bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling tracer transport at the MADE site: The importance of heterogeneity
Authors: Salamon P. , Fernàndez‐Garcia D. , Gómez‐Hernández J. J.
Published: August 2007

We examine three stochastic transport models of the Macrodispersion Experiment (MADE) site using high‐resolution conductivity fields derived from a new geostatistical interpretation of the flowmeter data. Evaluation of the spatial continuity of the hydraulic conductivity data revealed a hole effect structure indicating the occurrence of periodic structures, i.e., clustered lenses or facies. Alternatively, we examine geostatistical models based on indicator variables and found a similarity to bivariate Gaussian properties. Tritium transport was simulated in kriged fields and in random fields generated using different geostatistical models, at a grid spacing equal to the vertical support scale of the flowmeter measurements to explicitly represent small‐scale heterogeneity. Only those simulations obtained using the hole effect model resulted in a subset of realizations which reproduced the strong anomalous tracer spreading. Neglecting the hole effect structure of the spatial model in the Gaussian simulations resulted in a reduced tailing of the tracer, illustrating the importance of preferential flow on anomalous solute transport at the Columbus aquifer. Furthermore, we found that a multivariate Gaussian random function is adequate to model the spatial distribution of hydraulic conductivity at the MADE site, based on the results of the indicator transport simulations and the univariate and bivariate normality detected in the analysis of the flowmeter data. We conclude that, when small‐scale variability of hydraulic conductivity is correctly modeled at the flowmeter measurement support scale, the ADE is capable of reproducing the tracer spreading. Results suggest that the main contributor to the operational “memory function” used in previous successful mass transfer models is mostly a reflection of the suppressed spatial variation of hydraulic conductivity at the model scale.
Usefulness of the reversible jump Markov chain Monte Carlo model in regional flood frequency analysis
Authors: Ribatet M. , Sauquet E. , Grésillon J. M. , Ouarda T. B. M. J.
Published: August 2007

Regional flood frequency analysis is a convenient way to reduce estimation uncertainty when few data are available at the gauging site. In this work, a model that allows a non‐null probability to a regional fixed shape parameter is presented. This methodology is integrated within a Bayesian framework and uses reversible jump techniques. The performance on stochastic data of this new estimator is compared to two other models: a conventional Bayesian analysis and the index flood approach. Results show that the proposed estimator is absolutely suited to regional estimation when only a few data are available at the target site. Moreover, unlike the index flood estimator, target site index flood error estimation seems to have less impact on Bayesian estimators. Some suggestions about configurations of the pooling groups are also presented to increase the performance of each estimator.
Capillary pressure overshoot as a function of imbibition flux and initial water content
Authors: DiCarlo David A.
Published: August 2007

Infiltration into well‐sorted sands can show an anomalous behavior called saturation overshoot where the saturation at the infiltrating front is higher than the saturation behind the front for certain fluxes and initial water contents. Similarly, capillary pressure overshoot is defined as when the capillary pressure is greater behind the front than it is at the front, which is contrary to normal infiltration. In this paper, pressure profiles are reported for water infiltrating into sand for a range of fluxes and initial water content. Capillary pressure overshoot is observed for sands with an initial water saturation of 0.06 and less, while no overshoot is observed for greater initial saturations. Capillary pressure overshoot does not show much dependence on flux, but the capillary pressure at the front does decrease with increasing flux. These results are combined with the previous saturation measurements, and it is found that the capillary pressure‐saturation imbibition curve is not dependent on the velocity of the front. The implications of the results on the stability of three‐dimensional flows are discussed.
Is isotropic turbulence relevant in the atmosphere?
Authors: Lovejoy S. , Tuck A. F. , Hovde S. J. , Schertzer D.
Published: August 2007

The problem of turbulence is ubiquitous in the Earth sciences, astrophysics and elsewhere. Virtually the only theoretical paradigm that has been seriously considered is strongly isotropic in the sense that scaling exponents are the same in all directions so that any remaining anisotropy is “trivial.” Using 235 state‐of‐the‐art drop sonde data sets of the horizontal wind at ≈5 m resolution in the vertical, we show that the atmosphere is apparently outside the scope of these isotropic frameworks. It suggests that anisotropy may frequently be strong requiring different scaling exponents in the horizontal and vertical directions.
Solvation dynamics in protein environments: Comparison of fluorescence upconversion measurements of coumarin 153 in monomeric hemeproteins with molecular dynamics simulations
Authors: Halder Mintu , Mukherjee Prasun , Bose Sayantan , Hargrove Mark S. , Song Xueyu , Petrich Jacob W.
Published: August 2007

The complexes of the fluorescence probe coumarin 153 with apomyoglobin and apoleghemoglobin are used as model systems to study solvation dynamics in proteins. Time-resolved Stokes shift experiments are compared with molecular dynamics simulations, and very good agreement is obtained. The solvation of the coumarin probe is very rapid with approximately 60% occurring within 300fs and is attributed to interactions with water (or possibly to the protein itself). Differences in the solvation relaxation (or correlation) function C(t) for the two proteins are attributed to differences in their hemepockets.
Analysis of rapid chain dynamics in isochronal dielectric measurements of polymers
Authors: Yang Yuning , Lai Wei-Chi , Hsu Shaw Ling
Published: August 2007

