bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of non-thermal atmospheric plasmas to reduce the viability ofBacillus subtilison spacecraft surfaces
Authors: Schuerger Andrew C. , Trigwell Steven , Calle Carlos I.
Published: January 2008

Atmospheric pressure glow-discharge (APGD) plasmas have been proposed for sterilizing spacecraft surfaces prior to launch. The advantages of APGD plasmas for the sterilization of spacecraft surfaces include low temperatures at treatment sites, rapid inactivation kinetics of exposed microbial cells, physical degradation and removal of microbial cells, physical removal of organic biosignature molecules, and short exposure times for the materials. However, few studies have tested APGD plasmas on spacecraft materials for their effectiveness in both sterilizing surfaces and removal of microbial cells or spores. A helium (He)+oxygen (O2) APGD plasma was used to expose six spacecraft materials (aluminum 6061, polytetrafluoroethylene (PTFE), polycarbonate, Saf-T-Vu, Rastex, and Herculite 20) doped with spores of the common spacecraft contaminant,Bacillus subtilis, for periods of time up to 6 min. Results indicated that greater than six orders of magnitude reductions in viability were observed forB. subtilisspores in as short of time as 40 s exposure to the APGD plasmas. Spacecraft materials were not affected by exposures to the APGD plasmas. However, Saf-T-Vu was the only material in which spores ofB. subtilisadhered more aggressively to plasma-treated coupons when compared to non-plasma treated coupons; all other materials exhibited no significant differences between plasma and non-plasma treated coupons. In addition, spores ofB. subtiliswere physically degraded by exposures to the plasmas beginning at the terminal ends of spores, which appeared to be ruptured after only 30 s. After 300 s, most bacteria were removed from aluminium coupons, and only subtle residues of bacterial secretions or biofilms remained. Results support the conclusion that APGD plasmas can be used as a prelaunch cleaning and sterilization treatment on spacecraft materials provided that the biocidal and cleaning times are shorter than those required to alter surface properties of materials.
Predicting School Achievement from Motivation and Personality
Authors: Steinmayr Ricarda , Spinath Birgit
Published: January 2008

Abstract. The present study aims at comparing the predictive power of motivation and broad personality traits for school performance and contributes to an understanding of the nomological network of personality. A sample of German adolescent students (N = 342 11th and 12th graders, age M = 16.94, SD = .71) gave self-reports of need for achievement, domain-specific ability self-concepts and task values in German and Math as well as the Big Five of personality. Grades in German and mathematics as well as grade-point average served as performance criteria. On a bivariate zero-order level, the motivational constructs showed the hypothesized positive associations with school achievement in Math, German, and GPA. With respect to personality, only Conscientiousness was consistently positively associated with grades, whereas Neuroticism, Extraversion, Openness to Experience, and Agreeableness were either not or weakly associated with one or two out of three performance criteria. Hierarchical and stepwise regression analyses were performed with grades in Math and German as well as GPA as dependent variables. When comparing motivation and personality, domain-specific ability self-concepts were the strongest predictors of all performance criteria. Together, the present results confirm the predominance of motivational concepts over the Big Five of personality for the prediction of performance criteria and substantiate the importance to integrate trait conceptions of motivation into the nomological network of personality.
Farming the planet: 1. Geographic distribution of global agricultural lands in the year 2000
Authors: Ramankutty Navin , Evan Amato T. , Monfreda Chad , Foley Jonathan A.
Published: January 2008

Agricultural activities have dramatically altered our planet's land surface. To understand the extent and spatial distribution of these changes, we have developed a new global data set of croplands and pastures circa 2000 by combining agricultural inventory data and satellite‐derived land cover data. The agricultural inventory data, with much greater spatial detail than previously available, is used to train a land cover classification data set obtained by merging two different satellite‐derived products (Boston University's MODIS‐derived land cover product and the GLC2000 data set). Our data are presented at 5 min (∼10 km) spatial resolution in longitude by longitude, have greater accuracy than previously available, and for the first time include statistical confidence intervals on the estimates. According to the data, there were 15.0 (90% confidence range of 12.2–17.1) million km2 of cropland (12% of the Earth's ice‐free land surface) and 28.0 (90% confidence range of 23.6–30.0) million km2 of pasture (22%) in the year 2000.
Threshold exceedances and cumulative ozone exposure indices at tropical suburban site
Authors: Beig G. , Ghude Sachin D. , Polade S. D. , Tyagi B.
Published: January 2008

