bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preliminary evidence of altered gray and white matter microstructural development in the frontal lobe of adolescents with attention‐deficit hyperactivity disorder: A diffusional kurtosis imaging study
Authors: Helpern Joseph A. , Adisetiyo Vitria , Falangola Maria F. , Hu Caixia , Di Martino Adriana , Williams Kathleen , Castellanos Francisco X. , Jensen Jens H. 
Published: December 2010

AbstractPurposeTo investigate non‐Gaussian water diffusion using diffusional kurtosis imaging (DKI) to assess age effects on gray matter (GM) and white matter (WM) microstructural changes in the prefrontal cortex (PFC) of adolescents with attention‐deficit hyperactivity disorder (ADHD) compared to typically developing controls (TDC).Materials and MethodsIn this preliminary cross‐sectional study, T1‐weighted magnetization‐prepared rapid gradient echo (MPRAGE) and DKI images were acquired at 3T from TDC (n = 13) and adolescents with ADHD (n = 12). Regression analysis of the PFC region of interest (ROI) was conducted.ResultsTDC show a significant kurtosis increase of WM microstructural complexity from 12 to 18 years of age, particularly in the radial direction, whereas WM microstructure in ADHD is stagnant in both the axial and radial directions. In ADHD, GM microstructure also lacked a significant age‐related increase in complexity as seen in TDC; only kurtosis measures were able to detect this difference.ConclusionThese findings support the prevailing theory that ADHD is a disorder affecting frontostriatal WM. Our study is the first to directly quantify an aberrant age‐related trajectory in ADHD within GM microstructure, suggesting that the assessment of non‐Gaussian directional diffusion using DKI provides more sensitive and complementary information about tissue microstructural changes than conventional diffusion imaging methods. J. Magn. Reson. Imaging 2011;33:17–23. © 2010 Wiley‐Liss, Inc.
High‐resolution 3D coronary vessel wall imaging with near 100% respiratory efficiency using epicardial fat tracking: Reproducibility and comparison with standard methods
Authors: Scott Andrew D. , Keegan Jennifer , Firmin David N. 
Published: December 2010

AbstractPurposeTo quantitatively assess the performance and reproducibility of 3D spiral coronary artery wall imaging with beat‐to‐beat respiratory‐motion‐correction (B2B‐RMC) compared to navigator gated 2D spiral and turbo‐spin‐echo (TSE) acquisitions.Materials and MethodsHigh‐resolution (0.7 × 0.7 mm) cross‐sectional right coronary wall acquisitions were performed in 10 subjects using four techniques (B2B‐RMC 3D spiral with alternate (2RR) and single (1RR) R‐wave gating, navigator‐gated 2D spiral (2RR) and navigator‐gated 2D TSE (2RR)) on two occasions. Wall thickness measurements were compared with repeated measures analysis of variance (ANOVA). Reproducibility was assessed with the intraclass correlation coefficient (ICC).ResultsIn all, 91% (73/80) of acquisitions were successful (failures: four TSE, two 3D spiral (1RR) and one 3D spiral (2RR)). Respiratory efficiency of the B2B‐RMC was less variable and substantially higher than for navigator gating (99.6 ± 1.2% vs. 39.0 ± 7.5%, P < 0.0001). Coronary wall thicknesses (± standard deviation [SD]) were not significantly different: 1.10 ± 0.14 mm (3D spiral (2RR)), 1.20 ± 0.16 mm (3D spiral (1RR)), 1.14 ± 0.15 mm (2D spiral), and 1.21 ± 0.17 mm (TSE). Wall thickness reproducibility ranged from good (ICC = 0.65, 3D spiral (1RR)) to excellent (ICC = 0.87, 3D spiral (2RR)).ConclusionHigh‐resolution 3D spiral imaging with B2B‐RMC permits coronary vessel wall assessment over multiple thin contiguous slices in a clinically feasible duration. Excellent reproducibility of the technique potentially enables studies of disease progression/regression. J. Magn. Reson. Imaging 2011;33:77–86. © 2010 Wiley‐Liss, Inc.
Automatic segmentation propagation of the aorta in real‐time phase contrast MRI using nonrigid registration
Authors: Odille Freddy , Steeden Jennifer A. , Muthurangu Vivek , Atkinson David 
Published: December 2010

