bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear synchronization in EEG and whole‐head MEG recordings of healthy subjects
Authors: Stam Cornelis J. , Breakspear Michael , van Walsum Anne‐Marie van Cappellen , van Dijk Bob W. 
Published: May 2003

AbstractAccording to Friston, brain dynamics can be modelled as a large ensemble of coupled nonlinear dynamical subsystems with unstable and transient dynamics. In the present study, two predictions from this model (the existence of nonlinear synchronization between macroscopic field potentials and itinerant nonlinear dynamics) were investigated. The dependence of nonlinearity on the method of measuring brain activity (EEG vs. MEG) was also investigated. Dataset I consisted of 10 MEG recordings in 10 healthy subjects. Dataset II consisted of simultaneously recorded MEG (126 channels) and EEG (19 channels) in 5 healthy subjects. Nonlinear coupling was assessed with the synchronization likelihood S and dynamic itinerancy with the synchronization entropy Hs. Significance was assessed with a bootstrap procedure (“surrogate data testing”), comparing S and Hs with their distribution under the null hypothesis of stationary, linear dynamics. Significant nonlinear synchronization was detected in 14 of 15 subjects. The nonlinear dynamics were associated with a high index of itinerant behaviour. Nonlinear interdependence was significantly more apparent in MEG data than EEG. Synchronous oscillations in MEG and EEG recordings contain a significant nonlinear component that exhibits characteristics of unstable and itinerant behaviour. These findings are in line with Friston's proposal that the brain can be conceived as a large ensemble of coupled nonlinear dynamical subsystems with labile and unstable dynamics. The spatial scale and physical properties of MEG acquisition may increase the sensitivity of the data to underlying nonlinear structure. Hum. Brain Mapping 19:63–78, 2003. © 2003 Wiley‐Liss, Inc.
Effects of age and speed of processing on rCBF correlates of syntactic processing in sentence comprehension
Authors: Caplan David , Waters Gloria , Alpert Nathaniel 
Published: May 2003

AbstractPositron emission tomography (PET) was used to determine the effect of age on regional cerebral blood flow (rCBF) during syntactic processing in sentence comprehension. PET activity associated with making plausibility judgments about syntactically more complex subject object (SO) sentences (e.g., The juice that the child spilled stained the rug) was compared to that associated with making judgments about synonymous syntactically simpler object subject (OS) sentences (e.g., The child spilled the juice that stained the rug). In the first study, 13 elderly (70–80‐year‐old) subjects showed increased rCBF in the left inferior parietal lobe. This result contrasted with previous studies, which have shown activation in Broca's area in this task in young subjects. Elderly subjects were noted to have longer reaction times than young subjects previously tested. A second study found that young subjects whose reaction times were as long as those of the elderly subjects tested in Experiment 1 activated left superior parietal, and not left inferior frontal, structures. A third experiment found that elderly subjects with reaction times as fast as previously tested young subjects activated left inferior frontal structures. The results suggest that the speed of syntactic processing, but not age per se is related to the neural location where one aspect of syntactic processing is carried out. Hum. Brain Mapping 19:112–131, 2003. © 2003 Wiley‐Liss, Inc.
More “mapping” in brain mapping: Statistical comparison of effects
Authors: Jernigan Terry L. , Gamst Anthony C. , Fennema‐Notestine Christine , Ostergaard Arne L. 
Published: May 2003

AbstractThe term “mapping” in the context of brain imaging conveys to most the concept of localization; that is, a brain map is meant to reveal a relationship between some condition or parameter and specific sites within the brain. However, in reality, conventional voxel‐based maps of brain function, or for that matter of brain structure, are generally constructed using analyses that yield no basis for inferences regarding the spatial nonuniformity of the effects. In the normal analysis path for functional images, for example, there is nowhere a statistical comparison of the observed effect in any voxel relative to that in any other voxel. Under these circumstances, strictly speaking, the presence of significant activation serves as a legitimate basis only for inferences about the brain as a unit. In their discussion of results, investigators rarely are content to confirm the brain's role, and instead generally prefer to interpret the spatial patterns they have observed. Since “pattern” implies nonuniform effects over the map, this is equivalent to interpreting results without bothering to test their significance, a practice most of the experimentally‐trained would eschew in other contexts. In this review, we appeal to investigators to adopt a new standard of data presentation that facilitates comparison of effects across the map. Evidence for sufficient effect size difference between the effects in structures of interest should be a prerequisite to the interpretation of spatial patterns of activation. Hum. Brain Mapping 19:90–95, 2003. © 2003 Wiley‐Liss, Inc.
A wavelet‐based approximation of surface coil sensitivity profiles for correction of image intensity inhomogeneity and parallel imaging reconstruction
Authors: Lin Fa‐Hsuan , Chen Ying‐Jui , Belliveau John W. , Wald Lawrence L. 
Published: May 2003

