bluuebunny/crossref_metadata_2025_split huggingface dataset:
Partial characterization of the factor in theca‐cell conditioned medium that inhibits the progression of FSH‐induced meiosis of bovine oocytes surrounded by cumulus cells connected to the membrana granulosa
Authors: van Tol H.T.A. , Bevers M.M. 
Published: August 2002

AbstractA factor, secreted by theca cells, inhibits FSH induced resumption of meiosis in bovine oocytes that are surrounded by cumulus cells which are attached to a piece of the membrana granulosa (COCGs). In order to characterize this factor, theca cell conditioned medium (CMt) was heat‐treated, filtered through a 5 kD spin off filter, charcoal treated, chloroform extracted and protease treated. To investigate whether the meiosis inhibiting factor produced by theca cells was also present in follicular fluid (FF), the same traetments were done with 50% bovine follicular fluid (bFF). COCGs, originating from 2 to 8 mm follicles of bovine ovaries collected at a slaughterhouse, were cultured in groups of 15 per 600 µl medium supplemented with 0.05 IU ml FSH for 22 hr at 39°C in a humidified atmosphere of 5% CO2. After culture the oocytes were denuded, stained with orcein, and the nuclear status assessed. Heat treatment did not affect the meiosis arresting capacity of CMt since a similar proportion of the oocytes remained at the GV stage after 22 hr of culture in heat treated CMt as compared to the proportion of oocytes in the GV stage after culture in untreated CMt. Filtering through a 5 kD spin‐off filter revealed that the meiosis inhibiting action was maintained in the <5 kD fraction, although there was a significant (P < 0.05) loss of inhibiting activity compared to nonfiltered CMt. No significant decrease was observed in the meiosis arresting capacity of the <5 kD fraction after charcoal or protease treatment. Extraction of the <5 kD fraction with chloroform also did not affect the theca cell produced factor. The effect of the theca cell factor on the progression of meiosis of the oocytes that resumed meiosis, as demonstrated by a very low percentage of the oocytes that matured up to the M2 stage, was not affected following any of the treatments. With regard to bFF, the results show a lower percentage of the oocytes in the GV stage after culture in 50% bFF as compared to culture in CMt, but progression of meiosis was clearly inhibited as demonstrated by a significant higher proportion of the oocytes blocked in the M1 stage after resumption of meiosis. In general, with regard to meiotic inhibition, bFF showed the same pattern as CMt following the various treatments. It is concluded that the theca cell secreted factor which inhibits the FSH‐induced resumption of meiosis in COCGs is a small, stable, polar molecule which is not a peptide. Mol. Reprod. Dev. 60:418‐424, © 2001 Wiley‐Liss, Inc.
Oscillating dual‐equilibrium steady‐state angiography
Authors: Overall William R. , Conolly Steven M. , Nishimura Dwight G. , Hu Bob S. 
Published: August 2002

AbstractA novel technique of generating noncontrast angiograms is presented. This method, called oscillating dual‐equilibrium steady‐state angiography (ODESSA), utilizes a modified steady‐state free precession (SSFP) pulse sequence. The SSFP sequence is modified such that flowing material reaches a steady state which oscillates between two equilibrium values, while stationary material attains a single, nonoscillatory steady state. Subtraction of adjacent echoes results in large, uniform signal from all flowing spins and zero signal from stationary spins. Venous signal can be suppressed based on its reduced T2. ODESSA arterial signal is more than three times larger than that of traditional phase‐contrast angiography (PCA) in the same scan time, and also compares favorably with other techniques of MR angiography (MRA). Pulse sequences are implemented in 2D, 3D, and volumetric‐projection modes. Angiograms of the lower leg, generated in as few as 5 s, show high arterial signal‐to‐noise ratio (SNR) and full suppression of other tissues. Magn Reson Med 47:513–522, 2002. © 2002 Wiley‐Liss, Inc.
Bayesian technique for investigating linearity in event‐related BOLD fMRI
Authors: Kershaw Jeff , Kashikura Kenichi , Zhang Xiaojiang , Abe Sumiko , Kanno Iwao 
Published: August 2002

