bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiotherapy for medulloblastoma in children: A perspective on current international clinical research efforts
Authors: Freeman Carolyn R. , Taylor Roger E. , Kortmann Rolf‐Dieter , Carrie Christian 
Published: October 2002

AbstractBackgroundThe North America and four European pediatric cooperative groups have undertaken prospective studies for medulloblastoma continuously since the 1970s. In this article, we will review the results of these studies with respect specifically to the use of radiotherapy, and trace the developments that have led up to the present trials for patients with this tumor.ProcedurePublished and unpublished data from the North American CCG and POG and now COG studies, from the UKCCG and SIOP groups, as well as from the French and German groups were reviewed. Issues of especial interest included radiotherapy dose and dose fractionation schedules, scheduling of chemotherapy and radiotherapy, and technical aspects of treatment with radiotherapy that might impact on outcome.Results and ConclusionsMuch progress has been made in the management of medulloblastoma in childhood as a consequence of the studies undertaken sequentially by these groups over the past two decades. It now seems clear that chemotherapy plays an important role for all patients. In patients with average risk disease, the use of chemotherapy has allowed a reduction in the dose of radiotherapy to the craniospinal axis and the combination of chemotherapy with radiotherapy appears to have brought about a significant improvement in disease‐free and overall survival in this patient population. Patients with high‐risk disease fare better now than in the past as a consequence of the routine use of aggressive chemotherapy and preliminary data suggest that the use of higher doses of radiation as in the POG studies is associated with a particularly favorable outcome. Accurate delivery of radiotherapy is essential for optimal results. The avail‐ability of better tools at the treating centres and quality control as an integral part of cooperative studies are likely to bring about further improvements in outcome in the future. Med Pediatr Oncol 2002;39:99–108. © 2002 Wiley‐Liss, Inc.
Long‐term survival of children with neuroblastoma prior to the neuroblastoma screening project in Germany
Authors: Burkhardt‐Hammer Tatjana , Spix Claudia , Brenner Hermann , Kaatsch Peter , Berthold Frank , Hero Barbara , Michaelis Jörg 
Published: October 2002

AbstractBackgroundIn the last decades, prognosis of children with neuroblastoma has improved only slightly. Traditional estimates of survival reflect the survival experience of children diagnosed many years ago, and may thus not capture more recent progress in prognosis. We applied a new method of survival analysis, denoted period analysis, to provide more up‐to‐date estimates of long‐term prognosis. We selected the cases diagnosed before the German neuroblastoma screening project in 1995, allowing to assess the method by comparing the 1994 projected survival estimates with the observations made today (2000).ProcedureThe data comes from the population based German Childhood Cancer Registry. We included all 1,353 children diagnosed with neuroblastoma below age 15 between 1980 and 1994. We derived 5‐, 10‐, and 15‐year survival estimates using traditional analysis or period analysis as needed. Where possible we compared the period analysis estimates with the later obtained actual estimates. We showed trends in survival for the sample as a whole and for prognostic subgroups.ResultsSurvival probabilities increased over time especially in the subgroups with poor prognosis. Short‐term survival probabilities improved more than long‐term survival probabilities. Evaluation of the period‐analysis estimates showed them to provide accurate and timely projections of prognosis of newly diagnosed patients.ConclusionsThe results suggest major improvements in prognosis of children with neuroblastoma, even prior to the start of the German neuroblastoma screening project, especially in advanced disease. This could have been disclosed with the application of the period analysis method in 1995 even then with considerable accuracy. We recommend a more widespread application of this method especially in population‐based cancer registries. Med Pediatr Oncol 2002;39:156–162. © 2002 Wiley‐Liss, Inc.
Transient transmission of a transgene in mouse offspring following in vivo transfection of male germ cells
Authors: Celebi Catherine , Auvray Pierrick , Benvegnu Thierry , Plusquellec Daniel , JÉgou Bernard , Guillaudeux Thierry 
Published: October 2002

