bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular cloning and expression during spermatogenesis of a cDNA encoding testicular 11β‐hydroxylase (P45011β) in rainbow trout (Oncorhynchus mykiss)
Authors: Kusakabe Makoto , Kobayashi Tohru , Todo Takashi , Mark Lokman P. , Nagahama Yoshitaka , Young Graham 
Published: October 2002

AbstractCytochrome P450 1β‐hydroxylase (P45011β) is an important steroidogenic enzyme for glucocorticoid and mineralocorticoid production in vertebrates. In teleosts, P45011β also plays a role in the production of 11‐ketotestosterone (11‐KT), the predominant androgen in male fish. In this study, we cloned a cDNA encoding rainbow trout (Oncorhynchus mykiss) testicular P45011β. The cDNA contains 1,740 nucleotides that encode a protein of 551 amino acids which shares 65.2% homology with testicular P45011β from Japanese eel, and 33–45% homology with adrenal P45011β from rat, human, and frog. HEK293 cells transfected with an expression vector containing the rainbow trout P45011β cDNA open reading frame showed 11β‐hydroxylating activity in the presence of exogenous testosterone. Analysis of tissue distribution by RT‐PCR showed great abundance of P45011β mRNA in testis and head kidney. In order to clarify the sites of P45011β gene expression, cRNA in situ hybridization analysis was performed. Hybridization signals were detected in Leydig cells and head kidney inter‐renal cells. The results of Northern blot analysis indicated a single 1.8‐kb transcript encoding P45011β in testis and in head kidney, suggesting that the testicular form of P45011β may also be involved in cortisol production by inter‐renal cells. Seasonal changes in total P45011β mRNA levels in testes during spermatogenesis showed a pattern similar to that of plasma androgens. These results suggest that androgen production in male rainbow trout is partially regulated by changes in abundance of P45011β mRNA. Mol. Reprod. Dev. 62:456–469, 2002. © 2002 Wiley‐Liss, Inc.
Characterization of anisotropy in high angular resolution diffusion‐weighted MRI
Authors: Frank Lawrence R. 
Published: October 2002

AbstractThe methods of group theory are applied to the problem of characterizing the diffusion measured in high angular resolution MR experiments. This leads to a natural representation of the local diffusion in terms of spherical harmonics. In this representation, it is shown that isotropic diffusion, anisotropic diffusion from a single fiber, and anisotropic diffusion from multiple fiber directions fall into distinct and separable channels. This decomposition can be determined for any voxel without any prior information by a spherical harmonic transform, and for special cases the magnitude and orientation of the local diffusion may be determined. Moreover, non‐diffusion–related asymmetries produced by experimental artifacts fall into channels distinct from the fiber channels, thereby allowing their separation and a subsequent reduction in noise from the reconstructed fibers. In the case of a single fiber, the method reduces identically to the standard diffusion tensor method. The method is applied to normal volunteer brain data collected with a stimulated echo spiral high angular resolution diffusion‐weighted (HARD) acquisition. Magn Reson Med 47:1083–1099, 2002. Published 2002 Wiley‐Liss, Inc.
Single‐point (constant‐time) imaging in radiofrequency Fourier transform electron paramagnetic resonance†
Authors: Subramanian Sankaran , Devasahayam Nallathamby , Murugesan Ramachandran , Yamada Kenichi , Cook John , Taube Andrew , Mitchell James B. , Lohman Joost A.B. , Krishna Murali C. 
Published: October 2002

