bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ventilation‐synchronous magnetic resonance microscopy of pulmonary structure and ventilation in mice
Authors: Chen Ben T. , Yordanov Alexander T. , Johnson G. Allan 
Published: December 2004

AbstractIncreasing use of transgenic animal models for pulmonary disease has raised the need for methods to assess pulmonary structure and function in a physiologically stable mouse. We report here an integrated protocol using magnetic resonance microscopy with gadolinium (Gd)‐labeled starburst dendrimer (G6–1B4M‐Gd, MW = 192 ± 1 kDa, Rh = 5.50 ± 0.04 nm) and hyperpolarized 3helium (3He) gas to acquire images that demonstrate pulmonary vasculature and ventilated airways in live mice (n = 9). Registered three‐dimensional images of 1H and 3He were acquired during breath‐hold at 2.0 T using radial acquisition (total acquisition time of 38 and 25 min, respectively). The macromolecular Gd‐labeled dendrimer (a half‐life of ∼80 min) increased the signal‐to‐noise by 81 ± 30% in the left ventricle, 43 ± 22% in the lung periphery, and −4 ± 5% in the chest wall, thus increasing the contrast of these structures relative to the less vascular surrounding tissues. A constant‐flow ventilator was developed for the mouse to deliver varied gas mixtures of O2 and N2 (or 3He) during imaging. To avoid hypoxemia, instrumental dead space was minimized and corrections were made to tidal volume lost due to gas compression. The stability of the physiologic support was assessed by the lack of spontaneous breathing and maintenance of a constant heart rate. We were able to stabilize the mouse for >8 hr using ventilation of 105 breath/min and ∼0.2 mL/breath. The feasibility of acquiring both pulmonary vasculature and ventilated airways was demonstrated in the mouse lung with in‐plane spatial resolution of 70 × 70 μm2 and slice thickness of 800 μm. Magn Reson Med 53:69–75, 2005. © 2004 Wiley‐Liss, Inc.
Proton‐decoupled 31P MRS in untreated pediatric brain tumors
Authors: Albers Mark J. , Krieger Mark D. , Gonzalez‐Gomez Ignacio , Gilles Floyd H. , McComb J. Gordon , Nelson Marvin D. , Blüml Stefan 
Published: December 2004

AbstractProton‐decoupled 31P and 1H MRS was used to quantify markers of membrane synthesis and breakdown in eight pediatric patients with untreated brain tumors and in six controls. Quantitation of these compounds in vivo in humans may provide important indicators for tumor growth and malignancy, tumor classification, and provide prognostic information. The ratios of phosphoethanolamine to glycerophosphoethanolamine (PE/GPE) and phosphocholine to glycerophosphocholine (PC/GPC) were significantly higher in primitive neuroectodermal tumors (PNET) (16.30 ± 5.73 and 2.97 ± 0.93) when compared with controls (3.42 ± 1.62, P < 0.0001 and 0.45 ± 0.13, P < 0.0001) and with other tumors (3.93 ± 3.42, P < 0.001 and 0.65 ± 0.30, P < 0.0001). Mean PC/PE was elevated in tumors relative to controls (0.48 ± 0.11 versus 0.24 ± 0.05, P < 0.001), but there was no difference between PNET and other tumors. Total choline concentration determined with quantitative 1H MRS was significantly elevated (4.78 ± 3.33 versus 1.73 ± 0.56 mmol/kg, P < 0.05), whereas creatine was reduced in tumors (4.89 ± 1.83 versus 8.28 ± 1.50 mmol/kg, P < 0.05). A quantitative comparison of total phosphorylated cholines (PC+GPC)/ATP measured with 31P MRS and total choline measured with 1H MRS showed that in tumors a large fraction of the choline signal (>54 ± 36%) was not accounted for by PC and GPC. The fraction of unaccounted choline was particularly large in PNET (>78 ± 7%). The pH of tumor tissue was higher than the pH of normal brain tissue (7.06 ± 0.03 versus. 6.98 ± 0.03, P < 0.001). Magn Reson Med 53:22–29, 2005. © 2004 Wiley‐Liss, Inc.
Continuously moving table SENSE imaging
Authors: Keupp Jochen , Aldefeld Bernd , Börnert Peter 
Published: December 2004

