bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of localized 19F magnetic resonance spectroscopy for the detection of fluorinated drugs in the human liver
Authors: Klomp Dennis W.J. , van Laarhoven Hanneke W.M. , Kentgens Arno P.M. , Heerschap Arend
Published: July 2003

Fluorine MR spectroscopy (19F MRS) is an indispensable tool for assessing the pharmacokinetics of fluorinated drugs. Since the metabolism of 5‐fluorouracil (5FU), a frequently used cytotoxic drug, is expected to be different in normal liver and in tumor tissue, spatial localization is required for detection by MRS. In this study, three independent signal‐to‐noise ratio (SNR) optimizations were combined to enable chemical shift imaging (CSI) as a localization method in the detection of 5FU and its metabolites in tumor tissue. First, the hardware was optimized by using circularly polarized coils together with integrated preamplifiers. Second, the optimal pulse angle (Ernst angle) was determined on the basis of T1 relaxation time measurements of 5FU. Finally, averaging of CSI phase‐encoding steps was optimized by using the applied Hamming filter as a weighting function. The combination of these three methods enables the in vivo detection of 5FU and α‐fluoro‐β‐alanine (FBAL) by 19F MRS, localized in three dimensions in tumor and liver tissue at a time resolution of 4 min at 1.5 Tesla. Magn Reson Med 50:303–308, 2003. © 2003 Wiley‐Liss, Inc.
Detection of Alzheimer's amyloid in transgenic mice using magnetic resonance microimaging
Authors: Wadghiri Youssef Zaim , Sigurdsson Einar M. , Sadowski Marcin , Elliott James I. , Li Yongsheng , Scholtzova Henrieta , Tang Cheuk Ying , Aguinaldo Gilbert , Pappolla Miguel , Duff Karen , Wisniewski Thomas , Turnbull Daniel H.
Published: July 2003

The presence of amyloid‐β (Aβ) plaques in the brain is a hallmark pathological feature of Alzheimer's disease (AD). Transgenic mice overexpressing mutant amyloid precursor protein (APP), or both mutant APP and presenilin‐1 (APP/PS1), develop Aβ plaques similar to those in AD patients, and have been proposed as animal models in which to test experimental therapeutic approaches for the clearance of Aβ. However, at present there is no in vivo whole‐brain imaging method to detect Aβ plaques in mice or men. A novel method is presented to detect Aβ plaques in the brains of transgenic mice by magnetic resonance microimaging (μMRI). This method uses Aβ1‐40 peptide, known for its high binding affinity to Aβ, magnetically labeled with either gadolinium (Gd) or monocrystalline iron oxide nanoparticles (MION). Intraarterial injection of magnetically labeled Aβ1‐40, with mannitol to transiently open the blood–brain barrier (BBB), enabled the detection of many Aβ plaques. Furthermore, the numerical density of Aβ plaques detected by μMRI and by immunohistochemistry showed excellent correlation. This approach provides an in vivo method to detect Aβ in AD transgenic mice, and suggests that diagnostic MRI methods to detect Aβ in AD patients may ultimately be feasible. Magn Reson Med 50:293–302, 2003. © 2003 Wiley‐Liss, Inc.
Hyperpolarized 13C MR angiography using trueFISP
Authors: Svensson Jonas , Månsson Sven , Johansson Edvin , Petersson J. Stefan , Olsson Lars E.
Published: July 2003

A 13C‐enriched water‐soluble compound (bis‐1,1‐(hydroxymethyl)‐1‐13C‐cyclopropane‐D8), with a 13C‐concentration of approximately 200 mM, was hyperpolarized to ∼15% using dynamic nuclear polarization, and then used as a contrast medium (CM) for contrast‐enhanced magnetic resonance angiography (CE‐MRA). The long relaxation times (in vitro: T1 ≈ 82 s, T2 ≈ 18 s; in vivo: T1 ≈ 38 s, T2 ≈ 1.3 s) are ideal for steady‐state free precession (SSFP) imaging with a true fast imaging and steady precession (trueFISP) pulse sequence. It was shown both theoretically and experimentally that the optimal flip angle was 180°. CE‐MRA was performed in four anesthetized live rats after intravenous injection of 3 ml CM. The angiograms covered the thoracic/abdominal region in two of the animals, and the head‐neck region in the other two. Fifteen consecutive images were acquired in each experiment, with a flip‐back pulse at the end of each image acquisition. In the angiograms, the vena cava (SNR ≈ 240), aorta, renal arteries, carotid arteries (SNR ≈ 75), jugular veins, and several other vessels were visible. The SNR in the cardiac region was 500. Magnetization was preserved from one image acquisition to the next using the flip‐back technique (SNRcardiac ≈ 10 in the 15th image). Magn Reson Med 50:256–262, 2003. © 2003 Wiley‐Liss, Inc.
Nonlinear phase correction for navigated diffusion imaging
Authors: Miller Karla L. , Pauly John M.
Published: July 2003

