bluuebunny/crossref_metadata_2025 huggingface dataset:
Intrathecal cGMP elicits pressor responses and maintains mean blood pressure during haemorrhage in anaesthetized rats
Authors: Malik V. , Holobotovskyy V. V. , Phillips J. K. , McKitrick D. J. , Arnolda L. F.
Published: March 2007

The intracellular second messenger, cyclic guanosine monophosphate (cGMP), a soluble guanylate cyclase (GC) product, is a primary mechanism for the transduction of a nitric oxide (NO)‐initiated signal in the central nervous system. NO is produced from l‐arginine by neuronal nitric oxide synthase (NOS), which is found in sympathetic preganglionic neurons of the intermediolateral cell column. This suggests the possibility that NO is a modulator of sympathetic nervous activity (SNA) through a cGMP‐mediated mechanism. The aim of this study was to determine the effects of intrathecally injected membrane‐permeant 8‐bromo‐cGMP and 1H‐[1,2,4]oxadiazole[4,3‐a]quinoxalin‐1‐one (ODQ), a selective inhibitor of the soluble form of GC, on arterial pressure in urethane anaesthetized (1.4 g kg−1i.p.) rats. The effects of intrathecal cGMP and ODQ on haemodynamic responses to haemorrhage were also investigated. Finally, l‐arginine, the NO precursor, was also injected intrathecally, alone and in the presence of ODQ. Baseline mean arterial pressure (MAP) increased significantly after intrathecal 8‐Br‐cGMP injection (10 μl, 1, 3, 10, 30, 100 μm). A dose–effect relationship (1 μm to 100 μm) was also established (EC50= 6.03 μm). During continuous haemorrhage, MAP was maintained in animals injected with 8‐Br‐cGMP, relative to the control group. Although no change in baseline MAP was observed as a result of intrathecal ODQ injection (10 μl, 100 mm), a greater rate of fall in MAP was observed during haemorrhage. Injecting l‐arginine (10, 100, 1000 μm, 10 μl) showed a pressor effect that was consistent with the effect of the downstream messenger, cGMP. Furthermore, its pressor effect was blocked by ODQ pre‐administration. The results indicate that cGMP increases blood pressure, and thus suggest that cGMP increases SNA. This supports the hypothesis that the sympathoexcitatory effects of spinal delivery of NO are mediated by a cGMP‐dependent mechanism.
Spino‐dendritic cross‐talk in rodent Purkinje neurons mediated by endogenous Ca2+‐binding proteins
Authors: Schmidt Hartmut , Kunerth Svenja , Wilms Christian , Strotmann Rainer , Eilers Jens
Published: March 2007

The range of actions of the second messenger Ca2+ is a key determinant of neuronal excitability and plasticity. For dendritic spines, there is on‐going debate regarding how diffusional efflux of Ca2+ affects spine signalling. However, the consequences of spino‐dendritic coupling for dendritic Ca2+ homeostasis and downstream signalling cascades have not been explored to date. We addressed this question by four‐dimensional computer simulations, which were based on Ca2+‐imaging data from mice that either express or lack distinct endogenous Ca2+‐binding proteins. Our simulations revealed that single active spines do not affect dendritic Ca2+ signalling. Neighbouring, coactive spines, however, induce sizeable increases in dendritic [Ca2+]i when they process slow synaptic Ca2+ signals, such as those implicated in the induction of long‐term plasticity. This spino‐dendritic coupling is mediated by buffered diffusion, specifically by diffusing calbindin‐bound Ca2+. This represents a central mechanism for activating calmodulin in dendritic shafts and therefore a novel form of signal integration in spiny dendrites.
Additive protective effects of the addition of lactic acid and adrenaline on excitability and force in isolated rat skeletal muscle depressed by elevated extracellular K+
Authors: De Paoli Frank Vincenzo , Overgaard Kristian , Pedersen Thomas Holm , Nielsen Ole Bækgaard
Published: March 2007

During strenuous exercise, extracellular K+ ([K+]o) is increased, which potentially can reduce muscle excitability and force production. In addition, exercise leads to accumulation of lactate and H+ and increased levels of circulating catecholamines. Individually, reduced pH and increased catecholamines have been shown to counteract the depressing effect of elevated K+. This study examines (i) whether the effects of addition of lactic acid and adrenaline on the excitability of isolated muscles are caused by separate mechanisms and are additive and (ii) whether the effect of adding lactic acid or increasing CO2 is related to a reduction of intra‐ or extracellular pH. Rat soleus muscles were incubated at a [K+]o of 15 mm, which reduced tetanic force by 85%. Subsequent addition of 20 mm lactic acid or 10−5m adrenaline led to a small recovery of force, but when added together induced an almost complete force recovery. Compound action potentials showed that the force recovery was associated with recovery of muscle excitability. The improved excitability after addition of adrenaline was associated with increased Na+–K+ pump activity resulting in hyperpolarization and an increase in the chemical Na+ gradient. In contrast, addition of lactic acid had no effect on the membrane potential or the Na+–K+ pump activity, but most likely increased excitability via a reduction in intracellular pH. It is concluded that the protective effects of acidosis and adrenaline on muscle excitability and force took place via different mechanisms and were additive. The results suggest that circulating catecholamines and development of acidosis during exercise may improve the tolerance of muscles to elevated [K+]o.
Spin Rate of Asteroid (54509) 2000 PH5 Increasing Due to the YORP Effect
Authors: Taylor Patrick A. , Margot Jean-Luc , Vokrouhlický David , Scheeres Daniel J. , Pravec Petr , Lowry Stephen C. , Fitzsimmons Alan , Nolan Michael C. , Ostro Steven J. , Benner Lance A. M. , Giorgini Jon D. , Magri Christopher
Published: March 2007