AbstractA combination of continuously moving table imaging and parallel imaging based on sensitivity encoding (SENSE) is presented. One specific geometry is considered, where the receiver array is fixed to the MR magnet and does not move with the table, which allows for head‐to‐toe imaging with a small total number of coils. Sensitivity maps are defined for the enlarged virtual field of view and are composed according to the k‐space sampling scheme such that established parallel reconstruction techniques are applicable to good approximation. In vivo experiments show the feasibility of this approach, and simulations determine the application range. Three‐dimensional head‐to‐toe imaging of volunteers is performed in 77 s with a SENSE reduction factor of 2 in a virtual field of view of 1800 × 460 × 100 mm3. Magn Reson Med 53:217–220, 2005. © 2004 Wiley‐Liss, Inc.
High‐resolution T1 and T2 mapping of the brain in a clinically acceptable time with DESPOT1 and DESPOT2
Authors: Deoni Sean C. L. , Peters Terry M. , Rutt Brian K. 
Published: December 2004

AbstractVariations in the intrinsic T1 and T2 relaxation times have been implicated in numerous neurologic conditions. Unfortunately, the low resolution and long imaging time associated with conventional methods have prevented T1 and T2 mapping from becoming part of routine clinical evaluation. In this study, the clinical applicability of the DESPOT1 and DESPOT2 imaging methods for high‐resolution, whole‐brain, T1 and T2 mapping was investigated. In vivo, 1‐mm3 isotropic whole‐brain T1 and T2 maps of six healthy volunteers were acquired at 1.5 T with an imaging time of <17 min each. Isotropic maps (0.34 mm3) of one volunteer were also acquired (time <21 min). Average signal‐to‐noise within the 1‐mm3 T1 and T2 maps was ∼20 and ∼14, respectively, with average repeatability standard deviations of 46.7 ms and 6.7 ms. These results demonstrate the clinical feasibility of the methods in the study of neurologic disease. Magn Reson Med 53:237–241, 2005. © 2004 Wiley‐Liss, Inc.
SQUID‐detected MRI at 132 μT with T1‐weighted contrast established at 10 μT–300 mT
Authors: Lee Seung Kyun , Möβle Michael , Myers Whittier , Kelso Nathan , Trabesinger Andreas H. , Pines Alexander , Clarke John 
Published: December 2004

AbstractT1‐weighted contrast MRI with prepolarization was detected with a superconducting quantum interference device (SQUID). A spin evolution period in a variable field between prepolarization and detection enabled the measurement of T1 in fields between 1.7 μT and 300 mT; T1 dispersion curves of agarose gel samples over five decades in frequency were obtained. SQUID detection at 5.6 kHz drastically reduces the field homogeneity requirements compared to conventional field‐cycling methods using Faraday coil detection. This allows T1 dispersion measurements to be easily combined with MRI, so that T1 in a wide range of fields can be used for tissue contrast. Images of gel phantoms with T1‐weighted contrast at four different fields between 10 μT and 300 mT demonstrated dramatic contrast enhancement in low fields. A modified inversion recovery technique further enhanced the contrast by selectively suppressing the signal contribution for a specific value of the low‐field T1. Magn Reson Med 53:9–14, 2005. Published 2004 Wiley‐Liss, Inc.
Internal radiation therapy of liver tumors: Qualitative and quantitative magnetic resonance imaging of the biodistribution of holmium‐loaded microspheres in animal models
Authors: Seppenwoolde Jan‐Henry , Nijsen Johannes F. W. , Bartels Lambertus W. , Zielhuis Sander W. , van het Schip Alfred D. , Bakker Chris J. G. 
Published: December 2004

AbstractIn internal radiation therapy of unresectable liver tumors, microspheres containing a radionuclide are injected in the hepatic artery to achieve a preferential deposition of microspheres in the lesions. In this study, MR imaging techniques for qualitative and quantitative assessment of the biodistribution of holmium‐loaded microspheres (HoMS) were investigated for their use in selective internal radiation therapy of liver tumors. To achieve this goal, the relaxivity of HoMS was first investigated in gel experiments. The resultant calibration curve was subsequently employed to quantify the biodistribution of HoMS administered to 13 excised rabbit livers and to the livers of 3 live rabbits with an implanted tumor. Finally, the feasibility of MR imaging of the biodistribution during treatment of a large animal was investigated by MR imaging of hepatic administration of HoMS to a live pig. Overall, the study showed that MRI can clearly depict the biodistribution of HoMS, but that quantification by means of the gel calibration curve yields an underestimation that increases for higher amounts of HoMS. The observed underestimation is tentatively attributed to accumulations of HoMS in larger liver vessels. The exploratory quantification experiments suggest the feasibility of MR dosimetry. Magn Reson Med 53:76–84, 2005. © 2004 Wiley‐Liss, Inc.
Rapid quantitation of magnetization transfer using pulsed off‐resonance irradiation and echo planar imaging
Authors: Tyler Damian J. , Gowland Penny A. 
Published: December 2004