Motion during diffusion‐weighted imaging (DWI) introduces phase errors that can cause significant artifacts in brain images. One method of correcting these errors uses additional navigator data to measure the phase corruptions. Standard navigator methods correct for rigid‐body motion but cannot correct for nonrigid deformations of the brain related to the cardiac cycle. This work derives a generalized reconstruction that corrects for nonrigid motion based on a least‐squares formulation. Since this reconstruction has the disadvantage of being computationally expensive, an approximation is presented, called a refocusing reconstruction. The refocusing reconstruction is both efficient and straightforward. Each readout is multiplied in image space by the phase conjugate of the navigator image, and these rephased readouts are then summed. The conditions under which the refocusing reconstruction is sufficient are considered and methods to improve the quality of refocused images are discussed. In particular, synchronization of the acquisition to the cardiac cycle can provide data that is well‐conditioned to the refocusing reconstruction without incurring the large time penalty traditionally associated with cardiac gating. These methods are applied to steady‐state DWI, a promising pulse sequence that is particularly sensitive to motion‐induced phase artifacts. The refocusing reconstruction is shown to significantly improve SS‐DWI over standard rigid‐body corrections. Magn Reson Med 50:343–353, 2003. © 2003 Wiley‐Liss, Inc.
Improved molecular imaging contrast agent for detection of human thrombus
Authors: Winter Patrick M. , Caruthers Shelton D. , Yu Xin , Song Sheng‐Kwei , Chen Junjie , Miller Brad , Bulte Jeff W.M. , Robertson J. David , Gaffney Patrick J. , Wickline Samuel A. , Lanza Gregory M.
Published: July 2003

Molecular imaging of microthrombus within fissures of unstable atherosclerotic plaques requires sensitive detection with a thrombus‐specific agent. Effective molecular imaging has been previously demonstrated with fibrin‐targeted Gd‐DTPA‐bis‐oleate (BOA) nanoparticles. In this study, the relaxivity of an improved fibrin‐targeted paramagnetic formulation, Gd‐DTPA‐phosphatidylethanolamine (PE), was compared with Gd‐DTPA‐BOA at 0.05‐4.7 T. Ion‐ and particle‐based r1 relaxivities (1.5 T) for Gd‐DTPA‐PE (33.7 (s*mM)‐1 and 2.48 × 106 (s*mM)‐1, respectively) were about twofold higher than for Gd‐DTPA‐BOA, perhaps due to faster water exchange with surface gadolinium. Gd‐DTPA‐PE nanoparticles bound to thrombus surfaces via anti‐fibrin antibodies (1H10) induced 72% ± 5% higher change in R1 values at 1.5 T (ΔR1 = 0.77 ± 0.02 1/s) relative to Gd‐DTPA‐BOA (ΔR1 = 0.45 ± 0.02 1/s). These studies demonstrate marked improvement in a fibrin‐specific molecular imaging agent that might allow sensitive, early detection of vascular microthrombi, the antecedent to stroke and heart attack. Magn Reson Med 50:411–416, 2003. © 2003 Wiley‐Liss, Inc.
Deconvolution algorithm based on automatic cutoff frequency selection for EPR imaging
Authors: Deng Yuanmu , He Guanglong , Kuppusamy Periannan , Zweier Jay L.
Published: July 2003

The large line‐width associated with electron paramagnetic resonance imaging (EPRI) requires effective algorithms to deconvolve the true spatial profiles of spins from the measured projection data. The commonly used Fourier transform (FT) deconvolution algorithm is easy to implement but suffers from the division‐by‐zero problem. As a result, a couple of parameters are used to control the deconvolution performance. However, this is inconvenient and the deconvolution results are subject to the experience of the operators. In the present work we examined FT deconvolution for EPRI, and proposed an automatic algorithm to determine the cutoff frequency by calculating the piecewise variance of the division result of the Fourier amplitude spectra. The deconvolution algorithm and the filtered back‐projection image reconstruction algorithm were implemented and validated using 3D phantom and in vivo imaging data. It was clearly observed that the image resolution improved after deconvolution with the proposed algorithm. Magn Reson Med 50:444–448, 2003. © 2003 Wiley‐Liss, Inc.
Proton electron double resonance imaging (PEDRI) of the isolated beating rat heart
Authors: Liebgott Thibaut , Li Haihong , Deng Yuanmu , Zweier Jay L.
Published: July 2003

Proton electron double resonance imaging (PEDRI) is a double resonance technique where proton MRI is performed with irradiation of a paramagnetic solute. A low‐field PEDRI system was developed at 20.1 mT suitable for imaging free radicals in biological samples. With a new small dual resonator, PEDRI was applied to image nitroxide free radicals in isolated beating rat hearts. Experiments with phantoms showed maximum image enhancement factors (IEF) of 42 or 28 with TEMPONE radical concentrations of 2–3 mM at EPR irradiation powers of 12W or 6W, respectively. In the latter case, image resolution better than 0.5 mm and radical sensitivity of 5 μM was obtained. For isolated heart studies, EPR irradiation power of 6W provided optimal compromise of modest sample heating with good SNR. Only a small increase in temperature of about 1°C was observed, while cardiac function remained within 10% of control values. With infusion of 3 mM TEMPONE an IEF of 15 was observed enabling 2D or 3D images to be obtained in 27 sec or 4.5 min, respectively. These images visualized the change in radical distribution within the heart during infusion and clearance. Thus, PEDRI enables rapid and high‐quality imaging of free radical uptake and clearance in perfused hearts and provides a useful technique for studying cardiac radical metabolism. Magn Reson Med 50:391–399, 2003. © 2003 Wiley‐Liss, Inc.
An image‐based finite difference model for simulating restricted diffusion
Authors: Hwang Scott N. , Chin Chih‐Liang , Wehrli Felix W. , Hackney David B.
Published: July 2003

Water diffusion in tissues is generally restricted and often anisotropic. Neural tissue is of particular interest, since it is well known that injury alters diffusion in a characteristic manner. Both Monte Carlo simulations and approximate analytical models have previously been reported in attempts to predict water diffusion behavior in the central nervous system. These methods have relied on axonal models, which assume simple geometries (e.g., ellipsoids, cylinders, and square prisms) and ignore the thickness of the myelin sheath. The current work describes a method for generating models using synthetic images. The computations are based on a 3D finite difference (FD) approximation of the diffusion equation. The method was validated with known analytic solutions for diffusion in a cylindrical pore and in a hexagonal array of cylinders. Therefore, it is envisioned that, by exploiting histologic images of neuronal tissues as input model, current method allows investigating the water diffusion behavior inside biological tissues and potentially assessing the status of neural injury and regeneration. Magn Reson Med 50:373–382, 2003. © 2003 Wiley‐Liss, Inc.
Novel nonparametric approach to canonical correlation analysis with applications to low CNR functional MRI data
Authors: Nandy Rajesh R. , Cordes Dietmar
Published: July 2003

