bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fiber‐optic stethoscope: A cardiac monitoring and gating system for magnetic resonance microscopy
Authors: Brau Anja C.S. , Wheeler Charles T. , Hedlund Laurence W. , Johnson G. Allan 
Published: August 2002

AbstractA fundamental problem associated with using the conventional electrocardiograph (ECG) to monitor a subject's cardiac activity during magnetic resonance imaging (MRI) is the distortion of the ECG due to electromagnetic interference. This problem is particularly pronounced in MR microscopy (MRI of small animals at microscopic resolutions (< 0.03 mm3)) because the strong, rapidly‐switching magnetic field gradients induce artifacts in the animal's ECG that often mimic electrophysiologic activity, impairing the use of the ECG for cardiac monitoring and gating purposes. The fiber‐optic stethoscope system offers a novel approach to measuring cardiac activity that, unlike the ECG, is immune to electromagnetic effects. The fiber‐optic stethoscope is perorally inserted into the esophagus of small animals to optically detect pulsatile compression of the esophageal wall. The optical system is shown to provide a robust cardiac monitoring and gating signal in rats and mice during routine cardiac MR microscopy. Magn Reson Med 47:314–321, 2002. © 2002 Wiley‐Liss, Inc.
Multislice first‐pass cardiac perfusion MRI: Validation in a model of myocardial infarction†
Authors: Epstein Frederick H. , London James F. , Peters Dana C. , Goncalves Lino M. , Agyeman Kwabena , Taylor Joni , Balaban Robert S. , Arai Andrew E. 
Published: August 2002

AbstractThe purpose of this study was to validate a first‐pass MRI method for imaging myocardial perfusion with multislice coverage and relatively small analyzable regions of interest (ROIs). A fast gradient‐echo (FGRE) sequence with an echo‐train (ET) readout was used to achieve multislice coverage, and a high dose of a contrast agent (CA) was used to achieve a high signal‐to‐noise ratio (SNR). Dogs (N = 6) were studied 1 day after reperfused myocardial infarction, and fluorescent microspheres were used as a standard for perfusion. First‐pass MRI correlated well vs. microsphere flow, achieving mean R values of 0.87 (range = 0.82–0.93), 0.71 (range = 0.46–0.85), and 0.72 (range = 0.49–0.95) for subendocardial ROIs, transmural ROIs, and the endocardial‐epicardial ratio, respectively. Additionally, analysis of myocardial time‐intensity curves (TICs) indicated that 15.8 ± 6.6° sectors, corresponding to 260 μl of endocardium, can be analyzed (R2 > 0.95). Magn Reson Med 47:482–491, 2002. Published 2002 Wiley‐Liss, Inc.
MRI of muscular fat
Authors: Schick Fritz , Machann Jürgen , Brechtel Klaus , Strempfer Andrea , Klumpp Bernhard , Stein Daniel T. , Jacob Stephan 
Published: August 2002

AbstractAn MRI technique with high selectivity and sensitivity to the signal components in the chemical shift range of methylene and methyl protons of fatty acids has been developed for noninvasive assessment of muscular fat in vivo. A spoiled gradient‐echo sequence with spatial‐spectral excitation by six equidistant pulses with 2°‐(−9°)‐17°‐(−17°)‐9°‐(−2°) and a multi‐echo train (TE = 16, 36, 56, 76, 96, and 116 ms) allowed a series of images to be recorded with a receiver bandwidth of 78 Hz per pixel. SIs from phantoms with lipid contents between 0.1% and 100% were compared to those from pure water. Thirty healthy volunteers underwent fat‐selective imaging of their lower leg, and parallel localized proton spectroscopy of the tibialis anterior and the soleus muscle by a single‐voxel stimulated echo acquisition mode (STEAM) technique (TR = 2 s, TE = 10 ms, TM = 15 ms). Results show a high correlation (r = 0.91) between fat imaging and the spectroscopic approach in the soleus muscle, considering the percentage total fat content of musculature. The correlation coefficient was clearly lower (r = 0.55) in the tibialis anterior muscle due to signal contaminations from adjacent subcutaneous fat in the images, inhomogeneous fat distribution, and generally lower lipid content in this muscle. Applications of the new imaging technique showed marked intra‐ and interindividual variability in the spatial distribution of lipids in the musculature of the lower leg. No significant correlation of the muscular fat with the thickness of the subcutaneous fat layer was found. In addition, the body mass index does not appear to determine muscular fat content, except in very obese cases. Magn Reson Med 47:720–727, 2002. © 2002 Wiley‐Liss, Inc.
Lactate discrimination incorporated into echo‐planar spectroscopic imaging
Authors: Bito Yoshitaka , Ebisu Toshihiko , Hirata Satoshi , Takegami Tetsuro , Yamamoto Yukari , Tanaka Chuzo , Naruse Shoji 
Published: August 2002

