bluuebunny/crossref_metadata_2025_split huggingface dataset:
Larval development of Phoronis pallida (Phoronida): Implications for morphological convergence and divergence among larval body plans
Authors: Santagata Scott 
Published: February 2004

AbstractMorphological variation among larval body plans must be placed into a phylogenetic and ecological context to assess whether similar morphologies are the result of phylogenetic constraints or convergent selective pressures. Investigations are needed of the diverse larval forms within the Lophotrochozoa, especially the larvae of phoronids and brachiopods. The actinotroch larva of Phoronis pallida (Phoronida) was reared in the laboratory to metamorphic competence. Larval development and growth were followed with video microscopy, SEM, and confocal microscopy. Early developmental features were similar to other phoronid species. Gastrulation was accomplished by embolic invagination of the vegetal hemisphere. Mesenchymal cells were found in the remaining blastocoelic space after invagination began. Mesenchymal cells formed the body wall musculature during the differentiation of larval features. Body wall musculature served as the framework from which all other larval muscles proliferated. Larval growth correlated best with developmental stage rather than age. Consistent with other phoronid species, differentiation of juvenile tissues occurred most rapidly at the latest stages of larval development. The minimum precompetency period of P. pallida was estimated to be ∼4–6 weeks. Previously published studies have documented that the planktonic embryos of P. pallida develop faster than the brooded embryos of P. vancouverensis. However, these data showed that the difference in developmental rate between the two species decreased in succeeding larval stages. There may be convergent selective pressures that result in similar timing to metamorphic competence among phoronid and brachiopod planktotrophic larval types. Morphological differences between these larval types result from heterochronic developmental shifts in the differentiation of juvenile tissue. Similarities in the larval morphology of phoronids and basal deuterostomes are likely the result of functional and developmental constraints rather than a shared (recent) evolutionary origin. These constraints are imposed by the functional design of embryological stages, feeding structures, and swimming structures. J. Morphol. 259:347–358, 2004. © 2004 Wiley‐Liss, Inc.
Comparative electron microscopic study of the stomach of Orchestia cavimana and Arcitalitrus sylvaticus (crustacea: Amphipoda)
Authors: Štrus Jasna , Storch Volker 
Published: February 2004

AbstractThe functional morphology of stomachs of the European semiterrestrial amphipod Orchestia cavimana and of the Australian terrestrial species Arcitalitrus sylvaticus was studied by electron microscopy. The stomach of the two amphipod species is divided longitudinally into a spacious dorsal food channel and two ventral filtration channels. Additionally, a prominent helically oriented circulation channel is situated on each lateral side of the stomach, forming a semicircular channel separated from the food channel by spines. The food channel conveys coarse food particles directly into the midgut through a funnel. The filtration channels receive fine material filtered through primary and secondary filters. Material forced through the secondary filters by the pressure of the laterally located inferolateralia eventually reaches the openings of the midgut glands. Washing of filters and soaking of ingested food items with enzymes probably is achieved by a forward stream of digestive juice from the midgut glands and conveyed through the circulatory channels. The specializations of the stomach of the two species of Amphipoda investigated are described and compared to the pertinent structures of Mysidacea and Isopoda. J. Morphol. 259:340–346, 2004. © 2004 Wiley‐Liss, Inc.
A comparison between the accuracy of voxel‐based morphometry and hippocampal volumetry in Alzheimer's disease
Authors: Testa Cristina , Laakso Mikko P. , Sabattoli Francesca , Rossi Roberta , Beltramello Alberto , Soininen Hilkka , Frisoni Giovanni B. 
Published: February 2004

AbstractPurposeTo compare the accuracy of voxel‐based morphometry (VBM) and region of interest (ROI)‐based hippocampal volumetry to detect medial temporal lobe atrophy in Alzheimer's disease (AD).Materials and MethodsA total of 27 AD patients (age 74 ± 9 years; 22 women; Mini‐Mental State Exam [MMSE] 21 ± 4) and 25 controls (age 70 ± 8; 16 women; MMSE 29 ± 1) were studied. Accuracy of VBM to detect gray matter loss in those seven AD patients and 11 controls with similar ROI‐based hippocampal measures and of ROI‐based volumetry to detect gray matter loss in those four AD patients and five controls with similar VBM‐based hippocampal measures was assessed. VBM was performed with statistical parametric mapping (SPM99).ResultsThe area under the curve was 0.96 (95% C.I., 0.92–1.00) for VBM, 0.89 (95% C.I., 0.80–0.98) for ROI‐based hippocampal measures, and 0.99 (95% C.I., 0.96–1.00) for both. In subjects with similar ROI‐based hippocampal measures, VBM detected atrophy in AD patients at P < 0.0001, while in subjects with similar VBM‐based hippocampal measure, volumetry was not significant (P = 0.11). Both measures independently contributed to discrimination (P = 0.004 and P = 0.032) in a logistic regression model.ConclusionThese results indicate that VBM is more accurate, but the combination of both methods provides the highest accuracy for detection of hippocampal atrophy in AD. J. Magn. Reson. Imaging 2004;19:274–282. © 2004 Wiley‐Liss, Inc.
Gadopentetate dimeglumine‐enhanced three‐dimensional MR‐angiography: Dosing, safety, and efficacy
Authors: Goyen Mathias , Debatin Jörg F. 
Published: February 2004

