bluuebunny/crossref_metadata_2025_split huggingface dataset:
1H‐ and 31P‐MR spectroscopy of primary and recurrent human brain tumors in vitro: malignancy‐characteristic profiles of water soluble and lipophilic spectral components
Authors: Lehnhardt Fritz‐Georg , Röhn Gabriele , Ernestus Ralf‐Ingo , Grüne Matthias , Hoehn Mathias 
Published: August 2002

AbstractIn vitro NMR spectrocopy was performed on specimen of human brain tumors. From all patients, tissue samples of primary tumors and their first recurrences were examined. 31P‐ and 1H‐spectra were recorded from samples of meningioma, astrocytoma and glioblastoma. A double extraction procedure of the tissue samples permitted acquisition of information from the membrane fraction and from the cytosolic fraction. 31P‐spectra were used to analyze the lipophilic fraction (phospholipids of the membrane) of the tissue extracts, while the 1H‐spectra reflected information on the metabolic alterations of the hydrophilic, cytosolic fraction of the tissue. The tumor types showed distinctive spectral patterns in both the 31P‐ and the 1H‐spectra. Based on the total detectable 31P signal, the level of phosphatidylcholine was about 34% lower in primary astrocytomas than in primary glioblastomas (p = 0.0003), whereas the level of sphingomyelin was about 45% lower in primary gioblastomas than in primary astrocytomas (p = 0.0061). A similar tendency of these phospholipids was observed when comparing primary and recurrent astrocytoma samples from the same individuals [+15% (p = 0.0103) and −23% (p = 0.0314) change, respectively]. 1H‐spectra of gliomas were characterized by an increase of the ratios of alanine, glycine and choline over creatine as a function of the degree of malignancy. In agreement with findings in the 31P‐spectra, the 1H‐spectra of recurrent astrocytomas showed metabolic profiles of increased malignancy in comparison to their primary occurrence. Since gliomas tend to increase in malignancy upon recurrence, this may reflect evolving tumor metabolism. 1H‐spectra of meningiomas showed the highest ratio of alanine over creatine accompanied by a near absence of myo‐inositol. Phospholipid profiles of meningiomas showed higher fractional contents of phosphatidylcholine along with lower phosphatidylserine compared to astrocytomas, while higher phosphatidylethanolamine and sphingomyelin fractional contents distinguished meningiomas from glioblastomas. The extraction method being used in this study combined with high‐resolution 1H‐ and 31P‐MRS provides a wide range of biochemical information, which enables differentiation not only between tumor types but also between primary and recurrent gliomas, reflecting an evolving tumor metabolism. Copyright © 2001 John Wiley & Sons, Ltd.
Spectrally inhomogeneous BOLD contrast changes detected in rodent tumors with high spectral and spatial resolution MRI
Authors: Al‐Hallaq Hania A. , Fan Xiaobing , Zamora Marta , River Jonathan N. , Moulder John E. , Karczmar Gregory S. 
Published: August 2002

AbstractMRI detects changes in blood‐oxygenation‐level dependent (BOLD) contrast in tumors caused by tumor oxygenating agents. These changes can be used to guide the design of improved tumor oxygenating treatments (TOXs). The conventional approach to detection of BOLD effects assumes that the water resonance is a single, homogeneously broadened Lorentzian line, and that changes in the T2* of this line owing to changes in deoxyhemoglobin are spectrally homogeneous. This model may not adequately describe BOLD contrast changes in complex water resonances that are often detected in tumors. The present work investigated: (a) whether changes in the water resonance in very small voxels caused by tumor oxygenating agents are spectrally inhomogeneous; and (b) whether high spectral and spatial resolution (HiSS) MRI of the water and fat resonances detects these changes more accurately than conventional gradient‐recalled echo (GRE) imaging. Carbogen (95% oxygen, 5% CO2) was used to increase tumor oxygenation. In two tumor models [mammary adenocarcinoma (R3230Ac; n = 5) and rhabdomyosarcoma (BA1112; n = 5)] proton signals were often complex and inhomogeneously broadened. Spectrally inhomogeneous changes during carbogen breathing occurred in at least 10% of the R3230AC tumor voxels that responded to carbogen and 18% of BA1112 tumor voxels. The largest changes during carbogen breathing in many voxels occurred at frequencies that were significantly different from the frequency of the primary water peak. Carbogen‐induced changes in proton T2* detected by simulated GRE and HiSS differed by more than 75% in 67% of voxels in R3230Ac tumors and in 65% of voxels in BA1112 tumors. The spectrally inhomogeneous effects of tumor oxygenating agents may reflect changes in sub‐voxelar microenvironements and thus may be important for accurate evaluation of the effects of therapy. Copyright © 2002 John Wiley & Sons, Ltd.
Quantitative functional imaging of the brain: towards mapping neuronal activity by BOLD fMRI
Authors: Hyder Fahmeed , Kida Ikuhiro , Behar Kevin L. , Kennan Richard P. , Maciejewski Paul K. , Rothman Douglas L. 
Published: August 2002

