bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional and structural correlates of the aging brain: Relating visual cortex (V1) gamma band responses to age‐related structural change
Authors: Gaetz William , Roberts Timothy P.L. , Singh Krish D. , Muthukumaraswamy Suresh D. 
Published: July 2011

AbstractThe gamma band response is thought to be a key neural signature of information processing in the mammalian brain, yet little is known about how age‐related maturation influences the γ‐band response. Recent MRI‐based studies have shown that brain maturation is accompanied by clear structural changes in both gray and white matter, yet the correspondence of these changes to brain function is unclear. The objective of this study was to relate visual cortex (V1) γ‐band responses to age‐related structural change. We evaluated MEG measured γ‐band responses to contrast gratings stimuli and structural MRIs from participants observed from two separate research centers (MEG lab at CUBRIC, Cardiff University, UK, and the Lurie Family Foundations MEG Imaging Center, (CHOP) at the Children's Hospital of Philadelphia). Pooled participant data (N = 59) ranged in age from 8.7 to 45.3 years. We assessed linear associations between age and MEG γ‐band frequency and amplitude, as well as between age and MRI volumetric parameters of the occipital lobe. Our MEG findings revealed a significant negative correlation for gamma band frequency versus age. Volumetric brain analysis from the occipital lobe also revealed significant negative correlations between age and the cortical thickness of pericalcarine and cuneus areas. Our functional MEG and structural MRI findings shows regionally specific changes due to maturation and may thus be informative for understanding physiological processes of neural development, maturation, and age‐related decline. In addition, this study represents (to our knowledge), the first published demonstration of multicenter data sharing across MEG centers. Hum Brain Mapp 33:2035–2046, 2012. © 2011 Wiley Periodicals, Inc.
A Novel, One‐Pot Four‐Component Route to 2′‐Thioxo‐2′,3′‐dihydrospiro[indole‐3,6′‐[1,3]thiazin]‐2‐one Derivatives
Authors: Alizadeh Abdolali , Mokhtari Javad 
Published: July 2011

AbstractAn efficient route to 2′,3′‐dihydro‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives is described. It involves the reaction of isatine, 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ5‐phosphanylidene)ethan‐1‐one, and different amines in the presence of CS2 in dry MeOH at reflux (Scheme 1). The alkyl carbamodithioate, which results from the addition of the amine to CS2, is added to the α,β‐unsaturated ketone, resulting from the reaction between 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ5‐phosphanylidene)ethan‐1‐one and isatine, to produce the 3′‐alkyl‐2′,3′‐dihydro‐4′‐phenyl‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives in excellent yields (Scheme 2). Their structures were corroborated spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS) and by elemental analyses.
Spin Trapping of Radical Intermediates Generated by the Oxidation of Substituted 4‐Methylphenols
Authors: Majzlík Petr , Omelka Ladislav , Superatová Renata , Holubcová Petra 
Published: July 2011

AbstractA series of substituted 4‐methylphenols 1 and 2 was oxidized with PbO2 in the presence of nitroso compounds 3–10. The formation of adducts of benzyl radicals with the nitroso spin traps in the reaction mixture was established, suggesting the abstraction of an H‐atom from the methyl substituent of 1 or 2. In the consecutive steps, the adducts underwent a further rearrangement to the corresponding nitrones. When the starting phenol contained bulky tBu groups in ortho‐position (see 2,6‐di(tert‐butyl)‐4‐methylphenol (1a)), the stable 2,6‐di(tert‐butyl)‐4R‐phenoxy radicals (R=CHN+(O−)X) were detected as the final radical products. The indirect evidence of nitrones in the reaction mixture was performed in one case by the reaction with a RO$\rm{{_{2}^{{^\cdot} }}}$ radicals.
Studies on the Radical Cyclization of 3‐Oxopropanenitriles and Alkenes with Cerium(IV) Ammonium Nitrate in Ether Solvents
Authors: Yılmaz Mehmet 
Published: July 2011

