bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time‐dependent biodistribution and excretion of silver nanoparticles in male Wistar rats
Authors: Dziendzikowska K. , Gromadzka‐Ostrowska J. , Lankoff A. , Oczkowski M. , Krawczyńska A. , Chwastowska J. , Sadowska‐Bratek M. , Chajduk E. , Wojewódzka M. , Dušinská M. , Kruszewski M. 
Published: June 2012

ABSTRACTSilver nanoparticles (AgNPs) are the most commonly used nanoparticles owing to their antimicrobial properties. The motivation of the present study was (1) to analyze the effect of silver particle size on rat tissue distribution at different time points, (2) to determine the accumulation of AgNPs in potential rat target organs, (3) to analyze the intracellular distribution of AgNPs and (4) to examine the excretion of AgNPs by urine and feces. AgNPs were characterized by dynamic light scattering (DLS), zeta potential measurements, BET surface area measurements, transmission and scanning electron microscopy. AgNPs (20 and 200 nm) were administered intravenously (i.v.) to male Wistar rats at a dose of 5 mg kg–1 of body weight. Biological material was sampled 24 h, 7 and 28 days after injection. Using inductively coupled plasma‐mass spectrometry (ICP‐MS) and transmission electron microscopy (TEM) it was observed that AgNPs translocated from the blood to the main organs and the concentration of silver in tissues was significantly higher in rats treated with 20 nm AgNPs as compared with 200 nm AgNPs. The highest concentration of silver was found in the liver after 24 h. After 7 days, a high level of silver was observed in the lungs and spleen. The silver concentration in the kidneys and brain increased during the experiment and reached the highest concentration after 28 days. Moreover, the highest concentration of AgNPs was observed in the urine 1 day after the injection, maintained high for 14 days and then decreased. The fecal level of silver in rats was the highest within 2 days after AgNPs administration and then decreased. Copyright © 2012 John Wiley & Sons, Ltd.
Health effects of extremely low‐frequency magnetic fields: reconsidering the melatonin hypothesis in the light of current data on magnetoreception
Authors: Vanderstraeten Jacques , Verschaeve Luc , Burda Hynek , Bouland Catherine , de Brouwer Christophe 
Published: June 2012

ABSTRACTThe so‐called ‘Melatonin Hypothesis’ proposed that decreased nocturnal production of melatonin (MLT) might explain the increased risk of breast cancer that has been formerly attributed to extremely low‐frequency (ELF) magnetic fields (MF) of weak intensity. Although the risk of ELF MF upon breast cancer was later dismissed, repeated reports were published of partial inhibition of MLT secretion in rats under long‐term (≥ 4 weeks) exposure to weak ELF MF. Since 2004, however, this topic has not been experimentally studied any more. In the present study, we propose to go back to the MLT hypothesis and apply it to childhood leukemia, for which an increased risk has been robustly associated with residential exposure to ELF MF. Contrary to the original hypothesis, however, we do not consider decreased MLT levels, but disruption of circadian rhythmicity per se as the effector mechanism. Indeed, the role of the circadian timing system in the development of childhood leukemia has been well established. Motivation for going back to the MLT hypothesis comes from recent data that suggest magnetosensory disruption by ELF MF in mammals, and magnetosensitivity in humans, together with current evidence for an influence on circadian rhythmicity from disruption of non‐photic sensory stimuli of various natures. We thus suggest further study on circadian rhythmicity in humans (children if possible) under long‐term exposure to weak ELF MF. Copyright © 2012 John Wiley & Sons, Ltd.
Silver nanoparticles: a brief review of cytotoxicity and genotoxicity of chemically and biogenically synthesized nanoparticles
Authors: de Lima Renata , Seabra Amedea B. , Durán Nelson 
Published: June 2012

