bluuebunny/crossref_metadata_2025 huggingface dataset:
How good is the relationship of solar and interplanetary plasma parameters with geomagnetic storms?
Authors: Kane R. P.
Published: February 2005

Since the work of Snyder et al. (1963), who showed a possible link between interplanetary solar wind speed V and geomagnetic index Kp, such a relationship has been examined by many workers and found to be rather loose. In the present communication this relationship is rechecked for all data during 1973–2003. It was noted that moderate or strong geomagnetic storms occurred only when solar wind speed V was above ∼350 km/s. However, above this limit, the plots of Dst versus V showed a large scatter, and any value of V could be associated with any value of Dst in a wide range of a factor of ∼2, or any Dst value could be associated with any value of V in a wide range of a factor of ∼2, indicating a poor relationship between V and Dst. The scatter could be partly because not V but VBs (product of V and the southward component Bs of interplanetary field B) is the appropriate variable relevant for Dst changes. This was checked. In the plot of Dst versus VBs it was noticed that the scatter was smaller and correlation better than that in the plot of Dst versus V. Since the relationship between V and Dst is poor, an estimate of V with some antecedence, as is done in a present‐day prediction scheme ((Gonzalez et al., 2004) V estimated from the lateral extension speed of side halo coronal mass ejections (CMEs) and assuming V2 proportional to Dst magnitudes) is not likely to give reliable estimates of Dst magnitudes. However, estimate of V could certainly be useful to estimate the time when the storm would hit the Earth but remembering that 15% of the halo CMEs may miss the Earth.
The remarkable 2003–2004 winter and other recent warm winters in the Arctic stratosphere since the late 1990s
Authors: Manney Gloria L. , Krüger Kirstin , Sabutis Joseph L. , Sena Sara Amina , Pawson Steven
Published: February 2005

The 2003–2004 Arctic winter was remarkable in the ∼50‐year record of meteorological analyses. A major warming beginning in early January 2004 led to nearly 2 months of vortex disruption with high‐latitude easterlies in the middle to lower stratosphere. The upper stratospheric vortex broke up in late December, but began to recover by early January, and in February and March was the strongest since regular observations began in 1979. The lower stratospheric vortex broke up in late January. Comparison with 2 previous years, 1984–1985 and 1986–1987, with prolonged midwinter warming periods shows unique characteristics of the 2003–2004 warming period: The length of the vortex disruption, the strong and rapid recovery in the upper stratosphere, and the slow progression of the warming from upper to lower stratosphere. January 2004 zonal mean winds in the middle and lower stratosphere were over 2 standard deviations below average. Examination of past variability shows that the recent frequency of major stratospheric warmings (7 in the past 6 years) is unprecedented. Lower stratospheric temperatures were unusually high during 6 of the past 7 years, with 5 having much lower than usual potential for polar stratospheric cloud (PSC) formation and ozone loss (nearly none in 1998–1999, 2001–2002, and 2003–2004, and very little in 1997–1998 and 2000–2001). Middle and upper stratospheric temperatures, however, were unusually low during and after February. The pattern of 5 of the last 7 years with very low PSC potential would be expected to occur randomly once every ∼850 years. This cluster of warm winters, immediately following a period of unusually cold winters, may have important implications for possible changes in interannual variability and for determination and attribution of trends in stratospheric temperatures and ozone.
The singlet electronic ground state isomers of dialuminum monoxide: AlOAl, AlAlO, and the transition state connecting them
Authors: Turney Justin M. , Sari Levent , Yamaguchi Yukio , Schaefer Henry F.
Published: February 2005

The singlet electronic ground state isomers, X̃Σg+1 (AlOAl D∞h) and X̃Σ+1 (AlAlO C∞ν), of dialuminum monoxide have been systematically investigated using ab initio electronic structure theory. The equilibrium structures and physical properties for the two molecules have been predicted employing self-consistent field (SCF) configuration interaction with single and double excitations (CISD), multireference CISD (MRCISD), coupled cluster with single and double excitations (CCSD), CCSD with perturbative triples [CCSD(T)], CCSD with iterative partial triple excitations (CCSDT-3 and CC3), and full triples (CCSDT) coupled cluster methods. Four correlation consistent polarized valence (cc-pVXZ) type basis sets were used. The AlAlO system is rather challenging theoretically. The two isomers are confirmed to have linear structures at all levels of theory. The symmetric isomer AlOAl is predicted to lie 81.9kcalmol−1 below the asymmetric isomer AlAlO at the cc-pV(Q+d)Z CCSD(T) level of theory. The predicted harmonic vibrational frequencies for the X̃Σg+1 AlOAl molecule, ω1=517cm−1, ω2=95cm−1, and ω3=1014cm−1, are in good agreement with experimental values. The harmonic vibrational frequencies for the X̃Σ+1 AlAlO structure, ω1=1042cm−1, ω2=73cm−1, and ω3=253cm−1, presently have no experimental values with which to be compared. With the same methods the barrier heights for the isomerization AlOAl→AlAlO and AlAlO→AlOAl reactions were predicted to be 84.3 and 2.4kcalmol−1, respectively. The dissociation energies D0 for AlOAl (X̃Σg+1) and AlAlO (X̃Σ+1)→AlO(XΣ+2)+Al(P2) were determined to be 130.8 and 48.9kcalmol−1, respectively. Thus, both symmetric AlOAl (X̃Σg+1) and asymmetric AlAlO (X̃Σ+1) isomers are expected to be thermodynamically stable with respect to the dissociation into AlO (XΣ+2)+Al(P2) and kinetically stable for the isomerization reaction (AlAlO→AlOAl) at sufficiently low temperatures.
Simulations of proton order and disorder in ice Ih
Authors: Rick Steven W.
Published: February 2005