AbstractNoninvasiveness, inherent three‐dimensionality allowing reformations in any desired plane, and safe contrast agents, coupled with high diagnostic accuracy have driven the rise in popularity of contrast‐enhanced MR angiography (CE‐MRA) within the medical community. Reflecting its dominant market share as a paramagnetic contrast agent, gadopentetate dimeglumine (Gd‐DTPA) has been used for the majority of clinically‐performed MRA exams. Over the period January 1994 to February 2002, a total of 172 original studies describing the use of gadolinium‐enhanced MRA in more than three human subjects were identified. Of these, 117 described the use of Gd‐DTPA as the contrast agent for MRA. A total of 4046 subjects who received Gd‐DTPA for MRA are described in these studies. Analysis of these data demonstrate Gd‐DTPA to be a safe contrast agent for MRA when applied in a dose ranging from 0.1 to 0.3 mmol/kg of bodyweight. The documented clinical results show Gd‐DTPA to be efficacious in the assessment of the arterial system. The effectiveness of Gd‐DTPA‐enhanced MRA extends beyond the detection, localization, and characterization of arterial disease, and encompasses choice and planning of appropriate therapy, as well as evaluation of therapeutic effectiveness. J. Magn. Reson. Imaging 2004;19:261–273. © 2004 Wiley‐Liss, Inc.
Limits of 8‐Tesla magnetic resonance imaging spatial resolution of the deoxygenated cerebral microvasculature
Authors: Dashner Roger A. , Kangarlu Allahyar , Clark David L. , RayChaudhury Abhik , Chakeres Donald W. 
Published: February 2004

AbstractPurposeTo quantify the minimum magnetic resonance imaging (MRI) spatial resolution of the visible deoxygenated microscopic vessels of the human brain at 8 T.Materials and MethodsThis study compared 8‐T gradient echo (GE) images of a human cadaver brain having an in‐plane resolution of 195 × 195 μm to corresponding digital photographs of 205 cryomicrotome sections of the same cadaver brain, along with summed images of 25 contiguous cryomicrotome sections. One‐millimeter‐thick GE images of a 1‐cm‐thick unfixed whole coronal brain section were acquired using techniques similar to those commonly utilized for 8‐T human imaging in vivo.ResultsThere was excellent MR visualization of the deoxygenated microscopic vessels within the brain down to a resolution of approximately 100 μm.ConclusionBy taking advantage of magnetic susceptibility‐based blood oxygenation level‐dependent (BOLD) contrast, deoxygenated microscopic blood vessels smaller than the pixel dimensions used for imaging can be visualized using a whole‐body 8‐T MRI system. J. Magn. Reson. Imaging 2004;19:303–307. © 2004 Wiley‐Liss, Inc.
Adrenal lesions with heterogeneous suppression on chemical shift imaging: Clinical implications
Authors: Gabriel Helena , Pizzitola Victor , McComb Erin N. , Wiley Elizabeth , Miller Frank H. 
Published: February 2004

AbstractPurposeTo investigate the frequency and significance of adrenal lesions that demonstrate heterogeneous suppression on chemical shift magnetic resonance imaging (MRI).Materials and MethodsA retrospective search of adrenal lesions identified on MR from November 1997–July 2001 was performed. The adrenal lesions were classified as having suppression typical for an adenoma, nonsuppression, or atypical heterogeneous suppression. Lesions with heterogeneous suppression were further reviewed. Follow‐up for the heterogeneous lesions consisted of imaging studies or pathology from surgical excision.ResultsAdrenal lesions were identified in 242 patients. Heterogeneously suppressing lesions were seen in 34 (14%) patients. Several different patterns of heterogeneous suppression were identified. Imaging or pathologic follow‐up was available for 18 of the heterogeneously suppressing lesions (one patient had both). Fifteen patients with follow‐up imaging showed stability of the lesion over a significant interval, suggesting a benign lesion. Pathology was available for four patients revealing two patients with adenomas and two patients with nodular hyperplasia. Thus, all 18 patients with heterogeneous suppression had a benign lesion.ConclusionAdrenal lesions that have a heterogeneous pattern of suppression on out‐of‐phase chemical shift MR images are a common finding. Our small series suggest that these lesions are probably benign. J. Magn. Reson. Imaging 2004;19:308–316. © 2004 Wiley‐Liss, Inc.
Comparison of three methods for generating group statistical inferences from independent component analysis of functional magnetic resonance imaging data
Authors: Schmithorst Vincent J. , Holland Scott K. 
Published: February 2004