This study provides the first analysis of threshold exceedances and cumulative ozone exposure indices from Pune, a tropical suburban site in India. We used the directives on ozone pollution in ambient air provided by the United Nations Economic Commission for Europe, and by the World Health Organization to assess the air quality from in situ measurements of surface ozone (during the years 2003–2006). We find that the exposure‐plant response index (Accumulated exposure Over a Threshold of 40 ppb (AOT40)) and target values for protection of human health (8‐h > 60 ppb) are regularly surpassed. This is a concern for agricultural and human health. Air‐mass classification based on back‐air trajectories shows that the excess of AOT40 values is quite plausibly due to long‐range transport of background ozone and its precursors to the measurement site.
Disequilibrium response of permafrost thaw to climate warming in Canada over 1850–2100
Authors: Zhang Yu , Chen Wenjun , Riseborough Daniel W.
Published: January 2008

Climate warming would induce permafrost thaw. However, the response of permafrost to atmospheric climate change could take from a few years to millennia. In this study, we simulated the transient changes in ground thermal regimes and permafrost status in Canada over 1850–2100 at a half‐degree latitude/longitude resolution using a process‐based model. The results show that the ground thermal regimes were in strong disequilibrium, with much stronger warming near the surface than in deeper ground. The reduction in permafrost extent (20.5–24.0%) by the end of the 21st century was much smaller than equilibrium projections, but permafrost thaw would continue after the 21st century even if air temperature stops increasing. Permafrost thaw from the top was very significant, and the area with supra‐permafrost taliks increased exponentially, especially during the 21st century. This marked permafrost thaw from the top could have significant impacts on hydrology, landscape, soil biogeochemistry, ecosystems, and infrastructure.
On the velocity of positive connecting leaders associated with negative downward lightning leaders
Authors: Becerra M. , Cooray V.
Published: January 2008

A self‐consistent leader propagation model is used to estimate the velocity of upward connecting positive leaders initiated from a tall tower under the influence of downward negative lightning leaders. The propagation of upward connecting leaders has been found to be influenced not only by the average velocity of the downward leader but also by the prospective return stroke current, the lateral position of the downward leader channel as well as by the ambient electric field. This result show that the velocity and propagation time of upward connecting positive leaders change from flash to flash due to the variations in these parameters.
Distributed Preparedness: The Spatial Logic of Domestic Security in the United States
Authors: Collier Stephen J , Lakoff Andrew
Published: January 2008

This paper examines the genealogy of domestic security in the United States through an analysis of post-World War II civil defense. Specifically, we describe the development of an organizational framework and set of techniques for approaching security threats that we call ‘distributed preparedness’. Distributed preparedness was initially articulated in civil defense programs in the early stages of the Cold War, when US government planners began to conceptualize the nation as a possible target of nuclear attack. These planners assumed that the enemy would focus its attacks on urban and industrial centers that were essential to US war-fighting capability. Distributed preparedness provided techniques for mapping national space as a field of potential targets, and grafted this map of vulnerabilities onto the structure of territorial administration in the United States. It presented a new model of coordinated planning for catastrophic threats, one that sought to limit federal intervention in local life and to preserve the characteristic features of American federalism. Over the course of the Cold War, distributed preparedness extended to new domains, and following 9/11 it has moved to the center of security discussions in the US.
Memorial Trees and Treescape Memories
Authors: Cloke Paul , Pawson Eric
Published: January 2008

The interconnections between trees and memorialisation are explored at three particular sites in the city of Christchurch, New Zealand. Memorial trees have been used as a seemingly blank canvas, to be coloured by the paintbox of memory. The ability of such trees to carry significant memories of past events into the present involves myriad slippages and all kinds of untidiness: the settings in which memorial trees are asked to perform are subject to significant and often transformative cultural change; the trees themselves are active organic components in the changing coconstitution of place and place meanings; and tree places can afford emotional responses and serve as spaces of much more immediate and prereflexive practice and performance. These dynamics suggest rather different connections between trees and memorialisation, which we term treescape memories.
‘Geography is Pregnant’ and ‘Geography's Milk is Flowing’: Metaphors for a Postcolonial Discipline?
Authors: Noxolo Pat , Raghuram Parvati , Madge Clare
Published: January 2008