Detection of activation in functional MRI (fMRI) is often complicated by the low contrast‐to‐noise ratio (CNR) in the data. The primary source of the difficulty is the fact that for activities that are subtle the signal can be hidden inside the inherent noise in the data. Classical univariate methods based on t‐test or F‐test are susceptible to noise, as they fail to harness systematic correlations in evoked responses within neighboring voxels. Here the power of a multivariate statistical analysis tool known as canonical correlation analysis (CCA) in fMRI studies is demonstrated where the CNR is low. As a further illustration of the power of the method, a comparative study of CCA and ordinary correlation analysis using simulated data under various noise levels is also performed. A novel nonparametric approach is introduced to calculate the P‐values from the distribution of the complicated test statistic. The circumstances under which CCA is a better performer as well as when it is not the case are discussed. As an example, this method is applied to detect hippocampal activation from memory‐related tasks. Magn Reson Med 50:354–365, 2003. © 2003 Wiley‐Liss, Inc.
Rapid quantitation of high‐speed flow jets
Authors: Nayak Krishna S. , Hu Bob S. , Nishimura Dwight G.
Published: July 2003

Flow jets containing velocities up to 5–7 m/s are common in patients with congenital defects and patients with valvular disease (stenosis and regurgitation). The quantitation of peak velocity and flow volume in these jets is clinically significant but requires specialized imaging sequences. Conventional 2DFT phase contrast sequences require lengthy acquisitions on the order of several minutes. Conventional spiral phase contrast sequences are faster, but are highly corrupted by flow artifacts at these high velocities due to phase dispersion and motion during the excitation and readout. A new prospectively gated method based on spiral phase contrast is presented, which has a sufficiently short measurement interval (<4 ms) to minimize flow artifacts, while achieving high spatial resolution (2 × 2 × 4 mm3) to minimize partial volume effects, all within a single breathhold. A complete single‐slice phase contrast movie loop with 22 ms true temporal resolution is acquired in one 10‐heartbeat breathhold. Simulations indicate that this technique is capable of imaging through‐plane jets with velocities up to 10 m/s, and initial studies in aortic stenosis patients show accurate in vivo measurement of peak velocities up to 4.2 m/s (using echocardiography as a reference). Magn Reson Med 50:366–372, 2003. © 2003 Wiley‐Liss, Inc.
Ifosfamide pharmacokinetics and hepatobiliary uptake in vivo investigated using single‐ and double‐resonance 31P MRS
Authors: Mancini Laura , Payne Geoffrey S. , Dzik‐Jurasz Andrzej S.K. , Leach Martin O.
Published: July 2003

MRS has considerable potential for the measurement of drug pharmacokinetics in vivo. In this study single‐ and double‐resonance 31P MRS was used to investigate the biodistribution, pharmacokinetics, and metabolism of ifosfamide following administration of 500 mg/kg ifosfamide in guinea pigs. 1H‐decoupling was found to nearly double the signal of detected peaks. However, in contrast to studies of ifosfamide in solution, the polarization transfer sequence gave no further signal enhancements. This was attributed to significantly reduced relaxation times in vivo. Chemical shift imaging (CSI) measurements showed that significant proportions of ifosfamide‐related 31P MRS signals arose from the liver, as expected, but also from the gall bladder, which was not predicted from the current literature. Signals were observed within 5 min of the end of administration. The halflife in liver was approximately 74 min, whereas in gall bladder there was no measurable signal decay during the 2.5‐hr studies. High‐resolution 31P MRS of bile showed that the “ifosfamide” peak in vivo consists of at least two compounds. The lower‐concentration peak is ifosfamide, and an investigation is under way to identify the higher‐concentration peak. Other peaks observed in bile are tentatively assigned to carboxy‐ifosfamide and dechloroethyl‐ifosfamide. Overall, 1H‐decoupled 31P MRS has proved to be a useful tool for investigating the metabolism of ifosfamide in vivo. Magn Reson Med 50:249–255, 2003. © 2003 Wiley‐Liss, Inc.
MRI‐based monitoring of inflammation and tissue damage in acute and chronic relapsing EAE
Authors: Rausch M. , Hiestand P. , Baumann D. , Cannet C. , Rudin M.
Published: July 2003

Experimental autoimmune encephalomyelitis (EAE) is a commonly used animal model that in several respects mimics human multiple sclerosis (MS), and can be used to design or validate new strategies for treatment of this disease. In the present study, different MRI techniques (macrophage tracking based on labeling cells in vivo by ultrasmall particles of iron oxide (USPIO), blood–brain barrier (BBB) breakdown, and magnetization transfer imaging (MTI)), as well as immunohistological staining were used to study the burden of disease in Lewis rats immunized by guinea pig myelin. The resulting imaging data was compared with behavioral readouts. Animals were studied during the acute phase and the first relapse. Activated monocytes were detected during both episodes in the brain stem or cortex. These areas coincided in part with areas of BBB breakdown. Significant changes of the magnetization transfer ratios (MTRs) of up to 35% were observed in areas of USPIO accumulation. This suggests that infiltrating monocytes are the major source of demyelination in EAE, but monocyte infiltration and breakdown of the BBB are temporally or spatially independent inflammatory processes. Magn Reson Med 50:309–314, 2003. © 2003 Wiley‐Liss, Inc.
New MRI method with contrast based on the macromolecular characteristics of tissues
Authors: Neufeld Arnon , Eliav Uzi , Navon Gil
Published: July 2003