AbstractPurposeTo evaluate the relative effectiveness of three previously proposed methods of performing group independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data.Materials and MethodsData were generated via computer simulation. Components were added to a varying number of subjects between 1 and 20, and intersubject variability was simulated for both the added sources and their associated time courses. Three methods of group ICA analyses were performed: across‐subject averaging, subject‐wise concatenation, and row‐wise concatenation (e.g., across time courses).ResultsConcatenating across subjects provided the best overall performance in terms of accurate estimation of the sources and associated time courses. Averaging across subjects provided accurate estimation (R > 0.9) of the time courses when the sources were present in a sufficient fraction (about 15%) of 100 subjects. Concatenating across time courses was shown not to be a feasible method when unique sources were added to the data from each subject, simulating the effects of motion and susceptibility artifacts.ConclusionSubject‐wise concatenation should be used when computationally feasible. For studies involving a large number of subjects, across‐subject averaging provides an acceptable alternative and reduces the computational load. J. Magn. Reson. Imaging 2004;19:365–368. © 2004 Wiley‐Liss, Inc.
Comparison of conventional fast spin echo, single‐shot two‐dimensional and three‐dimensional half‐fourier RARE for T2‐weighted female pelvic imaging
Authors: Sugimura Hiroshi , Yamaguchi Kenichiro , Furukoji Eiji , Tamura Shozo , Sakae Tatefumi , Koga Haruyuki , Machida Yoshio , Kitane Shinichi 
Published: February 2004

AbstractPurposeTo evaluate the usefulness of the three‐dimensional half‐Fourier RARE sequence in comparison with single‐shot two‐dimensional half‐Fourier RARE and conventional fast spin echo (FSE) for female pelvic imaging.Materials and MethodsImaging with all sequences was performed in 146 patients with 166 focal lesions on a 1.5‐T system. The images were compared on the basis of quality, lesion conspicuity, and lesion to the uterus contrast‐to‐noise ratio (CNR).ResultsThe sharpness of intrapelvic organs on the three‐dimensional half‐Fourier RARE sequence was better than that on two‐dimensional half‐Fourier RARE and worse than that on FSE. Motion‐related artifacts for three‐dimensional half‐Fourier RARE were more frequent than those for two‐dimensional half‐Fourier RARE. There was no statistical difference between the three‐dimensional half‐Fourier RARE sequence and FSE in regard to lesion conspicuity and overall image quality. The CNR of leiomyoma to myometrium and cervical cancer to cervical stroma was the highest with three‐dimensional half‐Fourier RARE (P< 0.05).ConclusionThe three‐dimensional half‐Fourier RARE sequence generates images with higher contrast and better image resolution than two‐dimensional‐RARE. The three‐dimensional data set provided images that can be observed in any orientation without acquiring an additional scan by using the multiplanar reconstruction (MPR) method. J. Magn. Reson. Imaging 2004;19:349–355. © 2004 Wiley‐Liss, Inc.
1H magnetic resonance spectroscopy of preinvasive and invasive cervical cancer: In vivo–ex vivo profiles and effect of tumor load
Authors: Mahon Marrita M. , Cox I. Jane , Dina Roberto , Soutter FRCOG W. Patrick , McIndoe MRCOG G. Angus , Williams Andreanna D. , deSouza Nandita M. 
Published: February 2004