AbstractSperm‐mediated gene transfer in vertebrates has undergone various developments over the last few years, in different laboratories. In the present study, we microinjected a circular plasmid, carrying the lacZ reporter gene mixed with noncommercial cationic lipids, into the seminiferous tubules of anesthetized adult mice. Histochemical analysis was used to estimate the transfection efficiency 48–96 hr and 40 days after injection. As early as 48–96 hr post‐injection, an efficient transfection was revealed by a β‐galactosidase expression within both immature and differentiated germ cells. By 40 days post‐injection, the specific LacZ expression was restricted to the most immature germ cells in the basal portion of the seminiferous tubules. At this time, some injected males were mated with wild‐type females and the progeny were analyzed by PCR and Southern blot. We showed that the transgene was transmitted to the offspring but remained episomal, as it was found in the tail of the young animals but not at adulthood. Therefore, the plasmid seemed to be lost during the numerous germ cells divisions. This plasmid stayed in some tissues, such as skeletal muscle and cardiac muscle. No integrative forms have yet been found with the use of a circular DNA. Mol. Reprod. Dev. 62:477–482, 2002. © 2002 Wiley‐Liss, Inc.
Neuropathology of Rett syndrome
Authors: Armstrong Dawna Duncan 
Published: October 2002

AbstractRett Syndrome is unlike any other pediatric neurologic disease, and its clinical‐pathologic correlation can not be defined with standard histology techniques. Based on hypotheses suggested by careful clinical observations, the nervous system of the Rett child has been explored utilizing morphometry, golgi preparations, computerized tomography, magnetic resonance imaging, chemistry, immunocytochemistry, autoradiography, and molecular biologic techniques. From these many perspectives we conclude that Rett syndrome is not a typical degenerative disorder, storage disorder, nor the result of gross malformation, infectious or neoplastic processes. There remain regions of the brain that have not been studied in detail but the available data suggest that the neuropathology of Rett syndrome can be summarized as follows: the Rett brain is small for theageand theheightof the patient; it does not become progressively smaller over three to four decades; it has small dendritic trees in pyramidal neurons of layers III and V in selected lobes (frontal, motor, and temporal); it has small neurons with an increased neuronal packing density; it has an immature expression of microtubular protein‐2 and cyclooxygenase; it exhibits a changing pattern of neurotransmitter receptors with an apparent reduction in many neurotransmitters, possibly contributing to some symptomatology. A mutation inMecp2causes this unique disorder of brain development. Neuronal mosaicism for normal and mutatedMecp2produces a consistent phenotype in the classic female patient and a small brain with some preserved islands of function, but with an inability to support hand use and speech. This paper summarizes our current observations about neuropathology of Rett syndrome. MRDD Research Reviews 2002;8:72–76. © 2002 Wiley‐Liss, Inc.
Two‐dimensional spatially‐selective RF excitation pulses in echo‐planar imaging
Authors: Rieseberg Susanne , Frahm Jens , Finsterbusch Jürgen 
Published: October 2002

AbstractTwo‐dimensional spatially‐selective RF (2DRF) excitation pulses were developed for single‐shot echo‐planar imaging (EPI) with reduced field of view (FOV) in the phase‐encoding direction. The decreased number of k‐space lines significantly shortens the length of the EPI echo train. Thus, both gradient‐echo and spin‐echo 2DRF‐EPI images of the human brain at 2.0 T exhibit markedly reduced susceptibility artifacts in regions close to major air cavities. Based on a blipped‐planar trajectory, implementation of a typical 2DRF pulse resulted in a 26‐ms pulse duration, a 5‐mm section thickness, a 40‐mm FOV along the phase‐encoding direction, and a 200‐mm distance of the unavoidable side excitations from the center of the FOV. For the above conditions and at 2 × 2 mm2 resolution, 2DRF‐EPI yielded an echo train length of only 21 ms, as opposed to 102 ms for conventional EPI. This gain in time may be used to achieve higher spatial resolution. For example, spin‐echo 2DRF‐EPI of a 40‐mm FOV at 1 × 1 mm2 resolution led to an echo train of 66 ms. Although the current implementation still lacks user‐friendliness, 2DRF pulses are likely to become a useful addition to the arsenal of advanced MRI tools. Magn Reson Med 47:1186–1193, 2002. © 2002 Wiley‐Liss, Inc.
MRI of the lungs using hyperpolarized noble gases
Authors: Möller Harald E. , Chen X. Josette , Saam Brian , Hagspiel Klaus D. , Johnson G. Allan , Altes Talissa A. , de Lange Eduard E. , Kauczor Hans‐Ulrich 
Published: October 2002