AbstractA technique for discriminating a lactate signal from overlapping lipid signals in 1H spectroscopic imaging is presented. It is based on J‐coupling between lactate protons and on the broad spectral bandwidth of lipid signal. Measurement parameters used in the technique are determined so that TE is separated from n/J (n: a natural number, J: J‐coupling constant) enough to suppress the lipid signal at the time when the lactate signal is strongest. Data processing is used to calculate the lactate signal intensity from the reconstructed spectra. This technique enables lactate to be discriminated in a single measurement and enables spectra of other metabolites to be acquired simultaneously. However, it necessitates a homogeneous magnetic field, long TE, and supplementary lipid suppression. Discrimination of the lactate signal is demonstrated by applying lactate‐discriminating echo‐planar spectroscopic imaging (EPSI), which combines this discrimination technique with the standard EPSI, to rat focal cerebral ischemia models. Magn Reson Med 45:568–574, 2001. © 2001 Wiley‐Liss, Inc.
MR microscopy of cobalt‐labeled nerve cells and pathways in an invertebrate brain (Sepia officinalis, Cephalopoda)
Authors: Quast Michael J. , Neumeister Heike , Ezell Edward L. , Budelmann Bernd U. 
Published: August 2002

AbstractThis article describes a novel application of contrast‐enhanced MR microscopy to trace nerve cells and pathways through small invertebrate brains. Using the cuttlefish Sepia officinalis (Cephalopoda) as a model, the cells and pathways of one of the brain nerves were labeled with paramagnetic cobalt(II) ions by conventional centripetal cobalt iontophoresis. In MR microscopy, the cobalt‐labeled cell bodies and pathways became hypointense in 9.4 T spin echo images. Their course and distribution were identical with those seen with conventional histological techniques after cobalt sulphide precipitation (with or without subsequent silver intensification). Magn Reson Med 45:575–579, 2001. © 2001 Wiley‐Liss, Inc.
High‐sensitivity single‐shot perfusion‐weighted fMRI†
Authors: Duyn Jeff H. , Tan Charlene X. , Gelderen Peter van , Yongbi Martin N. 
Published: August 2002

AbstractA method is presented for measurement of perfusion changes during brain activation using a single‐shot pulsed spin labeling technique. By employing a double‐inversion labeling strategy, stationary tissue (background) signal was suppressed while minimally affecting perfusion sensitivity. This allowed omission of the otherwise required reference scan, resulting in twofold‐improved temporal resolution. The method was applied to visual and motor cortex activation studies in humans, and compared to standard FAIR‐type perfusion labeling techniques. Experiments performed at 1.5T and 3.0T indicate a close to 90% suppression of background signal, at a cost of an 11% and 9%, respectively, reduction in perfusion signal. Combined with the twofold increase in signal averaging, and a reduction in background signal fluctuations, this resulted in a 64% (1.5T, N = 3) and a 128% (3T, N = 4) overall improvement in sensitivity for the detection of activation‐related perfusion changes. Magn Reson Med 46:88–94, 2001. Published 2001 Wiley‐Liss, Inc.
Chronic eosinophilic perimyositis with persistent myalgias
Authors: Zivkovic Sasa A. , Lacomis David , Clemens Paula R. 
Published: August 2002

AbstractA 43‐year‐old man with an 8‐year history of hypereosinophilia was evaluated for persistent muscle pain. Methotrexate and corticosteroids were ineffective. Examination, limited by pain even with passive motion, showed only mild weakness. Electromyography and muscle enzymes were normal. A needle muscle biopsy specimen revealed eosinophilic perimyositis. This case illustrates that the diagnosis of eosinophilic perimyositis requires histopathological evaluation, which should be pursued in patients with eosinophilia and persistent myalgia despite normal electromyography and muscle enzymes. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Correlation between nerve conduction studies and clinical scores in diabetic neuropathy
Authors: Feki Imed , Lefaucheur Jean‐Pascal 
Published: August 2002

