bluuebunny/crossref_metadata_2025 huggingface dataset:
Wavelength-selective organic field-effect phototransistors based on dye-doped poly-3-hexylthiophene
Authors: Meixner R. M. , Göbel H. , Yildirim F. A. , Bauhofer W. , Krautschneider W.
Published: August 2006

The authors present a strategy to manufacture wavelength-selective field-effect phototransistors by employing dye-doped poly-3-hexylthiophene (P3HT) as a semiconducting layer. The dye doping of the semiconductor P3HT was achieved by blending organic molecules—coumarin 6, oxazine 1, and nile red—into the conjugated organic polymer. Illuminating these transistors with monochromatic light in the range of 400–700nm resulted in varying conductivities for certain wavelengths in dependence on the particular dye. This effect is attributed to the photogeneration of excitons on the dye molecules, which are subsequently transferred to the conjugated polymer.
Induced free carrier modulation of photonic crystal optical intersection via localized optical absorption effect
Authors: Teo Selin H. G. , Liu A. Q. , Zhang J. B. , Hong M. H.
Published: August 2006

This letter reports demonstration of optically induced signal modulation in two-dimensional photonic crystal (PhC) optical intersections. High resolution and high aspect ratio PhC was fabricated for optical communication wavelengths. Besides characterization of the silicon PhC static properties, dynamic modulations through spatially localized applications of high intensity pump radiation were also demonstrated to yield normalized modulations of 15dB for incident intensity of 70MW∕cm2—corresponding well with first principles simulations. The effective modulation range and pump limit of the method were therefore determined and the potential of such a modulation scheme as a practical means of developing tunable PhC devices was realized.
Transmission and absorption of metallic films coated with corrugated dielectric layers
Authors: Han Dezhuan , Wu Fengqin , Li Xin , Xu Chun , Liu Xiaohan , Zi Jian
Published: August 2006

The authors study theoretically the optical properties of planar metallic films coated with periodically corrugated dielectric layers. Their calculations show that the transmission and absorption for these coated metallic films are enhanced considerably with respect to the uncoated ones. Enhanced transmission and absorption are found to result from the excitations of the coupled surface plasmon polaritons at the coated metallic films. Their results indicate that the introduction of periodically corrugated dielectric coating layers on metallic films offers an excellent approach to tune the reflection, transmission, and absorption properties.
Mechanism of laser plasma production and of plasma interaction with a target
Authors: Beilis I. I.
Published: August 2006

A model of plasma production by laser interaction with a solid target was developed taking into account plasma heating by the emitted electrons, as additional to the absorbed laser energy flux, and also target heating by ion bombardment, as additional heat source to the laser radiation. A system of equations, including equations for solid heat conduction, plasma generation, and the plasma expansion, was solved self-consistently. The proposed model allows to understand that the plasma, partially shielding the laser radiation from the target, also converts absorbed laser energies to kinetic and potential energy of the plasma particles, which transport this energy not only in the ambient vacuum but also through the electrostatic sheath to the solid surface.
Depletion potential between large spheres immersed in a multicomponent mixture of small spheres
Authors: Roth Roland , Kinoshita Masahiro
Published: August 2006

We analyze the depletion potential between large spheres in a multicomponent mixture of dense small spheres (up to seven components) using the integral equation theory (IET), in which semiempirical bridge functions are incorporated, and the insertion approach within the framework of density functional theory (DFT). The diameters of the small spheres considered are in the range of dS–5dS. The results from the IET and DFT are in close agreement with each other. The depletion potential in the mixture is substantially different from that in a one-component system of dense small spheres with diameter dS. In comparison with the latter, the former possesses in general a less pronounced oscillatory structure, and the free-energy barrier for large spheres to overcome before reaching the contact is significantly reduced. This tendency can be enhanced as the number of components increases. In a several-component mixture of small spheres whose diameters are suitably chosen and in which the packing fractions of the components share the same value, the depletion potential is essentially short ranged and attractive and possesses a sufficiently large, negative value at the contact.
Ga
N
∕
Al
Ga
N
ultraviolet/infrared dual-band detector
Authors: Ariyawansa G. , Rinzan M. B. M. , Alevli M. , Strassburg M. , Dietz N. , Perera A. G. U. , Matsik S. G. , Asghar A. , Ferguson I. T. , Luo H. , Bezinger A. , Liu H. C.
Published: August 2006

Group III-V wide band gap materials are widely used in developing solar blind, radiation-hard, high speed optoelectronic devices. A device detecting both ultraviolet (UV) and infrared (IR) simultaneously will be an important tool in fire fighting and for military and other applications. Here a heterojunction UV/IR dual-band detector, where the UV/IR detection is due to interband/intraband transitions in the Al0.026Ga0.974N barrier and GaN emitter, respectively, is reported. The UV threshold observed at 360nm corresponds to the band gap of the Al0.026Ga0.974N barrier, and the IR response obtained in the range of 8–14μm is in good agreement with the free carrier absorption model.
Effects of high pressure on the optical absorption spectrum of scintillating PbWO4 crystals
Authors: Errandonea D. , Martínez-García D. , Lacomba-Perales R. , Ruiz-Fuertes J. , Segura A.
Published: August 2006

