bluuebunny/crossref_metadata_2025_split huggingface dataset:
Subcellular Localization and Activity of Gambogic Acid
Authors: Guizzunti Gianni , Batova Ayse , Chantarasriwong Oraphin , Dakanali Marianna , Theodorakis Emmanuel A. 
Published: April 2012

AbstractThe natural product gambogic acid (GA) has shown significant potential as an anticancer agent as it is able to induce apoptosis in multiple tumor cell lines, including multidrug‐resistant cell lines, as well as displaying antitumor activity in animal models. Despite the fact that GA has entered phase I clinical trials, the primary cellular target and mode of action of this compound remain unclear, although many proteins have been shown to be affected by it. By thorough analysis of several cellular organelles, at both the morphological and functional levels, we demonstrate that the primary effect of GA is at the mitochondria. We found that GA induces mitochondrial damage within minutes of incubation at low‐micromolar concentrations. Moreover, a fluorescent derivative of GA was able to localize specifically to the mitochondria and was displaced from these organelles after competition with unlabeled GA. These findings indicate that GA directly targets the mitochondria to induce the intrinsic pathway of apoptosis, and thus represents a new member of the mitocans.
Disparity between angiographic coronary lesion complexity and lipid core plaques assessed by near‐infrared spectroscopy
Authors: Zynda Todd K. , Thompson Caleb D. , Hoang Khiet C. , Seto Arnold H. , Glovaci Diana , Wong Nathan D. , Patel Pranav M. , Kern Morton J. 
Published: April 2012

ObjectiveThe purpose of this study was to determine if there was a relationship between angiographic lesion complexity and the extent of lipid core plaque (LCP) identified by catheter‐based near‐infrared spectroscopy (NIRS).BackgroundThe angiographic complexity of coronary artery disease (CAD) is used to predict outcomes in patients undergoing percutaneous coronary intervention (PCI). The SYNTAX score, an angiographic tool quantifying the complexity of CAD, is associated with PCI outcomes. Recently, a novel catheter‐based imaging technique using NIRS can identify LCP, which also is associated with PCI periprocedural myocardial infarction (MI). However, it is unknown whether these events are related to distinct adverse event prone pathobiology, such as a LCP within a complex angiographic lesion. Thus, we hypothesized that LCP identified by NIRS would be associated with high SYNTAX score.MethodsSeventy‐eight patients who underwent coronary angiography and target‐vessel NIRS were selected from the Chemometric Observations of Lipid Core Containing Plaques of Interest in Native Coronary Arteries Registry, an industry sponsored registry to collate clinical findings in all patients undergoing NIRS evaluation. A lipid core burden index (LCBI) was obtained from the scan of the proximal 50 mm of the target vessel. Three vessel SYNTAX (total, tSYN) and target single vessel (only NIRS‐interrogated vessel) SYNTAX (1vSYN) scores were calculated and compared to LCBI. High LCBI was defined as (>110) and was compared to tertile scores for 1vSYN score (low 0–5, intermediate 6–10, high ≥11) and previously established tertiles for tSYN score (low 0–22, intermediate 23–32, high ≥33).ResultsPatients had mean age of 63 years with prevalence of females (10%), diabetes mellitus (28%), hypertension (88%), and smoking history (72%); 1vSYN and tSYN scores correlated poorly with LCBI [(r2 = 0.25; P = 0.02; n = 78) and (r2 = 0.24; P = 0.04; n = 78), respectively]. Mean LCBI did not differ significantly across all tertiles of 1vSYN or tSYN scores.ConclusionsAngiographic SYNTAX score only weakly correlated with LCBI. It is of interest as well that high LCBI was also present in cases of low SYNTAX scores. The disparity between the degree of angiographic complexity and the amount of LCP supports postulated mechanisms of the adverse event propensity even in patients who demonstrate low angiographic complexity. Future studies are necessary to address the clinical significance of high LCBI in patients with low‐to‐intermediate angiographic complexity and their potential for PCI‐related complications. © 2012 Wiley Periodicals, Inc.
Janus‐Like Squaramide‐Based Hosts: Dual Mode of Binding and Conformational Transitions Driven by Ion‐Pair Recognition
Authors: Soberats Bartomeu , Martínez Luis , Sanna Elena , Sampedro Angel , Rotger Carmen , Costa Antoni 
Published: April 2012

