult beagle dogs (n = 24). At, 1, 2, and 4 weeks post‐surgery, the animals were sacrificed and the samples were retrieved for removal torque tests, for nano indentation, and for histomorphometrical analysis. The results (mean ± 95% CI) showed that Group B (34.4 ± 8.7%) presented statistically higher bone‐to‐implant contact than the other groups (A = 23.9 ± 7.8%; C = 21.7 ± 8.3%) at 1 week, indicating an enhanced osteogenesis due to the peptide incorporation. The results suggested that the incorporation of P‐15 to implant surfaces increased its bioactivity and the effects were notable especially in the early stages of the healing process. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 430–440, 2014.
Pt‐Al2O3 interfaces in cofired ceramics for use in miniaturized neuroprosthetic implants
Authors: Guenther Thomas , Kong Charlie , Lu Hong , Svehla Martin J , Lovell Nigel H , Ruys Andrew , Suaning Gregg J 
Published: October 2013

AbstractA core element to miniaturized, hermetic encapsulations for neuroprosthetic implants with high numbers of stimulation channels is the creation of electrical feedthroughs. Platinum (Pt) and alumina (Al2O3) are necessary to connect the sealed electronics to external components including electrode arrays that provide a neural interface function, as well as to sources of power or data. Combined with laser micro‐processing, high‐density feedthrough arrays were created with up to 2500 channels per cm2. The chemistry, micro structure, and crystallography of the Pt‐Al2O3 interface created by the cofiring of Pt particles and Al2O3 particulate in binder were studied by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and selective area electron diffraction (SAED) to determine the nature of the Pt‐Al2O3 bond. While Pt‐Al2O3 interfaces only occurred in cases where the different grains were in distinct orientations where the crystal lattices matched, the addition of glass additives allowed for bonding nonmatching orientations by devitrification to form Pt‐glass‐Al2O3 interfaces. The conditions for the formation of both mechanisms were determined, and it was shown that higher order crystal planes than previously described can be matched. Analyzing the lattice matches in detail showed the ability of the material compound to compensate for mismatches by the formation of dislocations, out‐of‐angle matching, lattice distortion, and the existence of semi‐coherent interfaces in case of integer misfit ratios to create domain matching. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 500–507, 2014.
Comparative Assessment of Oriented Antibody Immobilization on Surface Plasmon Resonance Biosensing
Authors: Chang Chia‐Chen , Chuang Tsung‐Liang , Wang Da‐Shin , Wang Ching‐Ho , Lin Chii‐Wann 
Published: October 2013

AbstractProtein A and protein G are extremely useful molecules for the immobilization of antibodies. However, there are limited comparative reports available to evaluate their immobilization performance for use as biosensors. In this study, a comparative analysis was made of approaches that use protein A and protein G for avian leukosis virus detection. The antibody‐protein binding affinities were determined using surface plasmon resonance (SPR) analysis. The immobilization efficiency was obtained by calculating the number of the protein molecular binding sites. The positive influence of sensor response on antigen detection indicates that the amount of immobilized antibody plays a major role in the extent of immobilization. Moreover, the biosensors constructed using both proteins were found to be regenerative. The SPR results from this study suggest that the surfaces of protein G provide a better equilibrium constant and binding efficacy for immobilized antibodies, resulting in enhanced antigen detection.
RGS2 Regulates Urotensin II‐Induced Intracellular Ca2+ Elevation and Contraction in Glomerular Mesangial Cells
Authors: Adebiyi Adebowale 
Published: October 2013

AbstractUrotensin II (UII), a vasoactive peptide modulates renal hemodynamics. However, the physiological functions of UII in glomerular cells are unclear. In particular, whether UII alters mesangial tone remains largely unknown. The present study investigates the physiological effects of UII on glomerular mesangial cells (GMCs). This study also tested the hypothesis that the regulator of G‐protein signaling (RGS) controls UII receptor (UTR) activity in GMCs. RT‐PCR, Western immunoblotting, and immunofluorescence revealed UTR expression in cultured murine GMCs. Mouse UII (mUII) stimulated Ca2+ release from intracellular stores and activated store‐operated Ca2+ entry (SOCE) in the cells. mUII also caused a reduction in planar GMC surface area. mUII‐induced [Ca2+]i elevation and contraction were attenuated by SB 657510, a UTR antagonist, araguspongin B, an inositol 1,4,5‐trisphosphate receptor antagonist, thapsigargin, a sarco/endoplasmic reticulum Ca2+‐ATPase inhibitor, and La3+, a store‐operated Ca2+ channel blocker, but not nimodipine, an L‐type Ca2+ channel blocker. In situ proximity ligation assay indicated molecular proximity between endogenous RGS2 and UTR in the cells. Treatment of GMCs with mUII elevated plasma membrane expression of RGS2 by ∼2‐fold. mUII also increased the interaction between RGS2 and UTR in the cells. siRNA‐mediated knockdown of RGS2 in murine GMCs increased mUII‐induced [Ca2+]i elevation and contraction by ∼35 and 31%, respectively. These findings indicate that mUII‐induced SOCE results in murine GMC contraction. These data also suggest that UTR activation stimulates RGS2 recruitment to GMC plasma membrane as a negative feedback mechanism to regulate UTR signaling. J. Cell. Physiol. 229: 502–511, 2014. © 2013 Wiley Periodicals, Inc.
Taste and odorant receptors of the coelacanth—A gene repertoire in transition
Authors: Picone Barbara , Hesse Uljana , Panji Sumir , Van Heusden Peter , Jonas Mario , Christoffels Alan 
Published: October 2013