AbstractThe nuclear spin polarization of the noble gas isotopes3He and129Xe can be increased using optical pumping methods by four to five orders of magnitude. This extraordinary gain in polarization translates directly into a gain in signal strength for MRI. The new technology of hyperpolarized (HP) gas MRI holds enormous potential for enhancing sensitivity and contrast in pulmonary imaging. This review outlines the physics underlying the optical pumping process, imaging strategies coping with the nonequilibrium polarization, and effects of the alveolar microstructure on relaxation and diffusion of the noble gases. It presents recent progress in HP gas MRI and applications ranging from MR microscopy of airspaces to imaging pulmonary function in patients and suggests potential directions for future developments. Magn Reson Med 47:1029–1051, 2002. © 2002 Wiley‐Liss, Inc.
Phase coherent averaging in magnetic resonance spectroscopy using interleaved navigator scans: Compensation of motion artifacts and magnetic field instabilities
Authors: Thiel Thorsten , Czisch Michael , Elbel Gregor K. , Hennig Juergen 
Published: October 2002

AbstractThe quality of spectra in 1H magnetic resonance spectroscopy (MRS) is strongly affected by temporal signal instabilities during the acquisition. One reason for these instabilities are hardware imperfections, e.g., drifts of the main magnetic field in superconducting magnets. This is of special concern in high‐field systems where the specification of the field stability is close to the spectral linewidth. A second major potential source of artifacts, particularly in clinical MRS, is patient motion. Using standard acquisition schemes of phase‐cycled averaging of the individual acquisitions, long‐term effects (field drifts) as well as changes on a shorter time scale (motion) can severely reduce spectral quality. The new technique for volume‐selective MRS presented here is based on the additional interleaved acquisition of a navigator signal during the recovery time of the metabolite acquisition. It corrects for temporal signal instabilities by means of a deconvolution of the metabolite and the navigator signal. This leads to phase‐corrected individual metabolite scans and upon summation to a phase‐coherent averaging scheme. The interleaved navigator acquisition does not require any user interaction or supervision, while sequence efficiency is maintained. Magn Reson Med 47:1077–1082, 2002. © 2002 Wiley‐Liss, Inc.
Volume tracking cardiac 31P spectroscopy
Authors: Kozerke Sebastian , Schär Michael , Lamb Hildo J. , Boesiger Peter 
Published: October 2002

AbstractThe limited reliability and accuracy of cardiac spectroscopy have been partly attributed to effects from respiratory motion. In this work, we developed a prospective volume tracking method for respiratory motion compensation based on multiple navigator echoes and demonstrated its application in cardiac 31P spectroscopy. The sequence consists of two 2D selective excitation pulses preceding the spectroscopic experiment to sample respiratory motion components. The navigator information is evaluated in real‐time to calculate the shift of the heart from respiration. Based on the displacement information, the spectroscopic volume and/or grid position is prospectively corrected to track the volume of interest. The method was validated with a moving compartment phantom simulating in vivo respiratory motion. With volume tracking, no signal contamination was apparent. Spectra obtained in 14 healthy volunteers were evaluated using time‐domain fitting procedures. The fitting accuracy improved consistently with volume tracking compared to data from non‐navigated reference acquisitions. Compared to other gating approaches available for spectroscopy, the current technique does not degrade the scan efficiency, thus allowing effective use of scan time. Magn Reson Med 48:380–384, 2002. © 2002 Wiley‐Liss, Inc.
Gastrointestinal transit times in mice and humans measured with 27Al and 19F nuclear magnetic resonance
Authors: Schwarz Roman , Kaspar Armin , Seelig Joachim , Künnecke Basil 
Published: October 2002

