bluuebunny/crossref_metadata_2025 huggingface dataset:
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

MRI 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

Quantitative 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

In 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

Neuronal 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

The 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

The 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

Two 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

We 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

This 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

Based 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

A 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

This 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

Women'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

In 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

New 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.
Thermal and ionic‐conductive behaviors of liquid crystalline polymers with alkali metal salt
Authors: Akachi Yosuke , Kawamura Kenji , Koide Naoyuki
Published: August 2002

In order to investigate the relationship between ionic conductivity and liquid crystallinity, we prepared the main‐chain type polyester having 1,4‐bisstyrylbenzene units and ethyleneoxide chain in the repeating unit. The main‐chain type polyester with lithium salt at the ratio of 0.04 per polymer repeating unit exhibited a smectic phase. However, the polyester with lithium salt (0.11) showed a nematic phase. The ionic conductivity of the polyester with lithium salt increased with increasing lithium salt concentration.

The trans‐type polyester exhibited a liquid crystalline phase, while the cis‐type polyester did not show any mesophase. We found that the ionic conductivity of the trans‐type polyester with lithium salt (0.11) was larger than that of the cis‐type polyester with lithium salt (0.11).

However, a liquid crystalline phase was found in the side‐chain type polyether with alkoxy chain length of below 12. A smectic phase was induced for the non‐mesomorphic polyethers with lithium salt. The layer spacing of the smectic A phase for the non‐mesomorphic polyether with lithium salt decreased from 55 to 41 Å with increasing temperature. The ionic conductivity of the polyether with lithium salt increased with decreasing the layer spacing. Copyright © 2001 John Wiley & Sons, Ltd.
Low incidence of SV40‐like sequences in ependymal tumours
Authors: Reuther F. J. , Löhler J. , Herms J. , Hugo H.‐H. , Schindler C. , Leithäuser F. , Melzner I. , Möller P. , Scheil S.
Published: August 2002

Between 1955 and 1963, millions of children and adults were exposed to SV40‐contaminated poliovirus vaccines. The oncogenic potential of this polyomavirus was revealed when intracerebral inoculation of SV40 into newborn hamsters resulted in the development of ependymomas and choroid plexus papillomas. Subsequently, SV40‐like sequences were repeatedly detected in human ependymomas with broadly ranging incidence rates of 7–90%. Most epidemiological studies, however, have not described an increased occurrence of ependymomas. To gain more data on this controversial issue, this study examined 62 archived ependymal tumours from 31 children and 31 adults who underwent surgery between 1990 and 1999. Only three (5%) of the tumours – including 24 classical, 20 anaplastic, and 12 myxopapillary ependymomas; one subependymoma; and five ependymoblastomas – revealed subgenomic SV40 sequences. None of the ependymomas in patients born between 1920 and 1960 demonstrated SV40‐like sequences. The positive tumours represent 7% of grade II and III ependymomas (two paediatric and one adult tumour). DNA sequencing of the PCR product revealed identical sequences of SV40 in the positive ependymal tumours. Compared with the results from other countries, this incidence rate is relatively low. Therefore, it seems likely that significant differences between individual countries exist regarding the prevalence of SV40‐positive ependymomas. These differences may reflect different degrees of exposure to SV40‐contaminated polio vaccine. Copyright © 2001 John Wiley & Sons, Ltd.
Differences in in vitro invasive capacity induced by differences in Ki‐Ras protein mutations
Authors: Al‐Mulla Fahd , MacKenzie Elaine M.
Published: August 2002