AbstractWe evaluate a wavelet‐based algorithm to estimate the coil sensitivity modulation from surface coils. This information is used to improve the image homogeneity of magnetic resonance imaging when a surface coil is used for reception, and to increase image encoding speed by reconstructing images from under‐sampled (aliased) acquisitions using parallel magnetic resonance imaging (MRI) methods for higher spatiotemporal image resolutions. The proposed algorithm estimates the spatial sensitivity profile of surface coils from the original anatomical images directly without using the body coil for additional reference scans or using coil position markers for electromagnetic model‐based calculations. No prior knowledge about the anatomy is required for the application of the algorithm. The estimation of the coil sensitivity profile based on the wavelet transform of the original image data was found to provide a robust method for removing the slowly varying spatial sensitivity pattern of the surface coil image and recovering full FOV images from two‐fold acceleration in 8‐channel parallel MRI. The results, using bi‐orthogonal Daubechies 97 wavelets and other members in this family, are evaluated for T1‐weighted and T2‐weighted brain imaging. Hum. Brain Mapping 19:96–111, 2003. © 2003 Wiley‐Liss, Inc.
The design and synthesis of β‐trifluoromethylenol phosphates as potential insecticides
Authors: Ding Yixiang , Huang Xiaogen 
Published: May 2003

AbstractA new group of compounds, β‐trifluoromethylenol phosphates [(RO)2P(O)OCRCHCF3], has been designed and prepared by several methods. Some of them showed good insecticidal activities. In the molecular structure, the designed leaving group can rearrange to a powerful electrophilic agent, β,β‐difluorovinyl ketone, which would be a potential enzyme inhibitor. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:304–308, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10147
2,4,6‐Trialkylphenyl‐2H‐phospholes from slightly aromatic 1H‐phospholes and their use in [4 + 2] cycloaddition reactions
Authors: Keglevich György , Farkas Renáta , Imre Tímea , Ludányi Krisztina , Szöllősy Áron , Tőke László 
Published: May 2003

Abstract1‐(2,4,6‐Trialkylphenyl)phospholes 1a,b possess a moderate aromatic character. Despite of that they underwent a sigmatropic rearrangement at 150°C to afford 2H‐phospholes 2a,b which by trapping with tolane, or in reaction with another unit of 2 gave [4 + 2] cycloadducts 3a,b, or in a reversible reaction, dimer 6, respectively. Dedimerization of species 6 at 150°C in the presence of tolane, or at 0°C under oxidative circumstances, led to 1‐phosphanorbornadiene 3a, or phosphole oxide dimer 8, respectively. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:316–319, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10151
Chemo‐ and regioselective allylic oxidation: Oxo‐derivatives of 2‐phospholene sugar analogs
Authors: Reddy Valluru Krishna , Rao Lakonda Nagaprasada , Maeda Motoki , Haritha Buchammagari , Yamashita Mitsuji 
Published: May 2003

AbstractA convenient and facile chemo‐ and regioselective oxidation of the allylic methylene group in a 2‐phospholene ring system afforded the novel carbonyl derivatives of 2‐phospholenes (2a–i). The method gives high conversion and selectivity in the formation of allylic ketones. The advantages of this oxidation method in such a five‐membered pseudo sugar 2‐phospholene ring are mentioned, and the oxidation is examined on several substituted 2‐phospholenes (1a–i). © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:320–325, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10154
3‐Aryl‐5‐furylpyrazolines and their biological activities
Authors: Cetin A. , Cansiz A. , Digrak M. 
Published: May 2003

