bluuebunny/crossref_metadata_2025_split huggingface dataset:
Engineering protein filaments with enhanced thermostability for nanomaterials
Authors: Glover Dominic J. , Giger Lars , Kim Jihyun R. , Clark Douglas S. 
Published: September 2012

AbstractSelf‐assembling protein templates have enormous potential as biomaterials for the fabrication of multifunctional nanostructures that require precise positioning of individual molecules in regular patterns over large surface areas. Furthermore, the development of protein templates that are stable under extreme conditions of heat or chemical denaturants will expand processing conditions and end‐use applications for biomaterials that require exceptional stability and robustness. In the present work, we characterized the high thermal stability of a filamentous protein template, the γ‐prefoldin (γPFD) from the hyperthermophile Methanocaldococcus jannaschii, and subsequently used rational design to further enhance the filament's thermal stability for application as a biotemplate in the creation of platinum nanowires. The γPFD assembles into long fibers with lengths that exceed 2 μm, which when heated to various temperatures and examined by transmission electron microscopy, revealed a Tm of 93°C for the quaternary filament structure. Subsequently, we increased the hydrophobicity of the α‐helices of the γPFD's coiled‐coil, which appeared to strengthen the filamentous structure, leading to filaments of greater length at elevated temperatures. These enhanced filaments functioned as templates for the synthesis of platinum nanowires at unprecedented temperatures, and may create new opportunities for other applications of nanoscale biotemplates that require exceptional thermal stability.See accompanying commentary by Jonathan S. Dordick DOI: 10.1002/biot.201200338
Strategies for biological heart valve replacement: Stentless xenografts fail to evolve into an alternative pulmonary valve substitute in a Ross procedure
Authors: Weimar Timo , Roser Detlef , Liebrich Markus , Horke Alexander , Doll Nicolas , Hemmer Wolfgang B. 
Published: September 2012

AbstractThe Ross operation is a complex procedure for aortic valve replacement in which the pulmonary autograft is replaced by a homograft. However, homograft availability is becoming limited. This report evaluates the performance of porcine stentless prostheses as alternative pulmonary substitutes. Echocardiographic results from two patient cohorts were compared at time of discharge and 1 year after a Ross procedure. Thirty‐three patients (median age 42 years, range 17–62 years, 76% male) received a stentless prosthesis (median size 25.6 mm, range 25–29 mm) for right ventricular outflow tract reconstruction. Clinical data were not significantly different from 106 patients (median age 47 years, range 2–68 years, 75% male) who received cryopreserved homografts (median size 26 mm, range 20–33 mm). At time of discharge, peak pressure gradients (ΔPmax) across the stentless valve (median ΔPmax 13 mmHg, range 2–26 mmHg) were higher compared to homografts (median ΔPmax 7 mmHg, range 1–32 mmHg, p<0.001). At 1 year, gradients increased in both groups, but were significantly higher across stentless valves (median ΔPmax 23 mmHg, range 10–81 mmHg vs. median ΔPmax 13 mmHg, range 2–74 mmHg, p<0.001). Eleven patients (33%) in the stentless‐valve group were classified “at risk” with a ΔPmax of ≥30 mmHg. Four of them (12%) had to be re‐operated. In conclusion, stentless valves showed higher pressure gradients and their performance was inferior to cryopreserved homografts.See accompanying commentary by Ulrich Stock DOI: 10.1002/biot.201200341
Sterically Hindered o‐Quinone Annulated with Dithiete: A Molecule Comprising Diolate and Dithiolate Coordination Sites
Authors: Cherkasov Vladimir K. , Abakumov Gleb A. , Fukin Georgy K. , Klementyeva Svetlana V. , Kuropatov Viacheslav A. 
Published: September 2012

AbstractA new stable sterically hindered o‐quinone annelated with a 1,2‐dithiete ring was prepared by using mild conditions. The skeleton of the compound comprises diolate and dithiolate functions that have the potential to bind metals leading to the corresponding complexes. The reactivity of this compound as a ligand with respect to both coordination sites was studied. Reactions with metals indicate that the o‐quinone function is reduced in the first stage to give semiquinonate and catecholate complexes. The dithiolate coordination site was involved in the reaction in a few cases only after diolate was bound. A trinuclear manganese complex with coordination on both sites was obtained and characterized by EPR spectroscopy. The electrochemical study of this quinone fused with dithiete is reported.
Preparation of Various Prussian Blue Analogue Hollow Nanocubes with Single Crystalline Shells
Authors: Hu Ming , Torad Nagy L. , Yamauchi Yusuke 
Published: September 2012