AbstractNew tripodal squaramide‐based hosts have been synthesised and structurally characterised by spectroscopic methods. In 2.5 % (v/v) [D6]DMSO in CDCl3, compound 4 formed dimeric assemblies [log Kdim=3.68(8)] as demonstrated by 1H NMR spectroscopy and UV dilution experiments. AFM and SEM analyses revealed the formation of a network of bundled fibres, which indicates a preferential mechanism for aggregation. These C3‐symmetric tripodal hosts exhibited two different and mutually exclusive modes of binding, each one easily accessible by simultaneous reorientation of the squaramide groups. In the first, a convergent disposition of the NH squaramide protons allowed the formation of an array of NH⋅⋅⋅X− hydrogen bonds with anions. In the second mode, reorientation of carbonyl squaramide groups allowed multiple CO⋅⋅⋅H interactions with ammonium cations. The titration of 4 with different tetraalkylammonium iodides persistently showed the formation of 1:1 complexes, as well as 1:2 and 1:3 complexes. The corresponding stoichiometries and binding affinities of the complexes were evaluated by multi‐regression analysis. The formation of high‐order complexes, supported by ROESY, NOESY and mass spectrometry experiments, has been attributed to the insertion of NR4I ion pairs between the carbonyl and NH protons of the squaramide groups located in adjacent arms of 4. The observed effects reflect the induction of significant conformational changes in the hosts, mainly in relation to the relative orientation of the squaramide groups adapting their geometries to incoming ion‐pair complementary substrates. The results presented herein identify and fully describe two different modes of ion‐pair recognition aimed at directing conformational transitions in the host, therefore establishing a base for controlling more elaborate movements of molecular devices through ion‐pair recognition.
Optically Transparent Hydrogels from an Auxin–Amino‐Acid Conjugate Super Hydrogelator and its Interactions with an Entrapped Dye
Authors: Reddy Amarendar , Sharma Aashish , Srivastava Aasheesh 
Published: April 2012

AbstractLow‐molecular‐weight organic hydrogelators (LMHGs) that can rigidify water into soft materials are desirable in various applications. Herein, we report the excellent hydrogelating properties of a simple synthetic auxin–amino‐acid conjugate, naphthalene‐1‐acetamide of L‐phenylalanine (1‐NapF, Mw=333.38 Da), which gelated water even at 0.025 wt %, thereby making it the most‐efficient LMHG known. Optically transparent gels that exhibited negligible scattering in the range 350–900 nm were obtained. A large shift from the theoretical pKa value of the gelator was observed. The dependence of the minimum gelator concentration (MGC) and the gel‐melting temperatures on the pH value indicated the importance of H‐bonding between the carboxylate groups on adjacent phenylalanine molecules in the gelator assembly. FTIR spectroscopy of the xerogels showed a β‐sheet‐like assembly of the gelator. Variable‐temperature 1H NMR spectroscopy demonstrated that π stacking of the aromatic residues was also partly involved in the gelator assembly. TEM of the xerogel showed the presence of a dense network of thin, high‐aspect‐ratio fibrillar assemblies with diameters of about 5 nm and lengths that exceeded a few microns. Rheology studies showed the formation of stable gels. The entrapment of water‐soluble dyes afforded extremely fluorescent gels that involved the formation of J‐aggregates by the dye within gel. A strong induced‐CD band established that the RhoB molecules were interacting closely with the chiral gelator aggregates. H‐bonding and electrostatic interactions, rather than intercalation, seemed to be involved in RhoB binding. The addition of chaotropic reagents, as well as increasing the pH value, disassembled the gel and promoted the release of the entrapped dye with zero‐order kinetics.
Chiral Hetero‐ and Carbocyclic Compounds from the Asymmetric Hydrogenation of Cyclic Alkenes
Authors: Verendel J. Johan , Li Jia‐Qi , Quan Xu , Peters Byron , Zhou Taigang , Gautun Odd R. , Govender Thavendran , Andersson Pher G. 
Published: April 2012

AbstractSeveral types of chiral hetero‐ and carbocyclic compounds have been synthesized by using the asymmetric hydrogenation of cyclic alkenes. N,P‐Ligated iridium catalysts reduced six‐membered cyclic alkenes with various substituents and heterofunctionality in good to excellent enantioselectivity, whereas the reduction of five‐membered cyclic alkenes was generally less selective, giving modest enantiomeric excesses. The stereoselectivity of the hydrogenation depended more strongly on the substrate structure for the five‐ rather than the six‐membered cyclic alkenes. The major enantiomer formed in the reduction of six‐membered alkenes could be predicted from a selectivity model and isomeric alkenes had complementary enantioselectivity, giving opposite optical isomers upon hydrogenation. The utility of the reaction was demonstrated by using it as a key step in the preparation of chiral 1,3‐cis‐cyclohexane carboxylates.
Challenges in Climate Science and Contemporary Applied Mathematics
Authors: Majda Andrew J. 
Published: April 2012