AbstractPurposeTo assess the use of a nonrigid registration technique for semi‐automatic segmentation of the aorta from real‐time velocity mapping MRI.Materials and MethodsReal‐time phase contrast images were acquired to measure flow and stroke volumes in 10 subjects, during free breathing, at rest, and during exercise. A nonrigid registration algorithm was developed to propagate a manually drawn region of interest in the aorta from one frame to all other frames of the real‐time sequence (148 images). Thus the technique provided a semi‐automatic segmentation over the whole sequence of images. The accuracy was assessed by comparison with manual segmentations in terms of Dice overlap measures and stroke volumes (SV).ResultsSemi‐automatic segmentations were comparable to manual ones (Dice score of 0.89 ± 0.04). Inter‐observer reproducibility was similar for manual and semi‐automatic segmentations (Dice score of 0.90 ± 0.04 in both cases, the difference was not significant). SV measurements also showed good agreement between manual and semi‐automatic segmentations (correlation coefficient r > 0.94), and the differences were not statistically significant.ConclusionAlthough real‐time phase contrast images have compromised image quality, a fast and robust segmentation of the aorta was possible using the registration‐based technique. J. Magn. Reson. Imaging 2011;33:232–238. © 2010 Wiley‐Liss, Inc.
Usefulness of diffusion‐weighted imaging for differentiating between desmoid tumors and malignant soft tissue tumors
Authors: Oka Kiyoshi , Yakushiji Toshitake , Sato Hiro , Fujimoto Toru , Hirai Toshinori , Yamashita Yasuyuki , Mizuta Hiroshi 
Published: December 2010

AbstractPurposeTo evaluate the usefulness of diffusion‐weighted imaging (DWI) for differentiating between desmoid tumors and malignant soft tissue tumors.Materials and MethodsConventional MRI and DWI were performed for 8 desmoid tumors and 74 malignant soft tissue tumors. DWI was obtained with a single‐shot echo‐planar imaging sequence using a 1.5 Tesla (T) MR imager. DW images were acquired with motion‐probing gradient pulses applied along three directions (x, y, and z axes) with three b‐factors (0, 500, and 1000 s/mm2). Two observers blinded to clinical information measured three regions of interest within the solid tumor and selected a minimum apparent diffusion coefficient () in each lesion. The mean ADC of desmoid tumors was calculated and compared with that of malignant soft tissue tumors using the Mann‐Whitney U test.ResultsThe mean ADC of desmoid tumors and malignant soft tissue tumors was 1.36 ± 0.48 × 10−3 mm2/s and 0.88 ± 0.20 × 10−3 mm2/s (mean ± SD), respectively. The mean ADC of the desmoid tumors was significantly higher than that of malignant soft tissue tumors (P < 0.01).ConclusionDWI is considered to be useful for differentiating between desmoid tumors and malignant soft tissue tumors. In the future, further investigation in a large series is necessary. J. Magn. Reson. Imaging 2011;33:189–193. © 2010 Wiley‐Liss, Inc.
Evaluation of respiratory liver and kidney movements for MRI navigator gating
Authors: Song Ruitian , Tipirneni Aaryani , Johnson Perry , Loeffler Ralf B. , Hillenbrand Claudia M. 
Published: December 2010

AbstractPurposeTo determine the tracking factor by studying the relationship between kidney and diaphragm motions and to compare the efficiency of the gating‐and‐following and gating‐only algorithms in reducing motion artifacts in navigator‐gated scans.Materials and MethodsDiaphragm and kidney motions were measured by using real‐time TrueFISP sequences from 10 healthy human volunteers to determine tracking factors at different acceptance windows. Mean tracking factors were used to calculate mean residual errors and improvement factors for the gating‐and‐following and gating‐only algorithms.ResultsMean tracking factors for ±4, ±6, ±8 mm and full acceptance windows ranged from 0.6 to 0.7, with large interindividual variations. Acceptance rates increased as the size of the acceptance window increased (acceptance rate for a 4 mm window ∼50%). There was a greater reduction of motion errors by gating‐and‐following (maximum of 1.86 mm) than gating‐only (maximum of 7.05 mm).ConclusionMean tracking factors obtained in this study can be used as a guideline for using the gating‐and‐following algorithm in navigator‐gated kidney scans. The gating‐and‐following and gating‐only algorithms were quantitatively compared, and it was found that the former is more effective in reducing motion errors. J. Magn. Reson. Imaging 2011;33:143–148. © 2010 Wiley‐Liss, Inc.
High‐resolution interleaved water‐fat MR imaging of finger joints with chemical‐shift elimination
Authors: Kwok Wingchi E. , You Zhigang , Seo Gwysuk , Lerner Amy , Totterman Saara , Ritchlin Christopher , Monu Johnny 
Published: December 2010