Computer simulations of ice Ih with different proton orientations are presented. Simulations of proton disordered ice are carried out using a Monte Carlo method which samples over proton degree of freedom, allowing for the calculation of the dielectric constant and for the examination of the degree of proton disorder. Simulations are also presented for two proton ordered structures of ice Ih, the ferroelectric Cmc21 structure or ice XI and the antiferroelectric Pna21 structure. These simulations indicate that a transition to a proton ordered phase occurs at low temperatures (below 80 K). The symmetry of the ordered phase is found to be dependent on the water potential. The stability of the two proton ordered structures is due to a balance of short-ranged interactions which tend to stabilize the Pna21 structure and longer-range interactions which stabilize the Cmc21 structure.
Numerical study of the accuracy and efficiency of various approaches for Monte Carlo surface hopping calculations
Authors: Herman Michael F. , Moody Michael P.
Published: February 2005

A one-dimensional, two-state model problem with two well-separated avoided crossing points is employed to test the efficiency and accuracy of a semiclassical surface hopping technique. The use of a one-dimensional model allows for the accurate numerical evaluation of both fully quantum-mechanical and semiclassical transition probabilities. The calculations demonstrate that the surface hopping procedure employed accounts for the interference between different hopping trajectories very well and provides highly accurate transition probabilities. It is, in general, not computationally feasible to completely sum over all hopping trajectories in the semiclassical calculations for multidimensional problems. In this case, a Monte Carlo procedure for selecting important trajectories can be employed. However, the cancellation due to the different phases associated with different trajectories limits the accuracy and efficiency of the Monte Carlo procedure. Various approaches for improving the accuracy and efficiency of Monte Carlo surface hopping procedures are investigated. These methods are found to significantly reduce the statistical sampling errors in the calculations, thereby increasing the accuracy of the transition probabilities obtained with a fixed number of trajectories sampled.
Structural evolution of aqueous NaCl solutions dissolved in supercritical carbon dioxide under isobaric heating by mid and near infrared spectroscopy
Authors: Oparin R. , Tassaing T. , Danten Y. , Besnard M.
Published: February 2005

The local order in aqueous NaCl solutions diluted in supercritical carbon dioxide at constant pressure as a function of NaCl concentration and temperature has been investigated using near and mid infrared absorption spectroscopy. The near IR results have allowed us to estimate the water concentration in CO2 rich phase, whereas the state of water aggregation in CO2 phase was investigated using mid IR spectroscopy. The analysis of the band shape variations of the OD stretching mode of HOD led us to conclude that below 100 °C, water molecules dissolved in CO2 exist only under their monomeric form, whatever the salt concentration is, whereas hydrogen-bonded species, namely, dimers start to appear at higher temperatures. Larger aggregates have a negligible concentration in the range of temperature-pressure investigated. Using near and mid infrared data, we have calculated the concentrations of water species in the CO2 phase. Upon heating, it was found that the concentration of dimers considerably increases at the expense of the monomers and only dimers are detected in carbon dioxide at highest temperatures. Changing the salt concentration affects significantly the concentration of monomers and decreases strongly the dimers population as the solution becomes progressively saturated in salt. In the saturated solution, at 340 °C, the dimer concentration is at least two times smaller than in the binary water–CO2 mixture. These findings are in qualitative agreement with existing thermodynamics data showing that addition of NaCl to the binary H2O–CO2 system shifts the range of partial miscibility of water and CO2 towards higher pressure and temperature.
Role of molecular orbitals of the benzene in electronic nanodevices
Authors: Choi Young Cheol , Kim Woo Youn , Park Kee-Su , Tarakeshwar P. , Kim Kwang S. , Kim Tae-Suk , Lee Jin Yong
Published: February 2005

In an effort to examine the intricacies of electronic nanodevices, we present an atomistic description of the electronic transport properties of an isolated benzene molecule. We have carried out ab initio calculations to understand the modulation of the molecular orbitals (MOs) and their energy spectra under the external electric field, and conducting behavior of the benzene molecule. Our study shows that with an increase in the applied electric field, the energy of the third lowest unoccupied molecular orbital (LUMO) of benzene decreases, while the first and second LUMO energies are not affected. Above a certain threshold of the external electric field, the third LUMO is lowered below the original LUMO and becomes the real LUMO. Since the transport through a molecule is to a large extent mediated by the molecular orbitals, the change in MOs can lead to a dramatic increase in the current passing through the benzene molecule. Thus, in the course of this study, we show that the modulation of the molecular orbitals in the presence of a tuning parameter(s) such as the external electric field can play important roles in the operation of molecular devices. We believe that this understanding would be helpful in the design of electronic nanodevices.
Failure analysis of high temperature superconducting films at high microwave power using microsecond time domain measurements
Authors: Purnell A. J. , Cohen L. F. , Hao L. , Gallop J. C.
Published: February 2005