AbstractThis study describes the use of the single‐point imaging (SPI) modality, also known as constant‐time imaging (CTI), in radiofrequency (RF) Fourier transform (FT) electron paramagnetic resonance (EPR). The SPI technique, commonly used for high‐resolution solid‐state nuclear magnetic resonance (NMR) imaging, has been successfully applied to 2D and 3D RF‐FT‐EPR imaging of phantoms containing narrow‐line EPR spin probes. The SPI scheme is essentially a phase‐encoding technique that operates by acquiring a single data point in the free induction decay (FID) after a fixed delay (phase‐encoding time), following the pulsed RF excitation, in the presence of static magnetic field gradients. Since the phase‐encoding time remains constant for a given image data set, the spectral information is automatically deconvolved, providing well‐resolved pure spatial images. Therefore, images obtained using SPI are artifact‐free and the resolution is not significantly limited by the line width, compared to the images obtained using the conventional filtered back‐projection (FBP) scheme, suggesting that the SPI modality may have advantages for EPR imaging of large objects. In this work the advantages and limitations of SPI as compared to FBP are investigated by imaging suitable phantom objects. Although SPI takes longer to perform than the FBP method, optimization of the data collection scheme may increase the temporal resolution, rendering this technique suitable for in vivo studies. Spectral information can also be extracted from a series of SPI images that are generated as a function of the delay from the excitation pulse. Magn Reson Med 48:370–379, 2002. Published 2002 Wiley‐Liss, Inc.
Time‐resolved contrast‐enhanced imaging with isotropic resolution and broad coverage using an undersampled 3D projection trajectory
Authors: Barger Andrew V. , Block Walter F. , Toropov Yuriy , Grist Thomas M. , Mistretta Charles A. 
Published: October 2002

AbstractTime‐resolved contrast‐enhanced 3D MR angiography (MRA) methods have gained in popularity but are still limited by the tradeoff between spatial and temporal resolution. A method is presented that greatly reduces this tradeoff by employing undersampled 3D projection reconstruction trajectories. The variable density k‐space sampling intrinsic to this sequence is combined with temporal k‐space interpolation to provide time frames as short as 4 s. This time resolution reduces the need for exact contrast timing while also providing dynamic information. Spatial resolution is determined primarily by the projection readout resolution and is thus isotropic across the FOV, which is also isotropic. Although undersampling the outer regions of k‐space introduces aliased energy into the image, which may compromise resolution, this is not a limiting factor in high‐contrast applications such as MRA. Results from phantom and volunteer studies are presented demonstrating isotropic resolution, broad coverage with an isotropic field of view (FOV), minimal projection reconstruction artifacts, and temporal information. In one application, a single breath‐hold exam covering the entire pulmonary vasculature generates high‐resolution, isotropic imaging volumes depicting the bolus passage. Magn Reson Med 48:297–305, 2002. © 2002 Wiley‐Liss, Inc.
Multiecho segmented EPI with z‐shimmed background gradient compensation (MESBAC) pulse sequence for fMRI
Authors: Li Zhu , Wu Gaohong , Zhao Xiaoli , Luo Feng , Li Shi‐Jiang 
Published: October 2002

AbstractA MultiEcho Segmented EPI with z‐shimmed BAckground gradient Compensation (MESBAC) pulse sequence is proposed and validated for functional MRI (fMRI) study in regions suffering from severe susceptibility artifacts. This sequence provides an effective tradeoff between spatial and temporal resolution and reduces image distortion and signal dropout. The blood oxygenation level‐dependent (BOLD)‐weighted fMRI signal can be reliably obtained in the region of the orbitofrontal cortex (OFC). To overcome physiological motion artifacts during prolonged multisegment EPI acquisition, two sets of navigator echoes were acquired in both the readout and phase‐encoding directions. Ghost artifacts generally produced by single‐shot EPI acquisition were eliminated by separately placing the even and odd echoes in different k‐space trajectories. Unlike most z‐shim methods that focus on increasing temporal resolution for event‐related functional brain mapping, the MESBAC sequence simultaneously addresses problems of image distortion and signal dropout while maintaining sufficient temporal resolution. The MESBAC sequence will be particularly useful for pharmacological and affective fMRI studies in brain regions such as the OFC, nucleus accumbens, amygdala, parahippocampus, etc. Magn Reson Med 48:312–321, 2002. © 2002 Wiley‐Liss, Inc.
Brainstem reflexes: Electrodiagnostic techniques, physiology, normative data, and clinical applications
Authors: Aramideh M. , Ongerboer De Visser B.W. 
Published: October 2002