AbstractPurposeTo study the use of an interleaved water‐fat (IWF) sequence with a custom‐made radiofrequency (RF) coil for high‐resolution imaging of arthritic finger joints.Materials and MethodsHigh‐resolution finger magnetic resonance imaging (MRI) was performed using a custom‐made dedicated RF receiver coil and an IWF sequence. A phantom, a cadaver finger specimen, and the fingers of two normal controls and six arthritic subjects were imaged with a resolution of 156 × 156 × 600 μm. The appearance of anatomic structures on the IWF images were compared with images acquired with a regular sequence. The images were reviewed by two musculoskeletal radiologists for the depiction of anatomical structures and for the presence of abnormalities.ResultsThe high‐resolution images revealed detailed structures of the finger joints not detectable using typical clinical resolution. The IWF sequence gave more realistic depiction of subchondral bone thickness, and avoided false bone erosions displayed in the regular sequence. It also allowed better visualization of ligaments and tendons.ConclusionThis pilot study shows the feasibility and the potential usefulness of high‐resolution IWF imaging for finger joint evaluation. This technique may be useful for the diagnosis and treatment assessment of arthritis, and for the study of joint disease pathogenesis. J. Magn. Reson. Imaging 2011;33:245–251. © 2010 Wiley‐Liss, Inc.
Quantification of fat infiltration in oculopharyngeal muscular dystrophy: Comparison of three MR imaging methods
Authors: Gloor Monika , Fasler Susanne , Fischmann Arne , Haas Tanja , Bieri Oliver , Heinimann Karl , Wetzel Stephan G. , Scheffler Klaus , Fischer Dirk 
Published: December 2010

AbstractPurposeTo analyze and compare three quantitative MRI methods to determine the degree of muscle involvement in oculopharyngeal muscular dystrophy (OPMD).Materials and MethodsMuscle fat content (MFC) was determined based on water–fat quantification using a 2‐point Dixon (2PD) method and on a histogram analysis of the free induction decay (FID) signal of a gradient‐spoiled steady‐state free precession (SSFP) sequence. In addition, transverse relaxation times (T2) of muscle tissue were calculated using a monoexponential decay model.ResultsWe observed an increased mean MFC in OPMD patients as compared to healthy controls with the adductor magnus and soleus muscles being the most involved muscles in the thigh and calf, respectively. Furthermore, strong correlations (0.78 < R2 < 0.94) between different quantitative MR methods were observed. Fewer outliers, however, were obtained by the 2PD method and T2 measurements, suggesting these methods being superior to the SSFP‐FID method.ConclusionQuantitative MR techniques, such as fast multiecho Dixon methods and T2 imaging, can reliably differentiate between healthy and dystrophic muscles in OPMD, even if muscles are only marginally affected. Quantitative methods thus represent a promising tool that may be able to monitor more objectively the individual disease progression and treatment response in future clinical trials in muscular dystrophies. J. Magn. Reson. Imaging 2011;33:203–210. © 2010 Wiley‐Liss, Inc.
Structural variability of endotoxins from R‐type isogenic mutants of Shigella sonnei
Authors: Kilár Anikó , Dörnyei Ágnes , Bui Annamária , Szabó Zoltán , Kocsis Béla , Kilár Ferenc 
Published: December 2010

AbstractThe structural variations in the rough‐type endotoxins [lipopolysaccharides (LPSs)] of Shigella sonnei mutant strains (S. sonnei phase II—4303, R41, 562H and 4350) were investigated by Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) and tandem MS. A series of S. sonnei mutants had previously been the subject of analytical studies on the biosynthesis of heptose components in the core oligosaccharide region of LPSs. This study gives a complete overview on the structures of the full core and lipid A of S. sonnei mutant strains by MS. We found that the LPSs of the isogenic rough mutants were formed in a step‐like manner containing 0:1:2:3 heptose in the deep core region of 4350, 562H, R41 and 4303, respectively, and the longest LPS from the mutant S. sonnei 4303 contained also five hexoses. The structural variations in the lipid A moiety and in the oligosaccharide part of the intact LPS were followed by MALDI‐TOF‐MS/MS. For the dissolution and the ionization of the samples, 2,5‐dihydroxybenzoic acid in citric acid solution was applied as matrix. The detailed evaluation of the mass spectra indicates heterogeneity in the lipid part due to the differences in the phosphate and fatty acid composition. Copyright © 2010 John Wiley & Sons, Ltd.
Compositional studies of human RPE lipofuscin: mechanisms of molecular modifications
Authors: Murdaugh L. S. , Mandal S. , Dill A. E. , Dillon J. , Simon J. D. , Gaillard E. R. 
Published: December 2010