AbstractQuantitative magnetic resonance imaging (MRI) and spectroscopy (MRS) measurements of energy metabolism (i.e. cerebral metabolic rate of oxygen consumption, CMRO2), blood circulation (i.e. cerebral blood flow, CBF, and volume, CBV), and functional MRI (fMRI) signal over a wide range of neuronal activity and pharmacological treatments are used to interpret the neurophysiologic basis of blood oxygenation level dependent (BOLD) image‐contrast at 7 T in glutamatergic neurons of rat cerebral cortex. Multi‐modal MRI and MRS measurements of CMRO2, CBF, CBV and BOLD signal (both gradient‐echo and spin‐echo) are used to interpret the neuroenergetic basis of BOLD image‐contrast. Since each parameter that can influence the BOLD image‐contrast is measured quantitatively and separately, multi‐modal measurements of changes in CMRO2, CBF, CBV, BOLD fMRI signal allow calibration and validation of the BOLD image‐contrast. Good agreement between changes in CMRO2 calculated from BOLD theory and measured by 13C MRS, reveals that BOLD fMRI signal‐changes at 7 T are closely linked with alterations in neuronal glucose oxidation, both for activation and deactivation paradigms. To determine the neurochemical basis of BOLD, pharmacological treatment with lamotrigine, which is a neuronal voltage‐dependent Na+ channel blocker and neurotransmitter glutamate release inhibitor, is used in a rat forepaw stimulation model. Attenuation of the functional changes in CBF and BOLD with lamotrigine reveals that the fMRI signal is associated with release of glutamate from neurons, which is consistent with a link between neurotransmitter cycling and energy metabolism. Comparisons of CMRO2 and CBF over a wide dynamic range of neuronal activity provide insight into the regulation of energy metabolism and oxygen delivery in the cerebral cortex. The current results reveal the energetic and physiologic components of the BOLD fMRI signal and indicate the required steps towards mapping neuronal activity quantitatively by fMRI at steady‐state. Consequences of these results from rat brain for similar calibrated BOLD fMRI studies in the human brain are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
In‐vivo non‐invasive study of the thermoregulatory function of the blood vessels in the rat tail using magnetic resonance angiography
Authors: Vanhoutte G. , Verhoye M. , Raman E. , Roberts M. , Linden A. Van der 
Published: August 2002

AbstractIn rats, a significant portion of total body heat loss occurs through sympathetically mediated changes in tail blood flow, making the rat tail a convenient model to study vasomotor activity during thermoregulation. Our aim was to perform a non‐invasive study of the mechanisms of blood vessel control in the rat tail upon increasing body temperature. In anaesthetized rats, blood vessel temperature was monitored using non‐invasive thermistors positioned on the skin surface, covering the ventral artery (Ta) and lateral vein (Tv), and changes in blood vessel size were measured using in‐vivo magnetic resonance angiography (MRA). Two important regions of the tail (base and middle) were studied during a gradual rise of rectal temperature (Tr) from 37 to 40°C. MRA data show that increasing Tr causes increased diameter of both arteries and veins of the tail, that venous diameter changes are greater than arterial diameter changes, and that diameter changes of both types of vessel are greater at the base of the tail than in the middle. Temperature data allowed calculation of (Ta − Tv), which we used as an index of flow through arteriovenous anastomoses (AVAs). The data suggest that AVAs near the base of the tail are important in heat exchange, and that they remain open only for Tr values between 38 and 39°C. Copyright © 2002 John Wiley & Sons, Ltd.
Sympathetic neuronal survival induced by retinal trophic factors
Authors: Reis Ricardo A.M. , Cabral da Silva Maurício C. , Loureiro dos Santos Nelson E. , Bampton Edward , Taylor Jeremy S.H. , de Mello Fernando G. , Linden Rafael 
Published: August 2002