AbstractEvent‐related BOLD fMRI data is modeled as a linear time‐invariant system. Together with Bayesian inference techniques, a statistical test is developed for rigorously detecting linearity/nonlinearity in the BOLD response system. The test is applied to data collected from eight subjects using an event‐related paradigm with a switching checkerboard as the visual stimulus. Analyzed as a group, the results clearly find the response to be nonlinear. When each subject is analyzed individually, however, the results are predominantly nonlinear, but there is some evidence to suggest that there may be a crossover from a linear to a nonlinear regime and vice versa. This could be important when estimating physiological parameters for individuals. Additionally, estimates of the hemodynamic response function and corresponding response were obtained, but there was no consistent appearance of a poststimulus undershoot in the event‐related BOLD response. Magn Reson Med 45:1081–1094, 2001. © 2001 Wiley‐Liss, Inc.
Comments on “Gradient‐Induced Acoustic and Magnetic Field Fluctuations in a 4T Whole‐Body MR Imager”
Authors: Barnett Alan 
Published: August 2002

AbstractThe results published in the article Gradient‐Induced Acoustic and Magnetic Field Fluctuations in a 4T Whole‐Body MR Imager by Wu et al. (Magn Reson Med 2000;44:532–536) appear to be consistent with the response of a time‐stationary linear system. Since a linear system is more simply described than a nonlinear system, the authors are urged to reanalyze their data to test the linear‐system hypothesis. Magn Reson Med 46:207, 2001. Published 2001 Wiley‐Liss, Inc.
Qualitative and quantitative changes in acetylcholine receptor distribution at the neuromuscular junction following free muscle transfer
Authors: Hua Jiang , Samuel Tay Sam Wah , Kumar V.P. 
Published: August 2002

AbstractThe qualitative and quantitative changes in acetylcholine receptor distribution were studied in the gracilis muscle of the Wistar rat following free neurovascular transfer. Even at 30 weeks after transfer, the morphology of the neuromuscular junction failed to return to the presurgical state. The number of acetylcholine receptors at the reinnervated neuromuscular junction also remained lower than the control. The persistent weakness following free neurovascular muscle transfer may be attributed to these qualitative and quantitative changes at the neuromuscular junction. © 2002 Wiley Periodicals Inc. Muscle Nerve 25: 000–000, 2002
Block of recombinant nicotinic receptor channels by IgG from myasthenic patients
Authors: Krampfl Klaus , Dengler Reinhard , Bufler Johannes 
Published: August 2002

AbstractIn myasthenia gravis (MG), specific antibodies directed against nicotinic acetylcholine receptor (nAChR) channels are produced. Recently, a distinct blockade of native embryonic‐type nAChR channels by purified IgG from MG patients has been demonstrated. In the present study, we investigated the interaction of myasthenic IgG with recombinant embryonic‐ or adult‐type nAChR channels expressed on human embryonic kidney (HEK) 293 cells. For the experiments, the patch clamp technique was applied in combination with an ultra‐fast application system for agonists. Repetitive 20‐ms pulses of 1 mM acetylcholine (ACh) were applied with or without purified IgG added to the perfusion system. The purified IgG from MG patients blocked currents through both, embryonic‐ and adult‐type nAChR channels to a similar extent. A block by myasthenic IgG of adult‐type nAChR channels, which are present exclusively at the postsynaptic membrane of the neuromuscular synapse, was shown to occur. The reversible pharmacological blockade of adult‐type nAChR channels by myasthenic IgG may be one factor responsible for rapid fluctuations of weakness or rapid recovery of muscle strength after plasmapheresis in MG. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Metabolic costs of force generation for constant‐frequency and catchlike‐inducing electrical stimulation in human tibialis anterior muscle
Authors: Ratkevicius Aivaras , Quistorff Bjørn 
Published: August 2002