Fast dynamics within the microwave frequency range (approximately gigahertz) in polymer systems as a function of temperature (in the range from 20to190°C) were studied using high frequency dielectric spectroscopy. The frequency of radiation was varied from 0.5to18GHz. The isochronal dielectric loss data were taken to eliminate the complexity arising from the frequency-independent, temperature-dependent background loss in the condensed phase. These studies were conducted for poly(caprolactone) (PCL), poly(ethylene oxide) (PEO), poly(ethylene oxide) with methoxy end group (PEO-CH3), PLA-b-PEO-b-PLA triblock copolymers, and several polymers with high glass transition temperatures. These polymers possess glass temperatures ranging from −62°C (PCL) to 110°C (PMMA). One broad relaxation process was found only for polymers (PCL, PEO, and PLA-b-PEO-b-PLA) with low glass transition temperatures. The effect due to end groups was investigated by comparing the results of PEO with hydroxy versus methoxy end groups. The measured relaxation process was determined not to be associated with end groups. The results from temperature-dependent dielectric spectroscopy indicate that the relaxation process follows an Arrhenius T dependence suggesting that it is due to local motions. The activation energy of the relaxation process was measured and investigated based on the coupling model. The results suggest that the observed relaxation process behaves as a Johari-Goldstein β relaxation.
Range separated hybrid density functional with long-range Hartree-Fock exchange applied to solids
Authors: Gerber Iann C. , Ángyán János G. , Marsman Martijn , Kresse Georg
Published: August 2007

We report a plane wave-projector augmented wave implementation of the recently proposed exchange-only range separated hybrid (RSHX) density functional [Gerber and Ángyán, Chem. Phys. Lett. 415, 100 (2005)] and characterize its performance in the local density approximation (RSHXLDA) for a set of archetypical solid state systems, as well as for some transition metal oxides. Lattice parameters, bulk moduli, band gaps, and magnetic moments of the transition metal oxides have been calculated at different values of the range separation parameter and compared with results obtained with standard local density approximation (LDA), gradient corrected (PBE), and hybrid (HSE) functionals. The RSHX functional, which has the main feature of providing a correct asymptotic behavior of the exchange potential, has a tendency to improve the description of structural parameters with respect to local and generalized gradient approximations. The band gaps are too strongly opened by the presence of the long-range Hartree-Fock exchange in all but wide-gap systems. In the difficult case of transition metal oxides, the gap is overestimated, while magnetic moments and lattice constants are slightly underestimated. The optimal range separation parameter has been found around 0.4a.u., slightly lower than the value of 0.5a.u., recommended earlier for molecular systems.
Feedback controlled electromigration in four-terminal nanojunctions
Authors: Wu Zheng Ming , Steinacher M. , Huber R. , Calame M. , van der Molen S. J. , Schönenberger C.
Published: August 2007

The authors have developed a fast, yet highly reproducible method to fabricate metallic electrodes with nanometer separation using electromigration (EM). They employ four terminal instead of two-terminal devices in combination with an analog feedback to maintain the voltage U over the junction constant. After the initialization phase (U≲0.2V), during which the temperature T increases by 80–150°C, EM sets in shrinking the wire locally. This quickly leads to a transition from the diffusive to a quasiballistic regime (0.2V≲U≲0.6V). At the end of this second regime, a gap forms (U≳0.6V). Remarkably, controlled electromigration is still possible in the quasiballistic regime.
Buckling behaviors of single-walled carbon nanotubes filled with metal atoms
Authors: Wang L. , Zhang H. W. , Zhang Z. Q. , Zheng Y. G. , Wang J. B.
Published: August 2007

Molecular dynamics method is employed to investigate the buckling deformations of single-walled carbon nanotubes (SWCNTs) filled with nickel (Ni), copper (Cu), and platinum (Pt) atoms under axial compression. The critical buckling strains of filled tubes decrease linearly before a critical number of metal atoms and then increase linearly when more atoms are encapsulated. For SWCNT completely filled with metals, its critical strain is larger than that of the hollow tube. Furthermore, the critical strain of SWCNT completely filled with Ni atoms is larger than that of the tube fully filled with Cu or Pt atoms.
Control of full width at half maximum of Coulomb oscillation in silicon single-hole transistors at room temperature
Authors: Miyaji Kousuke , Hiramoto Toshiro
Published: August 2007

The full width at half maximum (FWHM), the sharpness of the Coulomb blockade oscillation in a single-hole transistor (SHT), has been controlled at room temperature by means of substrate capacitance control using substrate depletion and accumulation/inversion. When the substrate is depleted, the substrate capacitance is lower than when it is accumulated or inverted, resulting in a smaller FWHM. The SHT was fabricated on a thin buried oxide silicon-on-insulator substrate whose initial thickness was 10nm. Low temperature measurements have been performed on another SHT to support the results. The control of the sharpness in a single-charge transistor (SCT) may add further functionality to the SCT.
Improved performance of In0.6Ga0.4As∕AlAs0.67Sb0.33∕InP quantum cascade lasers by introduction of AlAs barriers in the active regions
Authors: Revin D. G. , Cockburn J. W. , Steer M. J. , Airey R. J. , Hopkinson M. , Krysa A. B. , Wilson L. R. , Menzel S.
Published: August 2007