AbstractAn overview is provided on the physiological aspects of the brainstem reflexes as they can be examined by use of clinically applicable neurophysiological tests. Brainstem reflex studies provide important information about the afferent and efferent pathways and are excellent physiological tools for the assessment of cranial nerve nuclei and the functional integrity of suprasegmental structures. In this review, the blink reflex after trigeminal and nontrigeminal inputs, corneal reflex, levator palpebrae inhibitory reflex, jaw jerk, masseter inhibitory reflex, and corneomandibular reflex are discussed. Following description of the recording technique, physiology, central pathways, and normative data of these reflexes, including an account of the recording of recovery curves, the application of these reflexes is reviewed in patients with various neurological abnormalities, including trigeminal pain and neuralgia, facial neuropathy, and brainstem and hemispherical lesions. Finally, simultaneous electromyographic recording from the orbicularis oculi and the levator palpebrae muscles is discussed briefly in different eyelid movement disorders. © 2002 Wiley Periodicals Inc. Muscle Nerve 26: 14–30, 2002
Central fatigue and motor cortical excitability during repeated shortening and lengthening actions
Authors: Löscher Wolfgang N. , Nordlund Maria M. 
Published: October 2002

AbstractA decline in voluntary muscle activation and adaptations in motor cortical excitability contribute to the progressive decline in voluntary force during sustained isometric contractions. However, the neuronal control of muscle activation differs between isometric and dynamic contractions. This study was designed to investigate voluntary activation, motor cortex excitability, and intracortical inhibition during fatiguing concentric and eccentric actions. Eight subjects performed 143 torque motor–controlled, repeated shortening and lengthening actions of the elbow flexor muscles. Transcranial magnetic stimulation (TMS) was applied three times every 20 cycles. Magnetic evoked motor potentials (MEP), duration of the silent period (SP), and the torque increase due to TMS were analyzed. TMS resulted in a small torque increase in unfatigued actions. With repeated actions, voluntary torque dropped rapidly and the amplitude of the TMS‐induced twitches increased, especially during repeated lengthening actions. MEP area of biceps brachii and brachioradialis muscles increased during repeated actions to a similar extent during lengthening and shortening fatigue. The duration of biceps and brachioradialis SP did not change with fatigue. Thus, voluntary activation became suboptimal during fatiguing dynamic actions and motor cortex excitability increased without any changes in intracortical inhibition. The apparent dissociation of voluntary activation and motor cortex excitability suggests that the central fatigue observed, especially during lengthening actions, did not result from changes in motor cortex excitability. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Mechanisms of force failure during repetitive maximal efforts in a human upper airway muscle
Authors: DelloRusso Christiana , Khurana Nilam , Rankin Lucinda , Sullivan Jenna , Fregosi Ralph F. 
Published: October 2002

AbstractThe upper airway respiratory muscles play an important role in the regulation of airway resistance, but surprisingly little is known about their contractile properties and endurance performance. We developed a technique that allows measurement of force and the electromyogram (EMG) of human nasal dilator muscles (NDMs). Endurance performance was quantified by measuring NDM “flaring” force and EMG activity as healthy human subjects performed 10 s maximal voluntary contractions (MVCs), separated by 10 s rest, until the area under the force curve fell to 50% MVC (the time limit of the fatigue task, Tlim), which was reached in 34.2 ± 3.1 contractions (685.0 ± 62.3 s). EMG activity was unchanged except at Tlim, where it averaged 78.7 ± 3.6% of pretest activity (P < 0.01). M‐wave amplitude did not change, suggesting that neuromuscular propagation was not impaired. MVC force increased to 80% of the pretest level within 10 min of recovery but twitch force failed to recover, suggesting low‐frequency fatigue. The data suggest that a failure of the nervous system to excite muscle could explain at most only a small fraction of the NDM force loss during an intermittent fatigue task, and then only at Tlim. Thus, the majority of the force failure during this task is due to impairment of mechanisms that reside within the muscle fibers. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 94–100, 2002
Small‐fiber neuropathy
Authors: Lacomis David 
Published: October 2002

AbstractSmall‐fiber neuropathy is a common disorder. It is often “idiopathic” and typically presents with painful feet in patients over the age of 60. Autoimmune mechanisms are often suspected, but rarely identified. Known causes of small‐fiber neuropathy include diabetes mellitus, amyloidosis, toxins, and inherited sensory and autonomic neuropathies. Occasionally, small‐fiber neuropathy is diffuse or multifocal. Depending on the type of small‐fiber neuropathy, autonomic dysfunction can be significant or subclinical. Diagnosis is made on the basis of the clinical features, normal nerve conduction studies, and abnormal specialized tests of small‐fiber function. These specialized studies include assessment of epidermal nerve fiber density as well as sudomotor, quantitative sensory, and cardiovagal testing. The sensitivities of these tests range from 59–88%. Each has certain advantages and disadvantages, and the tests may be complementary. Unless an underlying disease is identified, treatment is usually directed toward alleviation of neuropathic pain. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 173–188, 2002
Conduction slowing in diabetic distal polyneuropathy
Authors: Herrmann David N. , Ferguson Michele L. , Logigian Eric L. 
Published: October 2002