AbstractThe radical cyclization of 3‐oxopropanenitriles 1a–1e and alkenes 2a–2g with cerium(IV) ammonium nitrate (CAN) in ether solvents was investigated (Tables 1 and 2). In the optimization study, 1,3‐dioxolane, 1,4‐dioxane, 1,2‐dimethoxyethane, Et2O, and THF were used as ether‐based solvents, and the latter was found to be the most effective solvent in radical cyclizations mediated by cerium(IV). This system (cerium(IV)/THF) was applied to cyclizations of various 3‐oxopropanenitriles and 1,3‐dicarbonyl compounds with alkenes resulting in the formation of 4,5‐dihydrofurans in high yields (Table 2 and Scheme 2). The results of the cerium(IV)/THF radical cyclization were compared with those obtained with manganese(III) acetate/AcOH; the cerium(IV)/THF system turned out to be much more efficient.
A Novel Synthesis of γ,δ‐Unsaturated Aldehydes from α‐Formyl‐γ‐lactones
Authors: Snowden Roger L. , Brauchli Robert , Linder Simon 
Published: July 2011

AbstractA preparatively useful one‐step transformation of γ,γ‐disubstituted α‐formyl‐γ‐lactones into trisubstituted γ,δ‐unsaturated aldehydes is described, by means of catalytic amounts of either AcOH or AcOEt in the vapor phase over a glass support. A mechanistic rationale is proposed.
Simple, Efficient, and Catalyst‐Free Synthesis of (2‐Amino‐4H‐1‐benzopyran‐4‐yl)phosphonates in Polyethylene Glycol
Authors: Das Biswanath , Balasubramanyam Penagaluri , Chinna Reddy Gandolla , Salvanna Nayaki 
Published: July 2011

AbstractSeveral (2‐amino‐4H‐1‐benzopyran‐4‐yl)phosphonates were efficiently synthesized by employing a multicomponent protocol involving a salicylaldehyde, malononitrile or ethyl cyanoacetate, and a trialkyl phosphite in polyethylene glycol. The latter could be recovered and re‐used. No additional solvent or catalyst was required. To the best of our knowledge, this is the first report of the one‐pot preparation of (2‐amino‐4H‐1‐benzopyran‐4‐yl)phosphonic acid dimethyl esters.
Synthesis of 9,9‐Disubstituted 9H‐Pyrrolo[1,2‐a]indoles by Hydriodic Acid‐Catalyzed Cyclization of 1‐[2‐(1‐Aryl(or methyl)ethenyl)phenyl]‐1H‐pyrroles
Authors: Kobayashi Kazuhiro , Hashimoto Kenichi , Hashimoto Hiroo , Kondo Hideaki , Konishi Hisatoshi 
Published: July 2011

AbstractA novel method is reported for the synthesis of 9,9‐disubstituted 9H‐pyrrolo[1,2‐a]indoles. Cyclization of 1‐[2‐(1‐aryl(or methyl)ethenyl)phenyl]‐1H‐pyrroles, which can be easily prepared from 2‐(1‐aryl(or methyl)ethenyl)anilines, proceeds smoothly, in general, at 0° in the presence of a catalytic (or an equimolar) amount of HI in MeCN to provide the desired products.
Oligonucleotide Analogues with Integrated Bases and Backbone. Part 28
Authors: De Giacomo Fabio , Peifer Manuel , Rajic Zrinka , Vasella Andrea 
Published: July 2011