AbstractPolyneuropathy, a frequent complication of diabetes, can be assessed clinically and electrophysiologically. Neurological examination can be quantified by validated scores, e.g., the neuropathy symptom score (NSS) or the neuropathy disability score (NDS). Such scores exclude electrophysiological aspects of the neuropathy. A software tool was designed to convert electrophysiological data into one single index of polyneuropathy (IPN). This index was calibrated to grade the severity of a polyneuropathy from 0.00 to 1.00. In a series of 38 diabetic patients, we have calculated NSS, NDS, and IPN. We found correlations between these variables, NDS and IPN exhibiting the more significant association. The use of IPN allowed us to demonstrate that nerve conduction values correlated with clinical scores in diabetic polyneuropathy. Such a software tool, by providing a single electrophysiological index, may facilitate clinico‐electrophysiological assessment in large descriptive studies or therapeutic trials of diabetic polyneuropathy. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24:555–558, 2001
Urinary collagen metabolite excretion in amyotrophic lateral sclerosis
Authors: Ono Seiitsu , Shimizu Natsue , Imai Takashi , Rodriguez Gladys P. 
Published: August 2002

AbstractCollagen abnormalities of the spinal cord and the skin have been reported in patients with amyotrophic lateral sclerosis (ALS). The urinary concentrations of the hydroxylysine glycosides, i.e., glucosylgalactosyl hydroxylysine (glu‐gal Hyl) and galactosyl hydroxylysine (gal Hyl), indicate the tissue origin of the collagen metabolites and the rate of the degradation of collagen. We measured the urinary levels of glu‐gal Hyl and gal Hyl in 12 ALS patients, 10 diseased control subjects with other neurologic or muscular diseases (Control Group A), and 10 healthy control subjects (Control Group B). The urinary level of glu‐gal Hyl in ALS patients was significantly lower than in the two control groups. In addition, a significant negative relationship between glu‐gal Hyl urinary level and duration of illness was found in ALS patients. There was no marked difference in the urinary level of gal Hyl between ALS patients and the control groups. Our data suggest that the decreased urinary level of glu‐gal Hyl may be useful in assessing the alteration in collagen metabolism in ALS and may have a relationship with the progression of ALS. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 821–825, 2001
Incomplete recovery of voluntary isometric force after fatigue is not affected by old age
Authors: Allman Brian L. , Rice Charles L. 
Published: August 2002

AbstractThe 60‐min recovery profiles of voluntary and electrically stimulated force, contractile speed, surface electromyography, muscle activation via twitch interpolation, and muscle compound action potentials (M‐waves) in the elbow flexors of seven young men (24 ± 2 years) and seven men over 80 years of age (84 ± 2 years) were compared following intermittent (3 s on, 2 s off) contractions at 60% of each subject's maximum voluntary contraction (MVC) force. There was no age‐related difference between groups in the average time to fatigue or the rate of voluntary force loss; both groups lost 40% of their force within approximately 5 min. Despite a rapid increase to ∼83% of the prefatigue MVC by the third minute of recovery for both groups, MVC force did not return to the prefatigue value within 60 min (94 ± 4% young, 91 ± 3% old). These results suggest that the incomplete recovery of voluntary force was likely due to a peripheral limitation in the muscle at the level of excitation–contraction coupling, and was not affected by age. Delayed recovery of voluntary force and a greater degree of low‐frequency fatigue in the old men were not observed and there were no age‐related impairments in any parameter normalized to the prefatigue value during fatigue or recovery. We suggest that the specific fatigue task may be more important to recovery than proposed alterations in the aged neuromuscular system when normalization and matching of the fatigue task criteria occurs. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1156–1167, 2001
Disparate dysfunction of skeletal muscles located near and distant from burn site in the rat
Authors: Ibebunjo Chikwendu , Martyn Jeevendra 
Published: August 2002