The authors demonstrate that the performance of strain compensated InP-based InGaAs∕AlAsSb quantum cascade lasers (QCLs) can be improved if AlAsSb barriers in the laser active regions are replaced by AlAs layers. The introduction of AlAs is intended to help suppress compositional fluctuations due to interdiffusion at the quantum well/barrier interfaces. An In0.6Ga0.4As∕AlAs0.67Sb0.33 QCL with AlAs barriers displays pulsed laser operation at wavelength of 4.1μm, for temperatures up to at least 320K, with lower threshold current density and higher output optical power than the reference laser with identical design but with AlAs0.67Sb0.33 barriers throughout the entire core region.
Fabrication of in situ ultrathin anodic aluminum oxide layers for nanostructuring on silicon substrate
Authors: Yan Bo , Pham Hoa T. M. , Ma Yue , Zhuang Yan , Sarro Pasqualina M.
Published: August 2007

The authors demonstrate a method for the fabrication of in situ ultrathin porous anodic aluminum oxide layers (aspect ratio<2:1) on Si, which can be directly used as templates for nanodot preparation and for pattern transfer. The regular shape of the aluminum oxide pores is maintained even when the thickness of the aluminum oxide template is reduced to 50nm. By using these in situ ultrathin templates as lift-off masks, the authors successfully prepared a BaxSr1−xTiO3 nanodot array on Si surface. Furthermore, these nanotemplates are employed as lithographic masks to transfer the nanopattern into the silicon substrate.
Ultrafast interface magnetization dynamics in Fe∕AlGaAs (001) heterostructure
Authors: Zhao H. B. , Talbayev D. , Lüpke G. , Hanbicki A. T. , Li C. H. , Jonker B. T.
Published: August 2007

Time-resolved magnetization-induced second-harmonic generation is used to initiate and monitor coherent electronic spin precession in the Fe interface layer of a Fe∕AlGaAs (001) heterostructure. The frequency, phase, and hysteretic behavior of the interface magnetization precession are found to be different from the bulk Fe film. The results indicate that faster magnetization switching can be achieved in nanostructures where interface properties dominate.
Impact of low 6,13-pentacenequinone concentration on pentacene thin film growth
Authors: Salzmann Ingo , Duhm Steffen , Opitz Ricarda , Rabe Jürgen P. , Koch Norbert
Published: August 2007

Thin films of pentacene (P) have been vacuum codeposited on SiO2 with low concentrations of 6,13-pentacenequinone (PQ) in order to investigate the impact on the pentacene thin film structure. Within a range of 2%–20% PQ concentration no intercalation of the compounds can be observed by means of x-ray diffraction and infrared absorption spectroscopy. The crystalline quality of the P films stays unchanged by the presence of PQ, whereas P bulk phase contributions are being suppressed at PQ concentrations ⩾5%, which could be confirmed by means of atomic force microscopy. From the results the authors suggest phase-separated PQ growth as well as PQ nucleation at P grain boundaries.
Fabrication of nanoscale single crystal InP membranes
Authors: Hulko O. V. , Robinson B. J. , Kleiman R. N.
Published: August 2007

The authors have developed a process for fabricating fully enclosed single crystal InP freestanding membranes using entirely front side processing. A multilayer lattice matched InP∕InGaAs heterosystem incorporating a 500Å membrane layer was grown by molecular beam epitaxy followed by two step surface patterning, first for the support structure and then for the membrane structure definition. Membranes with lateral dimensions ranging from 1to10μm have been fabricated using optical and electron beam lithography. The process is easily scalable, limited only by the ability of the membrane layer to act as an effective etch stop, i.e., ∼30Å.
Transgenic farm animals: an update
Authors: Niemann Heiner , Kues Wilfried A.
Published: August 2007

The first transgenic livestock species were reported in 1985. Since then microinjection of foreign DNA into pronuclei of zygotes has been the method of choice. It is now being replaced by more efficient protocols based on somatic nuclear transfer that also permit targeted genetic modifications. Lentiviral vectors and small interfering ribonucleic acid (siRNA) technology are also becoming important tools for transgenesis. In 2006 the European Medicines Agency (EMEA) gave green light for the commercialistion of the first recombinant protein produced in the milk of transgenic animals. Recombinant antithrombin III will be launched as ATryn for prophylactic treatment of patients with congenital antithrombin deficiency. This important milestone will boost the research activities in farm animal transgenesis. Recent developments in transgenic techniques of farm animals are discussed in this review.
Faithful segregation of the multicopy yeast plasmid through cohesin-mediated recognition of sisters
Authors: Ghosh Santanu K. , Hajra Sujata , Jayaram Makkuni
Published: August 2007

The 2-μm yeast plasmid, a benign high-copy nuclear parasite, propagates itself with nearly the same fidelity as the chromosomes of its host. Equal plasmid segregation is absolutely dependent on the cohesin complex assembled at the plasmid partitioning locus
STB
. However, the mechanism of cohesin action in the context of multiple plasmid copies, resident within two separate clusters after DNA replication, is unknown. By using “single-copy” derivatives of the 2-μm plasmid, we demonstrate that recruitment of cohesin at
STB
during S phase indeed translates into cohesion between plasmid molecules. Through binary fluorescence tagging, we reveal that segregation of replicated plasmids occurs in a sister-to-sister fashion. Thus, cohesin serves the same fundamental purpose in plasmid and chromosome segregation.
Photoreceptor outer segment phagocytosis attenuates oxidative stress-induced apoptosis with concomitant neuroprotectin D1 synthesis
Authors: Mukherjee Pranab K. , Marcheselli Victor L. , de Rivero Vaccari Juan Carlos , Gordon William C. , Jackson Fannie E. , Bazan Nicolas G.
Published: August 2007