AbstractThis article discusses the challenges in climate science from the emerging viewpoint of stochastic‐statistical properties of turbulent dynamical systems. The mathematical topics discussed here include empirical information theory, fluctuation‐dissipation theorems, reduced‐order stochastic modeling, and the development of mathematically unambiguous exactly solvable test models for climate science that capture crucial features of vastly more complex scientific problems. The applied mathematics topics include the emerging development of multiscale algorithms for filtering/data assimilation and superparametrization for climate science and other problems in science and engineering, as well as suitable unambiguous mathematical test problems for their behavior. Interesting contemporary research directions and specific open problems are mentioned throughout the article. The perspective here should also be useful for applications to other complex dynamical systems arising in neural science, material science, and environmental/mechanical engineering. © 2011 Wiley Periodicals, Inc.
Thermodynamic Aspects of the Synthesis of Thin‐Film Materials for Solar Cells
Authors: Scragg Jonathan J. , Dale Phillip J. , Colombara Diego , Peter Laurence M. 
Published: April 2012

AbstractA simple and useful thermodynamic approach to the prediction of reactions taking place during thermal treatment of layers of multinary semiconductor compounds on different substrates has been developed. The method, which uses the extensive information for the possible binary compounds to assess the stability of multinary phases, is illustrated with the examples of Cu(In,Ga)Se2 and Cu2ZnSnSe4 as well as other less‐studied ternary and quaternary semiconductors that have the potential for use as absorbers in photovoltaic devices.
A Highly Stable Anode, Carbon‐Free, Catalyst Support Based on Tungsten Trioxide Nanoclusters for Proton‐Exchange Membrane Fuel Cells
Authors: Dou Meiling , Hou Ming , Zhang Huabing , Li Guangfu , Lu Wangting , Wei Zidong , Shao Zhigang , Yi Baolian 
Published: April 2012

AbstractDurability is an important issue in proton‐exchange membrane fuel cells (PEMFCs). One of the major challenges lies in the degradation caused by the oxidation of the carbon support under high anode potentials (under fuel starvation conditions). Herein, we report highly stable, carbon‐free, WO3 nanoclusters as catalyst supports. The WO3 nanoclusters are synthesized through a hard template method and characterized by means of electron microscopy and electrochemical analysis. The electrochemical studies show that the WO3 nanoclusters have excellent electrochemical stability under a high potential (1.6 V for 10 h) compared to Vulcan XC‐72. Pt nanoparticles supported on these nanoclusters exhibit high and stable electrocatalytic activity for the oxidation of hydrogen. The catalyst shows negligible loss in electrochemically active surface area (ECA) after an accelerated durability test, whereas the ECA of the Pt nanoparticles immobilized on conventional carbon decreases significantly after the same oxidation condition. Therefore, Pt/WO3 could be considered as a promising alternative anode catalyst for PEMFCs.
Redistribution of monocarboxylate transporter 2 on the surface of astrocytes in the human epileptogenic hippocampus
Authors: Lauritzen Fredrik , Heuser Kjell , de Lanerolle Nihal C. , Lee Tih‐Shih W. , Spencer Dennis D. , Kim Jung H. , Gjedde Albert , Eid Tore , Bergersen Linda H. 
Published: April 2012

AbstractEmerging evidence points to monocarboxylates as key players in the pathophysiology of temporal lobe epilepsy (TLE) with hippocampal sclerosis (mesial temporal lobe epilepsy, MTLE). Monocarboxylate transporters (MCTs) 1 and 2, which are abundantly present on brain endothelial cells and perivascular astrocyte endfeet, respectively, facilitate the transport of monocarboxylates and protons across cell membranes. Recently, we reported that the density of MCT1 protein is reduced on endothelial cells and increased on astrocyte plasma membranes in the hippocampal formation in patients with MTLE and in several animal models of the disorder. Because the perivascular astrocyte endfeet comprise an important part of the neurovascular unit, we now assessed the distribution of the MCT2 in hippocampal formations in TLE patients with (MTLE) or without hippocampal sclerosis (non‐MTLE). Light microscopic immunohistochemistry revealed significantly less perivascular MCT2 immunoreactivity in the hippocampal formation in MTLE (n = 6) than in non‐MTLE (n = 6) patients, and to a lesser degree in non‐MTLE than in nonepilepsy patients (n = 4). Immunogold electron microscopy indicated that the loss of MCT2 protein occurred on perivascular astrocyte endfeet. Interestingly, the loss of MCT2 on astrocyte endfeet in MTLE (n = 3) was accompanied by an upregulation of the protein on astrocyte membranes facing synapses in the neuropil, when compared with non‐MTLE (n = 3). We propose that the altered distribution of MCT1 and MCT2 in TLE (especially MTLE) limits the flux of monocarboxylates across the blood–brain barrier and enhances the exchange of monocarboxylates within the brain parenchyma. © 2012 Wiley Periodicals, Inc.
Towards a comprehensive approach to parameter estimation in land surface parameterization schemes
Authors: Rosolem Rafael , Gupta Hoshin V. , Shuttleworth W. James , de Gonçalves Luis Gustavo Gonçalves , Zeng Xubin 
Published: April 2012