AbstractWe report the preparation of monocrystalline Prussian blue (PB) analogue hollow nanocubes by applying a controlled chemical etching method with assistance of polyvinylpyrrolidone (PVP). The hollow particles obtained possess the original single‐crystalline structures, with retention of the high surface areas. Our synthetic route based on chemical etching is quite simple, and it can be scaled up for mass production.
Synthesis and Crystallochemical Characterisation of the Intermetallic Phases La(AgxMg1–x)12 (0.11 ≤ x ≤ 0.21), LaAg4+xMg2–x (–0.15 ≤ x ≤ 1.05) and LaAg2+xMg2–x (0 < x ≤ 0.45)
Authors: Solokha Pavlo , De Negri Serena , Pavlyuk Volodymyr , Saccone Adriana , Fadda Giuseppe 
Published: September 2012

AbstractThe crystal structures of three new La–Ag–Mg ternary phases were solved and refined from X‐ray diffraction data recorded on single crystals. All the studied phases show wide homogeneity regions extending at a constant La concentration. The Mg‐rich compound La(AgxMg1–x)12 (0.11 ≤ x ≤ 0.21) crystallises with a large tetragonal unit cell [I, I41/amd, tI208, own str. type, Z = 16, a = 10.1686(10), c = 46.539(5) Å, R1 = 0.013, wR2 = 0.025, x = 0.12]. The Ag‐rich phase LaAg4+xMg2–x (–0.15 ≤ x ≤ 1.05) shows two structural modifications: body‐centred tetragonal for an Ag content lower than ca. 70 at.‐% [II, I4/mmm, tI14, YbAl4Mo2‐type, Z = 2, a = 7.1995(3), c = 5.5996(2) Å, R1 = 0.031, wR2 = 0.081, x = 0.4] and primitive tetragonal for a higher Ag‐content [III, P4/nmm, tP14, own str. type, Z = 2, a = 7.2227(4), c = 5.4433(9) Å, R1 = 0.013, wR2 = 0.030, x = 0.9]. These two structural models are group‐subgroup related (LaAg5Mg is the k2 subgroup of LaAg4Mg2) as usual for second‐order transformations. The LaAg2+xMg2–x phase (0 < x ≤ 0.45) crystallises with an orthorhombic unit cell [IV, Cmcm, oS20, own str. type, Z = 4, a = 4.805(1), b = 17.258(4), c = 5.527(1) Å, R1 = 0.029, wR2 = 0.081, x = 0.25]. In order to gain insights into their bonding peculiarities, calculations of the electronic structures (LMTO approach) were performed on idealised stoichiometric models of the studied compounds representing a chemical modelling of mixed occupations. We also computed the structural parameters of the Ag‐rich phases and the vibrational properties of LaAg4+xMg2–x within the pseudopotential approach in generalised‐gradient approximation (GGA).
Steric Effect of a Phosphane Ligand on the Equilibrium of Ge–Ge Bond Formation at a Platinum Center
Authors: Arii Hidekazu , Watanabe Nakako , Mochida Kunio , Kawashima Takayuki 
Published: September 2012

AbstractReactions of zero‐valent platinum complexes having a diphosphane ligand with arylgermanes ArGeH3 [Ar = 2,4,6‐trimethylphenyl (Mes); 2,4,6‐triethylphenyl (TEP)] in a 1:2 molar ratio yield several bis(germyl)platinum complexes. The complex containing a five‐membered chelate ligand (dppe) is thermally stable even at 80 °C. Analogues bearing a six‐membered chelate ligand (dppp) were converted into the digermylplatinum complex through a 1,2‐germyl migration, and an equilibrium between the bis(germyl) and digermyl complexes was observed. In a comparison of the crystal structures, the bite angle of dppp is significantly larger than that of dppe, causing a reduction of the phosphane–germyl ligand distance. The 1,2‐germyl migration of the platinum center to the other germanium atom contributes to the decrease in steric repulsion between the phosphane and germyl ligands.
Hydrogen‐Bonding Thiourea Organocatalysts: The Privileged 3,5‐Bis(trifluoromethyl)phenyl Group
Authors: Lippert Katharina M. , Hof Kira , Gerbig Dennis , Ley David , Hausmann Heike , Guenther Sabine , Schreiner Peter R. 
Published: September 2012