AbstractPurposeTo compare in vivo 1H magnetic resonance (MR) spectra of preinvasive and invasive cervical lesions with ex vivo magic angle spinning (MAS) spectra of intact biopsies from the same subjects and to establish the effects of tumor load in the tissue sampled on the findings.Materials and MethodsA total of 51 subjects (nine with normal cervix, 10 with cervical intraepithelial neoplasia [CIN], and 32 with cervical cancer) underwent endovaginal MR at 1.5 T. Single‐voxel (3.4 cm3) 1H MR spectra were acquired and voxel tumor load was calculated (tumor volume within voxel as a percentage of voxel volume). Resonances from triglycerides –CH2 and –CH3 and choline‐containing compounds (Cho) were correlated with voxel tumor load. Biopsies analyzed by 1H MAS‐MR spectroscopy (MRS) had metabolite levels correlated with tumor load in the sample at histology.ResultsIn vivo studies detected Cho in normal, CIN, and cancer patients with no significant differences in levels (P = 0.93); levels were independent of voxel tumor load. Triglyceride –CH2 and –CH3 signals in‐phase with Cho were present in 77% and 29%, respectively, of cancer subjects (but not in normal women or those with CIN), but did not correlate with voxel tumor load. Ex vivo cancer biopsies showed levels of triglycerides –CH2 and –CH3 and of Cho that were significantly greater than in normal or CIN biopsies (P < 0.05); levels were independent of the tumor load in the sample. The presence of –CH2 in vivo predicted the presence of cancer with a sensitivity and specificity of 77.4% and 93.8% respectively, positive (PPV) and negative (NPV) predictive values were 96% and 68.2%; for –CH2 ex vivo, sensitivity was 100%; specificity, 69%; PPV, 82%; and NPV, 100%.ConclusionElevated lipid levels are detected by MRS in vivo and ex vivo in cervical cancer and are independent of tumor load in the volume of tissue sampled. J. Magn. Reson. Imaging 2004;19:356–364. © 2004 Wiley‐Liss, Inc.
Usefulness of contrast kinetics for predicting and monitoring tissue changes in muscle following thermal therapy in long survival studies
Authors: Cheng Hai‐Ling Margaret , Purcell Carrie M. , Bilbao Juan M. , Plewes Donald B. 
Published: February 2004

AbstractPurposeTo investigate Gd‐DTPA kinetics as indicators of subacute and subchronic histopathological changes following focused ultrasound (FUS) thermal therapy for improved evaluation.Materials and MethodsA total of 18 FUS lesions were created in the thigh muscle of five rabbits under magnetic resonance (MR) guidance at 1.5 Tesla. The rabbits were killed at different times: 40 hours, three days, and seven days. All lesions were analyzed histologically. An analysis of the uptake kinetics of Gd‐DTPA, injected within two hours postheating and before sacrifice, was performed. The resulting kinetic maps, permeability (Ktrans) and leakage space (ve), were correlated to T2‐weighted MR and histology.ResultsImages of Ktrans and ve better differentiate subacute and subchronic changes not visible on conventional MR in the days following therapy and are consistent with the histopathology observed. In particular, the border between nonviable and viable tissue is well demarcated. The extent of damage is best indicated on ve, whereas the borders of inflammation are shown on Ktrans. The total lesion extent is relatively stable over the 7 days posttherapy and can be predicted by ve or T2‐weighted MR at early times after heating.ConclusionOur results suggest that Gd‐DTPA kinetics can complement conventional MR for improved evaluation of FUS thermal therapy by providing finer differentiation of necrotic states, inflammation, and repair processes. J. Magn. Reson. Imaging 2004;19:329–341. © 2004 Wiley‐Liss, Inc.
Cardiac magnetic resonance parallel imaging at 3.0 Tesla: Technical feasibility and advantages
Authors: McGee Kiaran P. , Debbins Josef P. , Boskamp Ed B. , Blawat LeRoy , Angelos Lisa , King Kevin F. 
Published: February 2004

AbstractPurposeTo quantify changes in signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), specific absorption rate (SAR), RF power deposition, and imaging time in cardiac magnetic resonance imaging with and without the application of parallel imaging at 1.5 T and 3.0 T.Materials and MethodsPhantom and volunteer data were acquired at 1.5 T and 3.0 T with and without parallel imaging.ResultsDoubling field strength increased phantom SNR by a factor of 1.83. In volunteer data, SNR and CNR values increased by factors of 1.86 and 1.35, respectively. Parallel imaging (reduction factor = 2) decreased phantom SNR by a factor of 1.84 and 2.07 when compared to the full acquisition at 1.5 T and 3.0 T, respectively. In volunteers, SNR and CNR decreased by factors of 2.65 and 2.05 at 1.5 T and 1.99 and 1.75 at 3.0 T, respectively. Doubling the field strength produces a nine‐fold increase in SAR (0.0751 to 0.674 W/kg). Parallel imaging reduced the total RF power deposition by a factor of two at both field strengths.ConclusionsParallel imaging decreases total scan time at the expense of SNR and CNR. These losses are compensated at higher field strengths. Parallel imaging is effective at reducing total power deposition by reducing total scan time. J. Magn. Reson. Imaging 2004;19:291–297. © 2004 Wiley‐Liss, Inc.
Characterization of α‐ and γ‐glutamyl dipeptides by negative ion collision‐induced dissociation
Authors: Harrison Alex G. 
Published: February 2004