The pressure behavior of the absorption edge of PbWO4 was studied up to 15.3GPa. It redshifts at −71meV∕GPa below 6.1GPa, but at 6.3GPa the band gap collapses from 3.5to2.75eV. From 6.3to11.1GPa, the absorption edge moves with a pressure coefficient of −98meV∕GPa, undergoing additional changes at 12.2GPa. The results are discussed in terms of the electronic structure of PbWO4 which attribute the behavior of the band gap to changes in the local atomic structure. The changes observed at 6.3 and 12.2GPa are attributed to phase transitions.
Capillary electrophoresis of ultrasmall carboxylate functionalized silicon nanoparticles
Authors: Eckhoff Dean A. , Stuart Jeffrey N. , Sutin Jason D. B. , Sweedler Jonathan V. , Gratton Enrico
Published: August 2006

Capillary electrophoresis is used to separate ultrasmall (∼1nm) carboxylate functionalized Si nanoparticles (Si-np-COO−) prepared via hydrosilylation with an ω-ester 1-alkene. The electropherograms show a monodisperse Si core size with one or two carboxylate groups added to the surface. On-column detection of their laser-induced fluorescence demonstrates that the individual Si-np-COO− have narrow emissions (full width at half maximum =30–40nm) with a nearly symmetric lineshape. Preparative scale electrophoresis should be a viable route for purification of the Si-np-COO− for further study and future applications.
Subsoil constraints in Vertosols: crop water use, nutrient concentration, and grain yields of bread wheat, durum wheat, barley, chickpea, and canola
Authors: Dang Y. P. , Routley R. , McDonald M. , Dalal R. C. , Singh D. K. , Orange D. , Mann M.
Published: August 2006

Single or multiple factors implicated in subsoil constraints including salinity, sodicity, and phytotoxic concentrations of chloride (Cl) are present in many Vertosols including those occurring in Queensland, Australia. The variable distribution and the complex interactions that exist between these constraints limit the agronomic or management options available to manage the soil with these subsoil constraints. The identification of crops and cultivars adapted to these adverse subsoil conditions and/or able to exploit subsoil water may be an option to maintain productivity of these soils. We evaluated relative performance of 5 winter crop species, in terms of grain yields, nutrient concentration, and ability to extract soil water, grown on soils with various levels and combinations of subsoil constraints in 19 field experiments over 2 years. Subsoil constraints were measured by levels of soil Cl, electrical conductivity of the saturation extract (ECse), and exchangeable sodium percentage (ESP). Increasing levels of subsoil constraints significantly decreased maximum depth of water extraction, grain yield, and plant-available water capacity for all the 5 crops and more so for chickpea and durum wheat than bread wheat, barley, or canola. Increasing soil Cl levels had a greater restricting effect on water availability than did ECse and ESP. We developed empirical relationships between soil Cl, ECse, and ESP and crop lower limit (CLL) for estimating subsoil water extraction by 5 winter crops. However, the presence of gypsum influenced the ability to predict CLL based on the levels of ECse. Stronger relationships between apparent unused plant-available water (CLL – LL15; LL15 is lower limit at –1.5 MPa) and soil Cl concentrations than ESP or ECse suggested that the presence of high Cl in these soils most likely inhibited the subsoil water extraction by the crops. This was supported by increased sodium (Na) and Cl concentration with a corresponding decrease in calcium (Ca) and potassium (K) in young mature leaf of bread wheat, durum wheat, and chickpea with increasing levels of subsoil constraints. Of the 2 ions, Na and Cl, the latter appears to be more damaging than the former, resulting in plant dieback and reduced grain yields.
New eSSR and gSSR markers added to Australian barley maps
Authors: Willsmore Kerrie L. , Eckermann Paul , Varshney Rajeev K. , Graner Andreas , Langridge Peter , Pallotta Margaret , Cheong Judy , Williams Kevin J.
Published: August 2006

To enhance genetic maps of barley previously developed in Australia for identifying markers useable in molecular breeding, a new set of simple sequence repeat (SSR) and indel markers was added to the maps. These markers were developed through (i) database mining of barley expressed sequence tag (EST) sequences, (ii) comparative barley-rice genome analysis, and (iii) screening of a genomic library with SSR probes. The primer set selected for this study comprised 216 EST-SSR (eSSR) and 25 genomic SSR (gSSR) markers, which were screened for polymorphism on 4 doubled haploid (DH) or recombinant inbred line (RIL) populations. In total, 81 new markers were added to the maps, with good coverage on all 7 chromosomes, except 6H, which only had 2 new markers added. The marker order of previously published maps was re-evaluated by comparing recombination fractions calculated by 2 methods to discover the best position for each marker. The new SSR markers were then added to the updated maps. Several of these new markers are linked to important barley disease resistance genes such as those for cereal cyst nematode, spot form of net blotch, and leaf scald resistance, and are readily useable for marker-assisted barley breeding. The new maps are available on-line at www.genica.net.au.
The identification of QTLs for adult plant resistance to leaf scald in barley
Authors: Cheong Judy , Williams Kevin , Wallwork Hugh
Published: August 2006

Barley leaf scald disease, caused by the fungal pathogen Rhynchosporium secalis, can be economically damaging, causing both yield losses and lower quality from reduced grain size. Most genetic studies of scald resistance have concentrated on seedling reactions either because of a lack of access to field screening resources or else because of the more definitive phenotype obtained at the seedling stage. However, understanding the genetics of adult plant resistance (APR) to leaf scald could help to produce more durable resistance to this disease. APR to leaf scald in a Chebec/Harrington population (120 doubled haploid (DH) lines) and a Mundah/Keel population (95 DH lines) was determined at Turretfield, South Australia, in 2004. Two different conditions of scald infection were used for Chebec/Harrington, natural infection and inoculation with 2 known scald isolates, whereas Mundah/Keel was inoculated with 2 known isolates. Quantitative trait loci (QTLs) for scald resistance were identified using a previously published Chebec/Harrington map. Three QTLs (on chromosomes 7HS, 7HL, and 6HS) were identified using the natural infection data and one QTL on chromosome 6HL using the inoculated plant data. Two QTLs were identified on chromosome 3HL and 6HS, respectively, using a partial map of Mundah/Keel. An unmapped Schooner/O’Connor population, consisting of 116 DH lines, was also phenotyped for adult plant resistance to scald using natural infection at Turretfield in 2001. Bulked-segregant analysis was used to identify molecular markers linked to a scald resistance locus in the barley cultivar O’Connor on chromosome 6HS, at the same location as the QTLs identified from Harrington and Keel. Six of the QTLs for APR to leaf scald identified in this study were co-located with previously identified seedling resistance genes.
Evolving usage of materials from CIMMYT in developing Australian wheat varieties
Authors: Brennan John P. , Quade Kathryn J.
Published: August 2006