AbstractThe accumulation of lipofuscin has previously been implicated in several retinal diseases including Best's macular dystrophy, Stargardt's disease and age‐related macular degeneration (AMD). Previously one of the major fluorophores of lipofuscin was identified as a bis‐retinoid pyridinium salt called A2E, which is known to photochemically cause damage. In addition to A2E, there are numerous components in RPE lipofuscin that are unidentified. These compounds were determined to be structurally related to A2E by their fragmentation pattern with losses of 106, 190, 174 and/or 150 amu from the parent ion and the formation of fragments of ca 592 amu. The vast majority consists of relatively hydrophobic components corresponding to derivatized A2E with molecular weights in discrete groups of 800–900, 970–1080 and > 1200 m/z regions. In order to determine the mechanism of these modifications, A2E was chemically modified by; (1) the formation of specific esters, (2) reaction with specific aldehydes and (3) spontaneous auto‐oxidation. The contribution of ester formation to the naturally occurring components of lipofuscin was discounted since their fragmentation patterns were different to those found in vivo. Alternatively, reactions with specific aldehydes result in nearly identical products as those found in vivo. Artificial aging of RPE lipofuscin gives a complex mixture of structurally related components. This results from the auto‐ and/or photooxidation of A2E to form aldehydes, which then back react with A2E giving a series of higher molecular weight products. The majority of these modifications result in compounds that are much more hydrophobic than A2E. These higher molecular weight materials have increased values of log P compared to A2E. This increase in hydrophobicity most likely aids in the sequestering of A2E into granules with the concomitant diminution of its reactivity. Therefore, these processes may serve as protective mechanisms for the RPE. Copyright © 2010 John Wiley & Sons, Ltd.
Multiple unknown degradants generated from the insect repellent DEET by photoinduced processes on TiO2
Authors: Medana Claudio , Calza Paola , Dal Bello Federica , Raso Elena , Minero Claudio , Baiocchi Claudio 
Published: December 2010

AbstractThis paper deals with the photocatalytic transformation of N,N‐diethyl‐m‐toluamide (DEET), one of the most widespread and efficient mosquito repellents, under simulated solar irradiation using titanium dioxide as the photocatalytic source of oxidizing species. The investigation involved monitoring of the DEET decomposition, the identification of intermediate compounds and the assessment of mineralization. High‐resolution mass spectrometry was employed to assess the evolution of the photocatalyzed process over time. Fifty‐one main species were identified after DEET transformation. Several isomeric species were formed and were characterized by analyzing MS and MSn spectra in full, and by comparison with parent molecule fragmentation pathways. In the DEET molecule, the initial transformation involved mono‐ and polyhydroxylation followed by oxidation of the alcohol groups, cleavage of the alkyl chains or ring opening. All these intermediates are easily degraded and DEET is completely mineralized after 4 h of irradiation. Microtox bioassay (Vibrio fischeri) was employed to evaluate the ecotoxicity of solutions treated by photocatalysis. Copyright © 2010 John Wiley & Sons, Ltd.
A fully validated method for the determination of vardenafil in blood using gas chromatography/mass spectrometry
Authors: Papoutsis Ioannis , Nikolaou Panagiota , Athanaselis Sotirios , Pistos Constantinos , Maravelias Constantinos , Spiliopoulou Chara 
Published: December 2010