A generic characteristic of resonators can be exploited to determine whether thermal or magnetic mechanisms dominate the failure of high quality, high temperature superconducting thin films at high microwave power. We demonstrate that a transient response can be superimposed on a pulse wave form with a frequency equal to the difference between the driving frequency and the resonant frequency of the resonator. When a thermal failure mechanism dominates, the resonant frequency depends on the temporal separation between pulses. This is in marked contrast to a magnetic failure mechanism, which is insensitive to the pulse separation. For poor quality films the technique cannot differentiate between vortices in weak links and local heating at weak links that happen on a short time scale. We discuss the application of the technique to noncontact microwave bolometry.
Electroluminescence of 2,4-bis(4-(2′-thiophene-yl)phenyl)thiophene in organic light-emitting field-effect transistors
Authors: Oyamada Takahito , Sasabe Hiroyuki , Adachi Chihaya , Okuyama Suguru , Shimoji Noriyuki , Matsushige Kazumi
Published: February 2005

We succeeded in observing electroluminescence (EL) of 2,4-bis(4-(2′-thiophene-yl)phenyl)thio-phene (TPTPT) as an active layer in an organic field-effect transistor (OFET). In particular, an OFET with a short channel of dSD=0.8μm demonstrated higher EL efficiency than one with a much longer channel (dSD=9.8μm). We observed a maximum EL quantum efficiency (ηmax) of 6.4×10−3% in the short-channel-length device at an applied source-drain voltage of Vd=−100V and a gate voltage of Vg=−40V. From the OFET characteristics, although the TPTPT layer demonstrated typical p-type operation, the occurrence of EL clearly indicated simultaneous hole and electron injection from the source and drain electronics, respectively, under high Vd and Vg.
Current-induced metastable resistive state in epitaxial thin films of La1−xCaxMnO3 (x=0.2, 0.3)
Authors: Gao J. , Hu F. X.
Published: February 2005

The influence of a transport dc current on electric resistivity has been investigated in epitaxial thin films of La1−xCaxMnO3 (x=0.2, 0.3). A most prominent finding is the appearance of a remarkable resistive peak at temperatures well below the Curie temperature Tc. Such a resistive peak is developed when the dc current over a critical value was applied in a temperature cycling from 300 to 10 K. The resistance peak turns out to be extremely sensitive to a weak current. Even a very small current could greatly depress the height of the peak. Such a current-induced state with high resistivity is metastable compared to the pristine state. The stability of the induced state has been also studied.
Nanoscopic netted structure of compositional modulation in (Sm0.33Eu0.33Gd0.33)Ba2Cu3O7−δ superconductors
Authors: Hu A. , Hirabayashi I. , Winter M. , Koblischka M. R. , Hartmann U. , Zhou H.
Published: February 2005

We report a nanoscaled crisscross network in high-quality melt-processed (Sm0.33Eu0.33Gd0.33)Ba2Cu3O7−δ superconductors investigated with atomic force microscopy (AFM) and transmission electron microscopy. In the ten-micrometer scale, such a net was unveiled as a consequence of crossing annular stripes originating from ordering compositional modulation. The AFM topographic images further displayed that this compositional stripe result in a surface modulation with a few-nanometer wavelength and roughness. The forming mechanism of this compositional stripe and its role as strong δTc-type pinning defects were discussed in the context of rare earth∕Ba oscillation around the stoichiometric ratio and the spatial fluctuation of local Tc values.
Novel Disulfides with Antitumour Efficacy and Specificity
Authors: Griffiths Rebecca , Wong W. Wei-Lynn , Fletcher Stephen P. , Penn Linda Z. , Langler Richard F.
Published: February 2005

Some disulfides have previously been shown to possess antifungal and/or antileukaemic activity. Importantly, this cytotoxicity can be selective. We have previously shown that a subset of these compounds does not block the proliferative potential of normal, non-transformed cells. Based on these results and proposed mechanisms of action, a new set of structurally modified organosulfur compounds, including α-substituted disulfides and a thiosulfonate ester, have been prepared and evaluated for their potential as antileukaemic agents. Compounds were screened for antiproliferative activity against a panel of human cells derived from acute lymphocytic and acute myelogenous leukaemia, as well as non-transformed cells. We have identified five new disulfides and a thiosulfonate that can trigger tumour cells to undergo cell death by an apoptotic mechanism in a sensitive and specific manner.
Nucleoside Analogues from Branched-Chain Pyranosides
Authors: Otero Iran , Feist Holger , Herrera Lidcay , Michalik Manfred , Quincoces José , Peseke Klaus
Published: February 2005

Reaction of (pyranosid-3-yl)ethanal 2 with ethynylmagnesium bromide or lithium phenylacetylide in THF afforded (2R,S)-1-(methyl 2-O-benzyl-4,6-O-benzylidene-3-deoxy-α-d-altropyranosid-3-yl)but-3-yn-2-ols 3a and 3b, respectively. Oxidation of 3a and 3b yielded the 1-(methyl 2-O-benzyl-4,6-O-benzylidene-3-deoxy-α-d-altropyranosid-3-yl)but-3-yn-2-ones 4a and 4b, which upon treatment with hydrazine and hydrazine derivatives formed the 3-(methyl 2-O-benzyl-4,6-O-benzylidene-3-deoxy-α-d-altropyranosid-3-ylmethyl)pyrazoles 5a–5d. Compounds 4a and 4b also underwent reaction with amidinium and guanidinium salts under basic conditions to furnish the 4-(methyl 2-O-benzyl-4,6-O-benzylidene-3-deoxy-α-d-altropyranosid-3-ylmethyl)pyrimidines 8a–8f. Furthermore, treatment of 4a and 4b with 2-aminobenzimidazole yielded the 2-(methyl 2-O-benzyl-4,6-O-benzylidene-3-deoxy-α-d-altropyranosid-3-ylmethyl)benzo[4,5]imidazo[1,2-a]pyrimidines 11a and 11b. Deprotection of 5a and 8b in two steps afforded 3(5)-(methyl 3-deoxy-α-d-altropyranosid-3-ylmethyl)-1H(2H)-pyrazole 7 and 4-(methyl 3-deoxy-α-d-altropyranosid-3-ylmethyl)-2-phenylpyrimidine 10, respectively. Compound 11a was treated with AcOH/H2O to furnish 2-(methyl 2-O-benzyl-3-deoxy-α-d-altropyranosid-3-ylmethyl)benzo-[4,5]imidazo[1,2-a]pyrimidine 13.
Simple and Efficient Reduction of Aromatic Nitro Compounds Using Recyclable Polymer-Supported Formate and Magnesium
Authors: Abiraj Keelara , Srinivasa Gejjalagere R. , Gowda D. Channe
Published: February 2005