Wheat genetic materials developed at the International Maize and Wheat Improvement Center (CIMMYT) in Mexico for developing countries and varieties developed from those genetic materials have resulted in yield increases in Australia. The usage of the genetic materials obtained from CIMMYT has evolved over time, with fewer Australian varieties resulting from either direct CIMMYT crosses or having a CIMMYT line as a parent. There has been an increasing tendency to use adapted Australian lines with CIMMYT ancestry, rather than CIMMYT lines, as parents. These changes are examined, both in terms of varieties released in Australia and for the shares of wheat area sown to crosses of different origins, for each Australian state. The results demonstrate that for the benefits of international developments to be made available to Australian producers, Australian-based breeding programs are essential.
Occurrence of Beet western yellows virus and its aphid vectors in over-summering broad-leafed weeds and volunteer crop plants in the grainbelt region of south-western Australia
Authors: Coutts B. A. , Hawkes J. R. , Jones R. A. C.
Published: August 2006

During the summer periods of 2000, 2001, and 2002, presence of Beet western yellows virus (BWYV) was assessed in tests on samples from at least 12 broad-leafed weed species and 5 types of volunteer crop plants growing in the grainbelt region of south-western Australia. In 2000, BWYV was detected in 2 of 35 sites in 2% of 1437 samples, whereas in 2001 and 2002 the corresponding figures were 3 of 108 sites in 0.04% of 8782 samples, and 1 of 30 sites in 0.08% of 2524 samples, respectively. The sites with infection were in northern, central, and southern grainbelt districts, and in high and medium rainfall zones. The hosts in which BWYV was detected were the weeds Citrullus lanatus (Afghan or wild melon), Conzya spp. (fleabane), Navarretia squarrosa (stinkweed), and Solanum nigrum (blackberry nightshade), and the volunteer crop plant Brassica napus (canola). Small populations of aphids were found over-summering at 28% (2000), 4% (2001), and 17% (2002) of sites, mostly infesting volunteer canola and Raphanus raphanistrum (wild radish). They occurred in high, medium, and low rainfall zones, but were only found in central and southern grainbelt districts. The predominant aphid species found was Brevicoryne brassicae, with Acyrthosiphon pisum, Brachycaudus helichrysi, Hyperomyzus lactucae, Lipaphis erysimi, Myzus persicae, and Uroleucon sonchi present occasionally. The importance of these findings in relation to the epidemiology and control of BWYV in the grainbelt is discussed.
Confirmation of QTL mapping and marker validation for partial seedling resistance to crown rot in wheat line '2-49'
Authors: Collard B. C. Y. , Jolley R. , Bovill W. D. , Grams R. A. , Wildermuth G. B. , Sutherland M. W.
Published: August 2006

We have tested the efficacy of putative microsatellite single sequence repeat (SSR) markers, previously identified in a 2-49 (Gluyas Early/Gala) × Janz doubled haploid wheat (Triticum aestivum) population, as being linked to partial seedling resistance to crown rot disease caused by Fusarium pseudograminearum. The quantitative trait loci (QTLs) delineated by these markers have been tested for linkage to resistance in an independent Gluyas Early × Janz doubled haploid population. The presence of a major QTL on chromosome 1DL (QCr.usq-1D1) and a minor QTL on chromosome 2BS (QCr.usq-2B1) was confirmed. However, a putative minor QTL on chromosome 2A was not confirmed. The QTL on 1D was inherited from Gluyas Early, a direct parent of 2-49, whereas the 2B QTL was inherited from Janz. Three other putative QTLs identified in 2-49 × Janz (on 1AL, 4BL, and 7BS) were inherited by 2-49 from Gala and were not able to be confirmed in this study. The screening of SSR markers on a small sample of elite wheat genotypes indicated that not all of the most tightly linked SSR markers flanking the major QTLs on 1D and 1A were polymorphic in all backgrounds, indicating the need for additional flanking markers when backcrossing into some elite pedigrees. Comparison of SSR haplotypes with those of other genotypes exhibiting partial crown rot resistance suggests that additional, novel sources of crown rot resistance are available.
Persistence of morphologically diverse lucerne under continuous stocking and intensive grazing
Authors: Pecetti L. , Romani M. , Piano E.
Published: August 2006