AbstractA technique for producing a quantitative measure of magnetization transfer parameters in a clinically feasible time scale is proposed. The combination of pulsed off‐resonance irradiation and echo planar imaging has produced an imaging sequence that negates the need for continuous wave irradiation and allows the approach to steady‐state conditions to be studied. Data analysis involves the step‐by‐step numerical solution of the modified Bloch equations to generate a quantitative model of the measured signal intensity based on the relative size of the bound proton pool and the bound proton pool transverse relaxation time. The sequence and model are applied to the study of a series of agar gels of varying concentrations and the results are compared to those from the literature. Magn Reson Med 53:103–109, 2005. © 2004 Wiley‐Liss, Inc.
Motion‐corrected free‐breathing delayed enhancement imaging of myocardial infarction
Authors: Kellman Peter , Larson Andrew C. , Hsu Li‐Yueh , Chung Yiu‐Cho , Simonetti Orlando P. , McVeigh Elliot R. , Arai Andrew E. 
Published: December 2004

AbstractFollowing administration of Gd‐DTPA, infarcted myocardium exhibits delayed enhancement and can be imaged using an inversion‐recovery sequence. A conventional segmented acquisition requires a number of breath‐holds to image the heart. Single‐shot phase‐sensitive inversion‐recovery (PSIR) true‐FISP may be combined with parallel imaging using SENSE to achieve high spatial resolution. SNR may be improved by averaging multiple motion‐corrected images acquired during free breathing. PSIR techniques have demonstrated a number of benefits including consistent contrast and appearance over a relatively wide range of inversion recovery times (TI), improved contrast‐to‐noise ratio, and consistent size of the enhanced region. Comparison between images acquired using segmented breath‐held turbo‐FLASH and averaged, motion‐corrected, free‐breathing true‐FISP show excellent agreement of measured CNR and infarct size. In this study, motion correction was implemented using image registration postprocessing rather than navigator correction of individual frames. Navigator techniques may be incorporated as well. Magn Reson Med 53:194–200, 2005. Published 2004 Wiley‐Liss, Inc.
Gadodiamide T1 relaxivity in brain tissue in vivo is lower than in saline
Authors: Pickup Stephen , Wood Andrew K. W. , Kundel Harold L. 
Published: December 2004

AbstractIn vivo measurements of gadodiamide (Gd‐DTPA‐BMA) T1 relaxivity were performed at 4.7 T in injured and normal rat brains. Cerebral lesions were induced in nine rats by a localized freezing method. T1 maps of the lesions were generated before and after injection of Gd‐DTPA‐BMA (0.1–0.6 mmol/kg). Samples of normal and necrotic brain were collected postmortem; the wet and dry weights were determined, and Gd content was measured by inductively coupled plasma mass spectroscopy. The in vivo relaxivity was determined by a linear fit of a plot of the change in relaxation rate following injection of the contrast agent as a function of Gd content. This analysis yielded a relaxivity in the injured brain of 2.8 sec−1 mmol−1 kg tissue water at 36°C. The water weight fraction was 0.90 ± SD 0.02 wt/wt in injured brain and 0.79 ± 0.02 in normal brain. Relaxivity measurements were also performed on solutions of Gd‐DTPA‐BMA (0.0–0.6 mmol) and albumin (0–30% wt/wt) in normal saline at room and physiologic temperatures. The relaxivity in the albumin/saline increased with increasing solids content with values of 4.0–4.9 sec−1 mmol−1kg at 21°C and 3.4–4.5 sec−1 mmol−1 kg at 37°C. The relaxivity of the tissues differed significantly from that of the saline solutions of comparable solids content, suggesting that the solids content of a tissue is not the only factor that determines in vivo relaxivity. Magn Reson Med 53:35–40, 2005. © 2004 Wiley‐Liss, Inc.
Statistical motor unit number estimation assuming a binomial distribution
Authors: Blok Joleen H. , Visser Gerhard H. , de Graaf Sándor , Zwarts Machiel J. , Stegeman Dick F. 
Published: December 2004