AbstractThe protected hydrazide‐linked uracil‐ and adenine‐derived tetranucleoside analogues 17, 19, and 21 were synthesized in solution by coupling the dimeric hydrazines 6 and 10 with the carboxylic acids 7, 11, and 16. These hydrazines and acids were obtained by partially deprotecting the hydrazines 5, 9, and 15, and these were prepared by coupling the hydrazines 3 and 14 with the carboxylic acids 4 and 8. The crystal structure analysis of the fully protected UU dimer 5 showed the formation of an antiparallel cyclic duplex with the uracil units H‐bonded via HN(3) and OC(2). Stacking interactions were observed between the uracil units with a buckle twist of 30.9°, and between the uracil unit II and the fluoren‐9‐yl group of Fmoc (=9H‐fluoren‐9‐yl)methoxycarbonyl). The hydrazide HN(3′) and the CO group of Fmoc form an intramolecular H‐bond. The uracil‐ and adenine‐derived, water‐soluble hydrazide‐linked self‐complementary octamers 23–32 and the non‐self‐complementary uracil derived decamer 33 were obtained by coupling the carboxylic acids 4 and 8 on a solid support. 1H‐NMR Analysis in CDCl3, mixtures of CDCl3 and (D6)DMSO, and (D8)THF showed that the partially deprotected dimers 5, 6, 12, and 13 form weakly associated linear duplexes. The partially deprotected tetramers 17 and 18 do not associate. The hydrazide‐linked octamers 23–32 do not stack in aqueous solution, and the non‐self‐complementary decamer 33 does not stack with the complementary strands of DNA 43 and RNA 42. The Cbz‐protected amide‐linked octamers 51–56 derived from uracil, adenine, cytosine, and guanine were obtained as the main products by solid‐phase synthesis from the carboxylic acids 46–49. The fully deprotected amide‐linked octamers proved insoluble, and could neither be purified nor analysed.
WAVE2, N‐WASP, and mena facilitate cell invasion via phosphatidylinositol 3‐kinase‐dependent local accumulation of actin filaments
Authors: Takahashi Kazuhide , Suzuki Katsuo 
Published: July 2011

AbstractCell migration is accomplished by the formation of cellular protrusions such as lamellipodia and filopodia. These protrusions result from actin filament (F‐actin) rearrangement at the cell cortex by WASP/WAVE family proteins and Drosophila enabled (Ena)/vasodilator‐stimulated factor proteins. However, the role of each of these actin cytoskeletal regulatory proteins in the regulation of three‐dimensional cell invasion remains to be clarified. We found that platelet‐derived growth factor (PDGF) induces invasion of MDA‐MB‐231 human breast cancer cells through invasion chamber membrane pores. This invasion was accompanied by intensive F‐actin accumulation at the sites of cell infiltration. After PDGF stimulation, WAVE2, N‐WASP, and a mammalian Ena (Mena) colocalized with F‐actin at the sites of cell infiltration in a phosphatidylinositol 3‐kinase (PI3K)‐dependent manner. Depletion of WAVE2, N‐WASP, or Mena by RNA interference (RNAi) abrogated both cell invasion and intensive F‐actin accumulation at the invasion site. These results indicate that by mediating intensive F‐actin accumulation at the sites of cell infiltration, WAVE2, N‐WASP, and Mena are crucial for PI3K‐dependent cell invasion induced by PDGF. J. Cell. Biochem. 112: 3421–3429, 2011. © 2011 Wiley Periodicals, Inc.
Predicting the UV spectrum of polyoxometalates by TD‐DFT
Authors: Ravelli Davide , Dondi Daniele , Fagnoni Maurizio , Albini Angelo , Bagno Alessandro 
Published: July 2011

AbstractUV absorption spectra of the Lindqvist polyoxometalate [W6O19]2− were predicted by relativistic time‐dependent density functional theory with several combinations of density functional and basis set. Hybrid functionals with frozen‐core Slater basis sets were found to provide the best agreement with experiment while keeping reasonable computational demand. The approach was extended to [W10O32]4− and [PW12O40]3−, suggesting that it can be applied to the polyoxometalates family. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
Nandrolone and stanozolol induce leydig cell tumor proliferation through an estrogen‐dependent mechanism involving IGF‐I system
Authors: Chimento Adele , Sirianni Rosa , Zolea Fabiana , De Luca Arianna , Lanzino Marilena , Catalano Stefania , Andò Sebastiano , Pezzi Vincenzo 
Published: July 2011