ABSTRACTIn recent years interest in silver nanoparticles and their applications has increased mainly because of the important antimicrobial activities of these nanomaterials, allowing their use in several industrial sectors. However, together with these applications, there is increasing concerning related to the biological impacts of the use of silver nanoparticles on a large scale, and the possible risks to the environment and health. In this scenario, some recent studies have been published based on the investigation of potential inflammatory effects and diverse cellular impacts of silver nanoparticles. Another important issue related to nanoparticle toxicity in biological media is the capacity for increased damage to the genetic material, since nanoparticles are able to cross cell membranes and reach the cellular nucleus. In this regard, there is increasing interest in the analysis of potential nanoparticle genotoxicity, including the effects of different nanoparticle sizes and methods of synthesis. However, little is known about the genotoxicity of different silver nanoparticles and their effects on the DNA of organisms; thus further studies in this field are required. This mini‐review aims to present and to discuss recent publications related to genotoxicity and the cytotoxicity of silver nanoparticles in order to better understand the possible applications of these nanomaterials in a safe manner. This present work concludes that biogenic silver nanoparticles are generally less cyto/genotoxicin vivocompared with chemically synthesized nanoparticles. Furthermore, human cells were found to have a greater resistance to the toxic effects of silver nanoparticles in comparison with other organisms. Copyright © 2012 John Wiley & Sons, Ltd.
Suture pullout strength and in vitro fibroblast and RAW 264.7 monocyte biocompatibility of genipin crosslinked nanofibrous chitosan mats for guided tissue regeneration
Authors: Norowski P. A. , Mishra S. , Adatrow P. C. , Haggard W. O. , Bumgardner J. D. 
Published: June 2012

AbstractGuided tissue regeneration (GTR) is a surgical technique used to direct the formation of bone in the graft space by protecting it with a barrier membrane used to exclude soft tissues during healing. Chitosan has been advocated for GTR applications because of its biocompatibility, degradability, wound healing, and osteogenic properties. In this study, electrospun chitosan membranes, crosslinked with 5 mM or 10 mM geinipin, a natural crosslinker extracted from the gardenia plant, were evaluated for suture pullout strength, crystallinity, and cytocompatibility with normal human dermal fibroblast and TIB 71™ RAW 264.7 monocyte cells. Ultimate suture pullout strength was significantly lower (51–67%) than that of commercially available collagen membranes. Crystallinity of the electrospun chitosan mats decreased upon crosslinking by 14–17% (p = 0.013). The molecular weight of the chitosan polymer was decreased by 75% during the electrospinning process. Uncrosslinked and genipin‐crosslinked chitosan mats were cytocompatible and supported fibroblast cell proliferation for 9 days. Uncrosslinked and genipin‐crosslinked membranes did not activate monocytes to produce nitric oxide (NO) in vitro in the absence of lipopolysaccharide (LPS). Finally, chitosan membranes inhibited LPS‐induced NO production of RAW 264.7 cells by 59–67% as compared to tissue culture plastic and collagen membrane. Improvements are needed in the tear strength of electrospun chitosan membranes for clinical application. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:2890–2896, 2012.
Breast epithelial tissue morphology is affected in 3D cultures by species‐specific collagen‐based extracellular matrix
Authors: Dhimolea Eugen , Soto Ana M. , Sonnenschein Carlos 
Published: June 2012

AbstractCollagen‐based gels have been widely used to determine the factors that regulate branching morphogenesis in the mammary gland. The patterns of biomechanical gradients and collagen reorganization influence the shape and orientation of epithelial structures in three‐dimensional (3D) conditions. We explored in greater detail whether collagen type I fibers with distinct biomechanical and fiber‐assembling properties, isolated from either bovine or rat tail tendon, differentially affected the epithelial phenotype in a tissue culture model of the human breast. Rat tail collagen fibers were densely packed into significantly longer and thicker bundles compared to those of the bovine type (average fascicle length 7.35 and 2.29 μm, respectively; p = 0.0001), indicating increased fiber alignment and biomechanical enablement in the former. MCF10A epithelial cells formed elaborated branched tubular structures in bovine but only nonbranched ducts and acini in rat tail collagen matrices. Ductal branching in bovine collagen was associated with interactions between neighboring structures mediated through packed collagen fibers; these fiber‐mediated interactions were absent in rat tail collagen gels. Normal breast fibroblasts increased the final size and number of ducts only in rat tail collagen gels while not affecting branching. Our results suggest that the species of origin of collagen used in organotypic cultures may influence epithelial differentiation into alveolar or ductal structures and the patterns of epithelial branching. These observations underscore the importance of considering the species of origin and fiber alignment properties of collagen when engineering branching organs in 3D matrices and interpreting their role in the tissue phenotype. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:2905–2912, 2012.
Binding and leakage of barium in alginate microbeads
Authors: Mørch Yrr A. , Qi Meirigeng , Gundersen Per Ole M. , Formo Kjetil , Lacik Igor , Skjåk‐Bræk Gudmund , Oberholzer Jose , Strand Berit L. 
Published: June 2012