A new MRI method with a contrast that is derived from the macromolecular composition and spin dynamics in the tissue is described and demonstrated on excised mouse brain and rat spinal cord. In the method, magnetization is selectively excited in the macromolecules by using a double quantum filter and subsequently transferred to water. The new imaging method differs from previous methods that rely on magnetization transfer contrast (MTC) in that it enables a separate and independent control of the effect of the macromolecule characteristics, chemical exchange, and water‐related parameters on the images. Magn Reson Med 50:229–234, 2003. © 2003 Wiley‐Liss, Inc.
Assessment and compensation of susceptibility artifacts in gradient echo MRI of hyperpolarized 3He gas
Authors: Wild Jim M. , Fichele Stan , Woodhouse Neil , Paley Martyn N.J. , Swift Andrew , Kasuboski Larry , van Beek Edwin J.R.
Published: July 2003

The effects of macroscopic background field gradients upon 2D gradient echo images of inhaled 3He in the human lung were investigated at 1.5 T. Effective compensation of in‐slice signal loss in 3He gradient echo images was then demonstrated using a multiple acquisition interleaved single gradient echo sequence. This method restores signal dephasing through a combination of separate images acquired with different slice refocusing gradients. In vivo imaging of volunteers with the sequence shows substantial restoration of signal at the lung periphery and close to blood vessels. The technique presented may be useful when using 3He MRI for volumetric measurements of lung ventilation and in studies using 3He combined with intravenous contrast as a means of assessing lung ventilation/perfusion (V/Q). Magn Reson Med 50:417–422, 2003. © 2003 Wiley‐Liss, Inc.
Direct monitoring of coronary artery motion with cardiac fat navigator echoes
Authors: Nguyen Thanh D. , Nuval Anthony , Mulukutla Suresh , Wang Yi
Published: July 2003

Navigator echoes (NAVs) provide an effective means of monitoring physiological motion in magnetic resonance imaging (MRI). Motion artifacts can be suppressed by adjusting the data acquisition accordingly. The standard pencil‐beam NAV has been used to detect diaphragm motion; however, it does not monitor cardiac motion effectively. Here we report a navigator approach that directly measures coronary artery motion by exciting the surrounding epicardial fat and sampling the signal with a k‐space trajectory sensitized to various motion parameters. The present preliminary human study demonstrates that superior‐inferior (SI) respiratory motion of the coronary arteries detected by the cardiac fat NAV highly correlates with SI diaphragmatic motion detected by the pencil‐beam NAV. In addition, the cardiac fat navigator gating is slightly more effective than the diaphragmatic navigator gating in suppressing motion artifacts in free‐breathing 3D coronary MR angiography (MRA). Magn Reson Med 50:235–241, 2003. © 2003 Wiley‐Liss, Inc.
Steady‐state imaging for visualization of endovascular interventions
Authors: Martin Alastair J. , Weber Oliver M. , Saeed Maythem , Roberts Timothy P.L.
Published: July 2003

Steady‐state imaging techniques offer the potential to couple high spatial and temporal resolution with good signal‐to‐noise ratio (SNR), which makes them ideally suited for fluoroscopic applications. However, disturbance of the steady state can result in artifacts and substantially reduced signal levels. In this study the use of steady‐state imaging techniques was investigated as a means of guiding endovascular interventions with fluoroscopic MRI. Devices containing localized susceptibility defects were shown to disturb the steady‐state signal of spins that pass through the magnetic field disturbances. It was demonstrated that these effects are appreciable and can make delineation of interventional devices difficult in the presence of flow. T1‐shortening contrast agents were shown to dramatically reduce these effects by reducing the time taken to achieve steady state. The addition of a blood pool agent in an in vivo model was found to be necessary for adequate visualization of a dysprosium‐marked catheter. Magn Reson Med 50:434–438, 2003. © 2003 Wiley‐Liss, Inc.
Combination of transfection agents and magnetic resonance contrast agents for cellular imaging: Relationship between relaxivities, electrostatic forces, and chemical composition
Authors: Kalish H. , Arbab A.S. , Miller B.R. , Lewis B.K. , Zywicke H.A. , Bulte J.W.M. , Bryant L.H. , Frank J.A.
Published: July 2003

The purpose of this study was to investigate the changes in electrostatic and magnetic resonance (MR) properties observed when MR contrast agents (CAs) (Feridex®, MION‐46L, or G5‐dendrimer‐DOTA‐Gd) are combined with transfection agents (TAs) under various conditions for use as a CA‐TA complex basis for cellular labeling and MRI. CAs were incubated with various classes of TAs for 0–48 hr in solutions of varying concentrations and pH values. NMR relaxation rates (1/T1, 1/T2), MRI and zeta potential (ZP) of CA‐TA solutions were measured. TAs decreased the 1/T1 and 1/T2 of G5‐DOTA‐Gd, Feridex®, and MION‐46L by 0–95%. Altering the pH of G5‐DOTA‐Gd‐TA decreased the T1‐weighted signal intensity (SI) on MRI from 0 to 78%. Measured ZP values for G5‐DOTA‐Gd, Feridex®, and MION‐46L were −51, −41, and −2.0 mV, respectively. The TA LV had a negative ZP, while the other TAs had ZPs ranging from +20 to +65 mV. The alteration of the ZP and NMR relaxivities of the MR CAs, Feridex®, MION‐46L, and G5‐DOTA‐Gd by TAs has been demonstrated. These results enhance our understanding of the relationship between electrostatic and MR properties. Magn Reson Med 50:275–282, 2003. Published 2003 Wiley‐Liss, Inc.
Lyme disease and the peripheral nervous system
Authors: Halperin John J.
Published: July 2003