AbstractAryl‐furyl substituted pyrazolines 2a–c and 4a–c were prepared by the reaction of α,β‐unsaturated carbonyl compounds with hydrazine or phenyl hydrazine. N‐chloroacetyl derivatives 3a–c were obtained by the N‐acetylation of 2a–c. The antibacterial activities of synthesized pyrazolines were examined by employing the disk‐diffusion technique. All synthesized compounds showed antibacterial effects in 1200 μg concentration. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:345–347, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10159
Reactivity of diacyloxyiodobenzenes toward trivalent phosphorus nucleophiles
Authors: Makowiec Sławomir , Rachon Janusz 
Published: May 2003

AbstractThe reaction of diacyloxyiodobenzenes and tetravalent phosphorus nucleophiles was investigated. It was established that both H‐phosphonates and secondary phosphine oxides react with diacetoxyiodobenzene in alcohols in the presence of sodium alcoholates yielding trialkyl phosphates and alkyl phosphinates respectively. For this transformation reactive intermediate 6 is proposed. In contrast to this, the treatment of diacetoxyiodobenzene with 3 equiv of sodium diisopropyl phosphite in THF produces diisopropyl 1‐(diisopropoxyphosphinyl)ethylphosphonate with excellent yield. It was found that diacyloxyiodobenzene/PR3 system may serve as an acylating agent; the acylation process can proceed via carboxylic acid anhydride or acylphosphonium salt 17 depending on the protocol used. New very efficient method for synthesis of 2,4,6‐trimethylbenzoic anhydride was developed. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:352–359, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10161
2,2″‐Dimethoxy‐1,1′:3′,1″‐terphenyl as a novel protective group for low‐coordinated phosphorus compounds: The case of diphosphenes
Authors: Ionkin Alex S. , Marshall William J. 
Published: May 2003

AbstractA synthetic approach to meta‐terphenyls iodides bearing methoxy groups in the 2 and 2′′′ positions has been described. 2,2″‐Dimethoxy‐1,1′:3′,1″‐terphenyl groups have been shown to stabilize diphosphenes in solution. The existence of conformers of the diphosphene 7 has also been recorded. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:360–360, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10162
Synthesis of tert‐butylcalix[4]arenes modified with germanium‐containing side‐chains at the lower rim
Authors: Sakurai Takayuki , Takeuchi Yoshito 
Published: May 2003

AbstractBis‐, tris‐, and tetrakis‐trimethylgermylpropanoyl esters of p‐tert‐butylcalix[4]arenes 5, 7, and 8 were synthesized and their conformations in solution were determined by 1H and 13C NMR spectroscopy. The characteristic pair of doublets from the ArCH2Ar methylene protons was observed, indicating that all the prepared calixarenes were in the cone conformation. These germylated calixarenes failed to exhibit any appreciable cation‐capturing ability, indicating that further modification is required to make these compounds to be effective ditopic hosts. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:365–373, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10164
Biphasic role of TGF‐β1 in signal transduction and crosstalk
Authors: Wenner Charles E. , Yan Shaochun 
Published: May 2003

AbstractTGF‐β1 induces cell cycle activation in mouse embryonic fibroblasts by down regulation of p27Kip1 but it can also induce delay of EGF‐induced cell cycle activation in these cells under similar conditions. In an attempt to determine the basis for these responses, the study of early TGF‐β1‐induced signal transduction pathways in the presence and absence of EGF was undertaken. It is proposed that a likely target for the inhibition by TGF‐β1 of the early EGF‐induced p42/p44 MAPK is at the c‐Raf locus. The finding that the catalytic subunits of PKA are associated with Raf‐1 within minutes following application of TGF‐β1 but not EGF in fibroblasts arrested in early G1 is suggestive of a role of PKA‐Raf‐1 interaction in TGF‐β1 induced delay of EGF‐induced cell cycle kinetics. A model for TGF‐β1 induced translocation to the plasma membrane‐associated Raf‐1 is proposed. Reports that Rho‐like GTPase activity is critical for the activation of TGF‐β1 downstream pathways raises the question as to whether Rho proteins are involved in these observed TGF‐β1‐induced responses. Post‐receptor signaling mechanisms for TGF‐β1 and cross‐talk with PKA‐mediated pathways are examined in an effort to explain the modulation by TGF‐β1 of mitogen‐induced cell proliferation in mesenchymal cells. © 2003 Wiley‐Liss, Inc.
Overcoming resistance of cancer cells to apoptosis
Authors: Hersey Peter , Zhang Xu Dong 
Published: May 2003