AbstractMicrobeads of alginate crosslinked with Ca2+ and/or Ba2+ are popular matrices in cell‐based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high‐G and high‐M alginates. High‐G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low‐ and high‐Ba exposure compared with high‐G microbeads exposed to calcium solely and to high‐M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high‐G beads was found to be dose‐dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high‐G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high‐G microbeads made using high barium concentration. To reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high‐G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:2939–2947, 2012.
Biological responses of human bone marrow mesenchymal stem cells to Sr‐M‐Si (M = Zn, Mg) silicate bioceramics
Authors: Zhang Meili , Wu Chengtie , Lin Kaili , Fan Wei , Chen Lei , Xiao Yin , Chang Jiang 
Published: June 2012

AbstractStrontium (Sr), Zinc (Zn), magnesium (Mg), and silicon (Si) are reported to be essential trace elements for the growth and mineralization of bone. We speculated that the combination of these bioactive elements in bioceramics may be effective to regulate the osteogenic property of bone‐forming cells. In this study, two Sr‐containing silicate bioceramics, Sr2ZnSi2O7 (SZS) and Sr2MgSi2O7 (SMS), were prepared. The biological response of human bone marrow mesenchymal stem cells (BMSCs) to the two bioceramics (in the forms of powders and dense ceramic bulks) was systematically studied. In powder form, the effect of powder extracts on the viability and alkaline phosphatase (ALP) activity of BMSCs was investigated. In ceramic disc form, both direct and indirect coculture of BMSCs with ceramic discs were used to investigate their biological response, including attachment, proliferation, ALP activity, and bone‐related genes expression. Beta‐tricalcium phosphate (β‐TCP) and akermanite (Ca2MgSi2O7, CMS) were used as control materials. The results showed that the Sr, Zn, and Si (or Sr, Mg, and Si)‐containing ionic products from SZS and SMS powders enhanced ALP activity of BMSCs, compared to those from β‐TCP. Both SZS and SMS ceramic discs supported the growth of BMSCs, and most importantly, significantly enhanced the ALP activity and bone‐related genes expression of BMSCs as compared to β‐TCP. The results suggest that the specific combination of bioactive ions (Sr, Zn, Si, e.g.) in bioceramics is a viable way to improve the biological performance of biomaterials, and the form of materials and surface properties were nonnegligible factors to influence cell response. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:2979–2990, 2012.
Dendrimer building toolkit: Model building and characterization of various dendrimer architectures
Authors: Maingi Vishal , Jain Vaibhav , Bharatam Prasad V. , Maiti Prabal K. 
Published: June 2012

AbstractWe have developed a graphical user interface based dendrimer builder toolkit (DBT) which can be used to generate the dendrimer configuration of desired generation for various dendrimer architectures. The validation of structures generated by this tool was carried out by studying the structural properties of two well known classes of dendrimers: ethylenediamine cored poly(amidoamine) (PAMAM) dendrimer, diaminobutyl cored poly(propylene imine) (PPI) dendrimer. Using full atomistic molecular dynamics (MD) simulation we have calculated the radius of gyration, shape tensor and monomer density distribution for PAMAM and PPI dendrimer at neutral and high pH. A good agreement between the available simulation and experimental (small angle X‐ray and neutron scattering; SAXS, SANS) results and calculated radius of gyration was observed. With this validation we have used DBT to build another new class of nitrogen cored poly(propyl ether imine) dendrimer and study it's structural features using all atomistic MD simulation. DBT is a versatile tool and can be easily used to generate other dendrimer structures with different chemistry and topology. The use of general amber force field to describe the intra‐molecular interactions allows us to integrate this tool easily with the widely used molecular dynamics software AMBER. This makes our tool a very useful utility which can help to facilitate the study of dendrimer interaction with nucleic acids, protein and lipid bilayer for various biological applications. © 2012 Wiley Periodicals, Inc.
Electronic structure and thermodynamics of V2O3 polymorphs
Authors: Wessel C. , Reimann C. , Müller A. , Weber D. , Lerch M. , Ressler T. , Bredow T. , Dronskowski R. 
Published: June 2012