AbstractThe low‐energy CID mass spectra of the [M − H]− ions of a variety of dipeptides containing glutamic acid have been obtained using cone‐voltage collisional activation. Dipeptides with the γ‐linkage, H‐Glu(Xxx‐OH)‐OH, are readily distinguished from those with the α‐linkage, H‐Glu‐Xxx‐OH, by the much more prominent elimination of H‐Xxx‐OH from the [M − H]− ions of the former isomers, resulting in formation of m/z 128, presumably deprotonated pyroglutamic acid. Dipeptides with the reverse linkage, H‐Xxx‐Glu‐OH, show distinctive fragmentation reactions of the [M − H]− ions including enhanced elimination of CO2 and formation of deprotonated glutamic acid. Exchange of the labile hydrogens for deuterium has shown that there is considerable interchange of C‐bonded hydrogens with labile (N‐ and O‐bonded) hydrogens prior to most fragmentation reactions. All dipeptides show loss of H2O from [M − H]−. MS3 studies show that the [M − H − H2O]− ion derived from H‐Glu‐Gly‐OH has the structure of deprotonated pyroglutamylglycine while the [M − H − H2O]− ions derived from H‐Glu(Gly‐OH)‐OH and H‐Gly‐Glu‐OH show a different fragmentation behaviour indicating distinct structures for the fragment ions. Copyright © 2004 John Wiley & Sons, Ltd.
Rearrangement process occurring in the fragmentation of adefovir derivatives
Authors: Chen Xiaoyan , Xing Jie , Zhong Dafang 
Published: February 2004

AbstractThe fragmentation of the antiviral drug adefovir dipivoxil and its two active metabolites, adefovir and monopivoxil adefovir, was investigated using both ion trap and triple‐quadrupole mass spectrometers. Fragment ions due to loss of 30 Da were observed and attributed to an unanticipated rearrangement process by loss of formaldehyde. The proposed mechanism is supported with the aid of three newly synthesized adefovir derivatives and with accurate mass measurement. Other fragmentations by loss of a pivaloyl group, loss of water, C—P bond cleavage and C—O bond cleavage were also observed for adefovir derivatives. It was concluded that the compounds containing a >POO—CHR—OCO— group generally displayed a rearrangement reaction by loss of RCHO in collision‐induced dissociation, and the process generally required an activation energy lower than for a direct bond cleavage. Copyright © 2004 John Wiley & Sons, Ltd.
Mass spectra of N‐substituted cantharidinimides
Authors: Lin Pen‐Y. , Lin Shaw‐T. , Liang David W.‐M. 
Published: February 2004

AbstractThe mass spectra of a series of N‐substituted cantharidinimides were examined. The feature of this series compounds is a sequential double hydrogen transfer from the oxabicycloheptane unit to either the carbonyl group of the succinimide unit or the nitrogen atom of the pyridyl or thiazolyl substituent through space. The ability of the N‐substituent to accept a hydrogen atom possibly leads to the different fragmentation pathway. Copyright © 2004 John Wiley & Sons, Ltd.
Analysis of native amino acid and peptide enantiomers by high‐performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry
Authors: Desai Meera J. , Armstrong Daniel W. 
Published: February 2004

AbstractHigh‐performance liquid chromatography (HPLC) coupled to atmospheric pressure chemical ionization (APCI) mass spectrometry was used for the separation and detection of amino acid and peptide enantiomers. With detection limits as low as 250 pg, 25 amino acids enantiomers were baseline resolved on a Chirobiotic T chiral stationary phase. APCI demonstrated an order of magnitude better sensitivity over electrospray ionization (ESI) for free amino acids and low molecular mass peptides at the high LC flow‐rates necessary for rapid analysis. As the peptide chain length increased (peptides with Mr ≥ 300 Da), however, ESI proved to be the more ideal atmospheric pressure ionization source. A mobile phase consisting of 1% (w/w) ammonium trifluoroacetate in methanol and 0.1% (w/w) formic acid in water increased the sensitivity of the APCI method significantly. A step gradient was then used to separate simultaneously all 19 native protein amino acid enantiomers in less than 20 min using extracted ion chromatograms. Copyright © 2004 John Wiley & Sons, Ltd.