Radar and optical observations reveal that the continuous increase in the spin rate of near-Earth asteroid (54509) 2000 PH5 can be attributed to the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, a torque due to sunlight. The change in spin rate is in reasonable agreement with theoretical predictions for the YORP acceleration of a body with the radar-determined size, shape, and spin state of 2000 PH5. The detection of asteroid spin-up supports the YORP effect as an explanation for the anomalous distribution of spin rates for asteroids under 10 kilometers in diameter and as a binary formation mechanism.
Functional Taxonomy of Bacterial Hyperstructures
Authors: Norris Vic , den Blaauwen Tanneke , Cabin-Flaman Armelle , Doi Roy H. , Harshey Rasika , Janniere Laurent , Jimenez-Sanchez Alfonso , Jin Ding Jun , Levin Petra Anne , Mileykovskaya Eugenia , Minsky Abraham , Saier Milton , Skarstad Kirsten
Published: March 2007

The levels of organization that exist in bacteria extend from macromolecules to populations. Evidence that there is also a level of organization intermediate between the macromolecule and the bacterial cell is accumulating. This is the level of hyperstructures. Here, we review a variety of spatially extended structures, complexes, and assemblies that might be termed hyperstructures. These include ribosomal or “nucleolar” hyperstructures; transertion hyperstructures; putative phosphotransferase system and glycolytic hyperstructures; chemosignaling and flagellar hyperstructures; DNA repair hyperstructures; cytoskeletal hyperstructures based on EF-Tu, FtsZ, and MreB; and cell cycle hyperstructures responsible for DNA replication, sequestration of newly replicated origins, segregation, compaction, and division. We propose principles for classifying these hyperstructures and finally illustrate how thinking in terms of hyperstructures may lead to a different vision of the bacterial cell.
Phylogenetic relationships of Luziola (Poaceae: Oryzeae) and related genera from aquatic habitats
Authors: Martínez-y-Pérez José L. , Mejía-Saulés Teresa , Sosa Victoria
Published: March 2007

Luziola is a small aquatic genus consisting of nine American species and belonging to Poaceae (subfamily Ehrhartoideae, tribe Oryzeae). We surveyed 160 morphological characters and performed phylogenetic analyses to determine relationships within the genus and between it and its closest relatives, and to deduce the evolution of a number of characters in relation to the aquatic habit. Our results confirm that Luziola is a monophyletic group and that Zizaniopsis is its sister group among taxa examined but revealed only a few clades within Luziola, the best supported of which consists of Luziola fragilis Swallen, Luziola fluitans (Michx.) Terrell & H. Rob., and Luziola peruviana J.F. Gmel. We used this phylogenetic evidence to reconstruct the evolution of several characters hypothesized to be correlated to an aquatic life style, including reduction or absence of glumes, papillae arranged in horizontal rows on the lemmas, dumb-bell shaped silica bodies, and a change from hermaphrodite to unisexual florets.
Reindeer grazing reduces seed and propagule bank in the High Arctic
Authors: Cooper Elisabeth J.
Published: March 2007

It is commonly assumed that plant establishment in the High Arctic is limited by severe abiotic conditions and by a paucity of propagules and seeds. Heavy reindeer grazing may reduce plant allocation to reproduction and removes significant proportions of flowers and seeds, thus reducing contributions to seed rain and seed bank. In contrast, foraging and trampling may break up existing mature plants, increasing the vegetative propagules in the soil. To determine the effect of grazing on colonization potential in the High Arctic, two studies were carried out: (i) a comparison of seed bank inside and outside three long-term reindeer ( Rangifer tarandus platyrhnchus (Vrolic)) exclosures and (ii) an investigation of the germinable seed and propagule bank of two neighbouring peninsulas with contrasting reindeer grazing history in northwestern Svalbard (79°N, 12°E). Seed banks inside reindeer exclosures germinated significantly more seedlings (596 seedlings·m–2) than those outside (263 seedlings·m–2). Species composition and total plant cover was similar on both peninsulas, but forage-plant cover was lower on the heavily grazed peninsula (Brøggerhalvøya) than on the adjacent lightly grazed peninsula (Sarsøyra). Brøggerhalvøya had significantly lower species richness and density of seed and propagule bank (0.21 ± 0.02 germinating species per sample, 0.15 ± 0.02 propagule species per sample, 416 ± 103 seedlings·m–2, 283 ± 78 propagules·m–2) than did Sarsøyra (0.44 ± 0.40 germinating species per sample, 0.35 ± 0.03 propagule species per sample,1016 ± 188 seedlings·m–2, 782 ± 238 propagules·m–2). These results imply that reindeer depleted both the seed and the propagule banks, thus reducing the potential for colonization of disturbed areas. Grazing may, therefore, have a lasting impact on High Arctic plant communities.
Resolving the phylogenetic position of the Wallemiomycetes: an enigmatic major lineage of Basidiomycota
Authors: Matheny P. Brandon , Gossmann Jasmin A. , Zalar Polona , Kumar T.K. Arun , Hibbett David S.
Published: March 2007