AbstractA metastable bixbyite‐type polymorph of vanadium sesquioxide, V2O3, has recently been synthesized, and it transforms to the corundum‐type phase at temperatures around 550 °C. The possibility of a paramagnetic to canted antiferromagnetic or even spin‐glass‐like transition has been discussed. Quantum‐chemical calculations on the density‐functional theory level including explicit electronic correlation confirm the metastability as well as the semiconducting behavior of the material and predict that the bixbyite‐type structure is about 0.1 eV less stable than the well‐known corundum‐type phase. Nonetheless, quasiharmonic phonon calculations manifest that bixbyite‐type vanadium sesquioxide is a dynamically stable compound. Other possible V2O3 polymorphs are shown to be even less suitable candidates for the composition V2O3. © 2012 Wiley Periodicals, Inc.
A Mild and Highly Efficient Method for the Preparation of Silyl Ethers using Fe(HSO4)3/Et3N by Chlorosilanes
Authors: Abri Abdolreza , Assadi Mohammad Galeh , Pourreza Samira 
Published: June 2012

AbstractA very efficient and mild procedure for preparation of silyl ethers from benzylic, allylic, propargilic alcohols, phenols, naphtoles and some of phenolic drugs with trimethylsilylchloride (TMSCl), triethylsilylchloride (TESCl) and t‐buthyldimethylsilyl chloride (TDSCl) ethers in the presence of Fe(HSO4)3/Et3N in room temperature in excellent yields is reported. This procedure also allows the excellent selectivity for silylation of alcohols and phenols.
Adenovirus vector‐based in vitro neuronal cell model for Huntington's disease with human disease‐like differential aggregation and degeneration
Authors: Dong Xiaomin , Zong Shan , Witting Anke , Lindenberg Katrin S. , Kochanek Stefan , Huang Bin 
Published: June 2012

AbstractBackgroundNeuronal degeneration, in particular in the striatum, and the formation of nuclear and cytoplasmic inclusions are characteristics of Huntington's disease (HD) as a result of the expansion of a polyglutamine tract located close to the N‐terminus of huntingtin (htt). Because of the large (10‐kb) size of the htt cDNA, expression of full‐length htt in primary neurons has proved difficult in the past.MethodsWe generated a new chronic in vitro model that is based on high‐capacity adenovirus vector‐mediated transduction of primary murine striatal and cortical neurons. Because the vector has a large capacity for transport of foreign DNA, it was possible to quantitatively express in these primary cells normal and mutant full‐length htt (designed as fusion proteins with enhanced green fluorescent protein) in addition to its truncated versions. Pathological changes caused by mutant htt were characterized.ResultsThe model mimicked several features observed in HD patients: prominent nuclear inclusions in cortical but not in striatal neurons, preferential neuronal degeneration of striatal neurons and neurofilament fragmentation in this cell type. Compared with expressed truncated mutant htt, the expression of full‐length mutant htt in neurons resulted in a much slower appearance of pathological changes. Different from cortical neurons, the vast majority of nuclei in striatal cells contained only diffusely distributed N‐terminal htt fragments. Cytoplasmic inclusions in both cell types contained full‐length mutant htt.ConclusionsThis model and the adenovirus vectors used will be valuable for studying the function of htt and the pathogenesis of HD at molecular and cellular levels in different neuronal cell types. Copyright © 2012 John Wiley & Sons, Ltd.
Cougars are recolonizing the midwest: Analysis of cougar confirmations during 1990–2008
Authors: LaRue Michelle A. , Nielsen Clayton K. , Dowling Mark , Miller Ken , Wilson Bob , Shaw Harley , Anderson Charles R. 
Published: June 2012