ABSTRACTG‐protein coupled chemosensory receptors (GPCR‐CRs) aid in the perception of odors and tastes in vertebrates. So far, six GPCR‐CR families have been identified that are conserved in most vertebrate species. Phylogenetic analyses indicate differing evolutionary dynamics between teleost fish and tetrapods. The coelacanth Latimeria chalumnae belongs to the lobe‐finned fishes, which represent a phylogenetic link between these two groups. We searched the genome of L. chalumnae for GPCR‐CRs and found that coelacanth taste receptors are more similar to those in tetrapods than in teleost fish: two coelacanth T1R2s co‐segregate with the tetrapod T1R2s that recognize sweet substances, and our phylogenetic analyses indicate that the teleost T1R2s are closer related to T1R1s (umami taste receptors) than to tetrapod T1R2s. Furthermore, coelacanths are the first fish with a large repertoire of bitter taste receptors (58 T2Rs). Considering current knowledge on feeding habits of coelacanths the question arises if perception of bitter taste is the only function of these receptors. Similar to teleost fish, coelacanths have a variety of olfactory receptors (ORs) necessary for perception of water‐soluble substances. However, they also have seven genes in the two tetrapod OR subfamilies predicted to recognize airborne molecules. The two coelacanth vomeronasal receptor families are larger than those in teleost fish, and similar to tetrapods and form V1R and V2R monophyletic clades. This may point to an advanced development of the vomeronasal organ as reported for lungfish. Our results show that the intermediate position of Latimeria in the phylogeny is reflected in its GPCR‐CR repertoire. J. Exp. Zool. (Mol. Dev. Evol.) 322B: 403–414, 2014. © 2013 Wiley Periodicals, Inc.
Modeling radiation belt electron dynamics during GEM challenge intervals with the DREAM3D diffusion model
Authors: Tu Weichao , Cunningham G. S. , Chen Y. , Henderson M. G. , Camporeale E. , Reeves G. D. 
Published: October 2013

AbstractAs a response to the Geospace Environment Modeling (GEM) “Global Radiation Belt Modeling Challenge,” a 3D diffusion model is used to simulate the radiation belt electron dynamics during two intervals of the Combined Release and Radiation Effects Satellite (CRRES) mission, 15 August to 15 October 1990 and 1 February to 31 July 1991. The 3D diffusion model, developed as part of the Dynamic Radiation Environment Assimilation Model (DREAM) project, includes radial, pitch angle, and momentum diffusion and mixed pitch angle‐momentum diffusion, which are driven by dynamic wave databases from the statistical CRRES wave data, including plasmaspheric hiss, lower‐band, and upper‐band chorus. By comparing the DREAM3D model outputs to the CRRES electron phase space density (PSD) data, we find that, with a data‐driven boundary condition at Lmax = 5.5, the electron enhancements can generally be explained by radial diffusion, though additional local heating from chorus waves is required. Because the PSD reductions are included in the boundary condition at Lmax = 5.5, our model captures the fast electron dropouts over a large L range, producing better model performance compared to previous published results. Plasmaspheric hiss produces electron losses inside the plasmasphere, but the model still sometimes overestimates the PSD there. Test simulations using reduced radial diffusion coefficients or increased pitch angle diffusion coefficients inside the plasmasphere suggest that better wave models and more realistic radial diffusion coefficients, both inside and outside the plasmasphere, are needed to improve the model performance. Statistically, the results show that, with the data‐driven outer boundary condition, including radial diffusion and plasmaspheric hiss is sufficient to model the electrons during geomagnetically quiet times, but to best capture the radiation belt variations during active times, pitch angle and momentum diffusion from chorus waves are required.
Longitudinal variations of positive dayside ionospheric storms related to recurrent geomagnetic storms
Authors: Dmitriev A. V. , Huang C.‐M. , Brahmanandam P. S. , Chang L. C. , Chen K.‐T. , Tsai L.‐C. 
Published: October 2013