Aromatic nitro compounds were chemoselectively reduced to the corresponding amines using recyclable polymer-supported formate as a hydrogen donor in the presence of low-cost magnesium powder at room temperature. Use of the immobilized hydrogen donor affords the product amine in excellent yield (90–97%) without the need for any chromatographic purification steps. This method was found to be highly facile with selectivity over several other functional groups, such as halogen, alkene, nitrile, carbonyl, ester, amide, methoxy, phenol, and hydroxyl groups.
Observation of Te…π and X…X Bonding in para-Substituted Diphenyltellurium Dihalides, (p-Me2NC6H4)(p-YC6H4)TeX2 (X = Cl, Br, I; Y = H, EtO, Me2N)
Authors: Beckmann Jens , Dakternieks Dainis , Duthie Andrew , Mitchell Cassandra , Schürmann Markus
Published: February 2005

The supramolecular association of the previously described para-dimethylaminophenyl-substituted diorganotellurium dihalides (p-Me2NC6H4)2TeX2 (X = Cl (1), Br (2), I (3)) and (p-Me2NC6H4)RTeCl2 (R = Ph (4), p-EtOC6H4 (5)), was investigated by X-ray crystallography. Unlike almost all other structurally characterized diorganotellurium dihalides, (p-Me2NC6H4)2TeX2 (X = Cl (1), Br (2), I (3)) reveal no secondary Te∙∙∙X interactions, but X∙∙∙X interactions. The structure of (p-Me2NC6H4)PhTeCl2 (4) resembles that of Ph2TeCl2 and shows one secondary Te∙∙∙Cl contact, whereas (p-Me2NC6H4)(p-EtOC6H4)TeCl2 (5) exhibits neither secondary Te∙∙∙Cl nor Cl∙∙∙Cl interactions. The unusual structural characteristics of 1–5 are attributed to the occurrence of intermolecular Te∙∙∙π and π∙∙∙π contacts associated with quinoid π-electron delocalization across the para-dimethylaminophenyl (1–5) and para-ethoxyphenyl (5) groups.
The Optical Spectroscopy of Extraterrestrial Molecules
Authors: Schmidt Timothy W. , Sharp Robert G.
Published: February 2005

The ongoing quest to identify molecules in the interstellar medium by their electronic spectra in the visible region is reviewed. Identification of molecular absorption is described in the context of the elucidation of the carriers of the unidentified Diffuse Interstellar Bands, and molecular emission is discussed with reference to the unidentified Red Rectangle bands. The experimental techniques employed in undertaking studies on the optical spectroscopy of extraterrestrial molecules are described and critiqued in the context of their application.
Biomechanical properties of insects in relation to insectivory: cuticle thickness as an indicator of insect 'hardness' and 'intractability'
Authors: Evans Alistair R. , Sanson Gordon D.
Published: February 2005

The concept of ‘hardness’ has long been used to describe the biomechanical properties of the diet of many animals. However, due to the lack of a consistent definition, and the multitude of uses to which the term has been put, the use of the term ‘intractability’ has been advocated here to represent the extent to which the structural strength, stiffness and toughness are increased in a foodstuff. The thickness of the cuticle of an insect was a good measure of the intractability of cuticle. The tremendous advantage of the use of cuticle thickness as a measure of the biomechanical properties of invertebrates means that the dietary properties of a living insectivore can be directly quantified according to the thickness of the cuticle in its faeces. The quantitative measurement of intractability obtained through this technique can be used in correlations with adaptations of the masticatory apparatus, including tooth and skull morphology, as well as more general considerations of ecology. This is a major advance on previous measures of the biomechanical properties of insectivore diets, and may represent the best technique of any dietary group in assessing the properties of its diet.
Intranasal administration of nerve growth factor (NGF) rescues recognition memory deficits in AD11 anti-NGF transgenic mice
Authors: De Rosa Roberta , Garcia Addys Ancheta , Braschi Chiara , Capsoni Simona , Maffei Lamberto , Berardi Nicoletta , Cattaneo Antonino
Published: February 2005