This paper attempts to mobilise the metaphors of pregnancy and lactation to address the imperatives arising from British academic geography's postcolonial position. We embed our argument in our readings of extracts from two consciously postcolonial fictional texts. In the first part of the paper we consider geography as a discipline that is pregnant but ‘in trouble’ to illustrate the paradoxical struggle of the discipline to be a global discipline whilst at the same time marginalising the voices and perspectives that make it global. In the second part of the paper we consider geography as a discipline whose ‘milk is flowing’ to suggest ways that the discipline can acknowledge its global interconnectedness to produce a mutually responsible academic agency.
Recognition of the
Hyaloperonospora parasitica
effector ATR13 triggers resistance against oomycete, bacterial, and viral pathogens
Authors: Rentel Maike C. , Leonelli Lauriebeth , Dahlbeck Douglas , Zhao Bingyu , Staskawicz Brian J.
Published: January 2008

Phytopathogenic oomycetes cause some of the most devastating diseases affecting agricultural crops
. Hyaloperonospora parasitica
is a native oomycete pathogen of
Arabidopsis
and is related to other oomycete phytopathogens that include several species of
Phytophthora
, including the causal agent of potato late blight. Recently, four oomycete effector genes have been isolated, and several oomycete genomes have been sequenced. We have developed an efficient and genetically amenable system to test putative effector genes using the bacterial pathogen
Pseudomonas syringae
pv.
tomato
DC3000. The
H. parasitica
effector protein ATR13 was delivered via
P. syringae
by fusing the
ATR13
gene with the
avrRpm1
type three secretion signal peptide, a bacterial sequence that allows transfer of proteins into the host cell through the bacterial type III secretion system. We also inserted
ATR13
into the genome of the turnip mosaic virus, a single-stranded RNA virus. Our results show that delivery of ATR13 via the bacterial or viral pathogen triggers defense responses in plants containing the cognate resistance protein RPP13
Nd
, which restricts proliferation of both pathogens. Hence, recognition of ATR13 by RPP13 initiates defense responses that are effective against oomycete, bacterial and viral pathogens, pointing to a common defense mechanism. We have characterized regions of the RPP13
Nd
resistance protein that are essential for effector recognition and/or downstream signaling, using transient coexpression in
Nicotiana benthamiana
.
Impact of the Priority Follow-Up System on Quality of Life in Chinese Schizophrenia Patients
Authors: Xiang Yu-Tao , Leung Chi-Ming , Tang Wai-Kwong , Sandor Ungvari Gabor
Published: January 2008

Objective: Priority follow up (PFU) is a particular aspect of mental health care in Hong Kong whereby psychiatric patients with a history of violence or suspected proclivity to violence are identified and their management is closely monitored. The aim of the present study was to determine the impact of a PFU system on quality of life (QOL) in schizophrenia patients.

Methods: Two hundred and sixty-seven clinically stable outpatients with schizophrenia were randomly selected and interviewed in Hong Kong using standardized assessment instruments that covered their clinical condition and QOL.

Results: Patients with PFU status constituted 8.2% of the sample. PFU patients were more likely to be men, have a history of violence, and were poorer in the physical, psychological, social and environmental QOL domains than their non-PFU counterparts even after controlling for the effects of potential confounding variables.

Conclusions: More effective measures should be taken to improve QOL in PFU schizophrenia patients who are prone to violent behavior.
Clustering of Psychosocial Symptoms in Overweight Children
Authors: Gibson Lisa Y. , Byrne Susan M. , Blair Eve , Davis Elizabeth A. , Jacoby Peter , Zubrick Stephen R.
Published: January 2008

Objective: The aims of the present study were to (i) examine the relationship between children's degree of adiposity and psychosocial functioning; and (ii) compare patterns of clustering of psychosocial measures between healthy weight and overweight/obese children.

Method: Cross-sectional data from a population-based cohort of 158 healthy weight, 77 overweight, and 27 obese children aged 8–13 years were analysed. Height, weight depression, quality of life, self-esteem, body dissatisfaction, eating disorder symptoms, peer relationships and behavioural and emotional problems were measured.