AbstractThe pathophysiologic significance of motor conduction slowing observed in diabetic distal symmetrical polyneuropathy (DSP) remains controversial. We have used multiple linear regression analysis of compound muscle action potential (CMAP) amplitude vs. motor conduction velocity (CV) and distal latency (DL) in 57 patients with diabetic DSP and 34 patients with amyotrophic lateral sclerosis (ALS) to determine whether motor conduction slowing in diabetic DSP is due mainly to loss of large axons as in ALS or whether there is an additional demyelinative component. We found amplitude‐dependent slowing of CV and DL in both diabetic DSP and ALS in the upper and lower extremities, consistent with a loss of large myelinated fibers. However, in diabetic DSP, there was also significant amplitude‐independent slowing in intermediate but not distal nerve segments, supportive of an additional demyelinative component. CMAP amplitude vs. CV and DL regression analyses using ALS as a control group for relatively pure axon loss may provide pathophysiologic information about motor nerves in other neuropathic disorders. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 232–237, 2002
Tensor visualizations in computational geomechanics
Authors: Jeremić Boris , Scheuermann Gerik , Frey Jan , Yang Zhaohui , Hamann Bernd , Joy Kenneth I. , Hagen Hans 
Published: October 2002

AbstractWe present a novel technique for visualizing tensors in three dimensional (3D) space. Of particular interest is the visualization of stress tensors resulting from 3D numerical simulations in computational geomechanics. To this end we present three different approaches to visualizing tensors in 3D space, namely hedgehogs, hyperstreamlines and hyperstreamsurfaces. We also present a number of examples related to stress distributions in 3D solids subjected to single and load couples. In addition, we present stress visualizations resulting from single‐pile and pile‐group computations. The main objective of this work is to investigate various techniques for visualizing general Cartesian tensors of rank 2 and it's application to geomechanics problems. Copyright © 2002 John Wiley & Sons, Ltd.
The least‐squares finite element method in elasticity—Part I: Plane stress or strain with drilling degrees of freedom
Authors: Jiang Bo‐nan , Wu Jie 
Published: October 2002

AbstractA new least‐squares finite element method (LSFEM) for plane elasticity problems is developed based on the first‐order displacement–stress–rotation formulation which includes two new first‐order compatibility constraints among the stresses and the drilling rotation. This LSFEM can accommodate all kinds of equal‐order interpolations. Numerical experiments on various examples including incompressible materials show that the method achieves an optimal rate of convergence for all variables. Copyright © 2001 John Wiley & Sons, Ltd.
An efficient multi‐layer planar 3D fracture growth algorithm using a fixed mesh approach
Authors: Siebrits Eduard , Peirce Anthony P. 
Published: October 2002

AbstractWe present a planar three‐dimensional (3D) fracture growth simulator, based on a displacement discontinuity (DD) method for multi‐layer elasticity problems. The method uses a fixed mesh approach, with rectangular panel elements to represent the planar fracture surface. Special fracture tip logic is included that allows a tip element to be partially fractured in the tip region. The fracture perimeter is modelled in a piece‐wise linear manner. The algorithm can model any number of interacting fractures that are restricted to lie on a single planar surface, located orthogonal to any number of parallel layers. The multiple layers are treated using a Fourier transform (FT) approach that provides a numerical Green's function for the DD scheme. The layers are assumed to be fully bonded together. Any fracture growth rule can be postulated for the algorithm. We demonstrate this approach on a number of test problems to verify its accuracy and efficiency, before showing some more general results. Copyright © 2001 John Wiley & Sons, Ltd.
Detection of bifurcation points along a curve traced by a continuation method
Authors: Lopez S. 
Published: October 2002