AbstractWe present evidence that the privileged use of the 3,5‐bis(trifluoromethyl)phenyl group in thiourea organocatalysis is due to the involvement of the ortho‐CH bond in the binding event with Lewis‐basic sites. We utilized a combination of low‐temperature IR spectroscopy, 2D NMR spectroscopy, nano‐MS (ESI) investigations, as well as density functional theory computations [M06/6‐31+G(d,p), including solvent corrections as well as natural bond orbital and atoms‐in‐molecules analyses] to support our conclusions that bear implications for catalyst design.
Evidence of exposure to aristolochic acid in patients with urothelial cancer from a Balkan endemic nephropathy region of Romania
Authors: Schmeiser Heinz H. , Kucab Jill E. , Arlt Volker M. , Phillips David H. , Hollstein Monica , Gluhovschi Gheorghe , Gluhovschi Cristina , Modilca Mirela , Daminescu Liviu , Petrica Ligia , Velciov Silvia 
Published: September 2012

AbstractRecently, chronic Aristolochia poisoning was found responsible for the aetiology of Balkan endemic nephropathy (BEN) in Croatia, Serbia, and Bosnia, and diet was the likely route of exposure to aristolochic acid (AA). BEN, often associated with an increased incidence of upper urinary tract carcinoma (UUC), also affects residents of certain rural villages in Romania. AA is a nephrotoxin and human carcinogen that forms DNA adducts after metabolic activation, which induce characteristic TP53 mutations in urothelial tumours. Here we present the first evidence linking AA exposure to UUC in residents of an endemic region in the Romanian Mehedinti County. DNA was extracted from kidney and tumour tissue of seven patients who underwent nephroureterectomy for UUC and resided in BEN villages (endemic group). Five patients with UUC from nonendemic villages served as controls. AA‐DNA adducts (7‐(deoxyadenosin‐N6‐yl)‐aristolactam I), established biomarkers of AA exposure, were identified by 32P‐postlabelling in renal DNA of six patients from the endemic group and in one of the nonendemic group (adduct levels ranged from 0.3 to 6.5 adducts per 108 nucleotides). Additionally, an A to T transversion in TP53, a base substitution characteristic of AA mutagenic activity was found in urothelial tumour DNA of one patient from the endemic group. Our results provide a molecular link to the cause of urothelial tumours in BEN regions of Romania indicating that AA is the common aetiological agent for BEN across its numerous geographical foci. Environ. Mol. Mutagen., 2012. © 2012 Wiley Periodicals, Inc.
Probabilistic Multiobjective Operation Management of MicroGrids With Hydrogen Storage and Polymer Exchange Fuel Cell Power Plants
Authors: Niknam T. , Golestaneh F. 
Published: September 2012

AbstractThis paper models and solves the operation management problem of MicroGrids (MGs) including cost and emissions minimization under uncertain environment. The proposed model emphasizes on fuel cells (FCs) as a prime mover of combined heat and power (CHP) systems. An electro‐chemical model of the proton exchange membrane fuel cell (PEMFC) is used and linked to the daily operating cost and emissions of the MGs. A reformer is considered to produce hydrogen for PEMFCs. Moreover, in high thermal load intervals, in order to make the MG more efficient, a part of produced hydrogen is stored in a hydrogen tank. The stored hydrogen can be reused by PEMFCs to generate electricity or be sold to other hydrogen consumers. A probabilistic optimization algorithm is devised which consists of 2m + 1 point estimate method to handle the uncertainty in input random variables (IRVs) and a multi‐objective Self‐adaptive Bee Swarm Optimization (SBSO) algorithm to minimize the cost and emissions simultaneously. Several techniques are proposed in the SBSO algorithm to make it a powerful black‐box optimization tool. The efficiency of the proposed approach is verified on a typical grid‐connected MG with several distributed energy sources.
Regulation of microglia activation and deactivation by nuclear receptors
Authors: Saijo Kaoru , Crotti Andrea , Glass Christopher K. 
Published: September 2012