AbstractAlthough cougars (Puma concolor) were extirpated from much of midwestern North America around 1900, hard evidence of cougar presence has increased and populations have become established in the upper portions of the Midwest during the past 20 years. Recent occurrences of cougars in the Midwest are likely due to dispersal of subadult cougars into the region from established western populations, and may be indicative of further recolonization and range expansion. We compiled confirmed locations of cougars (i.e., via carcasses, tracks, photos, video, and DNA evidence) collected during 1990–2008 in 14 states and provinces of midwestern North America. We separated our study area into 2 regions (east and west), calculated number and types of confirmations, and assessed trends in confirmations during the study period. We recorded 178 cougar confirmations in the Midwest and the number of confirmations increased during the study period (r = 0.79, P ≤ 0.001). Confirmations by state or province ranged from 1 (Kansas, Michigan, and Ontario) to 67 (Nebraska). Carcasses were the most prevalent confirmation type (n = 56). Seventy‐six percent of known‐sex carcass confirmations were males, consistent with predominantly male‐biased dispersal in cougars. More confirmations (P = 0.05) were recorded in the western region $({\bar {x}} = 19.9\pm 22.8/{\rm yr})$ than the eastern region $({\bar {x}} = 4.3\pm 3.1/{\rm yr})$. Seventy‐nine percent of cougar confirmations occurred within 50 km of highly suitable habitat (i.e., forest areas with steep terrain and low road and human densities). Given the number of cougar confirmations, the increasing frequency of occurrences, and that long‐distance dispersal has been documented via radiocollared individuals, our research suggests that cougars are continuing to recolonize midwestern North America. © 2012 The Wildlife Society.
2–Butoxyethanol and benzyl alcohol reactions with the nitrate radical: Rate coefficients and gas‐phase products
Authors: Harrison Joel C. , Wells J. R. 
Published: June 2012

AbstractThe bimolecular rate coefficients k and k were measured using the relative rate technique at (297 ± 3) K and 1 atmosphere total pressure. Values of (2.7 ± 0.7) and (4.0 ± 1.0) × 10−15 cm3 molecule−1 s−1 were observed for k and k, respectively. In addition, the products of 2‐butoxyethanol + NO3• and benzyl alcohol + NO3• gas‐phase reactions were investigated. Derivatizing agents O‐(2,3,4,5,6‐pentafluorobenzyl)hydroxylamine and N, O‐bis (trimethylsilyl)trifluoroacetamide and gas chromatography mass spectrometry (GC/MS) were used to identify the reaction products. For 2‐butoxyethanol + NO3• reaction: hydroxyacetaldehyde, 3‐hydroxypropanal, 4‐hydroxybutanal, butoxyacetaldehyde, and 4‐(2‐oxoethoxy)butan‐2‐yl nitrate were the derivatized products observed. For the benzyl alcohol + NO3• reaction: benzaldehyde ((C6H5)C(O)H) was the only derivatized product observed. Negative chemical ionization was used to identify the following nitrate products: [(2‐butoxyethoxy)(oxido)amino]oxidanide and benzyl nitrate, for 2‐butoxyethanol + NO3• and benzyl alcohol + NO3•, respectively. The elucidation of these products was facilitated by mass spectrometry of the derivatized reaction products coupled with a plausible 2‐butoxyethanol or benzyl alcohol + NO3• reaction mechanisms based on previously published volatile organic compound + NO3• gas‐phase mechanisms. © 2012 Wiley Periodicals, Inc.*This article is a U.S. Government work and, as such, is in the public domain of the United States of America.
© 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 778–788, 2012
Thermal, Mechanical and Morphological Behavior of Poly(propylene)/Wood Flour Composites
Authors: Adhikari R. , Bhandari N. L. , Le H. H. , Henning S. , Radusch H.‐J. , Michler G. H. , Garda M.‐R. , Saiter J. M. 
Published: June 2012

AbstractThe comparative studies on the thermal, mechanical and morphological behavior of compression molded poly(propylene) (PP)/wood flour (WF) composites were performed using wood flours (WFs) of different origins. The comparison has been made on the basis of results obtained from thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile testing. It has been demonstrated that an addition of 5 wt.‐% of maleic anhydride grafted polypropylene (PP‐g‐MA) has a significant effect on the morphological and thermomechanical behavior of the composites. Although, microscopic examinations revealed no significant differences in the morphology of the compatibilized composites, a remarkable improvement of thermal degradation behavior was observed. From the view point of mechanical properties, the composites with high amount of filler (60 wt.‐%) showed similar behavior irrespective of the origin of wood flour.