Results: Multi-level analysis showed significant linear associations between child body mass index z-scores and the psychosocial variables, with increasing adiposity associated with increasing levels of psychosocial distress. Principal components analyses indicated subtle differences between the healthy weight and overweight/obese groups with regards to the clustering of psychosocial measures. In particular, in overweight/obese, but not in healthy weight children, global self-worth clustered with body image and eating disorder symptoms.

Conclusions: The psychosocial burden of excess weight is significant and broad reaching, with overweight/obese children showing multiple significant psychosocial problems.
Estimation of the distributions of anisotropic, elastic properties and wall stresses of saccular cerebral aneurysms by inverse analysis
Authors: Kroon Martin , Holzapfel Gerhard A
Published: January 2008

A new method is proposed for estimating the elastic properties of the inhomogeneous and anisotropic structure of saccular cerebral aneurysms by inverse analysis. The aneurysm is modelled as a membrane and the constitutive response of each individual layer of the passive tissue is characterized by a transversely isotropic strain energy function of exponential type. The collagen fibres in the aneurysm wall are assumed to govern the mechanical response. Four parameters characterize the constitutive behaviour of the tissue: two initial stiffnesses of the collagen fabric in the two in-plane principal directions, one parameter describing the degree of nonlinearity that the collagen fibres exhibit and the other structural parameter, i.e. the angle which defines the orientation of the collagen fibres. The parameter describing the fibre nonlinearity is assumed to be constant, while all others are assumed to vary continuously over the aneurysm surface. Two model aneurysms, with the same initial geometry, boundary and loading conditions, constitutive behaviour and finite-element discretization, are defined: a ‘reference model’ with known distributions of material and structural properties and an ‘estimation model’ whose properties are to be estimated. An error function is defined quantifying the deviations between the deformations from the reference and the estimation models. The error function is minimized with respect to the unknown parameters in the estimation model, and in this way the reference parameter distributions are re-established. In order to achieve a robust parameter estimation, a novel element partition method is employed. The accordance between the estimated and the reference distributions is satisfactory. The deviations of the maximum stress distributions between the two models are below 1%. Consequently, the wall stresses in the cerebral aneurysm estimated by inverse analysis are accurate enough to facilitate the assessment of the risk of aneurysm rupture.
Recovery from the most profound mass extinction of all time
Authors: Sahney Sarda , Benton Michael J
Published: January 2008

The end-Permian mass extinction, 251 million years (Myr) ago, was the most devastating ecological event of all time, and it was exacerbated by two earlier events at the beginning and end of the Guadalupian, 270 and 260 Myr ago. Ecosystems were destroyed worldwide, communities were restructured and organisms were left struggling to recover. Disaster taxa, such asLystrosaurus, insinuated themselves into almost every corner of the sparsely populated landscape in the earliest Triassic, and a quick taxonomic recovery apparently occurred on a global scale. However, close study of ecosystem evolution shows that true ecological recovery was slower. After the end-Guadalupian event, faunas began rebuilding complex trophic structures and refilling guilds, but were hit again by the end-Permian event. Taxonomic diversity at the alpha (community) level did not recover to pre-extinction levels; it reached only a low plateau after each pulse and continued low into the Late Triassic. Our data showed that though there was an initial rise in cosmopolitanism after the extinction pulses, large drops subsequently occurred and, counter-intuitively, a surprisingly low level of cosmopolitanism was sustained through the Early and Middle Triassic.
Donning your enemy's cloak: ground squirrels exploit rattlesnake scent to reduce predation risk
Authors: Clucas Barbara , Owings Donald H , Rowe Matthew P
Published: January 2008