AbstractMicroglia cells function as sentinels for innate immunity in the central nervous system (CNS). To perform this function, microglia express a diverse set of pattern recognition receptors (PRRs) for pathogen‐associated molecular patterns (PAMPs) that include Toll‐like receptors (TLRs) and inflammasomes. Several members of the TLR and inflammasome family also recognize endogenously derived molecules that are generated as a consequence of tissue injury or other pathological processes. Recognition of PAMPs or endogenous ligands by PRRs in microglia induces the robust activation of innate immune responses leading to the production of proinflammatory mediators and the activation of adaptive immunity. Activation of microglia is essential for clearance of infection and repair of tissue injury. However, uncontrolled inflammatory responses of microglia are also thought to contribute to the severity of many neurodegenerative diseases. Thus, activation of microglia must be properly and tightly regulated to maintain normal tissue homeostasis. Several mechanisms have been identified that appear to function in the active maintenance of quiescence under normal conditions and/or re‐establish this state following resolution of infection or injury. These mechanisms involve communication with neurons and other glia through secreted molecules or surface expressing receptors as well as actions of members of the nuclear receptor (NR) superfamily of transcription factors. Here, we review recent advances in our understanding of the regulation of microglia activation and deactivation with a focus on counter‐regulation of microglia activation by nuclear receptors. © 2012 Wiley Periodicals, Inc.
Using HPV prevalence to predict cervical cancer incidence
Authors: Sharma Monisha , Bruni Laia , Diaz Mireia , Castellsagué Xavier , Sanjosé Silvia de , Bosch F. Xavier , Kim Jane J. 
Published: September 2012

AbstractKnowledge of a country's cervical cancer (CC) burden is critical to informing decisions about resource allocation to combat the disease; however, many countries lack cancer registries to provide such data. We developed a prognostic model to estimate CC incidence rates in countries without cancer registries, leveraging information on human papilloma virus (HPV) prevalence, screening, and other country‐level factors. We used multivariate linear regression models to identify predictors of CC incidence in 40 countries. We extracted age‐specific HPV prevalence (10‐year age groups) by country from a meta‐analysis in women with normal cytology (N = 40) and matched to most recent CC incidence rates from Cancer Incidence in Five Continents when available (N = 36), or Globocan 2008 (N = 4). We evaluated country‐level behavioral, economic, and public health indicators. CC incidence was significantly associated with age‐specific HPV prevalence in women aged 35–64 (adjusted R‐squared 0.41) (“base model”). Adding geographic region to the base model increased the adjusted R‐squared to 0.77, but the further addition of screening was not statistically significant. Similarly, country‐level macro‐indicators did not improve predictive validity. Age‐specific HPV prevalence at older ages was found to be a better predictor of CC incidence than prevalence in women under 35. However, HPV prevalence could not explain the entire CC burden as many factors modify women's risk of progression to cancer. Geographic region seemed to serve as a proxy for these country‐level indicators. Our analysis supports the assertion that conducting a population‐based HPV survey targeting women over age 35 can be valuable in approximating the CC risk in a given country.
Does acupuncture activate endogenous analgesia in chronic whiplash‐associated disorders? A randomized crossover trial
Authors: Tobbackx Y. , Meeus M. , Wauters L. , De Vilder P. , Roose J. , Tom Verhaeghe J. , Nijs  
Published: September 2012

AbstractBackgroundMany patients with chronic pain, including those with chronic whiplash‐associated disorders (WAD), show features of central sensitization. Randomized trials examining whether treatments are able to influence the process of central sensitization in patients with chronic WAD are emerging. Therefore, the present study aimed at examining whether acupuncture results in activation of endogenous analgesia and relief in symptoms in patients with chronic WAD.MethodsIn this randomized crossover pilot trial with blinded assessors, each patient (n = 39) received two treatment sessions of identical duration, with acupuncture and relaxation therapy randomly crossed over in visit 2. Primary outcome measurement included immediate activation of endogenous analgesia i.e., pressure pain sensitivity and conditioned pain modulation. Secondary outcome measurements included pain relief and reduced disability level.ResultsLocal pressure pain sensitivity at baseline and during conditioned pain modulation decreased significantly more following acupuncture compared with relaxation (time × group interactions: p < 0.001), both in the neck and at a site distinct from the painful region. When comparing the effects of acupuncture versus relaxation, no differences were observed on conditioned pain modulation, temporal summation of pressure pain, neck disability or symptom severity (all p‐values >0.05).ConclusionIt was shown that one session of acupuncture treatment results in acute improvements in pressure pain sensitivity in the neck and calf of patients with chronic WAD. Acupuncture had no effect on conditioned pain modulation or temporal summation of pressure pain. Both acupuncture and relaxation appear to be well‐tolerated treatments for people with chronic WAD. These findings suggest that acupuncture treatment activates endogenous analgesia in patients with chronic WAD.
Neocellularization and neovascularization of nanosized bioactive glass‐coated decellularized trabecular bone scaffolds
Authors: Gerhardt L.‐C. , Widdows K. L. , Erol M. M. , Nandakumar A. , Roqan I. S. , Ansari T. , Boccaccini A.R. 
Published: September 2012