AbstractThe statistical method of motor unit number estimation (MUNE) uses the natural stochastic variation in a muscle's compound response to electrical stimulation to obtain an estimate of the number of recruitable motor units. The current method assumes that this variation follows a Poisson distribution. We present an alternative that instead assumes a binomial distribution. Results of computer simulations and of a pilot study on 19 healthy subjects showed that the binomial MUNE values are considerably higher than those of the Poisson method, and in better agreement with the results of other MUNE techniques. In addition, simulation results predict that the performance in patients with severe motor unit loss will be better for the binomial than Poisson method. The adapted method remains closer to physiology, because it can accommodate the increase in activation probability that results from rising stimulus intensity. It does not need recording windows as used with the Poisson method, and is therefore less user‐dependent and more objective and quicker in its operation. For these reasons, we believe that the proposed modifications may lead to significant improvements in the statistical MUNE technique. Muscle Nerve, 2005
Superficial motor units are larger than deeper motor units in human vastus lateralis muscle
Authors: Knight C. A. , Kamen G. 
Published: December 2004

AbstractPrevious studies have suggested that regionalization may occur for human motor units, whereby smaller motor units are located in deeper parts of the muscle and larger motor units are located in more superficial portions. We examined this possibility in the human vastus lateralis muscle using macro‐EMG (electromyography) to estimate motor unit size. The sample consisted of nine individuals from whom 114 motor units were recorded at forces ranging between 5% and 60% MVC. Peak‐to‐peak macro‐EMG amplitude was well correlated with macro area (Spearman rho = 0.96). There was a statistically significant inverse relationship between recording depth and macro peak‐to‐peak amplitude (rho = −0.402, p < 0.001). We conclude that there is a nonrandom distribution of motor units in human muscle, with larger motor units located in more superficial regions and smaller units located in deeper regions. Clinicians who monitor motor unit activity need to recognize that a representative sample of motor unit recordings should include motor units from both deeper and more superficial regions of muscle. Muscle Nerve, 2005
Enrichment of the R77C α‐sarcoglycan gene mutation in finnish LGMD2D patients
Authors: Hackman P. , Juvonen V. , Sarparanta J. , Penttinen M. , Äärimaa T. , Uusitalo M. , Auranen M. , Pihko H. , Alén R. , Junes M. , Lönnqvist T. , Kalimo H. , Udd B. 
Published: December 2004

AbstractLimb‐girdle muscular dystrophy 2D (LGMD2D) is caused by mutations in the α‐sarcoglycan gene (SGCA). The most frequently reported mutation, 229CGC>TGC (R77C) in exon 3 of SGCA, results in the substitution of arginine by cysteine. We present here the clinical, immunohistochemical, and genetic data of 11 Finnish patients with LGMD2D caused by mutations in SGCA. Mutational analysis showed 10 patients homozygous and 1 compound heterozygous for R77C. A wide spectrum of SGCA mutations has been reported previously. Our results show an enrichment of R77C in Finland, further underlined by the observed carrier frequency of 1 per 150. According to the annual birth rate of ∼60.000 in Finland, one LGMD2D patient with a homozygous mutation is expected to be born every 1 or 2 years on average. The presence of an ancient founder mutation is indicated by the fact that all patients shared a short common haplotype extending ≥790 kilibases. Our results emphasize the need to include the SGCA gene R77C mutation test in routine DNA analyses of severe dystrophinopathy‐like muscular dystrophies in Finland, and suggest that the applicability of this test in other populations should be studied as well. Muscle Nerve, 2005
Impact of different sized catheters on pressure‐flow studies in women with lower urinary tract symptoms
Authors: Costantini Elisabetta , Mearini Luigi , Biscotto Sauro , Giannantoni Antonella , Bini Vittorio , Porena Massimo 
Published: December 2004

AbstractAimsThis study assessed the impact of two catheters on urinary flow in women undergoing a pressure/flow (P/F) study for lower urinary tract symptoms (LUTS).Materials and MethodsWomen who agreed to undergo urodynamic testing were assigned prospectively to a 7 or 9 Fr catheter in P/F study according to a balanced randomized block design. Exclusion criteria: urinary tract infection, bladder stone or tumor, neuropathy, complete urinary retention, inability to void with catheter in place, free flowmetry volume below 150 ml, and urine volume varying by more than 20% on both free and P/F studies. We compared free flowmetry and P/F flowmetry with a 9 Fr catheter in 126/239 patients (Group A) and with a 7 Fr catheter in 113/239 (Group B). We determined the differences in the P/F results in terms of pre‐voided bladder volume, clinical and urodynamic categories, and age groups in the two groups. We compared the diagnosis of obstruction based on Qmax during the P/F study and on Qmax in free uroflowmetry.ResultsIn Groups A and B, the Qmax rate was significantly less (P < 0.001) in P/F studies. Catheter size did not impact significantly. In patients with cystocele, post‐void residue or obstruction flow was reduced more than in the other categories. Qmax diminished with age, by about 15% in women aged 50–60 and by 21% in women over 70 years old.ConclusionsQmax in P/F studies is always reduced independently of catheter size, volume of urine, age, and clinical or urodynamic category. This may have clinical implications when interpreting P/F results and in accurately diagnosing obstruction. © 2004 Wiley‐Liss, Inc.
Modification of the lie‐algebraic scheme and approximation error estimations
Authors: Bihun Oksana , Prytula Mykola 
Published: December 2004