The p21 proteins encoded by N‐, Ki‐, and H‐ras are small guanine nucleotide‐binding proteins that act as switches in several signal transduction pathways. Recently, evidence has been accumulating to suggest that valine‐12 mutation in the Ki‐Ras protein is associated with lung and colorectal tumours that are more aggressive than those carrying aspartate‐12 mutation. The purpose of this study was to determine whether cells transfected with different Ki‐ras codon‐12 mutants have different biological behaviours in vitro that could reflect the differences in behaviour in vivo. For that reason, Rat‐1 fibroblasts transfected with the valine‐12 or aspartate‐12 mutant or the wild‐type Ki‐ras gene were assessed in terms of in vitro invasion, transformation, and VEGF production. Both mutants demonstrated equal abilities to transform Rat‐1 cells and induce VEGF production, while cells transfected with wild‐type Ki‐Ras failed to do so. Most significantly, the valine‐12 mutants demonstrated a greater ability to invade Matrigel than cells expressing the aspartate‐12 mutant or wild‐type Ki‐Ras proteins. This study complements previous experimental data that specific Ras mutations differ in their effects in vivo and shows, for the first time, a significant difference in Matrigel invasion in vitro. The precise mechanisms behind these biological differences in vivo and in vitro should now be investigated. Copyright © 2001 John Wiley & Sons, Ltd.
A water‐based triphenyltetrazolium chloride method for the evaluation of green plant tissue viability
Authors: Lin Chin Ho , Chen Bing Shiunn , Yu Chih Wen , Chiang Shih Wen
Published: August 2002

A water‐based 2,3,5‐triphenyltetrazolium chloride (TTC) partitioning method using n‐hexane for the evaluation of green plant tissue viability has been developed. Conventionally, the reduction of TTC to insoluble red‐coloured triphenylformazan (TPF) has been used to detect seed, bud, leaf and cultured cell viability. However, the 95% ethanol used to extract TPF also extracts various pigments, such as chlorophyll, from plant tissues which interfere with the absorption of TPF at 485 nm. This new water‐based method improves upon the current method by eliminating the interfering pigments in the hexane layer, and by minimising the non‐enzymatic oxidation of the sample. When used to evaluate the tissue viability of chill‐stressed waxapple (Syzygium samarangense) plants, the refined method had a greater sensitivity than the electrolyte leakage method and thus provided a more precise assessment for the physiological state of various plant tissues. Copyright © 2001 John Wiley & Sons, Ltd.
Quantitative determination of liriodenine and moupinamide in five species of Mollinedia by high performance liquid chromatography
Authors: Moreira Davyson de Lima , Leitão Gilda Guimarães
Published: August 2002

A simple method for the resolution and subsequent quantitative determination of liriodenine and moupinamide in Mollinedia species was developed using reversed‐phase HPLC based on an octadecyl silane‐packed column eluted with gradients of methanol and water. Copyright © 2001 John Wiley & Sons, Ltd.
Polar lipid and fatty acid distribution in carotenolipoprotein complexes extracted from sea buckthorn fruits
Authors: Pintea Adela , Marpeau Anne , Faye Monique , Socaciu Carmen , Gleizes Michel
Published: August 2002

Sea buckthorn (Hippophae rhamnoides L., fam. Elaeagnaceae) fruits are rich in pigments and lipoproteins located in membranes and the fleshy mesocarp. In spite of many reports concerning the neutral lipids in the mesocarp, no data about the polar lipids and their fatty acid composition are available even though they play important structural and physiological roles in cell membranes and may offer interesting applications as emulsifiers and nutrients in cosmetic preparations. Carotenolipoprotein complexes are located particularly in fruit membranes where polar lipids may function as bridge compounds between the polar (protein) and non‐polar (carotenoid) moieties. The fatty acid compositions of total and individual polar lipids separated from carotenolipoprotein complexes were determined by HPTLC and GC. The polar lipids included 61% phospholipids and 39% galactolipids, which contained mainly 16:0, 16:1 (9c), 18:1 (9c), 18:1 (11c) and 18:2 (9c, 12c) fatty acids. Almost all polar lipids showed high ratios of 16:0/16:1 (11c) and 18:1 (9c)/18:1 (11c), and higher quantities of 18 carbon unsaturated fatty acids than of the saturated analogue. Galactolipids proved to be richest in 18:1 (9c) and 18:3 (9c, 12c, 15c) fatty acids, while phospholipids contained higher concentrations of 16:0 and 18:1 (9c). Copyright © 2001 John Wiley & Sons, Ltd.
Method for the extraction of the volatile compound salicylic acid from tobacco leaf material
Authors: Verberne Marianne C. , Brouwer Nynke , Delbianco Federica , Linthorst Huub J. M. , Bol John F. , Verpoorte Robert
Published: August 2002