Ground squirrels (
Spermophilus
spp.) have evolved a battery of defences against the rattlesnakes (
Crotalus
spp.) that have preyed on them for millions of years. The distinctive behavioural reactions by these squirrels to rattlesnakes have recently been shown to include self-application of rattlesnake scent—squirrels apply scent by vigorously licking their fur after chewing on shed rattlesnake skins. Here, we present evidence that this behaviour is a novel antipredator defence founded on exploitation of a foreign scent. We tested three functional hypotheses for snake scent application—antipredator, conspecific deterrence and ectoparasite defence—by examining reactions to rattlesnake scent by rattlesnakes, ground squirrels and ectoparasites (fleas). Rattlesnakes were more attracted to ground squirrel scent than to ground squirrel scent mixed with rattlesnake scent or rattlesnake scent alone. However, ground squirrel behaviour and flea host choice were not affected by rattlesnake scent. Thus, ground squirrels can reduce the risk of rattlesnake predation by applying rattlesnake scent to their bodies, potentially as a form of olfactory camouflage. Opportunistic exploitation of heterospecific scents may be widespread; many species self-apply foreign odours, but few such cases have been demonstrated to serve in antipredator defence.
The correlation of learning speed and natural foraging success in bumble-bees
Authors: Raine Nigel E , Chittka Lars
Published: January 2008

Despite the widespread assumption that the learning abilities of animals are adapted to the particular environments in which they operate, the quantitative effects of learning performance on fitness remain virtually unknown. Here, we evaluate the learning performance of bumble-bees (Bombus terrestris) from multiple colonies in an ecologically relevant associative learning task under laboratory conditions, before testing the foraging performance of the same colonies under the field conditions. We demonstrate that variation in learning speed among bumble-bee colonies is directly correlated with the foraging performance, a robust fitness measure, under natural conditions. Colonies vary in learning speed by a factor of nearly five, with the slowest learning colonies collecting 40% less nectar than the fastest learning colonies. Such a steep fitness function is suggestive of strong selection for higher learning speed. Partial correlation analysis reveals that other factors such as forager body size or colour preference appear to be negligible in our study. Although our study does not directly prove causality of learning on foraging success, our approach of correlating natural within-species variation in these two factors represents a major advance over traditional between-species correlative analyses where comparability can be compromised by the fact that species vary along multiple dimensions.
Genogroup I picobirnaviruses in pigs: evidence for genetic diversity and relatedness to human strains
Authors: Bányai K. , Martella V. , Bogdán Á. , Forgách P. , Jakab F. , Meleg E. , Bíró H. , Melegh B. , Szűcs G.
Published: January 2008

Picobirnaviruses (PBVs) are small, non-enveloped viruses with a bisegmented double-stranded RNA genome. Their pathogenic potential, ecology, and evolutionary features are largely unexplored. Here, we describe the molecular analysis of porcine PBVs identified in the intestinal content of dead pigs. Six of 13 positive samples were cloned and then subjected to single-strand conformation polymorphism analysis and nucleotide sequencing. All clones belonged to genogroup I PBVs and almost all clones clustered on separate branches from human strains. A single strain shared a notably close genetic relationship with a Hungarian human PBV strain (89.9 nt and 96.4 % aa identity). Genetic diversity was also observed among strains identified in mixed infections. Single point mutations and deleterious mutations within highly related strains suggested that PBVs exist as quasispecies in the swine alimentary tract. Clones with complete sequence identities originating from different animals suggested effective animal-to-animal transmission of the virus. Our findings indicate that infection with genogroup I PBVs is common in pigs.
The nsp1α and nsp1β papain-like autoproteinases are essential for porcine reproductive and respiratory syndrome virus RNA synthesis
Authors: Kroese Michiel V. , Zevenhoven-Dobbe Jessika C. , Bos-de Ruijter Judy N. A. , Peeters Ben P. H. , Meulenberg Janneke J. M. , Cornelissen Lisette A. H. M. , Snijder Eric J.
Published: January 2008

The two N-terminal cleavage products, nsp1α and nsp1β, of the replicase polyproteins of porcine reproductive and respiratory syndrome virus (PRRSV) each contain a papain-like autoproteinase domain, which have been named PCPα and PCPβ, respectively. To assess their role in the PRRSV life cycle, substitutions and deletions of the presumed catalytic cysteine and histidine residues of PCPα and PCPβ were introduced into a PRRSV infectious cDNA clone. Mutations that inactivated PCPα activity completely blocked subgenomic mRNA synthesis, but did not affect genome replication. In contrast, mutants in which PCPβ activity was blocked proved to be non-viable and no sign of viral RNA synthesis could be detected, indicating that the correct processing of the nsp1β/nsp2 cleavage site is essential for PRRSV genome replication. In conclusion, the data presented here show that a productive PRRSV life cycle depends on the correct processing of both the nsp1α/nsp1β and nsp1β/nsp2 junctions.
Prevalence and diversity of avian influenza viruses in environmental reservoirs
Authors: Lang Andrew S. , Kelly Anke , Runstadler Jonathan A.
Published: January 2008