The Wallemiomycetes includes three species of molds from the genus Wallemia . These fungi are adapted to environments of high osmotic stress, contaminate various foods, cause respiratory disease, and have an unusual mode of asexual reproduction. Wallemia was recently proposed as a new class based on 18S ribosomal RNA gene sequences to accommodate the isolated position of the clade in the Basidiomycota. We analyzed the phylogenetic position of the Wallemiomycetes using 3451 nucleotide characters of the 18S, 25S, and 5.8S ribosomal RNA genes and 1282 amino acid positions of rpb1, rpb2, and tef1 nuclear protein-coding genes across 91 taxa. Different gene regions and methods of phylogenetic inference produce mildly conflicting placements of the Wallemiomycetes. Parsimony analyses of nrDNA data suggest that the Wallemiomycetes is an early diverging lineage of Basidiomycota, occupying a basal position near the Entorrhizomycetidae. Ultrastructural data, some Bayesian analyses, and amino acid sequences suggest the Wallemiomycetes may be the sister group of the Agaricomycotina or Ustilaginomycotina. The combined gene tree supports the Wallemiomycetes as a lineage basal to a core clade of Pucciniomycotina, Ustilaginomycotina, and Agaricomycotina with robust measures of branch support. This study reinforces the isolated position of Wallemia in the Basidiomycota using molecular data from six nuclear genes. In total, five major lineages of Basidiomycota are recognized: the Agaricomycotina, Ustilaginomycotina, Pucciniomycotina, Entorrhizomycetidae, and the Wallemiomycetes.
Growth and reproductive potential of the invasive exotic vine Vincetoxicum rossicum in northern New York State
Authors: Smith Larissa L. , DiTommaso Antonio , Lehmann Johannes , Greipsson Sigurdur
Published: March 2007

The alien invasive vine Vincetoxicum rossicum (Kleopow) Barbar. is problematic in the Lower Great Lakes Basin of North America. The lack of effective control strategies exacerbates the need for a better understanding of the growth and reproductive potential of V. rossicum. Thus, a 2-year field experiment was performed in a field site in 2003 and 2004 that was densely colonized by V. rossicum. Mean height of V. rossicum stems was 20% and 45% greater in naturally shaded plots compared with plots receiving full sun in 2003 and 2004, respectively. During the 2-year study, the density of stems 10 cm or taller averaged 134 stems·m–2, substantially greater than reported in previous field studies for this species. The high densities of stems and seedlings indicate that this field site may be near or at carrying capacity. Each stem produced, on average, 17 mature follicles with some stems producing as many as 100 follicles. Each follicle yielded an average of 15 seeds, each composed of an average of two viable embryos. A typical V. rossicum stand in this site produced as many as 54 000 seedlings·m–2 annually. More flowers (2400 flowers·m–2), follicles (2250 follicles·m–2), and total seeds (32 000 seeds·m–2) were produced in plots receiving intermediate light compared with plants in full sun (1650 flowers·m–2, 1600 follicles·m–2, and 25 000 seeds·m–2) or shaded (1600 flowers·m–2, 2000 follicles·m–2, and 28 000 seeds·m–2) plots. Seeds harvested from follicles in the low light plots were 41% more likely to be dormant than seeds collected from follicles in full sun plots. Seeds collected from plants in full sun plots had the lowest frequency (∼36%) of single embryo seeds and the highest frequency (∼64%) of multiple embryo seeds. These findings suggest that V. rossicum growth and reproductive output is influenced by light environment. While competitive strategies differ between the light environments, the decrease in viability and germination in shaded sites may not be large enough to affect population growth over multiple generations. The substantially greater growth and reproduction of V. rossicum reported in this study relative to previous research may explain the increasing abundance and range expansion of this species in many Lower Great Lakes regions of Ontario and New York State.
Transgenic Brassica napus fields and Brassica rapa weeds in Quebec: sympatry and weed-crop in situ hybridization
Authors: Simard Marie-Josée , Légère Anne , Warwick Suzanne I.
Published: March 2007

Hybridization between the herbicide-resistant transgenic crop Brassica napus L. (canola) and its weedy relative Brassica rapa L. (bird rape) has been documented in Quebec. Our goal was to evaluate the actual hybridization potential based on range overlap and actual in situ hybridization rates. This was done by mapping B. napus canola fields, comparing them with the sampling locations of B. rapa herbarium specimens from Quebec, gathering information on the presence of B. rapa in certified canola seed production fields, and surveying for B. rapa populations located in, or close to B. napus field margins. Progeny from these populations were screened for herbicide resistance (HR) and for the presence of the HR transgene. Two fields were also selected to evaluate B. rapa density effects on hybridization rates. Significant sympatry was observed in several areas of the province; hybridization occurred in all eight populations (1.1% to 17.5% hybrid seed) located in field margins and in one (1.1%) out of three populations located less than 10 m from a B. napus field. Hybridization rates decreased exponentially as B. rapa density increased, but interplant rates (0% to 68%) were highly variable. Environmental problems could be generated by the release of B. napus crops with traits conferring fitness benefits in nonmanaged areas.
The shoot apical meristem: an historical perspectiveThis review is one of a selection of papers published on the Special Theme of Shoot Apical Meristems.
Authors: Steeves Taylor A.
Published: March 2007

Although much of the current investigation of shoot apical meristems is in the realm of molecular genetic analysis, it is important that previous structural and functional studies not be overlooked as essential background to these studies. Since Caspar Friedrich Wolff described the shoot apical meristem in 1759, many and varied interpretations have arisen. In the early 19th century, the apical cell was recognized in seedless vascular plants and this interpretation was extended to seed plants. However, by the 1860s, this view was replaced in seed plants by the histogen concept, which recognized meristem layers in the apical meristem giving rise to specific tissues. In 1924, the tunica–corpus interpretation of angiosperm shoot apices became widespread, the two regions being distinguished by different planes of cell division. In the 1950s, the “méristème d’attente” concept appeared in France, which argued that the central region of the apex remained essentially inactive until the onset of flowering. Meanwhile, the recognition of zonation patterns in angiosperm and gymnosperm shoot apices assumed growing functional importance. Clonal analysis based on chimeras in the meristem indicated the presence of initial cells but also their replacement. Surgical experimentation and culture of excised apices in vitro stressed the autonomy of the shoot apex and its role in shoot development. Present molecular genetic analysis may help to resolve some of the persistent questions concerning the organization and functioning of shoot apical meristems.
The efficient and chemoselective MoO3-catalyzed oxidation of sulfides to sulfoxides and sulfones with H2O2
Authors: Khodaei Mohammad Mehdi , Bahrami Kiumars , Khedri Mohammad
Published: March 2007