Grazing tolerance of lucerne is an attribute of growing interest worldwide. A breeding method relying on direct selection for persistence under continuous stocking and intensive grazing was here applied to germplasm first selected for the presence of positive traits, hoping to combine an effective selection procedure with the advantages of a favourable morphology. Progenies belonging to diversified plant ‘models’, previously synthesised, were evaluated under sheep grazing in 2 trials in northern Italy with reference to a tolerant and an intolerant check variety. The reliability of the assessment according to recommended standard procedures was ensured by the recorded difference in persistence of the 2 checks. Two semi-prostrate models proved very tolerant to grazing, and another, semi-erect model proved partly tolerant. When the spring biomass was measured before grazing imposition, the grazing-tolerant models showed lower values than the other models and the checks, but they featured the highest biomass after the grazing seasons in both trials, owing to their outstanding tolerance. The best germplasm will be used to develop grazing-tolerant varieties. The most tolerant models displayed a long cold-season rest. Nonetheless, they could also be of interest in areas with relatively mild winters, for instance in mixtures with winter-active annual species, or in intercropping situations. Based on reported evidence, germplasm selected under intensive grazing and continuous stocking is expected to retain its tolerance under more rational management systems.
Fish assemblages of an Australian dryland river: abundance, assemblage structure and recruitment patterns in the Warrego River, Murray - Darling Basin
Authors: Balcombe Stephen R. , Arthington Angela H. , Foster Neal D. , Thoms Martin C. , Wilson Glenn G. , Bunn Stuart E.
Published: August 2006

Fish in dryland rivers must cope with extreme variability in hydrology, temperature and other environmental factors that ultimately have a major influence on their patterns of distribution and abundance at the landscape scale. Given that fish persist in these systems under conditions of high environmental variability, dryland rivers represent ideal systems to investigate the processes contributing to and sustaining fish biodiversity and recruitment in variable environments. Hence, spatial and temporal variation in fish assemblage structure was examined in 15 waterholes of the Warrego River between October 2001 and May 2003. Fish assemblages in isolated waterholes were differentiated at the end of the dry 2001 winter but were relatively similar following high summer flows in January 2002 as a consequence of high hydrological connectivity among waterholes. Small, shallow waterholes supported more species and higher abundances than large-deep waterholes. Large, deep waterholes provided important refuge for large-bodied fish species such as adult yellowbelly, Macquaria ambigua, and the eel-tailed catfish, Tandanus tandanus. Recruitment patterns of bony bream (Nematalosa erebi), Hyrtl’s tandan (Neosilurus hyrtlii) and yellowbelly were associated with high flow events and backwater inundation; however recruitment of yellowbelly and bony bream was also evident following a zero-flow period. Departures from typical flood-induced seasonal spawning patterns may reflect opportunistic spawning behaviours appropriate to the erratic patterns of flooding and dry spells in dryland rivers.
Wild bees enhance honey bees’ pollination of hybrid sunflower
Authors: Greenleaf Sarah S. , Kremen Claire
Published: August 2006

Pollinators are required for producing 15–30% of the human food supply, and farmers rely on managed honey bees throughout the world to provide these services. Yet honey bees are not always the most efficient pollinators of all crops and are declining in various parts of the world. Crop pollination shortages are becoming increasingly common. We found that behavioral interactions between wild and honey bees increase the pollination efficiency of honey bees on hybrid sunflower up to 5-fold, effectively doubling honey bee pollination services on the average field. These indirect contributions caused by interspecific interactions between wild and honey bees were more than five times more important than the contributions wild bees make to sunflower pollination directly. Both proximity to natural habitat and crop planting practices were significantly correlated with pollination services provided directly and indirectly by wild bees. Our results suggest that conserving wild habitat at the landscape scale and altering selected farm management techniques could increase hybrid sunflower production. These findings also demonstrate the economic importance of interspecific interactions for ecosystem services and suggest that protecting wild bee populations can help buffer the human food supply from honey bee shortages.
Testing gene function early in the B cell lineage in mb1-cre mice
Authors: Hobeika E. , Thiemann S. , Storch B. , Jumaa H. , Nielsen P. J. , Pelanda R. , Reth M.
Published: August 2006

Themb1gene encodes the Ig-α signaling subunit of the B cell antigen receptor and is expressed exclusively in B cells beginning at the very early pro-B cell stage in the bone marrow. We examine here the efficacy of themb1gene as a host locus for cre recombinase expression in B cells. We show that by integrating a humanized cre recombinase into the mb1 locus we obtain extraordinarily efficient recombination ofloxPsites in the B cell lineage. The results from a variety of reporter genes including the splicing factor SRp20 and the DNA methylase Dnmt1 suggest that mb1-cre is probably the best model so far described for pan-B cell-specific cre expression. The availability of a mouse line with efficient cre-mediated recombination at an early developmental stage in the B lineage provides an opportunity to study the role of various genes specifically in B cell development and function.
Role and timing of GTP binding and hydrolysis during EF-G-dependent tRNA translocation on the ribosome
Authors: Wilden Berthold , Savelsbergh Andreas , Rodnina Marina V. , Wintermeyer Wolfgang
Published: August 2006

The translocation of tRNA and mRNA through the ribosome is promoted by elongation factor G (EF-G), a GTPase that hydrolyzes GTP during the reaction. Recently, it was reported that, in contrast to previous observations, the affinity of EF-G was much weaker for GTP than for GDP and that ribosome-catalyzed GDP–GTP exchange would be required for translocation [Zavialov AV, Hauryliuk VV, Ehrenberg M (2005)
J Biol
4:9]. We have reinvestigated GTP/GDP binding and show that EF-G binds GTP and GDP with affinities in the 20 to 40 μM range (37°C), in accordance with earlier reports. Furthermore, GDP exchange, which is extremely rapid on unbound EF-G, is retarded, rather than accelerated, on the ribosome, which, therefore, is not a nucleotide-exchange factor for EF-G. The EF-G·GDPNP complex, which is very labile, is stabilized 30,000-fold by binding to the ribosome. These findings, together with earlier kinetic results, reveal that EF-G enters the pretranslocation ribosome in the GTP-bound form and indicate that, upon ribosome-complex formation, the nucleotide-binding pocket of EF-G is closed, presumably in conjunction with GTPase activation. GTP hydrolysis is required for rapid tRNA–mRNA movement, and P
i
release induces further rearrangements of both EF-G and the ribosome that are required for EF-G turnover.
Pregnane X receptor (PXR) activation: A mechanism for neuroprotection in a mouse model of Niemann–Pick C disease
Authors: Langmade S. Joshua , Gale Sarah E. , Frolov Andrey , Mohri Ikuko , Suzuki Kinuko , Mellon Synthia H. , Walkley Steven U. , Covey Douglas F. , Schaffer Jean E. , Ory Daniel S.
Published: August 2006