AbstractMetabolic costs of force generation were compared for constant‐frequency and catchlike‐inducing electrical stimulation. Repetitive catchlike‐inducing trains consisted of 2 interpulse intervals (IPIs) at 12.5 ms, 1 IPI at 25 ms, and 5 IPIs at 50 ms. Constant‐frequency trains consisted of 8 IPIs at 37.5 ms. One train was delivered to the peroneal nerve every 2.5 s for 36 times under ischemic conditions. Anaerobic adenosine triphosphate (ATP) turnover was determined using 31‐phosphorus magnetic resonance spectroscopy (P‐MRS) of the human tibialis anterior muscle. Compared with constant‐frequency trains, catchlike‐inducing trains produced a faster force generation and were more effective in maintaining the force–time integral as well as peak force. However, ATP costs of force generation were similar for the catchlike‐inducing and constant‐frequency stimulation (6.7 ± 1.1 and 6.6 ± 1.0 μmol ATP/kg wet weight/N·s, respectively, P = 0.601). This suggests that the positive effects of catchlike‐inducing stimulation on force maintenance are mediated by potentiated Ca2+ release from the sarcoplasmic reticulum rather than by lower metabolic costs of muscle force generation. Our findings also suggest that catchlike‐inducing stimulation produces larger forces in fatigued muscle than constant‐frequency trains and thus may be beneficial for muscle training or rehabilitation when muscle loading needs to be maintained in repetitive contractions. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Effects of training on contractile properties of paralyzed quadriceps muscle
Authors: Gerrits H.L. , Hopman M.T.E. , Sargeant A.J. , Jones D.A. , De Haan A. 
Published: August 2002

AbstractEffects of two different training regimens on the contractile properties of the quadriceps muscle were studied in six individuals with spinal cord injury. Each subject had both limbs trained with the two regimens, consisting of stimulation with low frequencies (LF) at 10 HZ or high frequencies (HF) at 50 HZ; one limb of each subject was stimulated with the LF protocol and the other with the HF regimen. Twelve weeks of daily training increased tetanic tension by ∼20%, which was not significantly different between training regimens. Interestingly, after HF but not LF training, the unusual high forces at the low frequency range of the force–frequency relationship decreased, possibly due to a reduced activation per impulse. After LF but not HF training, force oscillation amplitudes declined (by 33%) as relaxation tended to slow, which may have opposed possible effects of reduced activation as seen after HF training. Finally, fatigue resistance also increased rapidly after LF training (by 43%) but not after HF training. These results indicate that different types of training may selectively change different aspects of function in disused muscles. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
When to use the combined sensory index
Authors: Kaul Matthew P. , Pagel Keith J. , Dryden John D. 
Published: August 2002

AbstractA recently developed electrodiagnostic technique, the combined sensory index (CSI), has been recommended for its greater sensitivity in diagnosing carpal tunnel syndrome (CTS). The CSI requires a greater number of procedures and therefore involves greater time, cost, and patient discomfort than does conventional electrodiagnostic testing. The CSI is composed of three commonly used electrodiagnostic techniques. There is a close correlation between the components of the CSI, and in most cases, all three components of the CSI are in agreement. We performed a study to develop and validate an algorithm that could be used to identify subsets of patients with CTS in whom CSI testing is particularly useful. Subjects were consecutive outpatient veterans referred by a heterogeneous group of specialists and generalists for electrodiagnostic evaluation of paresthesias in a median distribution with nocturnal exacerbation of symptoms. The CSI served as our gold standard. Using our simple algorithm, we found that in approximately 95% of cases, it was unnecessary to perform the CSI. This management strategy improves patient comfort and reduces electrodiagnostic cost while identifying the minority of patients for whom the CSI is indicated. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1078–1082, 2001
Parameter identification for a suction‐dependent plasticity model
Authors: Simoni L. , Schrefler B. A. 
Published: August 2002

AbstractIn this paper, the deterministic parameter identification procedure proposed in a companion paper is applied to suction‐dependent elasto‐plasticity problems. A mathematical model for such type of problems is firstly presented, then it is applied to the parameter identification using laboratory data. The identification procedure is applied in a second example to exploitation of a gas reservoir. The effects of the extraction of underground fluids appear during and after quite long periods of time and strongly condition the decision to profit or not of the natural resources. Identification procedures can be very useful tools for reliable long‐term predictions. Copyright © 2001 John Wiley & Sons, Ltd.
A constitutive model for the dynamic and high‐pressure behaviour of a propellant‐like material: Part II: Model development and applications
Authors: Trumel Harvé , Dragon André , Fanget Alain , Lambert Philippe 
Published: August 2002