Hydrogen peroxide together with MoO3 as catalyst can efficiently and chemoselectivity oxidize sulfides to sulfoxides and sulfones in the presence of other oxidized functional groups in ethanol at 50 °C in short reaction times.Key words: oxidation, sulfides, sulfoxides, sulfones, H2O2–MoO3 system.
Heterogeneities in sol–gel-derived paramagnetics-doped forsterites and willemites — Electron microprobe analysis and stretched-exponential29Si MAS NMR spin–lattice relaxation studies
Authors: Hartman J Stephen , Narayanan Arjun , Rigby Suzie S , Sliwinski David R , Halden Norman M , Bain Alex D
Published: March 2007

We report the synthesis and analysis of sol–gel-derived samples of forsterite (Mg2SiO4) and willemite (Zn2SiO4), doped with paramagnetic Cu2+, Ni2+, and Co2+, at a range of dopant concentrations. Electron probe microanalysis and backscattered electron imaging show the presence of major micrometre-scale heterogeneities in the distribution of paramagnetic centres. Despite the inhomogeneities, the29Si NMR spin–lattice relaxation behaviour is well-behaved and is consistent with the stretched-exponential expression Mz(t) = Mz(∞){1 – a exp[–(t/T′)n]}. The exponent n is 0.5 within the experimental error in some samples. This value is consistent with relaxation by immobile isolated paramagnetic impurities with negligible29Si spin diffusion from the impurity centres, but careful curve fitting confirms that n is significantly larger than 0.5 in other samples. Relaxation efficiency is highly dependent on the dopant ion and its concentration. Although the purely empirical stretched-exponential function does not provide a unique physical picture, it is noteworthy that it is sufficiently robust to describe spin–lattice relaxation even in highly inhomogeneous systems. Spin–lattice relaxation is a useful probe of paramagnetics-doped solid samples, but NMR does not provide information on homogeneity. Careful sample characterization on the micrometre scale is highly desirable, as a complement to NMR studies.Key words: MAS NMR, spin–lattice relaxation,29Si, forsterite, willemite, stretched-exponential relaxation, sol–gel, minor-component heterogeneity, backscattered electron analysis.
Cadmium chloride-catalyzed regioselective opening of oxiranes with aromatic amines — An improved protocol for the synthesis of 2-amino alcohols
Authors: Kumar S Ramesh , Leelavathi P
Published: March 2007

Epoxides undergo rapid CdCl2-catalyzed ring-opening reaction with aromatic amines in mild reaction conditions (room temperature), affording the corresponding 2-amino alcohols with high regioselectivity.Key words: epoxides, aromatic amines, cadmium chloride, 2-amino alcohols.
Ruthenium(III) acetylacetonate [Ru(acac)3] — An efficient recyclable catalyst for the acetylation of phenols, alcohols, and amines under neat conditions
Authors: Varala Ravi , Nasreen Aayesha , Adapa Srinivas R
Published: March 2007

A catalytic amount of ruthenium(III) acetylacetonate (2 mol%) [Ru(acac)3] enables solvent-free acetylation of phenols, alcohols, and amines at ambient temperature in good to excellent yields. Furthermore, the catalyst could be recovered and reused at least three times without a significant loss in yields.Key words: acetylation, protecting groups, ruthenium(III) acetylacetonate, phenols, alcohols, amines.
Chemistry of the potassium, silver, and tetra(n-butyl)ammonium salts of sydnone N-oxide (Traube's anion)
Authors: Arulsamy Navamoney , Bohle D Scott , Perepichka Inna
Published: March 2007

Traube's dianion, 4-methylcarboxysydnone-3-hydroxylate (2), and its monomethyl ester (1) are readily isolated as their di- and mono-potassium salts from the reaction of nitric oxide with dimethylmalonate and potassium methoxide in methanol. Metathesis reactions of 1 with silver nitrate and tetra(n-butyl)ammonium bromide yield the silver and tetra(n-butyl)ammonium salts of 4-methylcarboxysydnone-3-hydroxylate. In contrast to other known sydnone derivatives, the present sydnones are stable in both acidic and basic solutions. Single crystal X-ray diffraction data obtained for 2 and the silver salt (3) reveal planarity and delocalization of double bonds in the sydnone ring, indicating aromatic behavior. The tetra(n-butyl)ammonium salt (4) is soluble in a range of organic compounds. Cyclic voltammetric data measured for 4 in acetonitrile reveal an irreversible oxidation peak at +1.09 V vs. Fc–Fc+ couple suggesting that the sydnone derivatives can be oxidized with an appropriate oxidizing agent. Differential scanning calorimetry data reveal thermal stability at ambient conditions and exothermic decomposition at high temperatures (>229 °C). The sydnone derivatives are characterized by two strong electronic absorptions in the UV region and rich vibrational (IR and Raman) spectra in the 1800–1500 cm–1 region. Density functional theory (B3LYP/6-311+++G**) is applied to estimate the aromaticity of the sydnone ring and to assign the vibrational spectral data.Key words: sydnone, trans-diazeniumdiolate, N-oxide.
Aluminum pentafluorophenyl–amide complexes
Authors: Cornelissen Carsten , Chan Gigi , Masuda Jason D , Stephan Douglas W
Published: March 2007