Niemann–Pick type C1 (NPC1) disease is a fatal neurodegenerative disease characterized by neuronal lipid storage and progressive Purkinje cell loss in the cerebellum. We investigated whether therapeutic approaches to bypass the cholesterol trafficking defect in NPC1 disease might delay disease progression in the
npc1
−/−
mouse model. We show that the neurosteroid allopregnanolone (ALLO) and T0901317, a synthetic oxysterol ligand, act in concert to delay onset of neurological symptoms and prolong the lifespan of
npc1
−/−
mice. ALLO and T0901317 therapy preserved Purkinje cells, suppressed cerebellar expression of microglial-associated genes and inflammatory mediators, and reduced infiltration of activated microglia in the cerebellar tissue. To establish whether the mechanism of neuroprotection in
npc1
−/−
mice involves GABA
A
receptor activation, we compared treatment of natural ALLO and
ent
-ALLO, a stereoisomer that has identical physical properties of natural ALLO but is not a GABA
A
receptor agonist.
ent
-ALLO provided identical functional and survival benefits as natural ALLO in
npc1
−/−
mice, strongly supporting a GABA
A
receptor-independent mechanism for ALLO action. On the other hand, the efficacy of ALLO,
ent
-ALLO, and T0901317 therapy correlated with the ability of these compounds to activate pregnane X receptor-dependent pathways
in vivo
. These findings suggest that treatment with pregnane X receptor ligands may be useful clinically in delaying the progressive neurodegeneration in human NPC disease.
Wake-Up in the Danish Ghetto
Authors: Jerichow Anders
Published: August 2006

GOOD MORNING DENMARK. WELCOME TO THE BIG WORLD OUT THERE
La France: Love It or Leave It!
Authors: Abdallah Mogniss , Routledge Mike
Published: August 2006

IN THE WAKE OF THEIR COVERAGE OF THE RIOTS IN THE BANLIEUE IN NOVEMBER, THE MEDIA ARE INDULGING IN A LITTLE SELF-CRITICISM, BUT IT’S A FRAGILE PROCESS AND THEIR LINKS WITH THE POLITICIANS REMAIN CLOSE
Fourth Arm of the State
Authors: Nicolae Valeriu
Published: August 2006

ROMANIA’S MEDIA IS A WILLING PARTNER IN THE PERPETUATION OF RACISM, PREJUDICE AND DISCRIMINATION
A War of Words
Authors: Mobasser Nilou
Published: August 2006

MEDIA DEBATE HAS BEEN CLOSED DOWN, BUT THE WEBSITE AND THE BLOG HAVE TAKEN UP THE CHALLENGE
Running On Empty
Authors: Braeckman Colette , Routledge Mike
Published: August 2006

DESPITE CONTINUING VIOLENCE IN THE EAST OF THE COUNTRY, CIVILIANS PREPARED FOR THE ELECTIONS THEY SEE AS AN ANTIDOTE TO WAR AND TO THE FAILURE OF THE STATE
Nonsense On Stilts
Authors: Petley Julian
Published: August 2006

GOVERNMENT AND PRESS HAVE JOINED FORCES IN A CAMPAIGN TO ABANDON THE HUMAN RIGHTS ACT — AND MAYBE MEMBERSHIP OF THE EU
Great Expectations
Authors: Hroub Khaled
Published: August 2006

IN ITS FIRST DECADE, THE QATARI TV CHANNEL AL-JAZEERA HAS CHANGED THE MEDIA LANDSCAPE OF THE ARAB WORLD. ON THE POLITICAL FRONT, HOWEVER, IT’S A DIFFERENT MATTER
The Fog of Forgetting
Authors: Gorriti Gustavo
Published: August 2006

THIRTEEN YEARS AND TWO TRIALS AFTER FIRST SENTENCING, THE LEADER OF PERU’S SHINING PATH IS BACK IN COURT
Reproductive and Developmental Toxicity of Arsenic in Rodents: A Review
Authors: Wang Amy , Holladay Steven D. , Wolf Douglas C. , Ahmed S. Ansar , Robertson John L.
Published: August 2006

Arsenic is a recognized reproductive toxicant in humans and induces malformations, especially neural tube defects, in laboratory animals. Early studies showed that murine malformations occurred only when a high dose of inorganic arsenic was given by intravenous or intraperitoneal injection in early gestation. Oral gavage of inorganic arsenic at maternally toxic doses caused reduced fetal body weight and increased resorptions. Recently, arsenic reproductive and developmental toxicity has been studied in situations more similar to human exposures and using broader endpoints, such as behavioral changes and gene expression. For the general population, exposure to arsenic is mostly oral, particularly via drinking water, repeated and prolonged over time. In mice and rats, methylated or inorganic arsenic via drinking water or by repeated oral gavage induced male and female reproductive and developmental toxicities. Furthermore, at nonmaternally toxic levels, inorganic arsenic given to pregnant dams via drinking water affected fetal brain development and postnatal behaviors. However, arsenic given by repeated oral gavage to pregnant mice and rats was not morphologically teratogenic. In this review of arsenic reproductive and developmental toxicity in rats and mice, the authors summarize recent in vivo studies and discuss possible underlying mechanisms. The influences of folate, selenium, zinc, and arsenic methylation on arsenic reproductive and developmental toxicity are also discussed.
Acetone in Drinking Water Does Not Modulate Humoral Immunity in Mice as Measured by the Antibody, Plaque-Forming Cell Assay
Authors: Woolhiser Michael R. , Houtman Carrie E. , Waechter John M.
Published: August 2006