AbstractThis paper presents the second part of a work that aims at developing a mechanical model for the behaviour of propellant‐like materials under high confining pressure and strain rate. The model is to be employed to determine the temperature rise due to mechanical dissipation during a dynamic penetration event. Using the kinematical and thermodynamic background derived in the first part, a viscoelastic–viscoplastic–compaction model is put forward and identified. Viscoelasticity and compaction refer to the elastomeric nature of the material, while viscoplasticity, including implicit damage through dilatancy, reflects its granular nature. Some numerical exercises are performed, in view of determining the major model forces and weaknesses, and of assessing the numerical algorithm robustness. A penetration event is preliminarily simulated, and a temperature rise field predicted. Necessary model improvements are finally discussed, together with several ways of research for a longer term approach. Copyright © 2001 John Wiley & Sons, Ltd.
A numerical study of flexural buckling of foliated rock slopes
Authors: Adhikary D. P. , Mühlhaus H.‐B. , Dyskin A. V. 
Published: August 2002

AbstractThe occurrence of foliated rock masses is common in mining environment. Methods employing continuum approximation in describing the deformation of such rock masses possess a clear advantage over methods where each rock layer and each inter‐layer interface (joint) is explicitly modelled. In devising such a continuum model it is imperative that moment (couple) stresses and internal rotations associated with the bending of the rock layers be properly incorporated in the model formulation. Such an approach will lead to a Cosserat‐type theory. In the present model, the behaviour of the intact rock layer is assumed to be linearly elastic and the joints are assumed to be elastic–perfectly plastic. Condition of slip at the interfaces are determined by a Mohr–Coulomb criterion with tension cut off at zero normal stress. The theory is valid for large deformations. The model is incorporated into the finite element program AFENA and validated against an analytical solution of elementary buckling problems of a layered medium under gravity loading. A design chart suitable for assessing the stability of slopes in foliated rock masses against flexural buckling failure has been developed. The design chart is easy to use and provides a quick estimate of critical loading factors for slopes in foliated rock masses. It is shown that the model based on Euler's buckling theory as proposed by Cavers (Rock Mechanics and Rock Engineering 1981; 14:87–104) substantially overestimates the critical heights for a vertical slope and underestimates the same for sub‐vertical slopes. Copyright © 2001 John Wiley & Sons, Ltd.
Characterizing the bit permutation networks obtained from the line digraphs of bit permutation networks
Authors: Hwang Frank K. , Yen Chih‐Hung 
Published: August 2002

AbstractA bit permutation network is an s‐stage interconnection network composed of dn−1 d × d crossbar switches in each stage. This class of networks includes most of the multistage interconnection networks. Recently, Chang et al. [Networks 33 (1999), 261–267] showed that an s‐stage d‐nary bit permutation network N with dn inputs (outputs) can be characterized by an (s − 1)‐vector (k1, …, ks−1), where kt ∈ {1, …, n − 1}. In this paper, we give a simple (but not trivial) formula to determine the characteristic vector of a new network G(N)+, which is, approximately, the line digraph of N. We use this formula to obtain relations between some well‐studied bit permutation networks. © 2001 John Wiley & Sons, Inc.
An algorithm for constructing minimal c‐broadcast networks
Authors: Lee Shiwoo , Ventura José A. 
Published: August 2002

Abstractc‐Broadcasting is a special process to disseminate a single message, originated at any node in a network, to all other nodes of the network by letting each informed node transmit the message to at most c neighbors simultaneously. A minimal c‐broadcast network (c‐mbn) is a communication network in which c‐broadcasting can be completed in minimum time from any node. An optimal c‐broadcast network (c‐obn) is a c‐mbn with the smallest number of edges. Previous studies showed that c‐obn's are extremely difficult to find. A network compounding algorithm is proposed to construct sparse c‐mbn's with n1n2 − i nodes by connecting a subset of nodes from several copies of a c‐mbn with n1 nodes using the structure of another c‐mbn with n2 nodes, such that n1 ≥ 1 and 0 ≤ i < n2, satisfying ⌈logc+1(n1n2 − i)⌉ = ⌈logc+1 n1⌉ + ⌈logc+1n2⌉. Computational results are also provided. © 2001 John Wiley & Sons, Inc.
Testosterone treatment increases the metabolic capacity of adult avian song control nuclei
Authors: Wennstrom Kira L. , Reeves Brendan J. , Brenowitz Eliot A. 
Published: August 2002