AbstractGastric emptying and gastrointestinal (GI) transit times in mice and humans were monitored noninvasively by using 27Al and 19F nuclear magnetic resonance (NMR). Al3+ bound to ion‐exchange resin and perfluorononane were administered orally as selective and specific markers for the stomach and the entire GI tract, respectively. 27Al‐ and 19F‐MR spectroscopy (MRS) was employed to follow quantitatively boli of the mixed markers in awake, fed mice over a period of 48 hr. The selectivity of the markers was confirmed by whole‐body 1H‐, 27Al‐, and 19F‐MRI of anesthetized mice. Gastric emptying in humans was also monitored with 27Al‐MRS of aluminum‐loaded ion exchange resin. GI transit was assessed by 19F projection imaging of pharmaceutical capsules tagged with perfluorononane. Quantitative analysis of the MR data revealed that gastric emptying in humans proceeded linearly, whereas in mice an exponential decay was observed. This difference is explained by the respective feeding patterns of humans and mice. Humans usually achieve nearly complete gastric emptying before each meal. In contrast, very short delays between successive food intakes in small animals result in successive dilution of the stomach contents. For stomach emptying in mice the exponential decay constant was 74 min, whereas the half‐time of the linear gastric emptying in humans was 30 min. Magn Reson Med 48:255–261, 2002. © 2002 Wiley‐Liss, Inc.
In vivo GABA+ measurement at 1.5T using a PRESS‐localized double quantum filter
Authors: McLean M.A. , Busza A.L. , Wald L.L. , Simister R.J. , Barker G.J. , Williams S.R. 
Published: October 2002

AbstractA point‐resolved spectroscopy (PRESS)‐localized double quantum filter was implemented on a 1.5T clinical scanner for the estimation of γ‐amino butyric acid (GABA) concentrations in vivo. Several calibrations were found to be necessary for consistent results to be obtained. The apparent filter yield was approximately 38%; filter strength was sufficient to reduce the singlet metabolite peaks in vivo to below the level of the noise. Metabolite‐nulled experiments were performed, which confirmed that significant overlap occurred between macromolecule signals and the GABA resonance at 3.1 ppm. Although the multiplet arm at 2.9 ppm was confirmed to be relatively free of contamination with macromolecules, some contribution from these and from peptides is likely to remain; therefore, the term GABA+ is used. GABA+ concentrations were estimated relative to creatine (Cr) at the same echo time (TE) in a group of controls, studied on two occasions. The GABA+ concentration in 35‐ml regions of interest (ROIs) in the occipital lobe was found to be 1.4 ± 0.2 mM, with scan‐rescan repeatability of 38%. Magn Reson Med 48:233–241, 2002. © 2002 Wiley‐Liss, Inc.
Impact of initial muscle length on force deficit following lengthening contractions in mammalian skeletal muscle
Authors: Gosselin Luc E. , Burton Harold 
Published: October 2002

AbstractThe purpose of this study was to determine whether initial muscle length influenced the extent of isometric force deficit following 20 in vitro lengthening contractions of the soleus muscle from Fischer 344 rats. Force deficit was evaluated following one of five protocols: (1) lengthening contractions from optimal muscle length (Lo) to 120% Lo; (2) lengthening contractions from 80% Lo to Lo; (3) lengthening contractions from Lo to 120% Lo but with a stimulation frequency that elicited the same force as protocol 2; (4) 20 isometric contractions at Lo; (5) 20 stretches ± 20% Lo in inactive muscle. Following lengthening contractions, extent of force deficit significantly differed between protocols 1, 2, and 3 (P < 0.05). Maximal isometric force (Po) was decreased by ∼32%, ∼8%, and ∼15% in protocols 1, 2, and 3, respectively. In contrast, neither isometric contractions nor passive stretching (protocols 4 and 5) resulted in any reduction in Po. Irrespective of muscle length, the extent of force deficit was highly correlated (R = −0.774, P < 0.001) with peak force during active lengthening. Thus, the magnitude of isometric force deficit following lengthening contractions is influenced by both initial muscle length and peak force development. These findings have important practical implications for both exercise conditioning and rehabilitation, which are discussed. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Molecular analysis of the superoxide dismutase 1 gene in Spanish patients with sporadic or familial amyotrophic lateral sclerosis
Authors: García‐Redondo A. , Bustos F. , Juan Y Seva B. , Del Hoyo P. , Jiménez S. , Campos Y. , Martín M. A. , Rubio J.C. , Cañadillas F. , Arenas J. , Esteban J. 
Published: October 2002