It has been reported that the repeated topical, nonoccluded application of acetone may modulate antibody production in mice, thus producing humoral immunosuppression. However, the evaporative loss expected following nonoccluded dermal application of acetone makes the systemic effect seem unlikely. This study was designed to investigate the immunotoxicity potential of acetone in mice following a more direct systemic route of dosing via drinking water for 28 days. CD-1 male mice consumed average daily acetone doses of 121, 621 or 1144 mg/kg/day. The antibody, plaque-forming cell (AFC) assay was performed to measure the T cell–dependent, anti-sheep red blood cell immunoglobulin M (IgM) response, and hematology and thymus weights were evaluated to provide additional insight into the potential effects to the immune system. Body weights, white blood cell (WBC), numbers, red blood cell (RBC) counts, and hemoglobin and hematocrit levels showed no treatment-related effects at any dose of acetone. Eosinophil percentages were variable but also showed no dose-related trends. Spleen and thymus weights were not statistically different from controls and there were no effects on spleen cellularity or AFC response as a result of acetone administration. The AFC responses ranged from 1088 to 1401 AFCs/106 splenocytes and were not statistically different from controls (1277 AFCs/106 cells). Mice treated with cyclophosphamide (20 mg/kg) on days 25 to 28 demonstrated a 94% reduction in AFC/106 cells. Thus, the direct systemic administration of acetone did not produce evidence for immunotoxicity in CD-1 mice and the no observed adverse effect level (NOAEL) in this study was determined to be 1144 mg/kg/day.
Congener-Specific Polychlorinated Biphenyl–Induced Cell Death in Human Kidney Cells In Vitro: Potential Role of Caspase
Authors: Chen Y. Q. , De S. , Ghosh S. , Dutta S. K.
Published: August 2006

Polychlorinated biphenyls (PCBs) are among the most widespread and persistent pollutants in the global environment. Coplanar and noncoplanar PCBs have been shown to cause congener-specific apoptosis mediated neurotoxicity in rats. Very few, if any, such studies have been reported on human renal cell toxicity. The authors report here caspase-dependent or caspase-independent renal toxicity, as measured by apoptotic death induced by PCBs, depending on the planarity of congeners PCB-77 (coplanar) and PCB-153 (noncoplanar) in human kidney cells (HK2) in vitro. The authors have combined morphological and biological techniques to discover the relevance of apoptosis in renal proximal tubule cell death induced by these two PCB congeners. Treatment with both PCB congeners caused accelerated apoptosis in a time-and concentration-dependent manner. Based on our findings using human kidney (HK2) cells, there was more apoptosis-mediated loss of cell viability by non– ortho-substituted PCB-77 when compared to PCB-153. A significant increase of caspase-3 expression through immunoblot studies showed the involvement of apoptosis by PCB-77 compared to none by PCB-153. The broad-spectrum caspase inhibitor z-VAD-fmk showed increased cell death when treated by PCB-153, but not by PCB-77, confirming that caspase inhibitor induced a switch in the mode of cell death. It is reasonable to assume that apoptotic cell death in the renal proximal tubule cells treated by PCBs may have both caspase-dependent and caspase-independent pathways.
Reevaluation of a Twenty-Four-Month Chronic Toxicity/Carcinogenicity Study of Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in the B6C3F1 Hybrid Mouse
Authors: Parker George A. , Reddy Gunda , Major Michael A.
Published: August 2006

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has been widely used as an explosive in U.S. army munitions formulations since World War II. Two-year carcinogenicity studies revealed RDX to be noncarcinogenic in two strains of rats, but a 2-year carcinogenicity study in B6C3F1 mice revealed an increased incidence of hepatocellular neoplasms in females. Based on results of the study in B6C3F1 mice, RDX has been classified as a possible carcinogen. The authors reevaluated the archived histological sections from the B6C3F1 mouse study, using current histopathologic diagnostic criteria and interpretations. The earlier evaluation showed a statistically significant increase in the incidence of hepatocellular adenoma/carcinoma in female mice from the three highest dose groups (7, 35, and 175/100 mg/kg/day). The revaluation yielded a slightly lower incidence at each of the dose levels in female mice. The reduced number of hepatocellular neoplasms was largely due to reclassification of hepatocellular adenomas as foci of cytoplasmic alteration, in compliance with current diagnostic criteria. The reevaluation was reviewed by a pathology working group (PWG), which arrived at a consensus classification of each lesion. Based on the consensus diagnoses of the PWG, only one female group (35 mg/kg/day) showed a significant increase when compared to controls. The incidence of hepatocellular neoplasms for all groups, including the 35 mg/kg/day group, was within the reported incidence range for spontaneous hepatocellular neoplasms in female B6C3F1 mice. The increased incidence of hepatocellular neoplasms in female mice given RDX at 35 mg/kg/day was interpreted as equivocal evidence of a carcinogenic effect.
Gene Expression Profiles in Rat Liver Slices Exposed to Hepatocarcinogenic Enzyme Inducers, Peroxisome Proliferators, and 17α-Ethinylestradiol
Authors: Werle-Schneider Gisela , Wölfelschneider Andreas , von Brevern Marie Charlotte , Scheel Julia , Storck Thorsten , Müller Dieter , Glöckner Reinhild , Bartsch Helmut , Bartelmann Matthias
Published: August 2006