The pentafluoroaryl amine (C6F5)2NH (1) reacts with AlH3·NEtMe2 to give [(C6F5)2N]AlH2·NEtMe2 (2) and [(C6F5)2N]2AlH·NEtMe2 (3). The related fluorinated-aryl amine (C6F5)(n-C4H9)NH (4) also reacts with AlH3·NEtMe2 to give [(C6F5)(n-C4H9)N]3Al·NEtMe2 (5). This latter compound undergoes ligand exchange with PMe3 or N-methylimidazole to form [(C6F5)(n-C4H9)N]3Al·PMe3 (6) and [(C6F5)(n-C4H9)N]3Al·(Me-imid) (7), respectively. The latter amine also reacts with AlMe3, affording [Me2AlN(C6F5)(n-C4H9)]2 (8).Key words: almunium, amides, pentafluorophenylamine.
ORBITAL INSULATORS AND ORBITAL ORDER–DISORDER INDUCED METAL–INSULATOR TRANSITION IN TRANSITION-METAL OXIDES
Authors: CHEN DONG-MENG , ZOU LIANG-JIAN
Published: March 2007

The role of orbital ordering on metal–insulator transition in transition-metal oxides is investigated by the cluster self-consistent field approach in the strong correlation regime. A clear dependence of the insulating gap of single-particle excitation spectra on the orbital order parameter is found. The thermal fluctuation drives the orbital order–disorder transition, diminishes the gap and leads to the metal–insulator transition. The unusual temperature dependence of the orbital polarization in the orbital insulator is also manifested in the resonant X-ray scattering intensity.
ESR STUDY OF SPIN-HAMILTONIAN PARAMETERS AND CRYSTAL FIELD ENERGY LEVELS FOR THE LOW C3 SYMMETRY Fe3+ CENTER IN GREEN SAPPHIRE CRYSTALS AND POWDER
Authors: LIMSUWAN P. , UDOMKAN N. , WINOTAI P.
Published: March 2007

In this report, Fe 3+ impurity ions present in green sapphire ( Al 2 O 3) were studied experimentally, by heating a light green sapphire in flowing oxygen atmosphere for 12 h from 1200, 1300, 1400, 1500 and 1600°C, respectively. Electron spin resonance (ESR) spectra in X-band (~9.45 GHz ) were recorded by mounting the crystal with the c-axis perpendicular (θ = 90°) to the magnetic field direction. The spectra were recorded and simulated by a numerical diagonalization of spin Hamiltonian matrix in the range from 0 to 180 degrees for every 15 degrees of rotation angle (φ). In our case, only the last two sets of peaks strongly depend on the rotation angle (φ), and each exhibits C 3 symmetry due to two magnetically inequivalent Fe 3+ sites in the corundum structure. For polycrystalline ESR spectra, seven main Fe 3+ ESR absorption peaks occur at the resonance magnetic fields of 100.20, 310.24, 486.80, 525.00, 550.60, 761.00 and 777.00 mT respectively. Specifically, ESR signals show that the number of paramagnetic Fe 3+ ions increase roughly linearly with the heat treating temperature, having the [Formula: see text] ratio ~1.41 at 1600°C.
COMPARISON OF HIGH FIELD ELECTRON TRANSPORT PROPERTIES IN WURTZITE AND ZINCBLENDE PHASE GaN AT ROOM TEMPERATURE
Authors: ARABSHAHI H.
Published: March 2007

An ensemble Monte Carlo simulation has been used to model bulk electron transport at 300 K for both the natural wurtzite and the zincblende lattice phases of GaN . Electronic states within the conduction band are represented by non-parabolic ellipsoidal valleys centred on important symmetry points of the Brillouin zone, but for zincblende GaN , the simpler spherical parabolic band approximation has also been tested, for comparison. In the case of wurtzite GaN , transport has been modeled with an electric field applied both parallel and perpendicular to the (0001) c-axis. The steady state velocity-field characteristics are in fair agreement with other recent calculations.
Ethanol induced NF-κB activation protects against cell injury in cultured rat gastric mucosal epithelium
Authors: Mustonen Harri , Hietaranta Antti , Puolakkainen Pauli , Kemppainen Esko , Paimela Hannu , Kiviluoto Tuula , Kivilaakso Eero
Published: March 2007

Ethanol is a well-established irritant inducing inflammation in gastric mucosa, but the effects at the cellular level remain unclear. This study investigates NF-κB activation in gastric mucosal cells by ethanol and assesses the effects of heat shock pretreatment in this ulcerogenic situation. Rat gastric mucosal epithelia were exposed to ethanol for different time periods. Heat shock was induced by incubating the cells at 42°C for 1 h prior to the experiments. For evaluation of NF-κB activation, the nuclear fraction of the cell lysates was analyzed with an EMSA or an ELISA-based assay. Caspase-3 (a promoter of apoptosis) activity was measured with a time-resolved fluorescence based assay, cell viability with a tetrazolium assay, and cell membrane integrity with a LDH assay. Ethanol (1–5%) induced NF-κB activation, reaching a maximum after 3 h, and also led to moderately increased COX-2 expression. Heat shock pretreatment and the intracellular calcium chelator BAPTA were able to inhibit ethanol-induced NF-κB activation. Heat shock pretreatment decreased ethanol-induced caspase-3 activation, decreased cell membrane damage, and retained cellular viability. Inhibition of NF-κB activation by NEMO-binding peptide, by decreasing RelA expression, or by inhibiting COX-2 activity by CAY-14040 promoted the effects of ethanol, such as increased caspase-3 activity and decreased cell viability. In conclusion, ethanol induces NF-κB activation via a calcium-dependent pathway and induces COX-2 expression. Inhibition of the NF-κB activation or COX-2 activity potentiates apoptosis and cell damage induced by ethanol, suggesting a protective role for NF-κB activation and COX-2 expression.
Intestinal epithelial cells from inflammatory bowel disease patients preferentially stimulate CD4+ T cells to proliferate and secrete interferon-γ
Authors: Dotan Iris , Allez Matthieu , Nakazawa Atsushi , Brimnes Jens , Schulder-Katz Micoll , Mayer Lloyd
Published: March 2007