Photoreceptor cell (rods and cones) renewal is accompanied by intermittent shedding of the distal tips of the outer segment followed by their phagocytosis in the retinal pigment epithelial (RPE) cells. This renewal is essential for vision, and it is thought that it fosters survival of photoreceptors and of RPE cells. However, no specific survival messenger/mediators have as yet been identified. We show here that photoreceptor outer segment (POS) phagocytosis markedly attenuates oxidative stress-induced apoptosis in ARPE-19 cells in culture. This phenomenon does not seem to be a generalized outcome of phagocytosis because nonbiological (polystyrene microsphere) phagocytosis did not elicit protection. The free docosahexaenoic acid (DHA) pool size and neuroprotectin D1 (NPD1) content increased during POS phagocytosis but not during microspheres phagocytosis. We have also explored other lipid mediators [lipoxin A4 and 15(
S
)- and 12(
S
)-hydroxyeicosatetraenoic acids] under these conditions and found them unchanged upon POS phagocytosis. Moreover, oxidative stress challenge to RPE cells undergoing POS phagocytosis further increased DHA and NPD1 content. Under these conditions, NPD1 was found within the RPE cells as well as in the culture medium, suggesting autocrine and paracrine bioactivity. Furthermore, using deuterium-labeled DHA, we show that as the availability of free DHA increases during oxidative stress, NPD1 synthesis is augmented in ARPE-19 cells. Our data suggest a distinct signaling that promotes survival of photoreceptor and RPE cells by enhancing the synthesis of NPD1 during phagocytosis. Taken together, NPD1 may be a mediator that promotes homeostatic regulation of cell integrity during photoreceptor cell renewal.
Persistence of the Same Strain ofLegionella pneumophilain the Water System of an Italian Hospital for 15 Years
Authors: Scaturro M. , Dell'Eva I. , Helfer F. , Ricci M. L.
Published: August 2007

In 2004, an outbreak of legionnaires disease occurred in a hospital in northern Italy with a water system that had been disinfected multiple times since 1990 and equipped with a continuous disinfecting system. Molecular typing linked the outbreak to contamination of the hospital water system and demonstrated the persistence of a predominant strain ofLegionella pneumophilafor 15 years.
Comparison of the Risk of Surgical Site Infection After Laparoscopic Cholecystectomy and Open Cholecystectomy
Authors: Biscione Fernando M. , Couto Renato C. , Pedrosa Tânia M. , Neto Mozar C.
Published: August 2007

We assessed the independent contributions of the surgical approach and other variables of the National Nosocomial Infections Surveillance System (NNIS) surgical patient component to the surgical site infection risk after cholecystectomy. Laparoscopic cholecystectomy was associated with a lower overall risk of surgical site infection and a lower risk of incisional infection but not a reduced risk of organ-space infection, compared with open cholecystectomy. The contribution of most of the variables of the NNIS surgical patient component to the risk of surgical site infection depended on the depth of the infection.
Health Implications of Antimicrobial Resistance for Patients With Acute Kidney Injury and Bloodstream Infection
Authors: Hoste Eric A. J. , Vandijck Dominique M. , Vanholder Raymond C. , De Waele Jan J. , Lameire Norbert H. , Claus Stefaan , De Schuijmer Johan , Dhondt Annemieke W. , Decruyenaere Johan M. A. , Verschraegen Gerda , Blot Stijn I.
Published: August 2007

Studies have produced conflicting findings on outcomes for patients with antimicrobial-resistant infection. This study evaluated whether infection with an antimicrobial-resistant organism affects outcome in critically ill patients with acute kidney injury treated with renal replacement therapy and whose clinical course is complicated with a nosocomial bloodstream infection. We found that infection with an antimicrobial-resistant organism did not adversely affect clinical outcome in this specific cohort, which already has a high mortality rate.
Duration of Influenza A Virus Shedding in Hospitalized Patients and Implications for Infection Control
Authors: Leekha Surbhi , Zitterkopf Nicole L. , Espy Mark J. , Smith Thomas F. , Thompson Rodney L. , Sampathkumar Priya
Published: August 2007

Objective.

To assess the duration of shedding of influenza A virus detected by polymerase chain reaction (PCR) and cell culture among patients hospitalized with influenza A virus infection.

Setting.

Mayo Clinic (Rochester, Minnesota) hospitals that cater to both the community and referral populations.

Methods.

Patients 18 years old and older who were hospitalized between December 1, 2004, and March 15, 2005, with a laboratory-confirmed (ie, PCR-based) diagnosis of influenza A virus infection were consecutively enrolled. Additional throat swab specimens were collected at 2, 3, 5, and 7 days after the initial specimen (if the patient was still hospitalized). All specimens were tested by PCR and culture (both conventional tube culture and shell vial assay). Information on demographic characteristics, date of symptom onset, comorbidities, immunosuppression, influenza vaccination status, and receipt of antiviral treatment was obtained by interview and medical record review. Patients were excluded if informed consent could not be obtained or if the date of symptom onset could not be ascertained.

Results.

Of 149 patients hospitalized with influenza A virus infection, 50 patients were enrolled in the study. Most patients were older (median age, 76 years), and almost all (96%) had underlying chronic medical conditions. Of 41 patients included in the final analysis, influenza A virus was detected in 22 (54%) by PCR and in 12 (29%) by culture methods at or beyond 7 days after symptom onset. All 12 patients identified by culture also had PCR results positive for influenza A virus.