Transcription profiling is used as an in vivo method for predicting the mode-of-action class of nongenotoxic carcinogens. To set up a reliable in vitro short-term test system DNA microarray technology was combined with rat liver slices. Seven compounds known to act as tumor promoters were selected, which included the enzyme inducers phenobarbital, α-hexachlorocyclohexane, and cyproterone acetate; the peroxisome proliferators WY-14,643, dehydroepiandrosterone, and ciprofibrate; and the hormone 17 α-ethinylestradiol. Rat liver slices were exposed to various concentrations of the compounds for 24 h. Toxicology-focused TOXaminer™DNA microarrays containing approximately 1500 genes were used for generating gene expression profiles for each of the test compound. Hierarchical cluster analysis revealed that (i) gene expression profiles generated in rat liver slices in vitro were specific allowing classification of compounds with similar mode of action and (ii) expression profiles of rat liver slices exposed in vitro correlate with those induced after in vivo treatment (reported previously). Enzyme inducers and peroxisome proliferators formed two separate clusters, confirming that they act through different mechanisms. Expression profiles of the hormone 17 α-ethinylestradiol were not similar to any of the other compounds. In conclusion, gene expression profiles induced by compounds that act via similar mechanisms showed common effects on transcription upon treatment in vivo and in rat liver slices in vitro.
Effect of Clofibric Acid on Desmin and Vimentin Contents in Rat Myocardiocytes
Authors: Sampayo-Reyes Adriana , Narro-Juárez Antonio , Saíd-Fernández Salvador , Lozano-Garza Héctor G. , Vargas-Villarreal Javier , Mata-Cárdenas Benito D. , Morales-Aguilera Antonio , González-Garza María Teresa , Cortés-Gutiérrez Elva I. , Cerda-Flores Ricardo M. , Martínez-Rodríguez Herminia G.
Published: August 2006

The aim of this experimental study was to analyze in vitro effects of clofibric acid on vimentin and desmin contents in rat myocardiocytes, which was carried out in primary myocardiocyte cells that were treated only with clofibric acid at 0.1 mM. The measurement of vimentin and desmin were done by Western blotting and densitometry. This study showed that myocardiocytes exposed to clofibric acid exhibit a 26.3% decrease in vimentin and a 42.1% decrease in desmin. Considering the role that these intermediate filaments play in the anchorage and cellular organization of myocardiocytes, the decrease of desmin and vimentin observed in cells treated with clofibric acid may be partially responsible for the adverse effects observed in patients. In conclusion, the alteration of cytoskeletal proteins may be a cause of cardiopathy in patients treated with these compounds.
Pore Formation of Thermostable Direct Hemolysin Secreted from Vibrio parahaemolyticus in Lipid Bilayers
Authors: Takahashi Akira , Yamamoto Chiyo , Kodama Toshio , Yamashita Kanami , Harada Nagakatsu , Nakano Masayuki , Honda Takeshi , Nakaya Yutaka
Published: August 2006

Vibrio parahaemolyticus secretes thermostable direct hemolysin (TDH), a major virulence factor. Earlier studies report that TDH is a pore-forming toxin. However, the characteristics of pores formed by TDH in the lipid bilayer, which is permeable to small ions, remain to be elucidated. Ion channel-like activities were observed in lipid bilayers containing TDH. Three types of conductance were identified. All the channels displayed relatively low ion selectivity, and similar ion permeability. The Cl− channel inhibitors, DIDS, glybenclamide, and NPPB, did not affect the channel activity of pores formed by TDH. R7, a mutant toxin of TDH, also forms pores with channel-like activity in lipid bilayers. The ion permeability of these channels is similar to that of TDH. R7 binds cultured cells and liposomes to a lower extent, compared to TDH. R7 does not display significant hemolytic activity and cell cytotoxicity, possibly owing to the difficulty of insertion into lipid membranes. Once R7 is assembled within lipid membranes, it may assume the same structure as TDH. The authors propose that the single glycine at position 62, substituted with serine in the R7 mutant toxin, plays an important role in TDH insertion into the lipid bilayer.
XRCC1 Arg399Gln Genetic Polymorphism in a Turkish Population
Authors: Kocabaş Neslihan Aygün , Karahalil Bensu
Published: August 2006

Humans are routinely exposed to mutagenic and carcinogenic chemicals. These chemicals can form DNA adducts in vivo and thus lead to DNA damage. The integrity of most of the so-damaged DNAs is typically restored as a consequence of the action of certain DNA-repairing enzymes. In several DNA repair genes, polymorphisms may result in reduced repair capacity, which has been implicated as a risk factor for various types of cancer. XRCC1 is a base-excision repair protein that plays a central role in the repair of DNA base damage and strand breaks. Amongst the known genetic polymorphisms of the DNA-repair genes, X-ray repair cross-complementing groups 1 and 3 ( XRCC1 and XRCC3) have been studied most commonly. Inconsistent results have been reported regarding the associations between the Arg399Gln (exon 10) polymorphism of XRCC1 and either functional significance or the risk of tobacco-associated cancers. The Gln allele of this polymorphism was associated with higher levels of DNA adducts. Therefore we genotyped one of the polymorphism of XRCC1, Gln allele. The frequency of the polymorphic alleles varies among populations, suggesting an ethnic distribution of genotypes. There has been no information on interindividual variability of Arg399Gln genotype in the Turkish population. Due to the association between the Arg399Gln polymorphism of XRCC1 and the risk of tobacco-associated cancers, we preferred to evaluate the allelic frequencies of Arg399Gln genotype than the other polymorphisms in XRCC1 gene in healthy Turkish population by polymerase chain reaction–restriction fragment polymorphism (PCR-RFLP) analysis to enable to show interindividual differences and compare to other populations.
Evaluation of the Developmental Toxicity of Acetyl Cedrene
Authors: Lapczynski Aurelia , Isola Daniel A. , Christian Mildred S. , Diener Robert M. , Api Anne Marie
Published: August 2006