Previous studies have suggested that intestinal epithelial cells (IECs) have the capacity to function as nonprofessional antigen presenting cells that in the normal state preferentially activate CD8+ T cells. However, under pathological conditions, such as those found in inflammatory bowel disease (IBD), persistent activation of CD4+ T cells is seen. The aim of this study was to determine whether the IBD IECs contribute to CD4+ T cell activation. Freshly isolated human IECs were obtained from surgical specimens of patients with or without IBD and cocultured with autologous or allogeneic peripheral blood T lymphocytes. Cocultures of normal T cells and IECs derived from IBD patients resulted in the preferential activation of CD4+ T cell proliferation that was associated with significant IFN-γ, but not IL-2, secretion. Cytokine secretion and CD4+ T cell proliferation was inhibited by pretreatment of the IBD IECs with the anti-DR MAb L243. In contrast, normal IECs stimulated the proliferation and cytokine secretion by CD4+ T cells to a significantly lesser degree than IBD IECs. Furthermore, blockade of human leukocyte antigen-DR had a lesser effect in the normal IEC-CD4+ T cell cocultures. We conclude that IECs can contribute to the ongoing CD4+ T cell activation seen in IBD. We suggest that the apparent differences between the secreted levels of IFN-γ indicate that it may play a dual role in intestinal homeostasis, in which low levels contribute to physiological inflammation whereas higher levels are associated with an uncontrolled inflammatory state.
Dose-dependent recruitment of CD25+ and CD26+ T cells in a novel F344 rat model of asthma
Authors: Skripuletz Thomas , Schmiedl Andreas , Schade Jutta , Bedoui Sammy , Glaab Thomas , Pabst Reinhard , von Hörsten Stephan , Stephan Michael
Published: March 2007

The ovalbumin (OVA)-induced airway inflammation in rats is a commonly used model to explore the pathobiology of asthma. However, its susceptibility varies greatly between rat strains, and presently Brown Norway (BN) rats are preferentially used. Since recruitment of T cells to the lungs depends on the CD26 (dipeptidyl peptidase IV, DPPIV) expression, Fischer 344 strain (F344) rats are a highly relevant rat strain, in particular because CD26-deficient substrains are available. To establish a F344 rat model of asthma, we challenged F344 rats using different doses of aerosolized antigen (0%, 1%, 2.5%, 5%, and 7.5% OVA) and compared these effects with intratracheal instillation of OVA (1.5 mg/0.3 ml). Asthmoid responsiveness was determined by analysis of early airway responsiveness (EAR), antigen-specific IgE levels, as well as airway inflammation including the composition of T cell subpopulations in the bronchoalveolar lavage (BAL) and lung tissue with special respect to the T cell activation markers CD25 and CD26. Even low allergen doses caused allergen-specific EAR and increases of antigen-specific IgE levels. However, EAR and IgE levels did not increase dose dependently. Higher concentrations of OVA led to a dose-dependent increase of several immunological markers of allergic asthma including an influx of eosinophils, T cells, and dendritic cells. Interestingly, a dose-dependent increase of CD4+/CD25+/CD26+ T cells was found in the lungs. Summarizing, we established a novel F344 rat model of aerosolized OVA-induced asthma. Thereby, we found a dose-dependent recruitment of cellular markers of allergic asthma including the activated CD4+/CD25+/CD26+ T cell subpopulation, which has not been described in asthma yet.
Activin-type II receptor B (ACVR2B) and follistatin haplotype associations with muscle mass and strength in humans
Authors: Walsh Sean , Metter E. Jeffrey , Ferrucci Luigi , Roth Stephen M.
Published: March 2007

Genetic variation in myostatin, a negative regulator of skeletal muscle, in cattle has shown remarkable influence on skeletal muscle, resulting in a double-muscled phenotype in certain breeds; however, DNA sequence variation within this gene in humans has not been consistently associated with skeletal muscle mass or strength. Follistatin and activin-type II receptor B ( ACVR2B) are two myostatin-related genes involved in the regulation and signaling of myostatin. We sought to identify associations between genetic variation and haplotype structure in both follistatin and ACVR2B with skeletal muscle-related phenotypes. Three hundred fifteen men and 278 women aged 19–90 yr from the Baltimore Longitudinal Study of Aging were genotyped to determine respective haplotype groupings (Hap Groups) based on HapMap data. Whole body soft tissue composition was measured by dual-energy X-ray absorptiometry. Quadriceps peak torque (strength) was measured using an isokinetic dynamometer. Women carriers of ACVR2B Hap Group 1 exhibited significantly less quadriceps muscle strength (shortening phase) than women homozygous for Hap Group 2 (109.2 ± 1.9 vs. 118.6 ± 4.1 N·m, 30°/s, respectively, P = 0.036). No significant association was observed in men. Male carriers of follistatin Hap Group 3 exhibited significantly less total leg fat-free mass than noncarriers (16.6 ± 0.3 vs. 17.5 ± 0.2 kg, respectively, P = 0.012). No significant associations between these haplotype groups were observed in women. These results indicate that haplotype structure at the ACVR2B and follistatin loci may contribute to interindividual variation in skeletal muscle mass and strength, although these data indicate sex-specific relationships.
Enhanced Expression of ANGPTL2 in the Microvascular Lesions of Diabetic Glomerulopathy
Authors: Sun Hua , Zheng Jing-min , Chen Shan , Zeng Cai-hong , Liu Zhi-hong , Li Lei-shi
Published: March 2007