AbstractWe have performed an analysis of case events and statistics of positive ionospheric storms in the dayside region of the equatorial ionization anomaly during recurrent geomagnetic storms (RGSs), which dominate in geomagnetic and ionospheric conditions on the declining phase of solar activity in 2004 to 2008. It is shown that total electron content (TEC) has a tendency to minimize before the beginning of RGSs and to peak 3 to 4 days after, i.e., on the RGS recovery phase produced by high‐intensity long‐duration continuous auroral activity. The maximum of TEC coincides with the maximum of solar wind velocity within high‐speed solar wind streams. An analysis of electron content vertical profiles, derived from two independent methods using ionosondes and Constellation Observing System for Meteorology, Ionosphere, and Climate /Formosa Satellite mission‐3 radio occultation, showed that in the maximum of an ionospheric storm on 28 March 2008, the F2 layer thickens, NmF2 increases by ~50%, and hmF2 elevates by a few tens of kilometers. The response of positive ionospheric storms to solar, heliospheric, and geomagnetic drivers reveals a prominent longitudinal asymmetry. In the longitudinal range from −90° to 90°, the solar illumination plays a major role, and in the range from 90° to −120°, the influence of heliospheric and geomagnetic drivers becomes significant. The highest correlations of the TEC enhancements with the heliospheric and geomagnetic drivers were found during December–February (r increased from ~0.3 to ~0.5). We speculate that the dynamics controlling this might result from an effect of solar zenith angle, storm time effects of thermospheric ΣO/N2 enhancement, and penetrating electric fields of interplanetary and magnetospheric origin.
Application of OMI, SCIAMACHY, and GOME‐2 satellite SO2 retrievals for detection of large emission sources
Authors: Fioletov V. E. , McLinden C. A. , Krotkov N. , Yang K. , Loyola D. G. , Valks P. , Theys N. , Van Roozendael M. , Nowlan C. R. , Chance K. , Liu X. , Lee C. , Martin R. V. 
Published: October 2013

AbstractRetrievals of sulfur dioxide (SO2) from space‐based spectrometers are in a relatively early stage of development. Factors such as interference between ozone and SO2 in the retrieval algorithms often lead to errors in the retrieved values. Measurements from the Ozone Monitoring Instrument (OMI), Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), and Global Ozone Monitoring Experiment‐2 (GOME‐2) satellite sensors, averaged over a period of several years, were used to identify locations with elevated SO2 values and estimate their emission levels. About 30 such locations, detectable by all three sensors and linked to volcanic and anthropogenic sources, were found after applying low and high spatial frequency filtration designed to reduce noise and bias and to enhance weak signals to SO2 data from each instrument. Quantitatively, the mean amount of SO2 in the vicinity of the sources, estimated from the three instruments, is in general agreement. However, its better spatial resolution makes it possible for OMI to detect smaller sources and with additional detail as compared to the other two instruments. Over some regions of China, SCIAMACHY and GOME‐2 data show mean SO2 values that are almost 1.5 times higher than those from OMI, but the suggested spatial filtration technique largely reconciles these differences.
Estimating the radiative forcing of carbonaceous aerosols over California based on satellite and ground observations
Authors: Xu Yangyang , Bahadur Ranjit , Zhao Chun , Ruby Leung L. 
Published: October 2013

AbstractCarbonaceous aerosols have the potential to impact climate directly through absorption of incoming solar radiation and indirectly by affecting cloud and precipitation. Recent modeling studies have made great efforts to simulate both the spatial and temporal distributions of carbonaceous aerosol's optical properties and radiative forcing. This study makes the first observationally constrained assessment of the direct radiative forcing of carbonaceous aerosols over California. By exploiting multiple observations (including ground sites and satellites), we constructed the distribution of aerosol optical depths and aerosol absorption optical depths (AAOD) over California for a 10 year period (2000–2010). We partitioned the total solar absorption into individual contributions from elemental carbon (EC), organic carbon (OC), and dust aerosols, using a newly developed scheme. Our results show that AAOD due to carbonaceous aerosols (EC and OC) at 440 nm was 50%–200% larger than natural dust, with EC contributing the bulk (70%–90%). Observationally constrained EC absorption agrees reasonably well with estimates from global and regional chemical transport models, but the models underestimate the OC AAOD by at least 50%. We estimated that the top of the atmosphere (TOA) forcing from carbonaceous aerosols was 0.7 W/m2 and the TOA forcing due to OC was close to zero. The atmospheric heating of carbonaceous aerosol was 2.2–2.9 W/m2, of which EC contributed about 80–90%. We estimated the atmospheric heating of OC at 0.1–0.4 W/m2, larger than model simulations. EC reduction over the last two decades may have caused a surface brightening of 1.5–3.5 W/m2.