Lyme disease, the multisystem infectious disease caused by the tick‐borne spirochete Borrelia burgdorferi, causes a broad variety of peripheral nerve disorders, including single or multiple cranial neuropathies, painful radiculopathies, and diffuse polyneuropathies. Virtually all appear to be varying manifestations of a mononeuropathy multiplex. Diagnosis requires that the patient should have had possible exposure to the only known vectors, Ixodes ticks, and also have either other pathognomonic clinical manifestations or laboratory evidence of exposure. Treatment with antimicrobial regimens is highly effective. The mechanism underlying these neuropathies remains unclear, although interactions between anti‐Borrelia antibodies and several peripheral nerve constituent molecules raise intriguing possibilities. Muscle Nerve 28: 133–143, 2003
The H‐reflex as a tool in neurophysiology: Its limitations and uses in understanding nervous system function
Authors: Misiaszek John E.
Published: July 2003

The Hoffmann reflex (H‐reflex) is extensively used as both a research and clinical tool. The ease with which this reflex can be elicited in several muscles throughout the body makes it an attractive tool. This review discusses some of the important limitations in using the H‐reflex. In particular, the inaccurate but widely held assumptions that the H‐reflex (1) represents the monosynaptic reflex of the Ia afferent onto homonymous motoneurons, and (2) can be used to measure motoneuronal excitability are addressed. The second part of this review explores the utility of the H‐reflex as a neural probe in neurophysiology and motor control research. Applications ranging from the investigation of the functional organization of neural circuitry to the study of adaptive plasticity in spinal structures in health and disease suggest that the H‐reflex will continue to be an extensively used tool in motor control neurophysiology. Muscle Nerve 28: 144–160, 2003
Paramyotonia congenita due to a de novo mutation: A case report
Authors: Fukudome Takayasu , Izumoto Hajime , Goto Hirofumi , Matsuo Hidenori , Yoshimura Toshiro , Sakoda Shun‐Ichi , Shibuya Noritoshi
Published: July 2003

A Japanese man with a negative family history of paramyotonia congenita (PMC) was evaluated for symptoms of cold‐induced weakness and stiffness. Exercise testing revealed findings characteristic of PMC, and a genetic analysis was therefore performed. A well‐known sodium channel mutation for PMC (T1313M) was identified in the patient, but was absent in his biological parents. These data demonstrate the occurrence of a de novo mutation, suggesting that evaluation for PMC should be performed in patients with typical symptoms even if the family history is negative. Muscle Nerve 28: 232–235, 2003
Effects of imagery motor training on torque production of ankle plantar flexor muscles
Authors: Zijdewind Inge , Toering Sjoukje T. , Bessem Bram , van der Laan Occo , Diercks Ron L.
Published: July 2003

The aim of this study was to investigate in control subjects the effect of imagery training on the torque of plantar‐flexor muscles of the ankle. Twenty‐nine subjects were allocated to one of three groups that performed either imagery training, low‐intensity strength training, or no training (only measurements). The low‐intensity training served as an attention control group. Plantar‐flexor torques were measured before, during, directly after, and 4 weeks after the training period. At the end of a 7‐week training program, significant differences were observed between the maximal voluntary torque production of the imagery training group (136.3 ± 21.8% of pretraining torque) vs. the low‐intensity training group (112.9 ± 29.0%; P < 0.02) and the control group (113.6 ± 19.2%; P < 0.02). The results of this study show that imagery training of lower leg muscles significantly increased voluntary torque production of the ankle plantar‐flexor muscles and that the force increase was not due to nonspecific motivational effects. Such muscle strengthening effects might be beneficial in rehabilitation for improving or maintaining muscle torque after immobilization. Muscle Nerve 28: 168–173, 2003
Changes in neuromuscular function after training by functional electrical stimulation
Authors: Marqueste Tanguy , Hug François , Decherchi Patrick , Jammes Yves
Published: July 2003

We examined whether the neuromuscular function of rectus femoris (RF) and flexor digitorum brevis (FDB) in humans was modified after a 6‐week training period of functional electrical stimulation (FES), and whether any effects persisted at the end of a 6‐week post‐FES recovery period. In both the stimulated and contralateral nonstimulated muscles, we recorded the muscle force, surface electromyogram, and M wave, and also measured the root mean square (RMS) and the median frequency (MF) during static contraction sustained until exhaustion at 60% of maximal voluntary contraction (MVC). FES was performed with symmetric biphasic pulses, with a ramp modulation of both the stimulation frequency and pulse duration. No changes in MCV and endurance time to exhaustion occurred in nonstimulated muscles, whereas a significant MVC increase occurred immediately after FES in RF (+14 ± 5%) and FDB (+13 ± 5%), these effects persisting 6 weeks after the end of FES. In FDB, FES also elicited a significant increase in endurance time to exhaustion (+18 ± 7%). The M‐wave characteristics never varied after FES, but a marked attenuation occurred in the MF decrease and the RMS increase measured at endurance time to sustained 60% MVC, especially in FDB, which contains the higher proportion of type II fibers. These data indicate that FES improves muscle function and elicits changes in central muscle activation. The benefits of FES were greater in FDB, which is highly fatigable, and persisted for at least a 6‐week period. Muscle Nerve 28: 181–188, 2003
Progressive arm weakness and tonic hand spasm from multifocal motor neuropathy in the brachial plexus
Authors: Veltkamp R. , Krause M. , Schranz C. , Meinck H.‐M.
Published: July 2003