Background: Diabetic nephropathy (DN) is one of the most important microvascular complications of diabetes mellitus. However, the underlying mechanisms remain unclear. We studied the expression characteristics of angiopoietin-like 2 (ANGPTL2), a novel DN-associated growth factor identified in our previous gene chip screening. Methods: Glomeruli were microdissected from renal biopsies from 24 patients with DN and 8 donor controls. The expression of ANGPTL2 was assessed by RT-PCR and immunohistochemistry, and then correlated with clinical and pathological indices of glomerular injury. Results: Consistent with the results of the gene chip experiment, abundant expression of ANGPTL2 was found more frequently in diabetic glomeruli as compared to donor controls (95 vs. 38%, χ2 = 15.9, p < 0.01). ANGPTL2 mRNA upregulation was more prominent in glomeruli with less microaneurysm (22 vs. 66%, p < 0.05), inflammatory influx (6 vs. 50%, p < 0.05) or endothelial foam cell formation (11 vs. 53%, p < 0.05). Immunostaining revealed an upregulation of ANGPTL2 protein in hypertrophied diabetic glomeruli, mainly distributed in podocytes, which were supposed to be the origin of ANGPTL2. Conclusion: The upregulation of ANGPTL2 in diabetic glomerulopathy shows a close relationship to abnormal microvasculature and endothelial inflammation. ANGPTL2 may play an important role in the pathogenesis of diabetic glomerulopathy.
Difference in the Role of Loss of Heterozygosity at 10p15 (KLF6 Locus) in Colorectal Carcinogenesis between Sporadic and Familial Adenomatous Polyposis and Hereditary Nonpolyposis Colorectal Cancer Patients
Authors: Miyaki Michiko , Yamaguchi Tatsuro , Iijima Takeru , Funata Nobuaki , Mori Takeo
Published: March 2007

Objectives: To clarify the role of the KLF6 (Kruppel-like factor 6) locus in multistep colorectal carcinogenesis, we analyzed loss of heterozygosity (LOH) at 10p15 (KLF6 locus) and mutations of the KLF6gene in 298 colorectal tumors at various pathological stages of sporadic and familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC) patients. Methods: 10p15 LOH was analyzed using KLF6M1 and KLF6M2, and KLF6 gene mutation was analyzed using PCR-SSCP and sequencing. Results: It was found that the frequencies of LOH (sum of M1 and M2) were 4% in adenomas, 0% in intramucosal carcinomas, 35% in invasive carcinomas, and 33% in liver metastases in sporadic cases. Invasive carcinomas from FAP patients showed only 6% LOH, and invasive carcinomas from HNPCC patients exhibited 0% LOH. Mutation analysis of the KLF6 gene in 298 colorectal tumors detected no somatic mutations. Conclusions: The present data suggest that LOH of the KLF6 locus at chromosome 10p15 contributes to the invasion step from an intramucosal carcinoma to an invasive carcinoma specifically in sporadic colorectal carcinogenesis, but is rarely involved in the carcinogenesis of FAP and HNPCC cases. Moreover, the absence of somatic mutations suggests the uncertainty of the KLF6 gene as a classical tumor suppressor gene at the lost 10p15 region in colorectal carcinogenesis.
Urinary Incontinence in Disabled Elderly Women: A Randomized Clinical Trial on the Effect of Training Mobility and Toileting Skills to Achieve Independent Toileting
Authors: van Houten Paul , Achterberg Wilco , Ribbe Miel
Published: March 2007

Background: Urinary incontinence is very prevalent in elderly women, and it is considered a major burden for both patient and caregiver. Objective: To determine feasibility and effect of training mobility and toileting skills on the severity of urinary incontinence in elderly, dependent women. Methods: In a randomized, single-blinded trial, 57 dependent, nondemented, elderly women with long-standing urinary incontinence and a mild to moderate disorder in mobility and transfers were recruited in 24 long-term care institutions. The participants were randomized to receive either no treatment (n = 28) or an individualized 8-week training program of mobility and toileting skills (n = 29), provided by physiotherapists and/or occupational therapists. Results: The intervention resulted in a 37.7% reduction in the daily amount of urine loss. Three women in the intervention group compared to none in the control group became continent. A change from dependent to independent toileting occurred in 6 women in the intervention group and in 2 women in the control group. All these results, however, were not statistically significant. The intervention did have a significant effect on the daytime sum score of the toilet timing test. Conclusions: This study suggests that it is possible to influence long-standing incontinence in dependent elderly women by training mobility and toileting skills. Future studies should have a larger sample size, and more attention should be paid to the motivation of the participants.
Magnetic Resonance Imaging Stereotaxy: Recognition and Utilization of the Commissures
Authors: Villemure J.-G. , Marchand E. , Peters T. , Leroux G. , Olivier A.
Published: March 2007

Magnetic Resonance Imaging (MRI) offers a non-invasive method to visualize the intracerebral structures. Coupled to a compatible stereotactic frame and software, MRI can be used to determine the coordinates of intracranial targets. Coordinates of the anterior commissure, posterior commissure, targets and intercommissural distance were obtained from positive contrast ventriculography and by MRI in 6 patients undergoing stereotactic localization prior to the implantation of stimulating thalamic electrodes for pain control. The correlation of coordinates and measurements obtained with ventriculography and MRI is ± 1 mm in most measurements, but up to 3 mm in 2 cases. Magnetic resonance stereotaxy allows non-invasive and precise localization of intracerebral targets, but does not yet allow its routine use with confidence. Further understanding of distortion and artifacts and corrections of these is mandatory.
Multi-Purpose Stereoadapter
Authors: Laitinen Lauri V. , Hariz Marwan I.
Published: March 2007