Nerve growth factor (NGF) delivery to the brain of patients appears to be an emerging potential therapeutic approach to neurodegenerative disease, such as Alzheimer's disease (AD). The intranasal route of administration could provide an alternative to intracere-broventricular infusion and gene therapy. We previously showed that intranasal administration of NGF determined an amelioration of cholinergic deficit and a decrease in the number of phosphotau-positive neurons and of β-amyloid accumulation in AD11 mice, which express transgenic antibodies neutralizing NGF action and exhibit a progressive Alzheimer-like neurodegeneration. In this study, we report that the Alzheimer-like neurodegeneration in AD11 mice is linked to progressive behavioral deficits in visual recognition memory and spatial memory starting from 4 months of age. To establish whether intranasal administration of NGF, started after the appearance of the first memory deficits, could revert the cognitive deficits in AD11 mice, we assessed the performance of NGF-treated or control AD11 mice in the object recognition test and in a test of memory for place and context. Deficits exhibited by untreated AD11 mice could be rescued by the intranasal administration of NGF. Thus, this route of administration provides a promising way to deliver NGF to the brain in a therapeutic perspective.
Effect of centrally administered C75, a fatty acid synthase inhibitor, on ghrelin secretion and its downstream effects
Authors: Hu Zhiyuan , Cha Seung Hun , van Haasteren Goedelle , Wang Jing , Lane M. Daniel
Published: February 2005

The central administration of the fatty acid synthase (FAS) inhibitor, C75, rapidly suppresses the expression of orexigenic neuropeptides [neuropeptide Y (NPY) and agouti-related protein (AgRP)] and activates expression of anorexigenic neuropeptides [proopiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART)] in the hypothalamus. The combined actions of these changes inhibit food intake and decrease body weight. Intracerebroventricular injection of C75 appears to rapidly inhibit the secretion of ghrelin by hypothalamic explants
ex vivo
and by the stomach
in vivo
. Ghrelin administered intracerebroventricularly reverses the anorexic effect of C75, suggesting that C75 acts upstream of ghrelin. Because ghrelin-producing neurons are known to form synapses onto NPY/AgRP neurons, we suggest that the reversal of C75-induced anorexia by ghrelin may be mediated by NPY/AgRP neurons. This hypothesis is supported by the finding that ghrelin reverses the C75-induced inactivation (assessed by c-Fos expression) of neurons in the arcuate nucleus that express NPY (assessed by immunohistochemical costaining). These effects closely correlate with appropriate changes downstream in the expression of the hypothalamic neuropeptides that regulate feeding behavior, i.e., down-regulation of the expression of NPY and AgRP and up-regulation of the expression of proopiomelanocortin/α-melanocyte-stimulating hormone, provoked by C75 and reversed by ghrelin. We propose a model in which ghrelin secretion plays an intermediary role between malonyl-CoA, the substrate of fatty acid synthase, and the neural circuitry regulating energy homeostasis.
Identification and Characterization of a Novel α-Kinase with a von Willebrand Factor A-like Motif Localized to the Contractile Vacuole and Golgi Complex inDictyostelium discoideum
Authors: Betapudi Venkaiah , Mason Cynthia , Licate Lucila , Egelhoff Thomas T.
Published: February 2005

We have identified a new protein kinase in Dictyostelium discoideum that carries the same conserved class of “α-kinase” catalytic domain as reported previously in myosin heavy chain kinases (MHCKs) in this amoeba but that has a completely novel domain organization. The protein contains an N-terminal von Willebrand factor A (vWFA)-like motif and is therefore named VwkA. Manipulation of VwkA expression level via high copy number plasmids (VwkA++cells) or gene disruption (vwkA null cells) results in an array of cellular defects, including impaired growth and multinucleation in suspension culture, impaired development, and alterations in myosin II abundance and assembly. Despite sequence similarity to MHCKs, the purified protein failed to phosphorylate myosin II in vitro. Autophosphorylation activity, however, was enhanced by calcium/calmodulin, and the enzyme can be precipitated from cellular lysates with calmodulin-agarose, suggesting that VwkA may directly bind calmodulin. VwkA is cytosolic in distribution but enriched on the membranes of the contractile vacuole and Golgi-like structures in the cell. We propose that VwkA likely acts indirectly to influence myosin II abundance and assembly behavior and possibly has broader roles than previously characterized α kinases in this organism, which all seem to be MHCKs.
Actin Depolymerization Transduces the Strength of B-Cell Receptor Stimulation
Authors: Hao Shengli , August Avery
Published: February 2005

Polymerization of the actin cytoskeleton has been found to be essential for B-cell activation. We show here, however, that stimulation of BCR induces a rapid global actin depolymerization in a BCR signal strength-dependent manner, followed by polarized actin repolymerization. Depolymerization of actin enhances and blocking actin depolymerization inhibits BCR signaling, leading to altered BCR and lipid raft clustering, ERK activation, and transcription factor activation. Furthermore actin depolymerization by itself induces altered lipid raft clustering and ERK activation, suggesting that F-actin may play a role in separating lipid rafts and in setting the threshold for cellular activation.
Specialization of the HOG Pathway and Its Impact on Differentiation and Virulence ofCryptococcus neoformans
Authors: Bahn Yong-Sun , Kojima Kaihei , Cox Gary M. , Heitman Joseph
Published: February 2005