AbstractNeuronal survival in the vertebrate peripheral nervous system depends on neurotrophic factors available from target tissues. In an attempt to identify novel survival factors, we have studied the effect of secreted factors from retinal cells on the survival of chick sympathetic ganglion neurons. Embryonic day 10 sympathetic neurons undergo programmed cell death after 48 h without appropriate levels of nerve growth factor (NGF). Retina Conditioned Media (RCM) from explants of embryonic day 11 retinas maintained for 4 days in vitro supported 90% of E10 chick sympathetic neurons after 48 h. Conditioned medium from purified chick retinal Muller glial cells supported nearly 100% of E10 chick sympathetic neurons. Anti‐NGF (1 μg/mL) blocked the survival effect of NGF, but did not block the trophic effect of RCM. Neither BDNF nor NT4 (0.1–50 ng/mL) supported E10 sympathetic neuron survival. Incubation of chimeric immunoglobulin‐receptors TrkA, TrkB, or TrkC had no effect on RCM‐induced sympathetic neuron survival. The survival effects were not blocked by anti‐GDNF, anti‐TGFβ, and anti‐CNTF and were not mimicked by FGFb (0.1–10 nM). LY294002 at 50 μM, but not PD098059 blocked sympathetic survival induced by RCM. Further, the combination of RCM and NGF did not result in an increase in neuronal survival compared with NGF alone (82% survival after 48 h). The secreted factor in RCM is retained in subfractions with a molecular weight above 100 kDa, binds to heparin, and is unaffected by dialysis, but is heat sensitive. Our results indicate the presence of a high‐molecular weight retinal secreted factor that supports sympathetic neurons in culture. © 2002 Wiley Periodicals, Inc. J Neurobiol 50: 13–23, 2002
Temporal regulation of neuropilin‐1 expression and sensitivity to semaphorin 3A in NGF‐ and NT3‐responsive chick sensory neurons
Authors: Pond Ausra , Roche Florence K. , Letourneau Paul C. 
Published: August 2002

AbstractThe extracellular molecule semaphorin 3A (Sema3A) is proposed to be a negative guidance cue that participates in patterning DRG sensory axons in the developing chick spinal cord. During development Sema3A is first expressed throughout the spinal cord gray matter, but Sema3A expression later disappears from the dorsal horn, where small‐caliber cutaneous afferents terminate. Sema3A expression remains in the ventral horn, where large‐muscle proprioceptive afferents terminate. It has been proposed that temporal changes in the sensitivity of different classes of sensory afferents to Sema3A contribute to the different pathfinding of these sensory afferents. This study compared the expression of the semaphorin 3A receptor subunit, neuropilin‐1, and the collapse response of growth cones to semaphorin 3A for NGF (cutaneous)‐ and NT3 (proprioceptive)‐dependent sensory axons extended from E6‐E10 chick embryos. Growth cones extended from E6 DRGs in NT3‐containing medium expressed neuropilin‐1 and collapsed in response to Sema3A. From E7 until E10 NT3‐responsive growth cones expressed progressively lower levels of neuropilin‐1, and were less sensitive to Sema3A. On the other hand, growth cones extended from DRGs in NGF‐containing medium expressed progressively higher levels of neuropilin‐1 and higher levels of collapse response to Sema3A over the period from E6–E10. Thus, developmental patterning of sensory terminals in the chick spinal cord may arise from changes in both Sema3A expression in the developing spinal cord and accompanying changes in neuronal expression of the Sema3A receptor subunit, neuropilin‐1. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 43–53, 2002
Inositol 1,4,5‐trisphosphate transduction cascade in taste reception of the fleshfly, Boettcherisca peregrina
Authors: Koganezawa Masayuki , Shimada Ichiro 
Published: August 2002