AbstractSeveral substances such as anabolic androgenic steroids (AAS), peptide hormones like insulin‐like growth factor‐I (IGF‐I), aromatase inhibitors and estrogen antagonists are offered via the Internet, and are assumed without considering the potential deleterious effects that can be caused by their administration. In this study we aimed to determine if nandrolone and stanozolol, two commonly used AAS, could have an effect on Leydig cell tumor proliferation and if their effects could be potentiated by the concomitant use of IGF‐I. Using a rat Leydig tumor cell line, R2C cells, as experimental model we found that nandrolone and stanozolol caused a dose‐dependent induction of aromatase expression and estradiol (E2) production. When used in combination with IGF‐I they were more effective than single molecules in inducing aromatase expression. AAS exhibited estrogenic activity and induced rapid estrogen receptor (ER)‐dependent pathways involving IGF1R, AKT, and ERK1/2 phosphorylation. Inhibitors for these kinases decreased AAS‐dependent aromatase expression. Up‐regulated aromatase levels and related E2 production increased cell proliferation as a consequence of increased cyclin E expression. The observation that ER antagonist ICI182,780 was also able to significantly reduce ASS‐ and AAS + IGF‐induced cell proliferation, confirmed a role for estrogens in AAS‐dependent proliferative effects. Taken together these data clearly indicate that the use of high doses of AAS, as it occurs in doping practice, enhances Leydig cell proliferation, increasing the risk of tumor development. This risk is higher when AAS are used in association with IGF‐I. To our knowledge this is the first report directly associating AAS and testicular cancer. J. Cell. Physiol. 227: 2079–2088, 2012. © 2011 Wiley Periodicals, Inc.
Motion‐sensitized driven equilibrium for blood‐suppressed T2* mapping
Authors: Newbould Rexford D. , Owen David R.J. , Shalhoub Joseph , Brown Andrew P. , Gambarota Giulio 
Published: July 2011

AbstractPurpose:To combine a motion‐sensitized driven equilibrium (MSDE) preparation with a multi‐echo spoiled gradient‐echo sequence (SPGR) to suppress the blood signal intensity in T2* mapping of carotid plaques and liver.Materials and Methods:The analytical solution of the Bloch equations for the multi‐echo SPGR sequence, with and without the MSDE preparation, was calculated to optimize sequence parameters. The sequence was implemented at 3 Tesla and T2* maps of carotid plaques and liver were first optimized for blood suppression, and then acquired from five healthy livers and six subjects with ultrasound‐identified carotid plaques.Results:Simulations and experimental data showed that the flip angle that gives maximal signal (Ernst angle) in the MSDE‐SPGR was greatly increased from that of pure SPGR. Robust blood suppression was obtained in the T2* maps of carotid plaques and liver, requiring suppression at a field of speed (FOS) of 30 cm/s in both the carotids and liver.Conclusion:MSDE provides a means to suppress the blood signal intensity in SPGR sequences. Tissue T2* maps can be obtained without the confounding effects originating from blood vessels. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Three‐dimensional plus time biventricular strain from tagged MR images by phase‐unwrapped harmonic phase
Authors: Venkatesh Bharath Ambale , Schiros Chun G. , Gupta Himanshu , Lloyd Steven G. , Dell'Italia Louis , Denney Thomas S. 
Published: July 2011

AbstractPurpose:To validate a method called bi‐ventricular strain unwrapped phase (BiSUP) for reconstructing three‐dimensional plus time (3D+t) biventricular strain maps from phase‐unwrapped harmonic phase (HARP) images derived from tagged cardiac magnetic resonance imaging (MRI).Materials and Methods:A set of 30 human subjects were imaged with tagged MRI. In each study, HARP phase was computed and unwrapped in each short‐axis and long‐axis image. Inconsistencies in unwrapped phase were resolved using branch cuts manually placed with a graphical user interface. The 3D strain maps were computed independently in each imaged time frame through systole and mid diastole in each study. The BiSUP strain and displacements were compared with those estimated by a 3D feature‐based (FB) technique and a 2D+t HARP technique.Results:The standard deviation of the difference between strains measured by the FB and the BiSUP methods was less than 4% of the average of the strains from the two methods. The correlation between peak minimum principal strain measured using the BiSUP and HARP techniques was over 83%.Conclusion:The BiSUP technique can reconstruct full 3D+t strain maps from tagged MR images through the cardiac cycle in a reasonable amount of time and user interaction compared with other 3D analysis methods. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Magnetic resonance elastography of the kidneys: Feasibility and reproducibility in young healthy adults
Authors: Rouvière Olivier , Souchon Rémi , Pagnoux Gaële , Ménager Jean‐Michel , Chapelon Jean‐Yves 
Published: July 2011