Conclusion.

Hospitalized patients with influenza A virus infection can shed detectable virus beyond the 5- to 7-day period traditionally considered the duration of infectivity. Additional research is needed to assess whether prolonging the duration of patient isolation is warranted to prevent nosocomial outbreaks during the influenza season.
Aberrant Chromatin Remodeling by Retinoic Acid Receptor α Fusion Proteins Assessed at the Single-Cell Level
Authors: Qiu Jihui , Huang Ying , Chen Guoqiang , Chen Zhu , Tweardy David J. , Dong Shuo
Published: August 2007

Acute promyelocytic leukemia (APL) is characterized by specific chromosomal translocations, which generate fusion proteins such as promyelocytic leukemia (PML)-retinoic acid receptor (RAR)α and promyelocytic leukemia zinc finger (PLZF)-RARα (X-RARα). In this study, we have applied lac operator array systems to study the effects of X-RARα versus wild-type RARα on large-scale chromatin structure. The targeting of these enhanced cyan fluorescent protein-lac repressor-tagged RARα-containing proteins to the gene-amplification chromosomal region by lac operator repeats led to local chromatin condensation, recruitment of nuclear receptor corepressor, and histone deacetylase complex. The addition of retinoic acid (RA) induced large-scale chromatin decondensation in cells expressing RARα; however, cells expressing X-RARα, especially PML-RARα, demonstrated insensitive response to this effect of all-trans retinoic acid (ATRA). Although we did not reveal differences in RA-dependent colocalization of either silencing mediator for retinoid and thyroid or steroid receptor coactivator (SRC)-1 with RARα versus X-RARα, the hormone-independent association between SRC-1 and X-RARα on the array has been identified. Rather, compared with cells expressing RARα, fluorescence recovery after photobleaching of live transfected cells, demonstrated decreased mobility of SRC-1 on the X-RARα–bound chromatin. Thus, the impaired ability of APL fusion proteins to activate gene transcription in response to ATRA corresponds to their reduced ability to remodel chromatin, which may link to their ability to impair the mobility of key nuclear receptor coregulators.
Hydroxycarbamide in combination with azacitidine or decitabine is antagonistic on DNA methylation inhibition
Authors: Choi Si Ho , Byun Hyang‐Min , Kwan Jennifer M. , Issa Jean‐Pierre J. , Yang Allen S.
Published: August 2007

Azacitidine and decitabine are cytidine analogues that inhibit DNA methylation, and are used to treat myeloid haematological malignancies. Hydroxycarbamide (HC) (also known as hydroxyurea), a ribonucleotide reductase (RR) inhibitor, blocks the conversion of ribonucleotides to deoxyribonucleotides, and is also used to treat leukaemia and sickle‐cell disease. Azacitidine is a ribonucleoside and decitabine is a deoxyribonucleoside; therefore, we hypothesized that inhibition of RR by HC would be antagonistic to azacitidine and synergistic to decitabine. HL‐60 and T24 cancer cell lines were treated with azacitidine or decitabine in combination with HC and DNA methylation of LRE1, MAGEA1 and CDKN2A was quantitatively measured by bisulphite‐polymerase chain reaction pyrosequencing. Surprisingly, we found that HC blocked the ability of both azacitidine and decitabine to inhibit DNA methylation and this antagonistic effect was attributable to the arrest of the cell cycle induced by HC. However, this antagonism could be avoided with sequential treatment of HC followed by azacitidine or decitabine. This data suggest that concurrent combination of HC blocks the ability of azacitidine and decitabine to inhibit DNA methylation and therefore these drugs should be used sequentially.
Activation of sphingosine kinase mediates suppressive effect of interleukin‐6 on human multiple myeloma cell apoptosis
Authors: Li Qing‐Fang , Wu Chu‐Tse , Duan Hai‐Feng , Sun Hui‐Yan , Wang Hua , Lu Zhuo‐Zhuang , Zhang Qun‐Wei , Liu Hong‐Jun , Wang Li‐Sheng
Published: August 2007

Interleukin 6 (IL‐6) influences the growth and survival of multiple myeloma (MM) cells via the activation of multiple signalling cascades. Although sphingosine kinase (SPHK) signalling is known to play important roles in the regulation of cell proliferation and apoptosis, the role of SPHK activation in IL‐6 signalling and in the pathology of MM remains unclear. This study found that IL‐6 activated SPHK in MM cells, which mediates the suppressive effects of IL‐6 on MM cell apoptosis. Both MM cell lines and primary MM cells constitutively expressed SPHK, and treatment of MM cells with IL‐6 resulted in activation of SPHK in a concentration‐dependent manner. Specific inhibitors of the phosphatidylinositol‐3 kinase and extracellular signal‐regulated kinase/mitogen‐activated protein kinase pathways blocked the IL‐6‐induced activation of SPHK. It was further demonstrated that IL‐6‐induced activation of SPHK inhibited dexamethasone‐induced apoptosis of MM cells. IL‐6 stimulation or retroviral‐mediated overexpression of SPHK1 in MM cells resulted in increased intracellular SPHK activity and upregulation of myeloid cell leukaemia‐1 (Mcl‐1), leading to increased cell proliferation and survival. Conversely, inhibition of SPHK1 by small interfering RNA reduced IL‐6‐induced upregulation of Mcl‐1 and blocked the suppressive effect of IL‐6 on MM cell apoptosis. Taken together, these results delineate a key role for SPHK activation in IL‐6‐induced proliferation and survival of MM cells, and suggest that SPHK may be a potential new therapeutic target in MM.
Inheritance of the concentration of water‐soluble carbohydrates and its relationship with the concentrations of fibre and crude protein in herbage of cocksfoot (Dactylis glomerata L.)
Authors: Sanada Y. , Takai T. , Yamada T.
Published: August 2007