Salicylic acid (SA) is a signalling compound in plants which is able to induce systemic acquired resistance. In the analysis of SA in plant tissues, the extraction recovery is often very low and variable. This is mainly caused by sublimation of SA, especially during evaporation of organic solvents. Techniques have been designed in order to overcome this problem. In the first part of the extraction procedure, sublimation of SA was prevented by addition of 0.2 M sodium hydroxide. At a later stage of the extraction procedure, sublimation of SA during solvent evaporation was controlled by the addition of a small amount of HPLC eluent. In this way, recoveries in the range of 71–91% for free SA and 65–79% for acid‐hydrolysed SA were obtained. Recoveries could be further optimised by the use of an internal standard to correct for volume changes after the addition of the HPLC eluent. Copyright © 2001 John Wiley & Sons, Ltd.
Comparative differential scanning calorimetric analysis of vegetable oils: I. Effects of heating rate variation
Authors: Tan C. P. , Man Y. B. Che
Published: August 2002

The melting curves of 11 vegetable oils have been characterised. Vegetable oil samples that were cooled at a constant rate (5°C/min) from the melt showed between one and seven melting endotherms upon heating at four different heating rates (1, 5, 10 and 20°C/min) in a differential scanning calorimeter (DSC). Triacylglycerol (TAG) profiles and iodine value analyses were used to complement the DSC data. Generally, the melting transition temperature shifted to higher values with increased rates of heating. The breadth of the melting endotherm and the area under the melting peak also increased with increasing heating rate. Although the number of endothermic peaks was dependent on heating rate, the melting curves of the oil samples were not straightforward in that there was no correlation between the number of endothermic peaks and heating rates. Multiple melting behaviour in DSC experiments with different heating rates could be explained by: (1) the melting of TAG populations with different melting points; and (2) TAG crystal reorganisation effects. On the basis of the corollary results obtained, vegetable oils and fats may be distinguished from their offset‐temperature (Toff) values in the DSC melting curves. The results showed that Toff values of all oil samples were significantly (p < 0.01) different in the melting curves scanned at four different scanning rates. These calorimetric results indicate that DSC is a valuable technique for studying vegetable oils. Copyright © 2002 John Wiley & Sons, Ltd.
Prenatal diagnosis of pyruvate dehydrogenase deficiency using magnetic resonance imaging
Authors: Robinson Julian N. , Norwitz Errol R. , Mulkern Robert , Brown Stephen A. , Rybicki Frank , Tempany Clare M. C.
Published: August 2002

Introduction

Pyruvate dehydrogenase deficiency is an inherited inborn error of metabolism associated with early neonatal death and long‐term neurologic sequelae in survivors. Prenatal diagnosis currently relies on isolation of fetal cells for subsequent genetic and/or biochemical studies. Magnetic resonance imaging and magnetic resonance spectroscopy have been used on occasion for both postnatal diagnosis and management of pyruvate dehydrogenase deficiency. We illustrate a case in which these non‐invasive modalities also prove useful for prenatal diagnosis of this condition.

Case

A 31‐year‐old multipara with a history of two prior infants affected with pyruvate dehydrogenase deficiency presented with a spontaneous dichorionic, diamniotic twin pregnancy. Magnetic resonance imaging and magnetic resonance spectroscopy were performed on both fetuses. Magnetic resonance imaging of the presenting (male) fetus demonstrated mild ventriculomegaly, increased extracerebrospinal fluid, and decreased cortical sulcation and gyration. The non‐presenting (female) fetus was structurally normal. Magnetic resonance spectroscopy spectra were obtained for both fetuses, and were normal. The diagnosis of pyruvate dehydrogenase deficiency was made in the presenting fetus after delivery on the basis of subsequent mortality from severe lactic acidosis.