AbstractIn climate models, the land–atmosphere interactions are described numerically by land surface parameterization (LSP) schemes. The continuing improvement in realism in these schemes comes at the expense of the need to specify a large number of parameters that are either directly measured or estimated. Also, an emerging problem is whether the relationships used in LSPs are universal and globally applicable. One plausible approach to evaluate this is to first minimize uncertainty in model parameters by calibration. In this paper, we conduct a comprehensive analysis of some model diagnostics using a slightly modified version of the Simple Biosphere 3 model for a variety of biomes located mainly in the Amazon. First, the degree of influence of each individual parameter in simulating surface fluxes is identified. Next, we estimate parameters using a multi‐operator genetic algorithm applied in a multi‐objective context and evaluate simulations of energy and carbon fluxes against observations. Compared with the default parameter sets, these parameter estimates improve the partitioning of energy fluxes in forest and cropland sites and provide better simulations of daytime increases in assimilation of net carbon during the dry season at forest sites. Finally, a detailed assessment of the parameter estimation problem was performed by accounting for the decomposition of the mean squared error to the total model uncertainty. Analysis of the total prediction uncertainty reveals that the parameter adjustments significantly improve reproduction of the mean and variability of the flux time series at all sites and generally remove seasonality of the errors but do not improve dynamical properties. Our results demonstrate that error decomposition provides a meaningful and intuitive way to understand differences in model performance. To make further advancements in the knowledge of these models, we encourage the LSP community to adopt similar approaches in the future. Copyright © 2012 John Wiley & Sons, Ltd.
Attachment‐based intervention for substance‐using mothers: A preliminary test of the proposed mechanisms of change
Authors: Suchman Nancy E. , Decoste Cindy , Rosenberger Patricia , McMahon Thomas J. 
Published: April 2012

AbstractAlthough randomized controlled trials examining the efficacy of attachment‐based interventions have been increasing in recent years, adequate measurement of treatment integrity, integrity–outcome associations, and mechanisms of change has been rare. The aim of this investigation was to conduct a rigorous test of proposed mechanisms of change in the Mothers and Toddlers Program (MTP) treatment model, a 12‐session, attachment‐based individual therapy for substance‐using mothers of children birth to 3 years of age. The MTP aims to improve maternal reflective functioning (RF) and representation quality (RQ) to bring about second‐order change in maternal caregiving behavior. Following guidelines from M.K. Nock (2007), it was hypothesized that (a) therapist adherence to unique MTP treatment components would uniquely predict improvement in RF and RQ and that (b) improvement in RF and RQ would function as unique mechanisms of change (when compared with other potential mechanisms—reduction in depression and increase in abstinence from drug use) in the improvement of caregiving behavior. Findings supported each hypothesis, confirming the proposed mechanisms of the treatment model. However, improvement in maternal depression also uniquely predicted improvement in caregiving behavior. Results underscore the potential value of attachment‐based parenting interventions for improving mother–child relations and the importance of providing these interventions in clinic settings where mothers have access to comprehensive care (e.g., psychiatric services).
Reversible photoswitching in fluorescent proteins: A mechanistic view
Authors: Bourgeois Dominique , Adam Virgile 
Published: April 2012