The concentration of water‐soluble carbohydrates (WSC) of cocksfoot is lower than that of other temperate grasses. Increasing the WSC concentration in cocksfoot is important in increasing its digestibility and preference by ruminants. The genetic variation in mono‐ and disaccharides, fructans and total WSC concentrations and their inter‐relationships with crude protein (CP) and fibre concentrations of cocksfoot (Dactylis glomerata L.) at the vegetative growth stage in half‐sib cross populations were assessed in two experiments conducted under spaced planting and sward conditions. There was a wide range in the means for concentrations of fructan, WSC and neutral‐detergent fibre (NDF) in parents and progeny whereas there was a narrow range of the means for concentrations of mono‐ and disaccharides, CP and acid‐detergent fibre (ADF). Mean concentrations of mono‐ and disaccharides showed the smallest range. Mean squares of entries in parents and progenies were significant for mono‐ and disaccharides, fructan and total WSC concentrations in all populations. The entry × year interactions for fructan and total WSC concentrations were significant in the parents and the half‐sib progeny. However, the entry × year interactions for mono‐ and disaccharide concentrations in progeny were not significant. Concentration of WSC was under genetic control as mean squares of the concentration values were significant and variance components for all traits were significantly larger than zero. There were negative genetic correlations between WSC and ADF and NDF concentrations. Narrow‐sense heritabilities (hn) estimated from variance components of progeny for total WSC concentrations were 0·59 and 0·53 in sward and spaced planting conditions respectively. The hn of fructan and WSC concentrations were similar in both sward and spaced planting conditions, whereas that of mono‐ and disaccharide concentrations varied from 0·20 to 0·69. It was found that the genetic variation of the total WSC concentration in cocksfoot depended mainly on genetic variation in fructan concentration. These results suggested that the forage quality of cocksfoot at the vegetative growth stage was influenced by an additive gene effect and could be improved genetically by recurrent selection.
A review of forage grass and clover seed use in Northern Ireland, UK between 1980 and 2004
Authors: Gilliland T. J. , Johnston J. , Connolly C.
Published: August 2007

The total amount and the composition of varieties of all forage grass and clover seed delivered for farm use in Northern Ireland was monitored over the 25‐year period of 1980–2004. Total seed use in Northern Ireland declined from the 1980s to the 1990s but then stabilized despite isolated drops in sales associated with outbreaks of animal diseases. This profile was mirrored by similar declines in the rest of the UK. The survey revealed the annual volatility of the market and its sensitivity to changes in government financial support, to changes in farm practice and farm incomes. Examination of the data on the grassland area under 5 years old showed them to be poor indicators of actual seed use. Levels of species use were very stable over the 25 years of the survey but reseeding of varieties of perennial ryegrass differing in maturity and ploidy type changed dramatically. When sufficient seed was available, selection of varieties complied with the contemporary recommended list ratings of agronomic value but in a few cases selection of varieties was determined by price. The current survey of seed sales provides a benchmark against which responses by farmers following the latest changes in the Common Agricultural Policy of the European Union can be measured.
Accuracy and stability of impression materials subjected to chemical disinfection – a literature review
Authors: KOTSIOMITI E. , TZIALLA A. , HATJIVASILIOU K.
Published: August 2007

Summary  Disinfection of impressions by immersion or spraying with disinfecting solutions is considered nowadays mandatory for effective infection control. The purpose of this review was to examine existing evidence on the effects that chemical disinfection may have on critical qualities of impressions, namely dimensional accuracy and stability over time. A PubMed search was conducted to include original laboratory research articles written in English, published between 1980 and 2005 in peer‐reviewed journals and investigating the effect of chemical disinfection, by immersion or spraying, on the dimensional changes that the impression materials experience after setting. Studies were also sought manually, by tracing the references cited in the retrieved articles. The reports on dimensional changes of disinfected impression materials, although rather numerous, are difficult to compare and analyze because of variations of the experimental design. The investigations broadly agree that the disinfection process does not generally affect the dimensional integrity of the impressions, in spite of the statistically significant differences occasionally found. However, the immersion in the disinfecting solution encourages water absorption phenomena in the case of the so‐called hydrophilic impression materials, especially after the long‐term immersion. Chemical interactions between impressions and disinfectants may occur, but they do not appear to influence the dimensional behaviour of the former. The overall effect of the disinfection is influenced not only by the changes experienced by the impression per se, but also by the alterations of the acrylic tray containing the impression and of the gypsum product poured in it.
Development of the Gagging Problem Assessment: a pilot study
Authors: VAN LINDEN VAN DEN HEUVELL G. F. E. C. , PELKWIJK B. J. TER , STEGENGA B.
Published: August 2007