AbstractIn this study, the in vivo recellularization and neovascularization of nanosized bioactive glass (n‐BG)‐coated decellularized trabecular bone scaffolds were studied in a rat model and quantified using stereological analyses. Based on the highest amount of vascular endothelial growth factor (VEGF) secreted by human fibroblasts grown on n‐BG coatings (0–1.245 mg/cm2), decellularized trabecular bone samples (porosity: 43–81%) were coated with n‐BG particles. Grown on n‐BG particles at a coating density of 0.263 mg/cm2, human fibroblasts produced 4.3 times more VEGF than on uncoated controls. After 8 weeks of implantation in Sprague–Dawley rats, both uncoated and n‐BG‐coated samples were well infiltrated with newly formed tissue (47–48%) and blood vessels (3–4%). No significant differences were found in cellularization and vascularization between uncoated bone scaffolds and n‐BG‐coated scaffolds. This finding indicates that the decellularized bone itself may exhibit growth‐promoting properties induced by the highly interconnected pore microarchitecture and/or proteins left behind on decellularized scaffolds. Even if we did not find proangiogenic effects in n‐BG‐coated bone scaffolds, a bioactive coating is considered to be beneficial to impart osteoinductive and osteoconductive properties to decellularized bone. n‐BG‐coated bone grafts have thus high clinical potential for the regeneration of complex tissue defects given their ability for recellularization and neovascularization. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 827–841, 2013.
An analytical method for computing atomic contact areas in biomolecules
Authors: Mach Paul , Koehl Patrice 
Published: September 2012

AbstractWe propose a new analytical method for detecting and computing contacts between atoms in biomolecules. It is based on the alpha shape theory and proceeds in three steps. First, we compute the weighted Delaunay triangulation of the union of spheres representing the molecule. In the second step, the Delaunay complex is filtered to derive the dual complex. Finally, contacts between spheres are collected. In this approach, two atoms i and j are defined to be in contact if their centers are connected by an edge in the dual complex. The contact areas between atom i and its neighbors are computed based on the caps formed by these neighbors on the surface of i; the total area of all these caps is partitioned according to their spherical Laguerre Voronoi diagram on the surface of i. This method is analytical and its implementation in a new program BallContact is fast and robust. We have used BallContact to study contacts in a database of 1551 high resolution protein structures. We show that with this new definition of atomic contacts, we generate realistic representations of the environments of atoms and residues within a protein. In particular, we establish the importance of nonpolar contact areas that complement the information represented by the accessible surface areas. This new method bears similarity to the tessellation methods used to quantify atomic volumes and contacts, with the advantage that it does not require the presence of explicit solvent molecules if the surface of the protein is to be considered. © 2012 Wiley Periodicals, Inc.
Synthesis of Novel Core Cross‐Linked Star‐Based Polyrotaxane End‐Capped via “CuAAC” Click Chemistry
Authors: Fu Qiang , Ren Jing M. , Tan Shereen , Xu Jiangtao , Qiao Greg G. 
Published: September 2012

AbstractThe first example of core cross‐linked star (CCS) polyrotaxane was prepared using the poly(ϵ‐caprolactone) (PCL) CCS three‐dimensional (3D) scaffold. The 3D CCS polymer was firstly prepared through the “arm‐first” approach. Then, the “arms” of the resultant PCL CCS polymer were threaded with α‐cyclodextrins (α‐CDs). The threaded α‐CDs were permanently locked by the “click” reaction of terminal alkyne functionalities of the star polymers with the azide‐functionalized end caps to afford the CCS polyrotaxanes. All analytical results confirm the formation of the CCS polyrotaxanes and reveal their characteristics, including fluorescence under UV, a channel‐type crystalline structure, a two‐step thermal decomposition, and a unique core‐shell structure in great contrast to the polymer precursors.