AbstractThis study tested the hypotheses that burn‐induced change in muscle function varies at sites local and distant from burn and is related to changes in expression of acetylcholine receptors (AChRs) and muscle mass. In anesthetized rats, ∼4% burn was inflicted over the tibialis anterior muscle of one limb. The contralateral leg served as control. In another study, a ∼45% body surface area burn was produced on the trunk; controls were body sham‐burned rats. The evoked twitch tensions of tibialis anterior muscles in both legs were measured together with AChR proteins and their transcripts. Compared with the contralateral leg, absolute tensions in the burned leg declined at days 1, 4, and 7 without loss of muscle mass so that tension per unit wet muscle mass (specific tension) decreased; at day 14, the tension decreased with muscle atrophy so that specific tension was unchanged. Membrane AChRs and/or the immature subunit transcript, AChRγ messenger ribonucleic acid (mRNA) increased at days 4, 7, and 14, and both were inversely related to evoked tension (r = .43, P < .01 and r = .61, P < .0001, respectively). There was a direct correlation between AChR and AChRγ mRNA (r = .82, P < .001), suggesting that the upregulated AChRs may contain the immature γ‐subunit isoform. After ∼45% body burn, AChRs and mRNA did not change and the evoked tensions did not decline, but there was relative loss of muscle mass at days 7 and 14 so that specific tension increased. Burn trauma initially causes weakness of muscles directly under the burn, and this weakness may be partially related to increased expression of immature AChRs and later to muscle atrophy. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1283–1294, 2001
Gentle dorsal root retraction and dissection can cause areflexia: Implications for intraoperative monitoring during “selective” partial dorsal rhizotomy
Authors: Logigian Eric L. , Soriano Sulpicio G. , Herrmann David N. , Madsen Joseph R. 
Published: August 2002

AbstractDuring partial dorsal rhizotomy (PDR), intraoperative dorsal rootlet stimulation often evokes nonreflex, rather than reflex, motor responses that are due to costimulation of adjacent ventral roots. Intraoperative areflexia typically predicts that motor responses evoked by dorsal rootlet stimulation are nonreflexive. The cause of areflexia during PDR is in part due to anesthesia, but other mechanisms are likely to play a role as well. In this study of three consecutive patients undergoing lumbosacral neurosurgery, soleus H‐reflexes evoked by tibial nerve stimulation at the popliteal fossa were found to suddenly decline in amplitude following retraction and gentle dissection of the S‐1 dorsal root. In one areflexic patient, dorsal rootlet stimulation proximal to the main site of dissection evoked soleus H‐reflexes, although they could not be evoked by tibial nerve stimulation. We conclude that the gentle retraction and dissection of dorsal rootlets that occurs during PDR can induce conduction block of reflex afferents. High‐intensity dorsal rootlet stimulation distal to the site of conduction block may then evoke not reflex responses, but rather nonreflex motor responses, due to the costimulation of adjacent ventral roots. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1352–1358, 2001
Nerve conduction abnormalities in aging mice deficient for myelin‐associated glycoprotein
Authors: Weiss Michael D. , Luciano Carlos A. , Quarles Richard H. 
Published: August 2002

AbstractUltrastructural, biochemical, and electrophysiological analyses were done on 12–14‐month‐old mice deficient for myelin‐associated glycoprotein (MAG) to further characterize the neuropathy that develops as they age. Electron microscopy demonstrated normal myelin compaction and axonal degeneration in a large number of myelinated nerve fibers. Western blots showed that the proteins of compact myelin, P0 glycoprotein, and myelin basic protein were not significantly altered in the mutants; however, the Schwann cell protein, 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase, was reduced to less than half the control level. Also, both total and phosphorylated high‐molecular‐weight neurofilament proteins (TNFH and PNFH, respectively) were significantly decreased, as was the PNFH:TNFH ratio. Electrophysiological evaluation revealed a mild, but statistically significant, reduction of conduction velocity and a nonsignificant mild decrease in compound muscle action potential amplitudes. This constellation of findings in aging MAG‐null mice is consistent with an axonopathy that resembles axonal Charcot–Marie–Tooth (CMT2) disease in many respects. Thus, mutation of a myelin‐associated gene expressed by Schwann cells can induce axonal degeneration and cause a neuropathy with minimal signs of demyelination. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1380–1387, 2001
Patterns of muscle involvement in inclusion body myositis: Clinical and magnetic resonance imaging study
Authors: Phillips Beverley A. , Cala Leslie A. , Thickbroom Gary W. , Melsom Alison , Zilko Paul J. , Mastaglia Frank L. 
Published: August 2002