Summary  An accepted management strategy for gagging problems appears not to exist. A reliable and valid instrument is needed to develop an evidence based treatment for this clinical problem. The aim of this pilot study was to evaluate the reliability and validity of a newly developed measurement tool for dental gagging: the Gagging Problem Assessment (GPA). An experimental group (n = 13) comprising individuals with gagging problems, and a control group (n = 12) that had received dental care without gagging, completed a questionnaire focused on general health aspects and dental anxiety and the patient part of the GPA. The dentist part consisted of tests with increasing intrusiveness. This part was completed by two dentists. Statistical analyses concerned inter‐rater reliability (Cohen’s κ) , reliability of the questionnaire (Cronbach’s α, Pearson correlation coefficient) and the statistical difference between the GPA and two dental anxiety questionnaires (Mann–Whitney U‐test, α = 0·05). Within the limits of this study, the findings suggested that dental gagging warranted the development of a diagnostic and evaluative instrument. Gagging appeared to be a specific problem that cannot be interpreted as some form of dental anxiety. The GPA proved to be a reliable questionnaire to assess the presence of gagging problems, with a satisfying inter‐rater reliability (κ = 0·64; s.d. = 0·16). Significant differences were noted between the experimental group and the control group. This pilot study will be followed by a confirmation study with a larger sample size, evaluated according to recently formulated quality criteria for measurement properties of health status questionnaires.
High temperature causes arrest of cell cycle in G2 phase in BmN cells derived from the silkworm, Bombyx mori
Authors: KIUCHI TAKASHI , AOKI FUGAKU , NAGATA MASAO
Published: August 2007

Abstract The influence of temperature on the insect cell line, BmN, derived from the silkworm, Bombyx mori is investigated. These cells proliferate at an accelerated pace as the temperature increases from 22 to 30 °C, but the growth rate slows at 34 °C, and proliferation stops at 38 °C. At high temperatures, abnormal cellular morphology is observed. Cells treated at 38 °C have cytoplasmic bilateral protrusions and they gradually aggregate and float in the medium. BmN cells without proliferation at 38 °C are viable but have reduced DNA synthesis. At high temperatures, the cell cycle of BmN cells halts at the G2 phase. After heat treatment of the larvae, an accumulation of larval haemocytes with high DNA content is found, which suggests that the cell cycle arrest at G2 also occurs in the silkworm at high temperatures.
NBS1 is involved in DNA repair and plays a synergistic role with ATM in mediating meiotic homologous recombination in plants
Authors: Waterworth Wanda M. , Altun Cagla , Armstrong Susan J. , Roberts Nicola , Dean Philip J. , Young Kim , Weil Clifford F. , Bray Clifford M. , West Christopher E.
Published: August 2007

The ability of plants to repair DNA double‐strand breaks (DSBs) is essential for growth and fertility. The Arabidopsis DSB repair proteins AtRAD50 and AtMRE11 form part of an evolutionarily conserved complex that, in Saccharomyces cerevisiae and mammals, includes a third component termed XRS2 and NBS1, respectively. The MRN complex (MRX in yeast) has a direct role in DSB repair and is also required for DNA damage signaling and checkpoint activation in a pathway mediated by the protein kinase ATM. This study characterizes Arabidopsis and maize NBS1 orthologues that share conserved protein motifs with human NBS1. Both plant NBS1 proteins interact with the corresponding MRE11 orthologues, and deletion analysis of AtNBS1 defines a region towards the C‐terminus (amino acids 465–500) that is required for interaction with AtMRE11. Arabidopsis lines homozygous for a T‐DNA insertional mutation in AtNBS1 display hypersensitivity to the DNA cross‐linking reagent mitomycin C, and this phenotype can be rescued by complementation with the wild‐type gene, consistent with a function for AtNBS1 in plant DSB repair. Analysis of atnbs1‐1 atatm double mutants revealed a role for AtNBS1 in meiotic recombination. While atatm mutants produce reduced seed numbers, plants deficient in both AtATM and AtNBS1 are completely infertile. Cytological analysis of these double mutants revealed incomplete chromosome pairing and synapsis in meiotic prophase, and extensive chromosome fragmentation in metaphase I and subsequent stages. These results suggest a novel role for AtNBS1 that is independent of AtATM‐mediated signaling and functions in the very early stages of meiosis.
Diversification and co‐option of RAD‐like genes in the evolution of floral asymmetry
Authors: Baxter Catherine E. L. , Costa Maria Manuela R. , Coen Enrico S.
Published: August 2007

To understand how changes in gene regulatory networks lead to novel morphologies, we have analysed the evolution of a key target gene, RAD, controlling floral asymmetry. In Antirrhinum, flower asymmetry depends on activation of RAD in dorsal regions of the floral meristem by the upstream regulators CYC and DICH. We show that Arabidopsis, a species with radially symmetric flowers, contains six RAD‐like genes, reflecting at least three duplications since the divergence of Antirrhinum and Arabidopsis. Unlike the situation in Antirrhinum, none of the Arabidopsis RAD‐like genes are activated in dorsal regions of the flower meristem. Rather, the RAD‐like genes are expressed in distinctive domains along radial or ab‐adaxial axes, consistent with a range of developmental roles. Introduction of a RAD genomic clone from Antirrhinum into Arabidopsis leads to a novel expression pattern that is distinct from the expression pattern of RAD in Antirrhinum and from the endogenous RAD‐like genes of Arabidopsis. Nevertheless, RAD is able to influence developmental targets in Arabidopsis, as ectopic expression of RAD has developmental effects in this species. Taken together, our results suggest that duplication and divergence of RAD‐like genes has involved a range of cis‐ and trans‐regulatory changes. It is possible that such changes led to the coupling of RAD to CYC regulation in the Antirrhinum lineage and hence the co‐option of RAD had a role in the generation of flower dorsoventral asymmetry.
AtDUR3 represents the major transporter for high‐affinity urea transport across the plasma membrane of nitrogen‐deficient Arabidopsis roots
Authors: Kojima Soichi , Bohner Anne , Gassert Brigitte , Yuan Lixing , Wirén Nicolaus von
Published: August 2007