Conclusion

Prenatal MR imaging of the fetal brain can be used for prenatal diagnosis in fetuses at risk for pyruvate dehydrogenase deficiency. Prenatal MR spectroscopy, although technically feasible, does not appear to have a role in the prenatal diagnosis of this condition. Copyright © 2001 John Wiley & Sons, Ltd.
Invasive assessment of fetal renal abnormalities: urinalysis, fetal blood sampling and biopsy
Authors: Nicolini Umberto , Spelzini Federico
Published: August 2002

There are a number of potential biochemcial markers that may have some role in predicting renal function postnatally. These include urinary sodium, calcium and β2‒microglobulin. The latter may also be measured in fetal serum. However, the accuracy of these parameters at a point in time is far from perfect as urinary tract obstruction is a progressive disease which may be best defined by repeated observations throughout pregnancy. Copyright © 2001 John Wiley & Sons, Ltd.
Ethical issues in pharmacoepidemiological research in Belgium
Authors: Verstraete Alain G. , Vander Stichele Robert H. , Deliens Luc H. J.
Published: August 2002

Purpose

To illustrate the ethical issues faced in pharmacoepidemiological research in Belgium.

Methods

The experience with three studies is described. The studies concern the use of drugs for euthanasia in medical practice, cytomegalovirus infection in single solid organ transplants and a comparison of benzodiazepine use in the general population and in acute self‐poisoning.

Results

With some creativity, it was possible to meet the requirements of the ethics committees and the law on computer databases, e.g. by bringing data validation closer to the data entry process, by assuring anonymity in mailing procedures, or by deleting identification labels as soon as they are no longer necessary.

Conclusions

The existing juridical vacuum has not really impeded pharmacoepidemiological research. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis and in vitro degradation properties of poly[(tetramethylene carbonate)‐co‐(sebacic anhydride)]
Authors: Xiao Congming , Zhu K J
Published: August 2002

A novel poly[(tetramethylene carbonate)‐co‐(sebacic anhydride)] (PTCSA) was synthesized by the melt polycondensation reaction of sebacic acid (SA) and the dicarboxylic acid which derived from oligo(tetramethylene carbonate) diol via the corresponding mixed anhydrides. The copolymer structure was confirmed by means of FTIR and [1H] NMR spectra. DSC analysis showed PTCSA was semicrystalline polymer which had low Tg (<−30 °C). The measurements of contact angles indicated that the hydrophobicity of PTCSA increased as the content of carbonate segments increased. In vitro degradation of PTCSA was performed in lipase‐free and lipase‐containing phosphate‐buffer saline (0.1 M, pH 7.4) at 37 °C. It was found that the degradation rate of PTCSA increased with the amount of SA. After 7 days of degradation in lipase‐free phosphate‐buffer saline, the weight loss of PTCSA was 74, 49 and 22% for 80, 58 and 32 mol% SA contained samples, respectively. The weight loss of PTCSA increased rapidly in the first week, then slowed down but could be greatly enhanced by lipase. After 3 weeks of degradation with or without lipase, the weight loss of PTCSA was 66 and 52% for 58 mol% SA‐containing samples, respectively. The size of the samples was gradually reduced and the surface became coarse. It was also found that the molecular weights of the outer layer were lower than those of the inner layer of the samples after degradation. The results suggested that PTCSA was some kind of biodegradation and surface‐erosion material.

© 2001 Society of Chemical Industry
Novel synthesis of branched polystyrenes by quasi‐living radical copolymerization using photofunctional inimer
Authors: Ishizu Koji , Mori Akihide
Published: August 2002

Branched polystyrenes were prepared by quasi‐living radical copolymerization of N,N‐diethylaminodithiocarbamoylmethylstyrene (inimer: DTCS) with styrene under UV irradiation. DTCS monomers play an important role in this copolymerization system as an inimer capable of initiating living radical polymerization of the vinyl group. Two monomers (DTCS and styrene) showed equal reactivity toward both propagating species, and the copolymer composition was the same as the comonomer feed. This result means that both the branching and chain length of the hyperbranched molecules can be controlled statistically by the feed monomer ratios. The compact nature of the branched macromolecules is demonstrated by viscosity measurements compared to the linear analogues.

© 2001 Society of Chemical Industry
Synthesis and characterization of novel polymers derived from gluconolactone
Authors: Narain Ravin , Jhurry Dhanjay
Published: August 2002

A novel synthesis of vinyl monomers derived from D‐gluconolactone, an interesting precursor obtained from D‐glucose, is reported. The derivatization of D‐gluconolactone is carried out by first reacting methacrylic acid with a diamine in water, followed by in situ amidation of the sugar compound. Three monomers containing different lengths of alkylamido groups between vinyl and sugar residues, have thus been obtained and homopolymerized with various free‐radical initiators. The resulting polymers were analysed by viscometry and were found to exhibit polyelectrolyte behaviour. Their structures were confirmed by NMR and consist of a predominantly syndiotactic structure. Copolymerization of the gluconamidoalkyl ammonium methacrylates with other hydrophilic monomers such as methacrylamide and vinylpyrrolidone was also achieved.