A 50‐year‐old waitress presented with a 10‐year history of progressive weakness in her right arm without atrophy and with tonic hand spasms suggesting a central motor disorder. Electromyography, however, disclosed chronic neurogenic changes including fasciculations and atypical cramps. Isolated motor conduction block in the right brachial plexus suggested a variant of multifocal motor neuropathy. Strength recovered and cramps disappeared after intravenous immunoglobulins. Motor neuropathies may thus manifest with features of central motor disorders. Muscle Nerve 28: 242–245, 2003
Decremental response of the nasalis and hypothenar muscles in myasthenia gravis
Authors: Niks Erik H. , Badrising Umesh A. , Verschuuren Jan J. , van Dijk J. Gert
Published: July 2003

Repetitive nerve stimulation (RNS) is a standard diagnostic procedure in myasthenia gravis (MG). Although RNS sensitivity is highest in weak muscles, RNS is easier to perform in distal muscles that are often not affected. Twenty‐five patients with MG were assessed to compare the sensitivity of RNS of the nasalis muscle to that of the hypothenar muscles. Abnormal decrement was found in hypothenar muscles in 9 patients (36%) and in the nasalis muscle in 13 patients (52%). RNS of the nasalis muscle appeared more useful to detect abnormal neuromuscular transmission in patients with oculobulbar MG (5 of 5) than hypothenar RNS (1 of 5). In patients with generalized MG, hypothenar muscles had a similar yield of abnormal RNS tests. Muscle Nerve 28: 236–238, 2003
Changing stimulation patterns improves performance during electrically elicited contractions
Authors: Scott Wayne B. , Binder‐Macleod Stuart A.
Published: July 2003

The clinical efficacy of functional electrical stimulation (FES) is limited by the rapid onset of fatigue. FES applications use electrical stimuli separated by regular interpulse intervals (constant‐frequency trains or CFTs) to activate muscles. However, doublet‐frequency trains (DFTs) may produce greater forces than CFTs, but also produce more fatigue. DFTs contain a series of doublets, two pulses separated by a short (5‐ms) interpulse interval. We hypothesized that a combination of CFTs followed by DFTs would improve performance compared to either train type alone. Quadriceps muscles of 15 normal subjects were fatigued with either 150 DFTs, or initially fatigued with CFTs until the targeted isometric force was no longer produced and then switched to DFTs. The combination reached the targeted isometric force (mean ± SEM) more times (59.80 ± 4.03) than either the CFTs alone (51.20 ± 3.50) or DFTs alone (55.33 ± 3.81). This finding suggests that combining train types may be a useful strategy to offset the rapid fatigue that persons with neurological dysfunction, such as spinal cord injury, experience when using FES. Muscle Nerve 28: 174–180, 2003
Evaluation of morphological and functional regeneration of rat nerve–muscle units after temporary and permanent tubulization
Authors: Odaka Mitsuaki , Uchiyama Yoshiyasu , Oka Yoshinori , Tamaki Tetsuro
Published: July 2003

We compared the ability of temporary and permanent tubing to achieve morphological and functional recovery of nerve–muscle units, following experimental nerve transection (8‐mm gap) in rat tibial nerve. Electrical stimulation of the sciatic nerve was used to analyze tension output, evoked electromyogram and conduction‐transmission time (CTT) of denervated nerve–muscle units. Morphological analysis of the nerve and muscle was also performed. Within 6 weeks, the nerve gap had been bridged by a thin nerve trunk, and a few myelinated fibers were observed, although there was still no functional recovery. The rats were divided into two groups: permanent tubing (PT) and temporary tubing (TT; tubing subsequently removed). At 10 weeks after the operation, the TT group showed apparently greater thickness of regenerated nerve trunks, significantly higher tension output of plantar flexors, shorter CTT, and heavier muscle mass. These results were consistent with the presence of myelinated fibers in the regenerated nerve trunks, as shown histologically. Thus, removal of the silicone chamber results in faster and better recovery than tubing left permanently in place. Muscle Nerve 28: 194–203, 2003
Monophasic and biphasic stimulation evoke different responses
Authors: Field‐Fote Edelle C. , Anderson Brent , Robertson Valma J. , Spielholz Neil I.
Published: July 2003

In 31 subjects, psychophysiological sensory perception threshold and the waveform of orthodromic sensory nerve action potentials (SNAPs) produced by constant‐current 100‐μs monophasic negative pulses were compared to those produced by biphasic (negative–positive) symmetrical pulses (100‐μs per phase). In addition, the effects of 200‐μs monophasic negative pulses were studied. Graded stimuli were delivered to the index finger, and SNAPs were recorded over the median nerve at the wrist. Perception threshold was significantly different among the three conditions. Furthermore, in 26 subjects, at the lower intensities at which SNAPs first appeared, the evoked potential waveform had two small negative phases with biphasic stimuli, but a single negative phase in response to monophasic pulses. At higher stimulus intensities, all SNAPs had a single large negative phase regardless of the stimulus. These perception and waveform findings suggest that, contrary to historical belief, the trailing positive phase of a biphasic pulse has a stimulating effect at low stimulus intensities. Muscle Nerve 28: 239–241, 2003
Motor unit number estimate of distal and proximal muscles in Charcot–Marie–Tooth disease
Authors: Lewis Richard A. , Li Jun , Fuerst Darren R. , Shy Michael E. , Krajewski Karen
Published: July 2003