AbstractWe performed a genetic analysis of the Cu/Zn superoxide dismutase gene (SOD1) in Spanish patients with sporadic or familial amyotrophic lateral sclerosis (ALS). We found mutations in 2 of 11 families (18%) with ALS. In addition, 1 of the 87 sporadic ALS patients studied harbored a mutation in the same gene. We identified G37R in exon 2 of the SOD1 gene in 1 family. Another patient, with sporadic ALS, showed a novel N65S in exon 3. In addition, we found a novel I112M in exon 4 in another family. Our data highlight the genetic heterogeneity of patients with ALS harboring mutations in the SOD1 gene and confirm that families with autosomal dominant inheritance of the trait, regardless of their ethnic background, are more likely to carry mutations in such a gene. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 274–278, 2002
Effect of moderate dehydration on torque, electromyography, and mechanomyography
Authors: Evetovich Tammy K. , Boyd Joseph C. , Drake Shawn M. , Eschbach Lawrence C. , Magal Meir , Soukup Jeffrey T. , Webster Michael J. , Whitehead Malcolm T. , Weir Joseph P. 
Published: October 2002

AbstractThe purpose of the present investigation was to test the hypotheses that the mechanomyographic (MMG) signal would be affected by hydration status due to changes in the intra‐ and extracellular fluid content (which could affect the degree of fluid turbulence), changes in the filtering properties of the tissues between the MMG sensor and muscle, and changes in torque production that may accompany dehydration. Ten subjects (age 22.5 ± 1.6 years) were tested for maximal isometric (MVC), submaximal isometric (25, 50, and 75%MVC), and maximal concentric isokinetic muscle strength of the biceps brachii in either a euhydrated or dehydrated state while the electromyographic (EMG) and MMG signals were recorded. Separate three‐way and two‐way ANOVAs indicated no change in torque, EMG amplitude, EMG mean power frequency (MPF), MMG amplitude, and MMG MPF with dehydration. The lack of dehydration effect suggests that MMG may be more reflective of the intrinsic contractile processes of a muscle fiber (torque production) or the motor control mechanisms (reflected by the EMG) than the tissues and fluids surrounding the muscle fiber. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 225–231, 2002
Identification of non‐linear stress–strain–time relationship of soils using genetic algorithm
Authors: Feng Xia‐Ting , Li Shaojun , Liao Hongjian , Yang Chengxiang 
Published: October 2002

AbstractRecognition of non‐linear constitutive rock/soil model from experimental results is often multi‐modal in the large parameter space. A genetic evolution algorithm is thus proposed for its recognition, including that of structure of the model and coefficients in the model. The structure of the model can be firstly determined according to mechanical mechanism if the mechanism is clearly understood or searched by using evolutionary algorithm. The coefficients to be determined are then searched in global optional space. With the new evolutionary algorithm, the non‐linear stress–strain–time constitutive law to describe strain softening behaviours of diatomaceous soil under consolidated and undrained state was recognized by learning stress–strain–time behaviour of an intact sample under consolidated pressure of σc=0.1 MPa and strain velocity ofa=0.175%/min. This model gave reasonable prediction for diatomaceous soils under varying consolidated pressures (0.1–3.5 MPa) and strain velocities (0.0044–1.75%/min). It indicates that the methodology proposed in this paper is robust enough and strongly attractive for recognition of non‐linear constitutive model of soil and rock materials. Copyright © 2002 John Wiley & Sons, Ltd.
On the availability of R out of N repairable systems
Authors: Frostig Esther , Levikson Benny 
Published: October 2002

AbstractAn R out of N repairable system consisting of N components and operates if at least R components are functioning. Repairable means that failed components are repaired, and upon repair completion they are as good as new. We derive formulas for the expected up‐time, expected down‐time, and the availability of the system, using Markov renewal processes. We assume that either the repair times of the components are generally distributed and the components' lifetimes are exponential or vice versa. The analysis is done for systems with either cold or warm stand‐by. Numerical examples are given for several life time and repair time distributions. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 483–498, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10025