© 2001 Society of Chemical Industry
Sorting out successful failures: Exploratory analyses of factors associated with academic and behavioral outcomes of retained students
Authors: Ferguson Phillip , Jimerson Shane R. , Dalton Michael J.
Published: August 2002

This prospective longitudinal study followed a sample of 106 kindergarten students through 11th grade examining the effects of family characteristics, school readiness, socialization, and student demographics on academic achievement and behavioral adjustment outcomes. These educational outcomes were contrasted among four groups consisting of: 1) early grade retainees; 2) transitionally placed retained students; 3) students recommended for transitional placement, but promoted; and 4) regularly promoted students. While previous studies examining the efficacy of early grade retention focus exclusively on between‐group comparisons, this study examines the family and individual characteristics of successful and unsuccessful retained students by including both between‐group and within‐group effects on academic and behavioral outcomes. The results of this study demonstrate that retained students' initial school readiness, socioeconomic status, mother's level of education, parental value of education, kindergarten personal‐social functioning, and chronological age are distinctly associated with subsequent academic or behavioral outcomes. Variables associated with relative educational success following early failure are delineated and research implications are discussed. © 2001 John Wiley & Sons, Inc.
Alternating π‐conjugated copolymer of dithiafulvene with 2,2′‐bipyridyl units
Authors: Naka Kensuke , Uemura Takashi , Chujo Yoshiki
Published: August 2002

A π‐conjugated polymer containing a dithiafulvene unit and a bipyridyl unit was prepared by cycloaddition polymerization of aldothioketene derived from 5,5′‐diethynyl‐2,2′‐bipyridine. Ultraviolet–visible (UV–vis) absorption spectra showed that the π‐conjugation system of the polymer expanded more effectively than that of a benzene analogue of poly(dithiafulvene) obtained from 1,4‐diethynylbenzene. Cyclic voltammetry measurements indicated that the dithiafulvene–bipyridyl polymer was a weaker electron‐donor polymer than the benzene analogue. These results supported the idea that the incorporation of the electron‐accepting bipyridyl moiety into conjugated poly(dithiafulvene) induced an intramolecular charge‐transfer (CT) effect between the units. Treatment of the dithiafulvene–bipyridyl polymer with bis(2,2′‐bipyridyl)dichlororuthenium (II) [Ru(bpy)2Cl2] afforded a ruthenium–polymer complex. A cyclic voltammogram of the complex showed broad redox peaks, which indicated electronic interaction between the dithiafulvene and tris(bipyridyl) ruthenium complex. The dithiafulvene–bipyridyl polymer formed CT complexes with 7,7,8,8‐tetracycanoquinodimethane (TCNQ) in dimethyl sulfoxide. The UV–vis absorption indicated that the resulting CT complex contained anion radical of TCNQ and partially charge‐transferred TCNQ. The polymer showed an unusually high electrical conductivity of 3.1 × 10−4 S/cm in its nondoped state due to the effective donor–acceptor interaction between the bipyridine unit and the dithiafulvene unit. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4083–4090, 2001
Polymer science with transition metals and main group elements: Towards functional, supramolecular inorganic polymeric materials
Authors: Manners Ian
Published: August 2002