AbstractThe methods for computing the singular points based on approximations of the equilibrium curve by asymptotic extrapolation usually have a limited range of validity. This is because the power series are only built on the local properties of the primary solution branch. This paper suggests ways to improve such a situation: the asymptotic extrapolation is used in the predictor phase of a continuation method and an effective parametrization equation is adopted. In this way the description of the equilibrium curve between two consecutive solution points is improved while the local nature of the extrapolation is retained. The bifurcation points computed on the extrapolation are then used to initialize a classical method for the detection of the bifurcation points on the exact equilibrium curve. Moreover the accurate location of the limit points is an immediate consequence of the precision obtained in the description of the solution curve in the predictor–corrector step. Overall the computational cost of the analysis is appreciably reduced. In effect a low number of predictor–corrector steps are required to complete the description of the solution curve and most of the computations performed in the detection of bifurcation points are carried out on the extrapolation. The good initialization obtained also makes Newton's classical method for calculating the bifurcation points on the exact equilibrium curve more reliable with regard to the convergence. Generalization to cases of more bifurcation points within two consecutive solution points is then obtained by a non‐linear subspace procedure defined on the asymptotic extrapolation. Applications to frame structures and cylindrical shells analysis are presented. Copyright © 2001 John Wiley & Sons, Ltd.
Higher‐order accurate time‐step‐integration algorithms by post‐integration techniques
Authors: Fung T. C. 
Published: October 2002

AbstractIn this paper, a framework to construct higher‐order‐accurate time‐step‐integration algorithms based on the post‐integration techniques is presented. The prescribed initial conditions are naturally incorporated in the formulations and can be strongly or weakly enforced. The algorithmic parameters are chosen such that unconditionally A‐stable higher‐order‐accurate time‐step‐integration algorithms with controllable numerical dissipation can be constructed for linear problems. Besides, it is shown that the order of accuracy for non‐linear problems is maintained through the relationship between the present formulation and the Runge–Kutta method. The second‐order differential equations are also considered. Numerical examples are given to illustrate the validity of the present formulation. Copyright © 2001 John Wiley & Sons, Ltd.
Three‐dimensional finite element calculations in acoustic scattering using arbitrarily shaped convex artificial boundaries
Authors: Tezaur Radek , Macedo Antonini , Farhat Charbel , Djellouli Rabia 
Published: October 2002

AbstractWe report on a generalization of the Bayliss–Gunzburger–Turkel non‐reflecting boundary conditions to arbitrarily shaped convex artificial boundaries. For elongated scatterers such as submarines, we show that this generalization can improve significantly the computational efficiency of finite element methods applied to the solution of three‐dimensional acoustic scattering problems. Copyright © 2001 John Wiley & Sons, Ltd.
On non‐linear behaviour of spherical shallow shells bonded with piezoelectric actuators by the differential quadrature element method (DQEM)
Authors: Wang Xinwei , Wang Yongliang 
Published: October 2002

AbstractThe static behaviour of spherical shallow shells bonded with piezoelectric actuators and subjected to electrical loading are studied in this paper by using the differential quadrature element method (DQEM). Geometrical non‐linear effects are considered. Detailed formulations for the DQ circular spherical shallow shell element and the DQ annular spherical shallow shell element are given for the first time. Numerical studies are performed to evaluate the effects of actuator size, thickness and boundary conditions. Very accurate results are obtained by the DQEM. Based on the results reported in this paper, one may conclude that the DQEM is a useful tool for obtaining solutions for smart materials and structures exhibiting geometric non‐linear behaviours. Thickness effects cannot be neglected when the actuator thickness is comparable to that of the base material. Snap‐through may occur when the applied voltage reaches a critical value even without mechanical loading for certain geometric configurations. Copyright © 2001 John Wiley & Sons, Ltd.
Stress analysis of gear teeth using displacement potential function and finite differences
Authors: Akanda M. A. Salam , Ahmed S. Reaz , Uddin M. Wahhaj 
Published: October 2002

AbstractA new numerical approach has been developed for the analysis of displacements and stresses in arbitrary‐shaped elastic bodies subjected to mixed boundary conditions. An ideal mathematical model, based on the displacement‐potential function, has been used in the finite‐difference solution to investigate the state of stresses at the critical sections of spur gear teeth. Two different types of gear tooth and two different regions of loading are included in the present analysis. The solutions found by the present approach are compared and discussed in the light of available finite‐element results in the literature. Copyright © 2001 John Wiley & Sons, Ltd.