AbstractThe differential patterns of muscle involvement in the upper and lower limbs in sporadic inclusion body myositis (sIBM) were examined in 18 patients using both quantitative and manual muscle testing as well as magnetic resonance imaging (MRI) in 9 patients. Weakness of the quadriceps femoris and the forearm flexors was present in most patients, but there was considerable variability in the patterns and severity of muscle involvement. MRI disclosed preferential patterns of muscle involvement within functional groups such as the quadriceps femoris, in which there was severe involvement of the vasti with relative sparing of the rectus femoris, and the triceps surae, in which selective involvement of the medial gastrocnemius was common. Involvement of flexor digitorum profundus on MRI was found in only one third of patients. The results emphasize the variability in the clinical phenotype and differential susceptibility of muscles to the disease process in sIBM. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1526–1534, 2001
A comprehensive model of spastic hypertonia derived from the pendulum test of the leg
Authors: Le Cavorzin Philippe , Poudens S. Annick , Chagneau Francis , Carrault Guy , Allain Hervé , Rochcongar Pierre 
Published: August 2002

AbstractWe propose a comprehensive model of spastic hypertonia based on clinical neurophysiology and validated using experimental data obtained from the pendulum test of the leg in 8 healthy volunteers and 15 spastic patients. This nonlinear computational model includes mechanical parameters and a stretch reflex representation involving three neural parameters: a threshold coefficient, the gain of the stretch reflex, and a time lag accounting for the reflex loop latency and the electromechanical coupling delay. Variation of the threshold coefficient alone allowed an overall reproduction of experimental data obtained from spastic and healthy subjects. We propose that this parameter could represent the supraspinal drive, supposed to be preserved in control subjects and decreased in spastic patients. No subsequent variation of the reflex gain was required to simulate spastic traces. Adjustment of the time lag influenced the duration of the swinging phase and oscillatory phenomena possibly occurring during the pendulum test. It could be related to the involvement of either short‐ or long‐latency stretch reflex loops. With respect to current neurophysiological concepts of motor control, this modeling approach may help in understanding mechanisms underlying spastic hypertonia, and in predicting the clinical effect of antispasticity agents. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1612–1621, 2001
Incrementalization of a single hardening constitutive model for frictional materials
Authors: Lade P. V. , Jakobsen K. P. 
Published: August 2002

AbstractThe governing equations for an elasto‐plastic constitutive model for frictional materials such as soil, rock, and concrete are presented, and the incremental form is indicated in preparation for implementation of the model in a user‐defined module for finite element calculations. This isotropic, work‐hardening and ‐softening model employs a single yield surface, it incorporates non‐associated plastic flow, and its capability of capturing the behaviour of different types of frictional materials under various three‐dimensional conditions has been demonstrated by comparison with measured behaviour, as presented in the literature. The incrementalization procedure is indicated and the resulting equations for the single hardening model are presented together with parameters for a dense sand. Following the implementation of the model, these parameters are used for evaluation of different integration schemes as presented in a companion paper by Jakobsen and Lade (Int. J. Numer. Anal. Meth. Geomech. 2002; 26:661). Copyright © 2002 John Wiley & Sons, Ltd.
Implementation algorithm for a single hardening constitutive model for frictional materials
Authors: Jakobsen K. P. , Lade P. V. 
Published: August 2002

AbstractAn advanced elasto‐plastic constitutive model for frictional materials, whose incremental version is presented in a companion paper (Int. J. Numer. Anal. Meth. Geomech., 2002; 26:647), is implemented in a user‐defined material module. The general calculation strategy inside this module is presented and discussed, including the initial intersection of the yield surface and the techniques for updating of stresses and hardening modulus. Several integration schemes are implemented in the module and their capabilities in relation to the advanced, three‐dimensional constitutive model are evaluated. The forward Euler, modified Euler, and Runge–Kutta–Dormand–Prince integration schemes are explained in detail, compared, and evaluated in view of error tolerances and computational efficiency. Copyright © 2002 John Wiley & Sons, Ltd.
Economic ordering quantities for recoverable item inventory systems
Authors: Teunter Ruud H. 
Published: August 2002

AbstractWe study a deterministic EOQ model of an inventory system with items that can be recovered (repaired/refurbished/remanufactured). We use different holding cost rates for manufactured and recovered items, and include disposal. We derive simple square root EOQ formulas for both the manufacturing batch quantity and the recovery batch quantity.