In order to determine the utility of motor unit number estimation (MUNE) in assessing axonal loss in chronic inherited neuropathies, we determined MUNEs in 54 patients with Charcot–Marie–Tooth (CMT) disease (29 patients with CMT‐1A, 13 with CMT‐X, and 12 with CMT‐2) by using spike‐triggered averaging (STA) of the ulnar‐innervated abductor digiti minimi/hypothenar muscles (ADM) and the musculo‐cutaneous innervated biceps/brachialis (BB) muscles. MUNEs were analyzed in relationship to the corresponding compound muscle action potential (CMAP) amplitudes as well as to clinical strength. Proximal muscles, which appeared strong clinically, had evidence of chronic denervation/reinnervation, although to a lesser extent than weak distal hand muscles, supporting the concept that axonal loss in CMT occurs in a length‐dependent fashion. The reduction in ADM‐MUNE strongly correlated with clinical weakness in the hand. Both the ADM‐MUNE and BB‐MUNE were abnormal more often than CMAP amplitude, probably reflecting extensive motor unit reconfiguration and enlargement that maintains CMAP amplitude despite severe motor unit loss. This study suggests that MUNE can assess motor unit loss in CMT and may better reflect axonal loss than CMAP amplitude. The STA technique of MUNE may be useful in longitudinal studies of proximal and distal motor unit changes in CMT. Muscle Nerve 28: 161–167, 2003
Dispersion of the distal compound muscle action potential in chronic inflammatory demyelinating polyneuropathy and carpal tunnel syndrome
Authors: Cleland James C. , Logigian Eric L. , Thaisetthawatkul Pariwat , Herrmann David N.
Published: July 2003

Median neuropathy at the wrist can confound the electrodiagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP), since both conditions can prolong median distal motor latency. Dispersion of the distal CMAP (DCMAP) has recently emerged as a potentially useful adjunct in the electrodiagnosis of CIDP, with good specificity in distinguishing CIDP from certain axon‐loss disorders. However, it is uncertain whether focal compression neuropathies produce dispersion of the DCMAP in a manner similar to CIDP. In this study we compared median DCMAP duration in 27 patients with CIDP and 86 with carpal tunnel syndrome, using 39 patients with non‐neuropathic musculoskeletal pain syndromes as electrophysiologic controls. We found that, in contrast to CIDP, dispersion of the median DCMAP is uncommon, even in advanced carpal tunnel syndrome, being seen in only 8 of 103 (7.8%) hands. Although the pathophysiologic reasons for a differential effect of focal compression‐mediated demyelination and multifocal immune‐mediated demyelination (CIDP) on DCMAP duration are uncertain, our findings suggest that the presence of dispersion of the median DCMAP may prove useful in distinguishing immune‐mediated demyelination from compression neuropathy alone. Muscle Nerve 28: 189–193, 2003
Noninactivating, tetrodotoxin‐sensitive Na+ conductance in peripheral axons
Authors: Tokuno Hajime A. , Kocsis Jeffery D. , Waxman Stephen G.
Published: July 2003

A noninactivating, persistent sodium current has been demonstrated previously in dorsal root ganglia neurons and in rat optic nerve. We report here that Na+ channel blockade with tetrodotoxin (TTX) in isolated dorsal and ventral roots elicits membrane hyperpolarization, suggesting the presence of a persistent Na+ current in peripheral axons. We used a modified sucrose‐gap chamber to monitor resting and action potentials and observed a hyperpolarizing shift in the nerve potential of rat dorsal and ventral roots by TTX. The block of transient inward Na+ currents was confirmed by the abolition of compound action potentials (CAPs). Moreover, depolarization of nerve roots by elevating extracellular K+ concentrations to 40 mM eliminated CAPs but did not significantly alter TTX‐induced hyperpolarizations, indicating that the persistent Na+ currents in nerve roots are not voltage‐dependent. Tetrodotoxin‐sensitive persistent inward Na+ currents are present in both dorsal and ventral root axons at rest and may contribute to axonal excitability. Muscle Nerve 28: 212–217, 2003
Preferential motor reinnervation in the mouse: Comparison of femoral nerve repair using a fibrin sealant or suture
Authors: Robinson Grant A. , Madison Roger D.
Published: July 2003

Previous studies in rat femoral nerve demonstrated that regenerating motor axons preferentially reinnervate a nerve branch to muscle as opposed to skin, a process that has been termed preferential motor reinnervation (PMR). This process has not been previously reported in the mouse, where the use of transgenic animals could be a powerful tool to study the basic mechanisms that determine accuracy of regenerating motor axons. In the mouse, we applied the same nerve repair (suture) and retrograde labeling strategies that successfully demonstrated PMR in the rat femoral nerve but surprisingly were unable to demonstrate PMR. However, if the mouse femoral nerve was repaired with a fibrin sealant, PMR was readily apparent, suggesting that PMR in the mouse is dependent on the method of nerve repair. Muscle Nerve 28: 227–231, 2003
Axonal pharyngeal‐cervical‐brachial variant of Guillain–Barré syndrome without Anti‐GT1a IgG antibody
Authors: Arai Motomi , Susuki Keiichiro , Koga Michiaki
Published: July 2003

We report two cases of pharyngeal‐cervical‐brachial (PCB) variant of Guillain–Barré syndrome (GBS). The patients developed dysphagia and weakness of the neck and arms subsequent to Campylobacter jejuni infection. Oropharyngeal palsy recovered poorly. Electrophysiological findings demonstrated axonal conduction failure. Anti‐GD1a immunoglobulin G (IgG) antibody was detected in one case, and anti‐GM1b IgG antibody in another. Anti‐GT1a IgG and immunoglobulin M (IgM) antibodies were negative in both cases. The current cases suggest that the PCB and axonal variants of GBS form a continuous spectrum from the viewpoint of electrophysiological studies as well as antiganglioside serology. Muscle Nerve 28: 246–250, 2003
Decomposition‐based quantitative electromyography: Methods and initial normative data in five muscles
Authors: Doherty Timothy J. , Stashuk Daniel W.
Published: July 2003