AbstractPurpose:To evaluate the feasibility and reproducibility of renal magnetic resonance elastography (MRE) in young healthy volunteers.Materials and Methods:Ten volunteers underwent renal MRE twice at a 4–5 week interval. The vibrations (45 and 76 Hz) were generated by a speaker positioned beneath the volunteers' back and centered on their left kidney. For each frequency, three sagittal slices were acquired (eight phase offsets per cycle, motion‐encoding gradients successively positioned along the three directions of space). Shear velocity images were reconstructed using the curl operator combined with the local frequency estimation (LFE) algorithm.Results:The mean shear velocities measured in the renal parenchyma during the two examinations were not significantly different and exhibited a mean variation of 6% at 45 Hz and 76 Hz. The mean shear velocities in renal parenchyma were 2.21 ± 0.14 m/s at 45 Hz (shear modulus of 4.9 ± 0.5 kPa) and 3.07 ± 0.17 m/s at 76 Hz (9.4 ± 0.8 kPa, P < 0.01). The mean shear velocities in the renal cortex and medulla were respectively 2.19 ± 0.13 m/s and 2.32 ± 0.16 m/s at 45 Hz (P = 0.002) and 3.06 ± 0.16 m/s and 3.10 ± 0.22 m/s at 76 Hz (P = 0.13).Conclusion:Renal MRE was feasible and reproducible. Two independent measurements of shear velocities in the renal parenchyma of the same subjects showed an average variability of 6%. J. Magn. Reson. Imaging 2011;. ©2011 Wiley‐Liss, Inc.
Novel segmentation method for abdominal fat quantification by MRI
Authors: Zhou Anqi , Murillo Horacio , Peng Qi 
Published: July 2011

AbstractPurpose:To introduce and describe the feasibility of a novel method for abdominal fat segmentation on both water‐saturated and non–water‐saturated MR images with improved absolute fat tissue quantification.Materials and Methods:A general fat distribution model which fits both water‐saturated (WS) and non–water‐saturated (NWS) MR images based on image gray‐level histogram is first proposed. Next, a novel fuzzy c‐means clustering step followed by a simple thresholding is proposed to achieve automated and accurate abdominal quantification taking into consideration the partial‐volume effects (PVE) in abdominal MR images. Eleven subjects were scanned at central abdomen levels with both WS and NWS MRI techniques. Synthesized “noisy” NWS (nNWS) images were also generated to study the impact of reduced SNR on fat quantification using the novel approach. The visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) amounts of the WS MR images were quantified with a traditional intensity thresholding method as a reference to evaluate the performance of the novel method on WS, NWS, and nNWS MR images.Results:The novel approach resulted in consistent SAT and VAT amounts for WS, NWS, and nNWS images. Automatic segmentation and incorporation of spatial information during segmentation improved speed and accuracy. These results were in good agreement with those from the WS images quantified with a traditional intensity thresholding method and accounted for PVE contributions.Conclusion:The proposed method using a novel fuzzy c‐means clustering method followed by thresholding can achieve consistent quantitative results on both WS and NWS abdominal MR images while accounting for PVE contributing inaccuracies. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Assessment of fast dynamic imaging and the use of Gd‐EOB‐DTPA for MR‐guided liver interventions
Authors: Fischbach Frank , Thormann Markus , Seidensticker Max , Kropf Siegfried , Pech Maciej , Ricke Jens 
Published: July 2011