The human pathogenic fungus Cryptococcus neoformans has diverged from a common ancestor into three biologically distinct varieties or sibling species over the past 10–40 million years. During evolution of these divergent forms, serotype A C. neoformans var. grubii has emerged as the most virulent and cosmopolitan pathogenic clade. Therefore, understanding how serotype A C. neoformans is distinguished from less successful pathogenic serotypes will provide insights into the evolution of fungal virulence. Here we report that the structurally conserved Pbs2-Hog1 MAP kinase cascade has been specifically recruited as a global regulator to control morphological differentiation and virulence factors in the highly virulent serotype A H99 clinical isolate, but not in the laboratory-generated and less virulent serotype D strain JEC21. The mechanisms of Hog1 regulation are strikingly different between the two strains, and the phosphorylation kinetics and localization pattern of Hog1 are opposite in H99 compared with JEC21 and other yeasts. The unique Hog1 regulatory pattern observed in the H99 clinical isolate is widespread in serotype A strains and is also present in some clinical serotype D isolates. Serotype A hog1Δ and pbs2Δ mutants are attenuated in virulence, further underscoring the role of the Pbs2-Hog1 MAPK cascade in the pathogenesis of cryptococcosis.
Dissociation of the Nuf2-Ndc80 Complex Releases Centromeres from the Spindle-Pole Body during Meiotic Prophase in Fission Yeast
Authors: Asakawa Haruhiko , Hayashi Aki , Haraguchi Tokuko , Hiraoka Yasushi
Published: February 2005

In the fission yeast Schizosaccharomyces pombe, centromeres remain clustered at the spindle-pole body (SPB) during mitotic interphase. In contrast, during meiotic prophase centromeres dissociate from the SPB. Here we examined the behavior of centromere proteins in living meiotic cells of S. pombe. We show that the Nuf2-Ndc80 complex proteins (Nuf2, Ndc80, Spc24, and Spc25) disappear from the centromere in meiotic prophase when the centromeres are separated from the SPB. The centromere protein Mis12 also dissociates during meiotic prophase; however, Mis6 remains throughout meiosis. When cells are induced to meiosis by inactivation of Pat1 kinase (a key negative regulator of meiosis), centromeres remain associated with the SPB during meiotic prophase. However, inactivation of Nuf2 by a mutation causes the release of centromeres from the SPB in pat1 mutant cells, suggesting that the Nuf2-Ndc80 complex connects centromeres to the SPB. We further found that removal of the Nuf2-Ndc80 complex from the centromere and centromere-SPB dissociation are caused by mating pheromone signaling. Because pat1 mutant cells also show aberrant chromosome segregation in the first meiotic division and this aberration is compensated by mating pheromone signaling, dissociation of the Nuf2-Ndc80 complex may be associated with remodeling of the kinetochore for meiotic chromosome segregation.
Lysophosphatidylcholine-induced Surface Redistribution Regulates Signaling of the Murine G Protein-coupled Receptor G2A
Authors: Wang Li , Radu Caius G. , Yang Li V. , Bentolila Laurent A. , Riedinger Mireille , Witte Owen N.
Published: February 2005

Intracellular trafficking and spatial dynamics of membrane receptors critically regulate receptor function. Using microscopic and subcellular fractionation analysis, we studied the localization of the murine G protein-coupled receptor G2A (muG2A). Evaluating green fluorescent protein-tagged, exogenously expressed as well as the endogenous muG2A, we observed that this receptor was spontaneously internalized and accumulated in endosomal compartments, whereas its surface expression was enhanced and stabilized by lysophosphatidylcholine (LPC) treatment. Monensin, a general inhibitor of recycling pathways, blocked LPC-regulated surface localization of muG2A as well as muG2A-dependent extracellular signal-regulated kinase (ERK) activation and cell migration induced by LPC treatment. Mutation of the conserved DRY motif (R→ A) enhanced the surface expression of muG2A, resulting in its resistance to monensin inhibition of ERK activation. Our data suggest that intracellular sequestration and surface expression regulated by LPC, rather than direct agonistic activity control the signaling responses of murine G2A toward LPC.
Multiple Myeloma and Peripheral Neuropathy in Myotonic Dystrophy Type 2 (DM2)
Authors: Walker Melanie , Weiss Michael D , Distad B Jane , Samii Ali
Published: February 2005

Myotonic dystrophy type 2 (DM2) is a phenotypically heterogeneous multisystem disorder, most dramatically involving the nervous system. Although multisystem involvement is common in this disease, we present a genetically proven DM2 patient with both peripheral neuropathy and blood dyscrasia, previously unreported in the literature, suggesting a distinct phenotype in this population. Routine electrophoresis in DM2 patients with neuropathy is recommended, and implications surrounding the etiology of peripheral neuropathy and paraproteinemia in DM2 are discussed.
Gastric Emptying in Premature Newborns with Acute Respiratory Distress
Authors: dos Santos Mezzacappa Maria Aparecida Marques , Collares Edgard Ferro
Published: February 2005

Objectives:

The authors hypothesized that acute respiratory distress (ARD) delays gastric emptying. The objective was to test this hypothesis by assessing gastric emptying on the second and seventh days of life in premature infants with ARD resulting from pulmonary disease.

Methods:

Thirty‐nine newborns with ARD starting on the first day of life were selected and paired with 39 healthy control newborns matched by weight (within 250 g). Gestational age was ≤35 weeks and birth weight was ≤1750 g for all subjects. Gastric emptying was assessed at 48.0 ± 24.0 hours and at 168.0 ± 24.0 hours of life. A test meal consisting of 3 mL/kg of 5% glucose in water labeled with phenol red was administered by gastric tube over 1 minute and gastric retention was determined as percent test meal remaining in the stomach 30 minutes after administration.

Results:

Gastric retention at 30 minutes varied considerably in both groups and was significantly higher (P < 0.01) in newborns with ARD (61.4%) than controls (51.8%) at 48.0 ± 24.0 hours, decreasing significantly after partial or full remission of ARD at 168 ± 24 hours of life. Gastric retention was 60.2% in newborns with feeding intolerance and 36.8% in tolerant newborns (P < 0.001) at 168 hours. ARD and periventricular or intraventricular hemorrhage were predictors of gastric retention at 48 ± 24 hours of life, whereas feeding intolerance and gestational age were predictors of gastric retention at 168 ± 24 hours. Gastric retention was inversely correlated with gestational age.