AbstractDiscovery of the B cell lymphoma gene 2 (Bcl‐2 gene) led to the concept that development of cancers required the simultaneous acquisition, not only of deregulated cell division, but also of resistance to programmed cell death or apoptosis. Apoptosis is arguably the common pathway to cell death resulting from a range of therapeutic initiatives, so that understanding the basis for the resistance of cancer cells to apoptosis may hold the key to development of new treatment initiatives. Much has already been learnt about the apoptotic pathways in cancer cells and proteins regulating these pathways. In most cells, apoptosis is dependent on the mitochondrial dependent pathway. This pathway is regulated by pro‐ and anti‐apoptotic members of the Bcl‐2 family, and manipulation of these proteins offers scope for a number of treatment initiatives. Effector caspases activated by the mitochondrial pathway or from death receptor signaling are under the control of the inhibitor of apoptosis protein (IAP) family. Certain proteins from mitochondrial can, however, competitively inhibit their binding to effector caspases. Information about the structure of these proteins has led to initiatives to develop therapeutic agents to block the IAP family. In addition to development of selective agents based on these two (Bcl‐2 and IAP) protein families, much has been learnt about signal pathways that may regulate their activity. These in turn might provide additional approaches based on selective regulators of the signal pathways. © 2003 Wiley‐Liss, Inc.
BRCA1 gene in breast cancer
Authors: Rosen Eliot M. , Fan Saijun , Pestell Richard G. , Goldberg Itzhak D. 
Published: May 2003

AbstractThe BRCA1 gene was identified and cloned in 1994 based its linkage to early onset breast cancer and breast‐ovarian cancer syndromes in women. While inherited mutations of BRCA1 are responsible for about 40–45% of hereditary breast cancers, these mutations account for only 2‐3% of all breast cancers, since the BRCA1 gene is rarely mutated in sporadic breast cancers. However, BRCA1 expression is frequently reduced or absent in sporadic cancers, suggesting a much wider role in mammary carcinogenesis. Since BRCA1 was cloned in 1994, its molecular function has been the subject of intense investigation. These studies have revealed multiple functions of the BRCA1 that may contribute to its tumor suppressor activity, including roles in: cell cycle progression, several highly specialized DNA repair processes, DNA damage‐responsive cell cycle checkpoints, regulation of a set of specific transcriptional pathways, and apoptosis. Many of these functions are linked to protein:protein interactions involving different portions of the 1,863 amino acid (aa) BRCA1 protein. BRCA1 functions in cell cycle progression and the DNA damage response appear to be regulated by distinct and specific phosphorylation events, but the molecular pathways activated by these phosphorylations are only beginning to be unraveled. In addition, the reason that BRCA1 mutation carriers develop specific tumor types (breast and ovarian cancers in women and possibly prostate cancers in men) is not clearly understood. Elucidation of the precise molecular functions of the BRCA1 gene product will greatly enhance our understanding of the pathogenesis of hereditary as well as sporadic mammary carcinogenesis. © 2003 Wiley‐Liss, Inc.
Effect of high phosphate concentration on osteoclast differentiation as well as bone‐resorbing activity
Authors: Kanatani Masanori , Sugimoto Toshitsugu , Kano Junichi , Kanzawa Michiko , Chihara Kazuo 
Published: May 2003