Despite the fact that urea is a ubiquitous nitrogen source in soils and the most widespread form of nitrogen fertilizer used in agricultural plant production, membrane transporters that might contribute to the uptake of urea in plant roots have so far been characterized only in heterologous systems. Two T‐DNA insertion lines, atdur3‐1 and atdur3‐3, that showed impaired growth on urea as a sole nitrogen source were used to investigate a role of the H+/urea co‐transporter AtDUR3 in nitrogen nutrition in Arabidopsis. In transgenic lines expressing AtDUR3‐promoter:GFP constructs, promoter activity was upregulated under nitrogen deficiency and localized to the rhizodermis, including root hairs, as well as to the cortex in more basal root zones. Protein gel blot analysis of two‐phase partitioned root membrane fractions and whole‐mount immunolocalization in root hairs revealed the plasma membrane to be enriched in AtDUR3 protein. Expression of the AtDUR3 gene in nitrogen‐deficient roots was repressed by ammonium and nitrate but induced after supply of urea. Higher accumulation of urea in roots of wild‐type plants relative to atdur3‐1 and atdur3‐3 confirmed that urea was the substrate transported by AtDUR3. Influx of 15N‐labeled urea in atdur3‐1 and atdur3‐3 showed a linear concentration dependency up to 200 μm external urea, whereas influx in wild‐type roots followed saturation kinetics with an apparent Km of 4 μm. The results indicate that AtDUR3 is the major transporter for high‐affinity urea uptake in Arabidopsis roots and suggest that the high substrate affinity of AtDUR3 reflects an adaptation to the low urea levels usually found in unfertilized soils.
Transplant reno‐vascular stenoses associated with early erythropoeitin use
Authors: Nagarajan Suja , Mansfield Elaine , Hsieh Sue , Liu Rosa , Hsieh Frank , Li Li , Salvatierra Oscar , Sarwal Minnie M
Published: August 2007

Abstract:  Background and objectives:  This report describes an unusual presentation of severe hypertension (HTN) in a subset of pediatric kidney recipients treated with a steroid avoidance pediatric renal transplantation protocol. The HTN was secondary to atypical, reno‐vascular abnormalities (RVA) of the transplanted vasculature, temporally associated with erythropoietin (EPO) use.

Design, setting, participants, and measurements:  To investigate the clinical significance underlying this event, a retrospective clinical study of 100 pediatric renal transplants was undertaken (50 steroid‐free and 50 matched steroid‐based controls), with peripheral blood transcriptional analysis of four RVA patients and controls.

Results:  Regardless of a higher observed incidence of anemia (p < 0.001) and greater overall EPO usage in the first post‐transplant year in steroid‐free patients, the incidence of new‐onset HTN at one yr was significantly less in the steroid‐free cohort (p = 0.03). Nevertheless, early EPO (first week post‐transplant) was significantly associated with the combinatory findings of new‐onset HTN (p = 0.03) and RVA (p = 0.007). Molecular mechanisms of RVA injury were investigated further by peripheral blood cDNA microarray gene expression profiling. A panel of 42 transcripts differentiated patients with RVA and HTN from three sets of matched controls, with and without HTN and EPO use, with 100% concordance (p < 0.001). The biological processes governed by these significant genes suggest a role for EPO regulation of growth factor receptor ubiquitination as a putative mechanism for renal vascular injury.

Conclusion:  This study cautions against the use early post‐transplant use of EPO in immunosuppression regimens with steroid minimization/avoidance, which may have an increased incidence of post‐transplant anemia.
Anaphylaxis to foods
Authors: Roberts Graham
Published: August 2007

Three crucial areas of the management of anaphylaxis due to food allgery are discussed: making a diagnosis, deciding who needs a self‐injectable adrenaline device and spotting the novel allgern. Managing children and teenagers with anaphylaxis is challenging due to the lack of available evidence that specific addresses these issue. The available evidence is presented and discussed.
Aggression, hostility, and irritability in children at risk for bipolar disorder
Authors: Farchione Tiffany R , Birmaher Boris , Axelson David , Kalas Cathy , Monk Kelly , Ehmann Mary , Iyengar Satish , Kupfer David , Brent David
Published: August 2007

Objectives:  To assess aggression, irritability and hostility in children at risk for bipolar disorder (BP).

Methods:  Using the parent and the child versions of the Children's Hostility Inventory (CHI), we assessed aggression, hostility, and irritability in 300 offspring aged 6–18 years old of BP parents and 169 children of community controls.

Results:  Children of BP parents have significantly higher scores on the total CHI and its subscales than do children of control parents. After adjusting for demographic variables, both parents’ non‐BP psychopathology, child psychopathology, and within‐family correlations, three factors remain significant: total CHI by parent rating, irritability subscale by parent rating, and irritability by child self‐report. The hostility subscale by parent rating became a trend.

Conclusions:  Children of BP parents score higher on ratings of hostility and irritability than children of community control parents, independent of child psychopathology and non‐BP parental psychopathology. Follow‐up of these children to evaluate whether these symptoms are markers for the development of BP or mood disorders is warranted.