Quantitative electromyographic (EMG) techniques provide clinically useful information to aid in the diagnosis and follow the course or response to treatment of diseases affecting the motor system. The purpose of this study was to describe a decomposition‐based quantitative electromyography method (DQEMG) designed to obtain clinically applicable information relating to motor unit
potential (MUP) size and configuration, and motor unit (MU) firing characteristics. Additionally, preliminary normative data were obtained from the deltoid, biceps brachii, first dorsal interosseous, vastus medialis, and tibialis anterior muscles of 13 control subjects. DQEMG was capable of efficiently and accurately extracting MUP data from complex interference patterns during mild to moderate contractions. MUP amplitude, surface‐detected MUP (S‐MUP) amplitude, MUP duration, number of phases, and MU firing frequencies varied significantly across muscles. The mean parameter values for the individual muscles studied were similar to previous reports based on other quantitative methods. The main advantages of this method are the speed of data acquisition and processing, the ability to obtain MUPs from MUs with low and higher recruitment thresholds, and the ability to obtain both S‐MUP or macro‐MUP data as well as MU firing rate information. Muscle Nerve 28: 204–211, 2003
Quadriceps muscle strength and voluntary activation after polio
Authors: Beelen Anita , Nollet Frans , de Visser Marianne , de Jong Bareld A. , Lankhorst Gustaaf J. , Sargeant Anthony J.
Published: July 2003

Quadriceps strength, maximal anatomical cross‐sectional area (CSA), maximal voluntary activation (MVA), and maximal relaxation rate (MRR) were studied in 48 subjects with a past history of polio, 26 with and 22 without postpoliomyelitis syndrome (PPS), and in 13 control subjects. It was also investigated whether, apart from CSA, MVA and MRR were determinants of muscle strength. Polio subjects had significantly less strength, CSA, and MRR in the more‐affected quadriceps than control subjects. MVA was reduced in 18 polio subjects and normal in all controls. PPS subjects differed from non‐PPS subjects only in that the MVA of the more‐affected quadriceps was significantly lower. Both CSA and MVA were found to be associated with muscle strength. Quadriceps strength in polio subjects was dependent not only on muscle mass, but also on the ability to activate the muscles. Since impaired activation was more pronounced in PPS subjects, the new muscle weakness and functional decline in PPS may be due not only to a gradual loss of muscle fibers, but also to an increasing inability to activate the muscles. Muscle Nerve 28: 218–226, 2003
An asymptotically optimal greedy heuristic for the multiperiod single‐sourcing problem: The cyclic case
Authors: Romeijn H. Edwin , Romero Morales Dolores
Published: July 2003

The dynamics of the environment in which supply chains evolve requires that companies frequently redesign their logistics distribution networks. In this paper we address a multiperiod single‐sourcing problem that can be used as a strategic tool for evaluating the costs of logistics network designs in a dynamic environment. The distribution networks that we consider consist of a set of production and storage facilities, and a set of customers who do not hold inventories. The facilities face production capacities, and each customer's demand needs to be delivered by a single facility in each period. We deal with the assignment of customers to facilities, as well as the location, timing, and size of inventories. In addition, to mitigate start and end‐of‐study effects, we view the planning period as a typical future one, which will repeat itself. This leads to a cyclic model, in which starting and ending inventories are equal. Based on an assignment formulation of the problem, we propose a greedy heuristic, and prove that this greedy heuristic is asymptotically feasible and optimal in a probabilistic sense. We illustrate the behavior of the greedy heuristic, as well as some improvements where the greedy heuristic is used as the starting point of a local interchange procedure, on a set of randomly generated test problems. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 412–437, 2003
Fully‐automated hex‐dominant mesh generation with directionality control via packing rectangular solid cells
Authors: Yamakawa Soji , Shimada Kenji
Published: July 2003

A new fully automatic hex‐dominant mesh generation technique of an arbitrary 3D geometric domain is presented herein. The proposed method generates a high‐quality hex‐dominant mesh by: (1) controlling the directionality of the output hex‐dominant mesh; and (2) avoiding ill‐shaped elements induced by nodes located too closely to each other. The proposed method takes a 3D geometric domain as input and creates a hex‐dominant mesh consisting mostly of hexahedral elements, with additional prism and tetrahedral elements. Rectangular solid cells are packed on the boundary of and inside the input domain to obtain ideal node locations for a hex‐dominant mesh. Each cell has a potential energy field that mimics a body‐centred cubic (BCC) structure (seen in natural substances such as NaCl) and the cells are moved to stable positions by a physically based simulation. The simulation mimics the formation of a crystal pattern so that the centres of the cells provide ideal node locations for a hex‐dominant mesh. Via the advancing front method, the centres of the packed cells are then connected to form a tetrahedral mesh, and this is converted to a hex‐dominant mesh by merging some of the tetrahedrons. Copyright © 2003 John Wiley & Sons, Ltd.
Preparative isolation of swainsonine from locoweed: extraction and puriﬁcation procedures
Authors: Gardner Dale R. , Lee Stephen T. , Molyneux Russell J. , Edgar John A.
Published: July 2003

The trihydroxy indolizidine alkaloid swainsonine, a plant toxin with potent α‐mannosidase‐inhibitory activity and chemotherapeutic potential, was isolated in gram quantities from locoweed (Astragalus lentiginosus). The key isolation and puriﬁcation step was a continuous liquid/liquid extraction procedure using dichloromethane to extract a basiﬁed aqueous methanol solution obtained after isolation of the polar base fraction by ion‐exchange. The concentration of swainsonine was increased from ca. 7% in the polar base material to 68% using the liquid/liquid extraction procedure. Pure swainsonine was then obtained by recrystallisation from ammonia‐saturated chloroform or by sublimation. Small samples of swainsonine were also puriﬁed by formation of the chloroform‐soluble methylboronate derivative, from which the alkaloid could be regenerated easily by hydrolysis. Copyright © 2003 John Wiley & Sons, Ltd.