Little is known about the ecology and evolution of avian influenza in the natural environment, despite how these affect the potential for transmission. Most work has focused on characterizing viruses isolated from hosts such as waterfowl, and there have also been several instances of isolation and detection from abiotic sources such as water and ice. We used RT-PCR to amplify and characterize the influenza virus sequences present in sediments of ponds that are used heavily by waterfowl. The detection rate of influenza virus was high (>50 %). Characterization of the viruses present by sequencing part of the haemagglutinin (HA) gene showed that there is a diverse collection of viruses in these sediments. We sequenced 117 partial HA gene clones from 11 samples and detected four different HA subtypes (H3, H8, H11 and H12), with approximately 65 % of clone sequences being unique. This culture-independent approach was also able to detect a virus subtype that was not found by sampling of birds in the same geographical region in the same year. Viruses were detected readily in the winter when the ponds were frozen, indicating that these sediments could be a year-to-year reservoir of viruses to infect birds using the ponds, although we have not shown that these viruses are viable. We demonstrate that this approach is a feasible and valuable way to assess the prevalence and diversity of viruses present in the environment, and can be a valuable complement to more difficult viral culturing in attempting to understand the ecology of influenza viruses.
Induction of xylem and fiber differentiation inPopulus tremuloidesThis article is one of a selection of papers published in the Special Issue on Poplar Research in Canada.
Authors: Schuetz Mathias , Haghighi-Kia Afsaneh , Wenzel Carol L. , Mattsson Jim
Published: January 2008

Vascular tissues are of particular importance to terrestrial plants as they allow long-distance transport within the plant and also provide support for upright growth. Nowhere are these traits more obvious than in tree species. Here we have evaluated the role of auxin transport in the differentiation of primary and secondary vascular tissues in a tree species, trembling aspen ( Populus tremuloides Michx). We found that a partial inhibition of auxin transport resulted in increased width and numbers of veins in leaves. A similar vascular overgrowth was observed during early secondary vascular differentiation of stems. This stem overgrowth consisted almost entirely of early differentiation of metaxylem and fibers. We hypothesize that the early differentiation of metaxylem and fibers results from inhibitor-induced accumulation of auxin in stems and that the differentiation of these tissues requires higher levels of auxin exposure than protoxylem. The controlled conditions used in this study also provide a framework for reverse genetics approaches to identify genes involved in vascular differentiation based on elevated expression in tissues developing vascular overgrowth.
In-ovary embryo culture as a tool for poplar hybridization
Authors: Raquin C. , Troussard L. , Villar M.
Published: January 2008

We report here the development of an easy in vitro method for culturing Populus sp. embryos. Half-capsules were cultured in an agar medium with Murashige and Skoog inorganic salts and sucrose. Embryos germinated in the half-capsule and were subcultured in jars before being transferred to the greenhouse. Twenty-one different intra- and inter-specific crosses were successful, with 89% of plantlets successfully acclimatized in greenhouse. Key words: embryo culture, Populus sp., interspecific hybridization.
Mechanical bending stress applied during dormancy and (or) growth stimulates stem diameter growth of Scots pine seedlings
Authors: Valinger Erik , Lundqvist Lars , Sundberg Björn
Published: January 2008

Five-year-old Scots pine (Pinus sylvestris L.) seedlings were given the following treatments: unbent control; bending during dormant period (frozen seedlings); bending during growth period; bending during both dormant and growth periods. Bending was executed manually to 30° from the vertical in four perpendicular directions. This was repeated on 9 occasions for the dormancy and growth treatments and on 18 occasions for the combined dormancy and growth treatment. There was increased xylem and bark production at the point of bending for all treatments. Growth response to bending during growth was of a higher magnitude than the response following bending during dormancy. Moreover, there was a tendency for bending during both dormant and growth phases to increase radial growth of xylem and bark more than the sum of each treatment administered singly. It is concluded that mechanical stress by wind and snow imposed during the dormant winter period could influence stem form.
The effects of ring width, stem position, and stand density on the relationship between foliage biomass and sapwood area in Scots pine (Pinussylvestris)
Authors: Mäkelä Annikki , Virtanen Katri , Nikinmaa Eero
Published: January 2008