Conclusion:

Gastric emptying is delayed in premature infants with ARD during the first 72 hours of life and may impair the initiation of enteral feeding.
Laparoscopic Antireflux Procedures in the Management of Gastroesophageal Reflux Following Esophageal Atresia Repair
Authors: Esposito Ciro , Langer Jacob C , Schaarschmidt Klaus , Mattioli Girolamo , Sauer Carolien , Centonze Antonella , Cigliano Bruno , Settimi Alessandro , Jasonni Vincenzo
Published: February 2005

Objectives:

The validity of open fundoplication after esophageal atresia (EA) repair is still disputed. The authors have retrospectively evaluated the results achieved in their centers using laparoscopic antireflux procedures (LARP) in children operated for EA at birth.

Methods:

From 1998 to 2002, 350 children underwent LARP. Of these, 21 (6%) underwent EA repair at birth. Our study focused only on the management of these 21 patients; 5 of them (23.8%) were neurologically impaired children (NIC). All underwent LARP, 9 patients according to Nissen, 9 according to Thal, and 3 according to Toupet. The 5 NIC with feeding problems underwent concomitant g‐tube placement during the same procedure.

Results:

All the procedures were completed in laparoscopy, without intraoperative complications. The mean operative time was 65 minutes (range 45‐140). We had no mortality in our series. Hospital stay varied from 2 to 9 days (median 3 days). At a maximum follow‐up of 6 years, all patients were evaluated with a 24‐hours pH‐metry and barium swallow. The 16 neurologically normal children were free of symptoms at the last follow‐up; five of them (31.2%) had mild dysphagia, which disappeared spontaneously within 3‐6 months. One girl experienced an important episode of aspiration 2 years after the LARP, although there was no evidence of reflux at the follow‐up examinations. As for the 5 NIC, one patient eats only through a g‐tube, the other 4 undergo mixed feeding (g‐tube and mouth); none have signs of GER, but two of them still present respiratory symptoms, and one has delayed gastric emptying.

Conclusions:

In our experience laparoscopic antireflux surgery is an appropriate treatment of GER in children operated for EA at birth, independently of the antireflux mechanism adopted; the 31.2% rate of short‐term dysphagia presenting as residual respiratory symptoms may be due to a primary dysmotility of the esophagus consequent to the esophageal atresia.
Using the Concept of Food Based Dietary Guidelines to Develop an Optimized Mixed Diet (OMD) for German Children and Adolescents
Authors: Kersting Mathilde , Alexy Ute , Clausen Kerstin
Published: February 2005

Objective:

To apply for the first time FAO/WHO standards for Food Based Dietary Guidelines (FBDG) to develop a total diet concept named Optimized Mixed Diet (OMD) for children and adolescents in a European country.

Methods:

Exact 7‐day menus were composed for sample age groups of children (4‐6 years) and adolescents (13‐14 years), taking into account the German meal patterns, common non‐fortified foods, and sensory preferences of children (practical criteria). Food amounts and food selection within the menus were optimized so far as to achieve a total of reference intakes for 22 nutrients (scientific criteria). Simple food based messages were deduced.

Results:

Compared to the existing high‐fat, low plant food diet reported from the DONALD Study (Dortmund Nutritional and Anthropometric Longitudinally Designed Study), the OMD is lower in fat and saturated fatty acids and contains ample amounts of plant foods. Reference nutrient densities for age groups between 1 and 18 years were achieved or exceeded, except folate. Foods from the optimized menus were summarized into 11 food groups based on nutritional and practical considerations. Proportions of food groups by weight are independent of age and can be used to recalculate food amounts for various age groups or energy requirements, respectively. For simplification, “recommended” foods were distinguished from “tolerated” foods by their nutrient densities; based on food amounts, 3 simple rules for food consumption were deduced, i.e. beverages and plant foods: ample; animal foods: moderate; high‐fat, high‐sugar foods: sparingly.

Conclusions:

Exact menus and food amounts are a prerequisite to ascertain nutrient adequacy of FBDG. The OMD demonstrates that a single diet concept with a core of quantified food groups can be adequate for age groups between 1 and 18 years within a country, such as Germany.
Celiac Disease in Children with Diarrhea Is More Frequent than Previously Suspected
Authors: Imanzadeh Farid , Sayyari Ali Akbar , Yaghoobi Mohammad , Akbari Mohammad Reza , Shafagh Hamed , Farsar Ahmad Reza
Published: February 2005

Background:

Celiac disease (CD) may be missed or diagnosed late in children with chronic diarrhea. In this study the authors estimated the frequency of CD among pediatric patients with chronic diarrhea based on serologic and pathologic examinations.

Methods:

During a 6‐year period, all patients with chronic diarrhea of more than 6 weeks referred to the authors' department were included. For each patient, an asymptomatic control was enrolled from among the patients referred to our clinic for other reasons. Serologic tests for CD including immunoglobulin A endomysial antibody and immunoglobulin A antigliadin antibody were performed in all patients and controls. If positive, duodenal biopsy was performed to confirm the diagnosis. Patients subsequently diagnosed as CD were placed on a gluten‐free diet and reevaluated after 6 months.