AbstractThe role of an inositol 1,4,5‐trisphosphate (IP3)‐mediated transduction cascade in the response of taste receptor cells of the fleshfly Boettcherisca peregrina was investigated by using the following reagents: neomycin (an inhibitor of IP3 production), U73122 (an inhibitor of phospholipase C), adenophostin A (an agonist of the IP3‐gated channel), IP3, ruthenium red (a blocker of the IP3‐gated channel), and 2‐aminoethoxydiphenylborate (2‐APB; an antagonist of the IP3‐gated channel). For introduction into the receptor cell, the reagents were mixed with a detergent, deoxycholate (DOC). After treatment with neomycin + DOC or U73122 + DOC, the response of the sugar receptor cell to sugars was depressed compared with responses after treatment with DOC alone. During the treatment of adenophostin A + DOC, the response of the sugar receptor cell was elicited. After treatment with IP3 + DOC, the response of the sugar receptor cell to sugars and to amino acids was apparently enhanced. When taste stimuli were administered in the presence of ruthenium red or 2‐APB, the response of the sugar receptor cell to glucose were inhibited. The expression of genes for substances involved in the IP3 transduction cascade, such as G protein α subunit (dGqα), phospholipase C (norpA), and IP3 receptor (itpr), were examined in the taste receptor cell of the fruitfly Drosophila melanogaster by using the pox‐neuro70 mutant (poxn70), which lacks taste receptor cells. The expressed levels of dGqα and itpr in the tarsus of poxn70 mutant flies were reduced compared with those of wild‐type flies. These results suggest that the IP3 transduction cascade is involved in the response of the sugar receptor cell of the fly. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 66–83, 2002
Spectral analysis of parallel incomplete factorizations with implicit pseudo‐overlap
Authors: Magolu monga Made M. , van der Vorst Henk A. 
Published: August 2002

AbstractTwo general parallel incomplete factorization strategies are investigated. The techniques may be interpreted as generalized domain decomposition methods. In contrast to classical domain decomposition methods, adjacent subdomains exchange data during the construction of the incomplete factorization matrix, as well as during each local forward elimination and each local backward elimination involved in the application of the preconditioner. Local renumberings of nodes are combined with suitable global fill‐in strategy in an (successful) attempt to overcome the well‐known trade‐off between high parallelism (locality) and fast convergence (globality). From an algebraic viewpoint, our techniques may be implemented as global renumbering strategies. Theoretical spectral analysis is provided, which displays that the convergence rate weakly depends on the number of subdomains. Numerical results obtained on a 16‐processor SGI Origin 2000 are reported, showing the efficiency of our parallel preconditionings. Copyright © 2001 John Wiley & Sons, Ltd.
Finite cloud method: a true meshless technique based on a fixed reproducing kernel approximation
Authors: Aluru N. R. , Li Gang 
Published: August 2002

AbstractWe introduce fixed, moving and multiple fixed kernel techniques for the construction of interpolation functions over a scattered set of points. We show that for a particular choice of nodal volumes, the fixed, moving and multiple fixed kernel approaches are identical to the fixed, moving and multiple fixed least squares approaches. A finite cloud method, which combines collocation with a fixed kernel technique for the construction of interpolation functions, is presented as a true meshless technique for the numerical solution of partial differential equations. Numerical results are presented for several one‐and two‐dimensional problems, including examples from elasticity, heat conduction, thermoelasticity, Stokes flow and piezoelectricity. Copyright © 2001 John Wiley & Sons, Ltd.
Topology synthesis of large‐displacement compliant mechanisms
Authors: Pedersen Claus B. W. , Buhl Thomas , Sigmund Ole 
Published: August 2002

AbstractThis paper describes the use of topology optimization as a synthesis tool for the design of large‐displacement compliant mechanisms. An objective function for the synthesis of large‐displacement mechanisms is proposed together with a formulation for synthesis of path‐generating compliant mechanisms. The responses of the compliant mechanisms are modelled using a total Lagrangian finite element formulation, the sensitivity analysis is performed using the adjoint method and the optimization problem is solved using the method of moving asymptotes. Procedures to circumvent some numerical problems are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Refined 9‐Dof triangular Mindlin plate elements
Authors: Wanji Chen , Cheung Y. K. 
Published: August 2002

AbstractBased on the Mindlin/Reissner plate theory, two refined triangular thin/thick plate elements, the conforming displacement element DKTM with one point quadrature for the part of shear strain and the element RDKTM with the re‐constitution of the shear strain, are proposed. In the formulations the exact displacement function of the Timoshenko's beam is used to derive the element displacements of the refined elements. Numerical examples are presented to show that the present models indeed possess properties of high accuracy for thin and thick plates, is capable of passing the patch test required for Kirchhoff thin plate elements, and does not exhibits extra zero energy modes. The element RDKTM is free of locking for very thin plate analysis and its convergence can be ensured theoretically. However, the element DKTM is not free of shear locking when the thickness/span ratios less than 10−2. Copyright © 2001 John Wiley & Sons, Ltd.
Least‐squares collocation meshless method
Authors: Zhang Xiong , Liu Xiao‐Hu , Song Kang‐Zu , Lu Ming‐Wan 
Published: August 2002