A noninvasive adapter for CT-, MRI- and angiography-guided stereo-taxis had originally been developed for morphological (tumor biopsy) surgery. Because of its high accuracy it has also been used for functional stereotaxis (e.g., thalamotomy, cingulotomy, hypothalamotomy, dentatotomy) and for external stereotactic irradiation of brain tumors and arteriovenous malformations with a conventional linear accelerator. Additionally, it has been used for locating subcortical brain tumors for open surgery. Recently, the adapter, supplied with a phantom base, has been used for percutaneous tumor biopsy and ventriculostomy without a stereotactic frame.
Automated Stereotactic Positioning System
Authors: Goerss Stephan J. , Kelly Patrick J. , Kall Bruce A.
Published: March 2007

An automated stereotactic machine has been interfaced to a surgical computer to complete a totally interactive surgical system capable of locating tumor volumes. Stepper motors, activated by the host computer, drive a three-dimensional slide to position the patient''s head with respect to a fixed arc, locating the surgical target. Linear encoders on each axis create a closed-loop positioning system and a digital display for visual inspection of the slide''s position. The 160-mm arc directs all instrumentation to its isocenter, regardless of the two angular settings, providing maximum freedom in selecting a safe trajectory to the target. Phantom test points compatible with computerized tomographic and magnetic resonance imaging were repeatedly scanned to determine the overall system accuracy, which approached 0.6 mm, depending on the spatial resolution of the image. This stereotactic device may be used to perform stereotactic laser craniotomies, biopsies, 192Ir implants for interstitial radiation, third ventriculostomies and functional procedures.
New Diagnostic and Therapeutic Tools in Stereotaxy
Authors: Heikkinen E.R. , Heikkinen M.I.
Published: March 2007

A definitive pathoanatomic diagnosis was achieved in 14 biopsies of deep cerebral tumors in which the Laitinen CT adapter was utilized. In 5 patients, a third-ventricular colloid cyst was aspirated or resected by stereotactic endoscopy, with excellent results after a mean follow-up time of 2.5 years. Several instruments, including a diagnostic ultrasound probe, an ultrasonic aspirator, a combination laser and an endoscope can be used stereotactically when mounted on a special instrument carrier. Integration of the Laitinen stereotactic device and the CT adapter was developed to allow noninvasive stereotactic radiotherapy in a conventional fractionation schedule by a standard linear accelerator. Technical experiences using this radiosurgical system in over 30 sessions for treating inoperable cerebral arteriovenous malformations are promising, but the follow-up time is too short for evaluating the clinical effect.
Brown-Roberts-Wells Stereotactic Frame Modifications to Accomplish Magnetic Resonance Imaging Guidance in Three Planes
Authors: Heilbrun M. Peter , Sunderland Peter M. , McDonald Paul R. , Wells Jr. Trent H. , Cosman Eric , Ganz Edward
Published: March 2007

The Brown-Roberts-Wells (BRW) computer tomography (CT) stereotactic guidance system has been modified to accommodate magnetic resonance imaging (MRI). A smaller head ring, which fits in standard MRI head coils, is constructed of a non-ferromagnetic aluminum ring that is split to prevent eddy currents and anodized to prevent MRI image distortion and resolution degradation. A new localizing device has been designed in a box configuration, which allows BRW stereotactic coordinates to be calculated from coronal and sagittal MRI images, in addition to axial images. The system was tested utilizing a phantom and T1- and T2-weighted images. Using 5-mm MRI scan slices, targets were localized accurately to a 5-mm cube in three combined planes. Optimized calibration of both low field strength (0.3 T) and high field strength (1.5 T) MRI systems is necessary to obtain thin slice (5 mm) images with acceptable image resolution. To date, 10 patients have had MRI stereotactic localization of brain lesions that were better defined by MRI than CT.
Computer-Assisted Stereotactic Biopsy of Intracranial Lesions
Authors: Davis Dudley H. , Kelly Patrick J. , Marsh W. Richard , Kall Bruce A. , Goerss Stephan J.
Published: March 2007

The use of a computer program that allows the integration of stereotacti-cally gathered CT, MRI and digital angiographic data in the planning of a biopsy trajectory is described. This system has been used to perform 447 stereotactic biopsies in 439 patients. Intracranial hemorrhages occurred in three patients; combined morbidity and mortality was less than 1%. Incorporation of angiographic data and visualization of the surgical trajectory enhances the safety and accuracy of stereotactic biopsy of intracranial lesions.
Stereotactic Brain Biopsies in Presenile Dementia
Authors: Waltregny Alain , Maula Alhakam Abdul , Brucher Jean-Marie
Published: March 2007

Early detection and precise diagnosis of presenile dementias are important since they determine subsequent medical care. Presently the only way to classify these syndromes is by neuropathological examination. Between 1972 and 1987, 222 stereotactic serial brain biopsies were performed in 25 selected demented patients. Comparison between preoperative clinical diagnosis and histological finding gives the following results: in 32% the clinical diagnosis has been confirmed, in 60% the diagnosis has been corrected or specified and in 8% the stereotactic brain biopsies only showed unspecific pathological gliosis.
Removable, Adjustable and Reusable Implants for Stereotactic Interstitial Radiosurgery of Brain Tumors
Authors: Benabid A.L. , Chirossel J.P. , Mercier C. , Louveau A. , Passagia J.G. , Henry S. , de Rougemont J. , Vrousos C.
Published: March 2007

Sixty primary brain tumors (gliomas) were treated by interstitial radiosurgery using 192Ir according to a protocol based on the size of the tumor. In all cases, the radioactive wires were left in place for periods ranging from 5 to 10 days, according to dosimetry calculations, and then removed, which was made possible by the use of removable implants. The stainless steel tubes are occluded on their inner side and adjustable in length depending on the depth of the tumor, and are introduced through screws inserted into the skull in an array depending on the preliminary dosimetry. The tubes were afterloaded with 192Ir and removed at the end of the calculated time. Forty-six patients (18 low-grade and 28 malignant gliomas) were treated using this method. One small hematoma was evacuated and no sepsis occurred.