AbstractA new modification of the the Lie‐algebraic scheme for solving partial differential equations with initial and boundary conditions based on constructing quasirepresentations of the Heisenberg‐Weyl algebra operators involving boundary conditions is proposed. Approximation errors for the modified scheme are evaluated. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fetal cardiac anomalies and genetic syndromes
Authors: Pajkrt Eva , Weisz Boaz , Firth Helen V. , Chitty Lyn S. 
Published: December 2004

AbstractCardiac anomalies may occur in isolation or can be part of a genetic syndrome. In this article, we describe some of the genetic syndromes commonly associated with cardiac anomalies where there are other sonographic features that may aid accurate prenatal diagnosis. Copyright © 2004 John Wiley & Sons, Ltd.
Application of partial least squares discriminant analysis to two‐dimensional difference gel studies in expression proteomics
Authors: Karp Natasha A. , Griffin Julian L. , Lilley Kathryn S. 
Published: December 2004

AbstractTwo‐dimensional difference gel electrophoresis (DIGE) is a tool for measuring changes in protein expression between samples involving pre‐electrophoretic labeling with cyanine dyes. In multi‐gel experiments, univariate statistical tests have been used to identify differential expression between sample types by looking for significant changes in spot volume. Multivariate statistical tests, which look for correlated changes between sample types, provide an alternate approach for identifying spots with differential expression. Partial least squares‐discriminant analysis (PLS‐DA), a multivariate statistical approach, was combined with an iterative threshold process to identify which protein spots had the greatest contribution to the model, and compared to univariate tests for three datasets. This included one dataset where no biological difference was expected. The novel multivariate approach, detailed here, represents a method to complement the univariate approach in identification of differentially expressed protein spots. This new approach has the advantages of reduced risk of false‐positives and the identification of spots that are significantly altered in terms of correlated expression rather than absolute expression values.
Structure conservation in cytochromes P450
Authors: Mestres Jordi 
Published: December 2004

AbstractThe recent availability of crystal structures for several diverse cytochromes P450 (CYPs) offers the possibility to perform an up‐to‐date comparative analysis to identify the degree of structure conservation among this superfamily of enzymes specially relevant for their involvement in drug metabolism and toxicity. A set of 9 CYPs sharing between 10% and 27% sequence identity was selected, including 7 class I (CYP 101, 107, 108, 119, 121, 51, and 55) and two class II (CYP 102, and 2C5) structures. After obtaining a multiprotein structure superimposition, a structure‐based sequence alignment was derived. Mapping the level of three‐dimensional structural conservation onto the sequence alignment revealed that over 28% of the alignment positions have the Cαcarbons of their residues within a root‐mean‐square deviation (RMSD) of 2 Å. This degree of structure conservation is found to be generally preserved, even when the structure undergoes dramatic conformational changes. Performing the analysis on 4 members of the CYP2 family (CYP 2B4, 2C5, 2C8, and 2C9), the percentage of alignment positions within 2 Å RMSD amounted to 73%, increasing to over 85% when only structures in a closed conformation are considered. The present findings suggest that it should be plausible to derive models of overall good quality for the major CYP2 metabolizing forms (CYP 2A6, 2C19, 2D6, and 2E1), whereas high levels of uncertainty are still likely to be expected in models for the remaining 2 major P450 metabolizing forms (CYP 1A2 and 3A4), with the corresponding implications for their potential applicability in drug design activities. Proteins 2005. © 2004 Wiley‐Liss, Inc.
Long‐range interactions between atoms and molecules
Authors: Dalgarno A. , Morrison I. H. , Pengelly R. M. 
Published: December 2004

AbstractThe refractive index data for various gases are fitted to analytical formulae from which may be calculated the coefficient of the leading term of the long‐range two‐body interactions and the coefficient of the leading term of the long‐range non‐additive three‐body interactions. Coefficients are obtained for mixtures of the gases He, Ne, A, Kr, Xe, H2, N2 and CH4, the probable error being 5%.