AbstractA finite point method, least‐squares collocation meshless method, is proposed. Except for the collocation points which are used to construct the trial functions, a number of auxiliary points are also adopted. Unlike the direct collocation method, the equilibrium conditions are satisfied not only at the collocation points but also at the auxiliary points in a least‐squares sense. The moving least‐squares interpolant is used to construct the trial functions. The computational effort required for the present method is in the same order as that required for the direct collocation, while the present method improves the accuracy of solution significantly. The proposed method does not require any mesh so that it is a truly meshless method. Three numerical examples are studied in detail, which show that the proposed method possesses high accuracy with low computational effort. Copyright © 2001 John Wiley & Sons, Ltd.
In‐plane vibrations of shear deformable curved beams
Authors: Eisenberger Moshe , Efraim Elia 
Published: August 2002

AbstractThis paper presents the exact dynamic stiffness matrix for a circular beam with a uniform cross‐section. The stiffness matrix is frequency dependent, and the natural frequencies are those that cause the matrix to become singular. Using this matrix the exact natural frequencies of circular beams with various boundary conditions are calculated and compared with available results in the literature. Copyright © 2001 John Wiley & Sons, Ltd.
Social role quality, physical health, and psychological well‐being in women after heart surgery
Authors: Plach Sandra K. , Heidrich Susan M. 
Published: August 2002

AbstractWomen's social role quality may be an important factor in their adaptation after heart surgery. Relationships among different dimensions of role quality, physical health, and psychological well‐being were examined in 157 midlife and older women who had undergone heart surgery. Overall, older women (n = 89) were similar to younger women (n=68) in physical recovery from heart surgery. Poorer health outcomes were associated with number of health problems, not age. Women with more health problems and lower subjective health perceptions had lower role quality. Multiple regression analyses indicated that, in general, role quality mediated the effects of physical health on psychological well‐being. Regardless of the extent of physical health problems, women with higher role quality had higher levels of psychological well‐being. © 2002 Wiley Periodicals, Inc. Res Nurs Health 25:189–202, 2002
Thermal stability of the ­spironaphthoxazine colored form in ­polymeric siloxanes
Authors: Nakao Ren , Noda Fumihiko , Horii Toyokazu , Abe Yasuo 
Published: August 2002

AbstractIn order to improve the thermal stability of colored merocyanine formed by the photochromic reaction of spironaphthoxazine, the spiro compound was incorporated in polymeric siloxanes. They are liquid poly(methylphenylsiloxane) and solid methyl‐ or phenyl‐siloxane resins prepared by the hydrolysis and condensation reactions of the corresponding di‐ or tri‐ethoxysilane. To the polymers the spirooxazine moiety is­bonded covalently. Higher stability of the colored form was not observed in the liquid polysiloxane, but in the solid resins. The phenyl substituent in the resin is more effective than the methyl one for stabilization, suggesting that the bulky substituent in the vicinity of the spirooxazine moiety is important as well as stiff polymer matrices. The phenylsiloxane resin with the spirooxazine moiety was enclosed in rigid sol–gel silica, but a further improvement of the thermal stability was not observed. Copyright © 2002 John Wiley & Sons, Ltd.
Flame‐retardant epoxy resin compounds containing novolac derivatives with aromatic compounds
Authors: Iji Masatoshi , Kiuchi Yukihiro 
Published: August 2002

AbstractNew flame‐retardant epoxy resin compounds containing novolac derivatives with specific aromatic compounds have been developed. After crosslinking reactions between epoxy resin and hardener, the epoxy resin compounds formed highly flame‐retardant network structures that were obtained by including biphenylene and phenylene moieties in the main chains of novolac‐type epoxy resin and phenol novolac resin hardener. The high flame retardancy is due mainly to the stable foam layers that form during combustion because of the low elasticity at high temperatures and the high pyrolysis resistance of the compounds. Furthermore, the addition of excess phenol derivative hardener not only facilitates the formation of the foam layers by decreasing the crosslink densities but also reduces the amount of flammable substances generated from the epoxy resin compounds during combustion. The use of a multifunctional epoxy resin containing four glycidyloxy groups in the compounds improved characteristics such as heat resistance and strength at high temperatures, while maintaining excellent flame retardancy. Copyright © 2001 John Wiley & Sons, Ltd.