AbstractPurpose:1) To analyze and compare fast dynamic imaging sequences to biopsy suspect liver lesions. 2) To evaluate the additional use of hepatocyte‐specific contrast agent compared to the nonenhanced fast dynamic scans and diagnostic liver imaging.Materials and Methods:Image acquisition was performed using a 1T open‐configured scanner suitable for interventional purposes. Transversal postcontrast T1‐weighted (T1w) fat‐saturated 3D high‐resolution examination (THRIVE) images were acquired >20 minutes postintravenous application of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd‐EOB‐DTPA). A single slice, crossing the level of the lesion, was acquired using intermediate‐weighted steady‐state free‐precession (bTFE), T1w‐gradient echo and spin echo (T1FFE/TSE), T2w‐spin echo (sshTSE) sequences. T1w imaging was acquired prior and after contrast media application. Diagnostic and fast dynamic images were compared based on a 10‐point rating scale. In addition, the liver‐to‐lesion‐contrast ratio was measured.Results:A total of 39 malignant lesions with a mean diameter of 13 mm (5–30 mm) in 39 patients were included. Concerning a test of noninferiority, there was no significant difference between rating score values of fast dynamic imaging employing contrast‐enhanced T1FFE‐sequences compared to diagnostic THRIVE (P = 0.001). Calculated liver‐to‐lesion contrast also showed no difference for either imaging sequence (P = 1.0). All other sequences tested showed significant inferiority (P ≤ 0.001).Conclusion:T1w Gd‐EOB‐DTPA contrast‐enhanced fast dynamic GRE imaging significantly improves the contrast behavior of malignant liver lesions comparable to diagnostic imaging and is best suited for liver intervention, especially at 1T open magnetic resonance imaging. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Rapid identification of phase I and II metabolites of artemisinin antimalarials using LTQ‐Orbitrap hybrid mass spectrometer in combination with online hydrogen/deuterium exchange technique
Authors: Liu Tian , Du Fuying , Wan Yakun , Zhu Fanping , Xing Jie 
Published: July 2011

AbstractArtemisinin drugs have become the first‐line antimalarials in areas of multi‐drug resistance. However, monotherapy with artemisinin drugs results in comparatively high recrudescence rates. Autoinduction of CYP‐mediated metabolism, resulting in reduced exposure, has been supposed to be the underlying mechanism. To better understand the autoinduction of artemisinin drugs, we evaluated the biotransformation of artemisinin, also known as Qing‐hao‐su (QHS), and its active derivative dihydroartemisinin (DHA) in vitro and in vivo, using LTQ‐Orbitrap hybrid mass spectrometer in conjunction with online hydrogen (H)/deuterium (D) exchange high‐resolution (HR)‐LC/MS (mass spectrometry) for rapid structural characterization. The LC separation was improved allowing the separation of QHS parent drugs and their metabolites from their diastereomers. Thirteen phase I metabolites of QHS have been identified in liver microsomal incubates, rat urine, bile and plasma, including six deoxyhydroxylated metabolites, five hydroxylated metabolites, one dihydroxylated metabolite and deoxyartemisinin. Twelve phase II metabolites of QHS were detected in rat bile, urine and plasma. DHA underwent similar metabolic pathways, and 13 phase I metabolites and 3 phase II metabolites were detected. Accurate mass data were obtained in both full‐scan and MS/MS mode to support assignments of metabolite structures. Online H/D exchange LC‐HR/MS experiments provided additional evidence in differentiating deoxydihydroxylated metabolites from mono‐hydroxylated metabolites. The results showed that the main phase I metabolites of artemisinin drugs are hydroxylated and deoxyl products, and they will undergo subsequent phase II glucuronidation processes. This study also demonstrated the effectiveness of online H/D exchange LC‐HR/MSn technique in rapid identification of drug metabolites. Copyright © 2011 John Wiley & Sons, Ltd.