Results:

825 cases of diarrhea and 825 controls were enrolled. CD was diagnosed in 54 (6.5%) of the diarrhea patients and seven (0.8%) of the controls. After 6 months of gluten‐free diet, 48 (88.8%) patients had significant improvement in symptoms and of these 41 (76.1%) were totally asymptomatic. Forty‐two patients allowed repeat endoscopy after 6 months of gluten‐free diet and 40 (95.2%) showed improvement in histologic findings.

Conclusion:

CD is common among patients labeled as chronic diarrhea. In this subgroup, gluten‐free diet may lead to a significant improvement in symptoms. Routine testing for CD may be indicated in all patients being evaluated for chronic diarrhea.
Chronic Abdominal Pain In Children: A Technical Report of the American Academy of Pediatrics and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition
Authors: Di Lorenzo Carlo , Colletti Richard B , Lehmann Horald P , Boyle John T , Gerson William T , Hyams Jeffrey S , Squires Robert H , Walker Lynn S , Kanda Pamela T
Published: February 2005

Chronic abdominal pain, defined as long‐lasting intermittent or constant abdominal pain, is a common pediatric problem encountered by primary care physicians, medical subspecialists and surgical specialists. Chronic abdominal pain in children is usually functional‐that is, without objective evidence of an underlying organic disorder. The Subcommittee on Chronic Abdominal Pain of the American Academy of Pediatrics and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition has prepared this report based on a comprehensive, systematic review and rating of the medical literature. This report accompanies a clinical report based on the literature review and expert opinion.

The subcommittee examined the diagnostic and therapeutic value of a medical and psychologic history, diagnostic tests, and pharmacological and behavioral therapy. The presence of alarm symptoms or signs (such as weight loss, gastrointestinal bleeding, persistent fever, chronic severe diarrhea and significant vomiting) is associated with a higher prevalence of organic disease. There was insufficient evidence to state that the nature of the abdominal pain or the presence of associated symptoms (such as anorexia, nausea, headache and joint pain) can discriminate between functional and organic disorders. Although children with chronic abdominal pain and their parents are more often anxious or depressed, the presence of anxiety, depression, behavior problems or recent negative life events does not distinguish between functional and organic abdominal pain. Most children who are brought to the primary care physician's office for chronic abdominal pain are unlikely to require diagnostic testing. Pediatric studies of therapeutic interventions were examined and found to be limited or inconclusive.
Seizure Anticipation: Do Mathematical Measures Correlate with Video‐EEG Evaluation?
Authors: Navarro Vincent , Martinerie Jacques , Le Van Quyen Michel , Baulac Michel , Dubeau François , Gotman Jean
Published: February 2005

Summary:  Purpose: Analysis of the EEG signal has recently shown evidence of dynamic changes preceding ictal onset in seizures selected from patients with clear epileptogenic foci. Most of the studies were conducted in highly selected EEG epochs and patients. In addition, these studies relied mostly on mathematical approaches and neglected clinical and visual EEG parameters. We therefore performed a systematic comparison of a nonlinear method (the similarity measure) with classic visual inspection of the EEG and the patient's clinical state.

Methods: We analyzed the dynamics of long epochs of intracranial EEG containing 129 electroclinical and 45 electrographic seizures in 13 successive unselected patients undergoing presurgical evaluation.

Results: (a) The similarity measure detected preictal dynamical changes of the EEG signal in two thirds of the seizures whether or not a clear focus was identified, and whether seizures were electroclinical or purely electrographic. The mean duration of preictal changes was 12 min. (b) The preictal changes were correlated with various visually detectable EEG changes in 78.9% of electroclinical seizures. (c) 81.5% of the preictal dynamic changes were correlated with changes of vigilance or behavior. (d) Fluctuations of the dynamics were not necessarily followed by seizures.

Conclusions: Our results indicate that EEG dynamics frequently change before seizures. These preictal changes are most often associated with the EEG changes accompanying transitions between states of vigilance. The preictal dynamic changes may represent physiologic changes acting as facilitating factors or pathologic changes reflecting a network dysfunction.
Consistent Localization of Interictal Epileptiform Activity on EEGs of Patients with Tuberous Sclerosis Complex
Authors: Jansen Floor E. , Van Huffelen Alexander C. , Bourez‐Swart Mireille , Van Nieuwenhuizen Onno
Published: February 2005

Summary: Purpose:We addressed consistent localization of focal interictal epileptiform activity on EEGs of patients with tuberous sclerosis complex (TSC) and epilepsy.

Methods:Twenty‐one patients with TSC with a 10‐year history of epilepsy and interictal epileptiform activity in three or more EEG recordings were included. None of the patients had undergone epilepsy surgery. Local maxima of interictal epileptiform activity were measured from 76 EEG traces and 33 EEG reports. Information about the patients' clinical course was extracted from their medical records. Magnetic resonance imaging (MRI) and neuropsychological examinations were performed. Statistical analysis was performed with the Mann–WhitneyUtest.

Results:In eight patients, interictal epileptiform activity was consistently detected in one or two regions (group 1), and in 13 patients, epileptiform activity was detected in three or more regions (group 2). The number of foci increased throughout the disease course in both groups. Age at seizure onset and IQ were significantly higher in group 1. Complex partial seizures occurred more often in the patients of group 1. In 19 of the 21 patients, the most consistent epileptiform activity was localized in the frontotemporal region.

Conclusions:Ninety percent of patients with TSC showed at least one region of consistent interictal epileptiform activity. Patients with one or two regions of epileptiform activity were older at seizure onset, often experienced complex partial seizures, and had mild or no mental deficits. These patients may be candidates for epilepsy surgery.