Inorganic polymers are relatively unexplored because the efficient formation of macromolecular chains from atoms of transition metals and main group elements has presented a synthetic challenge. Nevertheless, these materials offer exciting opportunities for accessing properties that are significantly different from and which therefore complement those available with the well‐established organic systems. Inorganic block copolymers are of particular interest for the generation of functional, nanoscale supramolecular architectures and hierarchical assemblies using self‐assembly processes. This article focuses on research in my group over the past decade, which has targeted the development of new and controlled routes to inorganic polymers and their subsequent use in forming supramolecular materials as well as studies of their properties and applications. The use of ring‐opening polymerization (ROP) and transition‐metal‐catalyzed polycondensation approaches are illustrated. Controlled ROP procedures have been developed that allow access to polyferrocene block copolymers that self‐assemble into interesting nanoscopic architectures such as cylinders and superstructures such as flowers. The future prospects for inorganic polymer science are discussed, and a growing emphasis on the study of supramolecular inorganic polymeric materials is predicted. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 179–191, 2002
Bulk cyclopolymerization of 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐1,2:5,6‐tetradeoxy‐D‐mannitol with quaternary ammonium salts leading to gel‐free thiosugar polymer
Authors: Satoh Toshifumi , Imai Tomoko , Sugie Norihiko , Nonokawa Ryuji , Yokota Kazuaki , Kakuchi Toyoji
Published: August 2002

The bulk cyclopolymerization of diepisulfide, 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐1,2:5,6‐tetradeoxy‐D‐mannitol (1), was studied using R4N+Br− (R = CH3, C2H5, C3H7, C4H9, and C7H15) and (C4H9)4N+X− (X = Cl, I, NO3, and ClO4) as the initiators. All the bulk polymerizations of 1 using quaternary tetraalkylammonium salts at 90 °C proceeded without gelation even at high conversion to produce gel‐free polymers consisting of 2,5‐anhydro‐1,5‐dithio‐D‐glucitol (I) as the major cyclic repeating unit along with 1,5‐anhydro‐2,5‐dithio‐D‐mannitol (II) and the desulfurized acyclic unit (III) as the minor units. The polymerization rate and molar fraction of the I unit increased with the increasing alkyl chain length of the tetraalkylammonium cation and the increasing nucleophilicity of the counteranion. Tetrabutylammonium chloride exhibited the highest catalytic activity and the highest stereoselectivity, that is, the thiosugar polymer with I:II:III = 81:15:4 and a number‐average molecular weight of 31.9 × 103 was obtained in 85% yield for a polymerization time of 0.5 h. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 965–970, 2002
Photoinitiators with functional groups. V. New water‐soluble photoinitiators containing carbohydrate residues and copolymerizable derivatives thereof
Authors: Liska Robert
Published: August 2002

The synthesis of new water‐soluble photoinitiators (PIs) based on hydroxyalkylphenones, benzophenones, and thioxanthones with carbohydrate residues such as glucose, cellobiose, and 1‐amino‐1‐deoxy‐D‐glucitol (glucamine) is described. In addition, selected initiators were reacted with methacryloyl chloride to obtain copolymerizable initiators with improved migration stability. Results from photo differential scanning calorimetry and gel‐content measurements in commercially available water‐thinnable and emulsion‐type resins as well as 2‐hydroxyethyl acrylate are included. Glucose‐modified PIs gave the best results with respect to compatibility with the resin, reactivity, and gel content. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1504–1518, 2002
Star poly(methyl methacrylate) with end‐functionalized arm chains by ruthenium‐catalyzed living radical polymerization
Authors: Baek Kyung‐Youl , Kamigaito Masami , Sawamoto Mitsuo
Published: August 2002

Star polymers with end‐functionalized arm chains (surface‐functionalized star polymers) were synthesized by the in situ linking reaction between ethylene glycol dimethacrylate (linking agent) and an α‐end‐functionalized linear living poly(methyl methacrylate) in RuCl2(PPh3)3‐catalyzed living radical polymerization; the terminal on the surface functionalities included amides, alcohols, amines, and esters. The star polymers were obtained in high yields (75–90%) with initiating systems consisting of a functionalized 2‐chloro‐2‐phenylacetate or ‐acetamide [FC(O)CHPhCl; F = nPrNH, HOCH2CH2O, Me2NCH2CH2O, or EtO; initiator] and n‐Bu3N (additive). The yield was lower with a functionalized 2‐bromoisobutyrate [Me2NCH2CH2OC(O)CMe2Br] initiator or with Al(Oi‐Pr)3 as an additive. Multi‐angle laser light scattering analysis showed that the star polymers had arm numbers of 10–100, radii of gyration of 6–23 nm, and weight‐average molecular weights of 1.3 × 105 to 3.0 × 106, which could be controlled by the molar ratio of the linking agent to the linear living polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1972–1982, 2002