AbstractPhototransformable fluorescent proteins (FPs) have received considerable attention in recent years, because they enable many new exciting modalities in fluorescence microscopy and biotechnology. On illumination with proper actinic light, phototransformable FPs are amenable to long‐lived transitions between various fluorescent or nonfluorescent states, resulting in processes known as photoactivation, photoconversion, or photoswitching. Here, we review the subclass of photoswitchable FPs with a mechanistic perspective. These proteins offer the widest range of practical applications, including reversible high‐density data bio‐storage, photochromic FRET, and super‐resolution microscopy by either point‐scanning, structured illumination, or single molecule‐based wide‐field approaches. Photoswitching can be engineered to occur with high contrast in both Hydrozoan and Anthozoan FPs and typically results from a combination of chromophore cis‐trans isomerization and protonation change. However, other switching schemes based on, for example, chromophore hydration/dehydration have been discovered, and it seems clear that ever more performant variants will be developed in the future. © 2012 IUBMB IUBMB Life, 2012
Real‐time three‐dimensional echocardiographic evaluation of left ventricular systolic synchronicity in patients with chronic heart failure: Comparison with tissue doppler imaging
Authors: Li Dong‐ye , Liang Li , Cao Guang‐ke , Xia Yong , Xu Tong‐da , Chen Jing , Wang Xiao‐ping , Chen Jun‐hong 
Published: April 2012

AbstractBackground.To investigate the clinical value of real‐time three‐dimensional echocardiography (RT‐3DE) for assessing of left ventricular systolic synchronicity.Methods.Thirty healthy volunteers and 62 patients with congestive heart failure (CHF) were enrolled. The SD of time to peak systolic motion (TDI‐Ts12‐SD) was measured with tissue Doppler imaging in 12 myocardial segments. The SD and maximal difference of the time to minimal systolic volume (Tmsv) between 16, 12, or 6 myocardial segments, expressed as a percentage of cardiac cycle duration, were measured with RT‐3DE and labeled Tmsv16‐SD%, Tmsv12‐SD%, Tmsv6‐SD%, Tmsv16‐D%, Tmsv12‐D%, and Tmsv6‐D%, respectively. The Spearman coefficient and Kappa value were calculated, and Bland‐Altman analysis was performed to investigate the correlation and agreement between the two methods. Tmsv values were compared with ejection fraction (EF).Results.There was a moderately positive (p< 0.01) correlation between TDI‐Ts12‐SD and Tmsv16‐SD%, Tmsv12‐SD%, Tmsv16‐D%, and Tmsv12‐D% (r = 0.65, 0.64, and 0.65, respectively, with Kappa values of 0.66, 0.65, 0.72, and 0.74, respectively, p< 0.01). Tmsv16‐SD%, Tmsv12‐SD%, and Tmsv12‐D% were significantly different between CHF patients with EF ≤ 35% and those with EF > 35%.Conclusions.RT‐3DE can be used in patients with CHF to quantify left ventricular mechanical dyssynchrony. Tmsv12‐SD% and Tmsv12‐D% were the best indices of left ventricular systolic synchronicity in relation to the severity of CHF as evaluated from EF. © 2012 Wiley Periodicals, Inc. J Clin Ultrasound 40:410–418, 2012
Test–retest stability analysis of resting brain activity revealed by blood oxygen level‐dependent functional MRI
Authors: Li Zhengjun , Kadivar Aniseh , Pluta John , Dunlop John , Wang Ze 
Published: April 2012

AbstractPurpose:To assess test–retest stability of four functional magnetic resonance imaging (fMRI)‐derived resting brain activity metrics: the seed‐region‐based functional connectivity (SRFC), independent component analysis (ICA)‐derived network‐based FC (NTFC), regional homogeneity (ReHo), and the amplitude of low frequency fluctuation (ALFF).Methods:Simulations were used to assess the sensitivity of SRFC, ReHo, and ALFF to noise interference. Repeat resting blood oxygen level‐dependent (BOLD) fMRI were acquired from 32 healthy subjects. The intraclass correlation coefficient (ICC) was used to assess the stability of the four metrics.Results:Random noise yielded small random SRFC, small but consistent ReHo and ALFF. A neighborhood size greater than 20 voxels should be used for calculating ReHo in order to reduce the noise interference. Both the anterior cingulate cortex (ACC) and posterior cingulate cortex (PCC)‐based SRFC were reproducible in more spatially extended regions than ICA NTFC. The two regional spontaneous brain activity (SBA) measures, ReHo and ALFF, showed test–retest reproducibility in almost the whole gray matter.Conclusion:SRFC, ReHo, and ALFF are robust to random noise interference. The neighborhood size for calculating ReHo should be larger than 20 voxels. ICC > 0.5 and cluster size > 11 should be used to assess the ICC maps for ACC/PCC SRFC, ReHo, and ALFF. BOLD fMRI‐based SBA can be reliably measured using ACC/PCC SRFC, ReHo, and ALFF after 2 months. J. Magn. Reson. Imaging 2012;36:344–354. ©2012 Wiley Periodicals, Inc.