AbstractVardenafil (VDN) is one of the three commercially available phosphodiesterase type 5 inhibitors and it is mainly used in the treatment of erectile dysfunction. A sensitive and specific gas chromatography/mass spectrometry (GC/MS) method for the determination of VDN in blood has been developed and validated. Sample preparation included solid‐phase extraction and derivatization with N‐methyl‐N‐tert‐butyldimethylsilyl‐trifluoroacetamide (MTBSTFA) and 1% tert‐butyldimethylsilylchloride (TBDMSCl). Protriptyline was used as the internal standard for this assay. Limits of detection and quantification for VDN were 0.70 and 2.00 µg/l, respectively. The calibration curves were linear within the dynamic range 2.00–200.0 µg/l with a correlation coefficient higher than 0.991. Absolute recovery ranged from 88.6% to 95.7% for the analyte of interest at three quality control levels. Intra‐ and inter‐day accuracy was found to be between − 6.1% to 10.8% and − 9.3% to 11.6%, respectively, whereas intra‐ and inter‐day precision was < 7.8% and 9.7%, correspondingly. The proposed method is the first fully validated GC/MS method for the determination of VDN in blood samples and it can be used in routine every day analysis by clinical and forensic laboratories for pharmacokinetic studies, for therapeutic drug level monitoring or for the investigation of related forensic cases. A few blood samples analyzed using the developed method is reported herein to demonstrate the suitability of the method. Copyright © 2010 John Wiley & Sons, Ltd.
Tautomerization in gas‐phase ion chemistry of isomeric C‐8 deoxyguanosine adducts from phenol‐induced DNA damage
Authors: Sagoo Sandeep , Beach Daniel G. , Manderville Richard A. , Gabryelski Wojciech 
Published: December 2010

AbstractCollision‐induced dissociation (CID) of 8‐(4″‐hydroxyphenyl)‐2′‐deoxyguanosine and 8‐(2″‐hydroxyphenyl)‐2′‐deoxyguanosine was investigated using sequential tandem mass spectrometry. These adducts represent biomarkers of DNA damage linked to phenolic radicals and were investigated to gain insight into the effects of chemical structure of a C‐8 modification on fragmentation pathways of modified 2′‐deoxyguanosine (dG). CID in MS2 of the deprotonated molecules of both the isomers generated the same product ion having the same m/z values. CID in MS3 of the product ion at m/z 242 and CID in MS4 experiments carried out on the selected product ions at m/z 225 and m/z 218 afford distinct fragmentation patterns. The conformational properties of isomeric product ions from CID showed that the ortho‐isomers possess the unique ability to tautomerize through an intramolecular proton transfer between the phenolic OH group and the imine nitrogen (N7). Tautomerization of ortho‐isomers to their keto‐tautomers led to differences in their system of conjugated double bonds compared with either their enol‐tautomer or the para‐isomer. The charge redistribution through the N‐7 site on the imidazole ring is a critical step in guanosine adduct fragmentation which is disrupted by the formation of the keto‐tautomer. For this reason, different reaction pathways are observed for 8‐(4″‐hydroxyphenyl)‐2′‐deoxyguanosine and 8‐(2″‐hydroxyphenyl)‐2′‐deoxyguanosine. We present herein the dissociation and the gas‐phase ion‐molecule reactions for highly conjugated ions involved in the CID ion chemistry of the investigated adducts. These will be useful for those using tandem mass spectrometry for structural elucidation of C‐8 modified dG adducts. This study demonstrates that the modification at the C‐8 site of dG has the potential to significantly alter the reactivity of adducts. We also show the ability of tandem mass spectrometry to completely differentiate between the isomeric dG adducts investigated. Copyright © 2010 John Wiley & Sons, Ltd.
Observations of different core water cluster ions Y−(H2O)n (Y = O2, HOx, NOx, COx) and magic number in atmospheric pressure negative corona discharge mass spectrometry
Authors: Sekimoto Kanako , Takayama Mitsuo 
Published: December 2010

AbstractReliable mass spectrometry data from large water clusters Y−(H2O)n with various negative core ions Y− such as O2−, HO−, HO2−, NO2−, NO3−, NO3−(HNO3)2, CO3− and HCO4− have been obtained using atmospheric pressure negative corona discharge mass spectrometry. All the core Y− ions observed were ionic species that play a central role in tropospheric ion chemistry. These mass spectra exhibited discontinuities in ion peak intensity at certain size clusters Y−(H2O)m indicating specific thermochemical stability. Thus, Y−(H2O)m may correspond to the magic number or first hydrated shell in the cluster series Y−(H2O)n. The high intensity discontinuity at HO−(H2O)3 observed was the first mass spectrometric evidence for the specific stability of HO−(H2O)3 as the first hydrated shell which Eigen postulated in 1964. The negative ion water clusters Y−(H2O)n observed in the mass spectra are most likely to be formed via core ion formation in the ambient discharge area (760 torr) and the growth of water clusters by adiabatic expansion in the vacuum region of the mass spectrometers (≈1 torr). The detailed mechanism of the formation of the different core water cluster ions Y−(H2O)n is described. Copyright © 2010 John Wiley & Sons, Ltd.