AbstractIn songbirds, the size of brain nuclei that control song learning and production change seasonally. These changes are mainly controlled by seasonal changes in plasma testosterone (T) concentration. One hypothesis to explain why it may be adaptive for these areas to regress in the fall is that this would decrease the metabolic demand of maintaining a large song system when singing is reduced or absent. We used a marker for cellular metabolism to examine birds with regressed song nuclei and compared them to birds whose song nuclei were induced to grow by administration of exogenous T. Photorefractory male Gambel's white‐crowned sparrows were captured during their autumnal migration and kept in outdoor aviaries on a natural photoperiod. We implanted birds with Silastic™ capsules containing T or with empty implants. Three weeks later the birds were sacrificed. We assayed the brains for cytochrome oxidase (CO) activity and measured the volume of four song nuclei: HVc, RA, 1MAN, and area X. All four nuclei increased in volume in response to T treatment. T treatment increased the metabolic capacity of area X, HVc, and RA relative to surrounding tissue but had no effect on the metabolic capacity of 1MAN. These results support the hypothesis that song nuclei are more metabolically active under the influence of T than they are when plasma T levels are low. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 256–264, 2001
Ovariectomy attenuates dendritic growth in hormone‐sensitive spinal motoneurons
Authors: Hebbeler S. L. , Verhovshek T. , Sengelaub D. R. 
Published: August 2002

AbstractThe lumbar spinal cord of rats contains the sexually dimorphic, steroid‐sensitive spinal nucleus of the bulbocavernosus (SNB). Dendritic development of SNB motoneurons in male rats is biphasic, initially showing exuberant growth through 4 weeks of age followed by a retraction to mature lengths by 7 weeks of age. The initial growth is steroid dependent, attenuated by castration or aromatase inhibition, and supported by hormone replacement. Dendritic retraction is also steroid sensitive and can be prevented by testosterone treatment, but is unaffected by aromatase inhibition. Together, these results suggest a role for estrogens during the initial growth phase of SNB development. In this study, we tested whether ovarian hormones could support SNB somal and dendritic development. Motoneuron morphology was assessed in normal males and in females perinatally masculinized with dihydrotestosterone and then either ovariectomized or left intact. SNB motoneurons were retrogradely labeled with cholera toxin‐HRP at 4 or 7 weeks of age and reconstructed in three dimensions. Initial growth of SNB dendrites was reduced after ovariectomy in masculinized females. However, no differences in dendritic length were seen at 7 weeks of age between intact and ovariectomized masculinized females, and lengths in both groups were significantly lower than those of normal males. Together with previous findings, these results suggest that estrogens are involved in the early growth of SNB dendrites, but not in their subsequent retraction. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 301–314, 2001
Developmental changes in BDNF protein levels in the hamster retina and superior colliculus
Authors: Frost Douglas O. , Ma Yun‐Tao , Hsieh Ted , Forbes M. Elizabeth , Johnson James E. 
Published: August 2002

AbstractQuantitative studies of ontogenetic changes in the levels of brain‐derived neurotrophic factor (BDNF) mRNA and its effector, BDNF protein, are not available for the retinal projection system. We used an electrochemiluminescence immunoassay to measure developmental changes in the tissue concentration of BDNF within the hamster retina and superior colliculus (SC). In the SC, we first detected BDNF (about 9 pg/mg tissue) on embryonic day 14 (E14). BDNF protein concentration in the SC rises about fourfold between (E14) and postnatal day 4 (P4), remains at a plateau through P15, then declines by about one‐third to attain its adult level by P18. By contrast, BDNF protein concentration in the retina remains low (about 1 pg/mg tissue) through P12, then increases 4.5‐fold to attain its adult level on P18. The developmental changes in retinal and collicular BDNF protein concentrations are temporally correlated with multiple events in the structural and functional maturation of the hamster retinal projection system. Our data suggest roles for BDNF in the cellular mechanisms underlying some of these events and are crucial to the design of experiments to examine those roles. © 2001 John Wiley & Sons, Inc. J Neurobiol 49: 173–187, 2001