The developmental toxicity of acetyl cedrene (AC), a widely used fragrance ingredient, was evaluated in pregnant Sprague-Dawley rats (25/group). Gavaged dosages of 0 (corn oil), 25, 50, or 100 mg/kg/day were administered on days 7 through 17 of gestation (GDs 7 to 17). First and last day dosing suspensions were analyzed for AC content. All rats were observed daily for viability, clinical signs, abortions, and premature deliveries. Body weights were recorded at frequent intervals. Cesarean-sectioning and necropsy examinations were performed on GD 21. Uteri were examined for number and distribution of implantations, live and dead fetuses, and early and late resorptions. The number of corpora lutea in each ovary was also recorded. Fetuses were weighed and examined for gender and gross external changes and soft tissue or skeletal alterations. Totals of 25, 23, 21, and 24 rats became pregnant in the 0 (control), 25, 50 and 100 mg/kg/day groups, respectively, and analysis of dosage preparations verified that administered dosages reflected calculated dosages ±10%. No deaths or premature deliveries occurred in the study. Clinical signs included excessive salivation, which was attributed to the administration of AC. When compared to controls, significant reductions in feed consumption and body weight gains occurred only at 100 mg/kg/day. Both absolute (g/day) and relative (g/kg/day) feed consumption values were significantly decreased on GDs 7 to 12. Relative values were decreased significantly on GDs 15 to 18. Body weight gains were significantly reduced on GDs 7 to 10. Mean maternal body weights remained significantly lower than controls on GDs 9 to 14, but a marked compensatory increase in feed consumption on GDs 15 to 18 prevented further deterioration in body weight gains. No cesarean-sectioning or litter parameters were affected by dosages of AC and necropsy of the dams after cesarean section did not reveal any gross changes attributable to AC. No gross external, soft tissue, or skeletal fetal alterations (malformations or variations) were attributed by dosages AC. The average number of ossifications sites per fetus per litter did not differ among the groups. Based on these data, maternal and developmental no-observable-adverse-effect levels (NOAELs) of 50 and 100 mg/kg/day, respectively, were established for AC.
The Case against Universal Varicella Vaccination
Authors: Goldman Gary S.
Published: August 2006

In 1995, the United States became the first country to implement a Universal Varicella Vaccination Program. Several questions remain: Is the varicella (chickenpox) vaccine needed? Is it cost effective as a routine immunization for all susceptible children? Or is it more beneficial for the disease to remain endemic so that adults may receive periodic exogenous exposures (boosts) that help suppress the reactivation of herpes zoster (shingles). In addition, as vaccination coverage becomes widespread, does loss of immunologic boosting cause a decline in vaccine efficacy and result in a reduced period of immunity? Scientific literature regarding safety of the varicella vaccine and its associated cost-benefit analysis have often reported optimistic evaluations based on ideal assumptions. Deleterious outcomes and their associated costs must be included when making a circumspect assessment of the Universal Varicella Vaccination Program.
T1 difficulty and the attentional blink: Expectancy versus backward masking
Authors: Visser Troy A. W.
Published: August 2006

According to bottleneck models of the attentional blink (AB), first-target (T1) processing difficulty should be related to AB magnitude. Tests of this prediction that have varied T1 difficulty in the context of a standard AB paradigm, however, have yielded mixed results. The present work examines two factors that may mediate the relationship between T1 difficulty and the AB: observer expectancy and backward masking of T1. In two experiments, omission of the backward mask consistently yielded the predicted relationship between T1 difficulty and the AB. In contrast, observer expectancy influenced target identification accuracy but did not mediate the relationship between T1 difficulty and the AB.
Zeading and reazing: Which is faster? The position of the diverging letter in a pseudoword determines reading time
Authors: Mulatti Claudio , Peressotti Francesca , Job Remo
Published: August 2006

We present evidence that (a) at least some components of the reading process are serial and (b) pseudoword reading is affected by lexical knowledge, even in a transparent orthographic system like Italian. Pseudowords deriving from five-letter words by changing either the first or the fourth letter were presented for reading aloud. Results showed an effect of the position of the diverging letter: Early diverging pseudowords were read more slowly than late diverging pseudowords. The dual-route cascaded (DRC) model (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001) successfully simulated the behavioural data.
When sparks get old
Authors: Melzer Werner
Published: August 2006

Sparks are transient local elevations of Ca ion concentration observed in different types of muscle cells. Such local Ca2+ signals can be provoked in skeletal muscle cells by altering the osmotic pressure of the extracellular solution. In this issue, Weisleder et al. (see p. 639) demonstrate that the Ca2+ response to osmotic stress is substantially altered in aged muscle. The study presents evidence for a link between this finding and a reduced expression of mitsugumin 29 (MG29), a small membrane protein of the sarcoplasmic reticulum (SR).