AbstractAlthough high inorganic phosphate (Pi) concentration in culture media directly inhibits generation of new osteoclasts and also inhibits bone resorption by mature osteoclasts, its precise mechanism and the physiological role have not been elucidated. The present study was performed to investigate these issues. Increase in extracellular Pi concentration ([Pi]e) (2.5–4 mM) concentration dependently inhibited 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3] or parathyroid hormone (PTH)‐(1‐34)‐induced osteoclast‐like cell formation from unfractionated bone cells in the presence of stromal cells. Increase in [Pi]e (2.5–4 mM) concentration dependently inhibited 1,25(OH)2D3‐, PTH‐(1‐34)‐, or receptor activator of NF‐κB ligand (RANKL) and macrophage colony‐stimulating factor (M‐CSF)‐induced osteoclast‐like cell formation from hemopoietic blast cells in the absence of stromal cells. Increase in [Pi]e (2.5–4 mM) dose dependently stimulated the expression of osteoprotegerin (OPG) mRNA and increased the expression of OPG mRNA suppressed by PTH‐(1‐34) or 1,25(OH)2D3 in unfractionated bone cells, while it did not affect RANKL mRNA. Increase in [Pi]e (2.5‐4 mM) concentration dependently inhibited the bone‐resorbing activity of isolated rabbit osteoclasts. Increase in [Pi]e (4 mM) induced the apoptosis of isolated rabbit osteoclasts while it did not affect the apoptosis of osteoclast precursor cells and mouse macrophage‐like cell line C7 cells that can differentiate into osteoclasts in the presence of RANKL and M‐CSF. These results indicate that increase in [Pi]e inhibits osteoclast differentiation both by up‐regulating OPG expression and by direct action on osteoclast precursor cells. It is also indicated that increase in [Pi]e inhibits osteoclastic activity at least in part by the direct induction of apoptosis of osteoclasts. © 2003 Wiley‐Liss, Inc.
Adhesion‐dependent control of Akt/protein kinase B occurs at multiple levels
Authors: Le Gall Maude , Chambard Jean‐Claude , Grall Dominique , Van Obberghen‐Schilling Ellen 
Published: May 2003

AbstractThe protein kinase Akt, also known as Protein Kinase B, has been implicated in the survival of several cell types challenged with various apoptotic stimuli. In CCL39 lung fibroblasts, apoptosis is induced by anchorage and mitogen removal. Mitogen‐induced activation of Akt is highly anchorage dependent in these cells and removal of adhesion is accompanied by a rapid loss in responsiveness to soluble agonists followed by a significant decrease in Akt abundance. Loss of the protein appears to be independent of kinase activation since the expression of a constitutively active form, gag‐Akt, is also dependent upon cell adhesion. Although the disappearance of Akt is coincident with the induction of programmed cell death, it cannot be fully prevented by treatment of cells with the caspase inhibitor ZVAD or by sustained activation of the anti‐apoptotic Raf/ERK pathway, in cells expressing an inducible ΔRaf‐1:ER construct. In addition, a previously unrecognized decrease in Akt mRNA levels following anchorage removal occurs suggesting that anchorage‐dependent transcriptional and/or post‐transcriptional mechanisms contribute to the adhesion‐dependent regulation of Akt expression. © 2003 Wiley‐Liss, Inc.
Transgenic mice with dominant negative PKC‐theta in skeletal muscle: A new model of insulin resistance and obesity
Authors: Serra C. , Federici M. , Buongiorno A. , Senni M.I. , Morelli S. , Segratella E. , Pascuccio M. , Tiveron C. , Mattei E. , Tatangelo L. , Lauro R. , Molinaro M. , Giaccari A. , Bouché Marina 
Published: May 2003

AbstractProtein kinase C θ (PKC‐θ) is the PKC isoform predominantly expressed in skeletal muscle, and it is supposed to mediate many signals necessary for muscle histogenesis and homeostasis, such as TGFβ, nerve‐dependent signals and insulin. To study the role of PKC‐θ in these mechanisms we generated transgenic mice expressing a “kinase dead” mutant form of PKC‐θ (PKC‐θK/R), working as “dominant negative,” specifically in skeletal muscle. These mice are viable and fertile, however, by the 6–7 months of age, they gain weight, mainly due to visceral fat deposition. Before the onset of obesity (4 months of age), they already show increased fasting and fed insulin levels and reduced insulin‐sensitivity, as measured by ipITT, but normal glucose tolerance, as measured by ipGTT. After the 6–7 months of age, transgenic mice develop hyperinsulinemia in the fasting and fed state. The ipGTT revealed in the transgenic mice both hyperglycemia and hyperinsulinemia. At the molecular level, impaired activation of the IR/IRS/PI3K pathway and a significant decrease both in the levels and in insulin‐stimulated activation of the serine/threonine kinase Akt were observed. Taken together these data demonstrate that over‐expression of dominant negative PKC‐θ in skeletal muscle causes obesity associated to insulin resistance, as demonstrated by defective receptor and post‐receptorial activation of signaling cascade. © 2003 Wiley‐Liss, Inc.