The effects of the average ring width of sapwood, bole length, and stand density on the relationship between foliage biomass and sapwood area at four different stem positions were studied in a data set comprising 20 ca. 35-year-old Scots pine (Pinussylvestris L.) trees in southern Finland. The average ring width within sapwood had no effect on the foliagersapwood ratio inside the crown, but a correlation was found when sapwood was measured at breast height or 20% relative height. The distance of the measuring point from the crown base provided a bigger improvement of foliage biomass prediction from sapwood, a finding emphasizing the significance of the taper of sapwood along the bole. After accounting for the sapwood taper, no differences could be detected between thinned and unthinned stands, nor between breast height and 20% relative height.
Vertical leaf area distribution, light transmittance, and application of the Beer–Lambert Law in four mature hardwood stands in the southern Appalachians
Authors: Vose James M. , Clinton Barton D. , Sullivan Neal H. , Bolstad Paul V.
Published: January 2008

We quantified stand leaf area index and vertical leaf area distribution, and developed canopy extinction coefficients (k), in four mature hardwood stands. Leaf area index, calculated from litter fall and specific leaf area (c2•g−1), ranged from 4.3 to 5.4 m2•m−2. In three of the four stands, leaf area was distributed in the upper canopy. In the other stand, leaf area was uniformly distributed throughout the canopy. Variation in vertical leaf area distribution was related to the size and density of upper and lower canopy trees. Light transmittance through the canopies followed the Beer–Lambert Law, and k values ranged from 0.53 to 0.67. Application of these k values to an independent set of five hardwood stands with validation data for light transmittance and litter-fall leaf area index yielded variable results. For example, at k = 0.53, calculated leaf area index was within ± 10% of litter-fall estimates for three of the five sites, but from −35 to + 85% different for two other sites. Averaged across all validation sites, litter-fall leaf area index and Beer-Lambert leaf area index predictions were in much closer agreement ( ± 7 to ± 15%).
SIGMA MESON PRODUCTION IN HEAVY ION COLLISIONS AT INTERMEDIATE ENERGIES
Authors: SRISAWAD PORNRAD , ZHENG YU-MING , FUCHS CHRISTIAN , FAESSLER AMAND , YAN YUPENG , KOBDAJ CHINORAT , XING YONG-ZHONG
Published: January 2008

The production of the sigma (σ) meson is investigated in the quantum molecular dynamics model for the p+A reactions with the nuclei A being 12 C , 40 Ca and 208 Pb at the incident proton energies Ep = 1.50 GeV . The simulation results indicates a distinctive A dependence of the sigma production, that is, the increase of A is followed by an increase of the production cross-sections. The σ meson production in proton induced reactions is strongly medium-dependent, and the produced σ mesons decaying in a denser medium experience a stronger mass shift towards lower masses. This mass shift is an experimentally accessible observable in the final state pion pairs which did not suffer reabsorption by the surrounding nucleons. It is pointed out that the ratio of the simulation results of measurable σ mesons (in the form of two pions) cross-sections as a function of the sigma invariant-mass from various reactions opens the possibility to address experimentally the mass shift of the σ in a dense nuclear environment.
Nerve Growth Factor Is a Potential Therapeutic Target in Breast Cancer
Authors: Adriaenssens Eric , Vanhecke Elsa , Saule Pasquine , Mougel Alexandra , Page Adeline , Romon Rodrigue , Nurcombe Victor , Le Bourhis Xuefen , Hondermarck Hubert
Published: January 2008

We show here that nerve growth factor (NGF), the prototypic neurotrophin, can be targeted in breast cancer to inhibit tumor cell proliferation, survival, and metastasis. Analysis of a series of biopsies revealed widespread expression of NGF in the majority of human breast tumors, with anti-NGF immunoreactivity concentrated in the epithelial cancer cells. Moreover, immunodeficient mice xenografted with human breast cancer cells and treated with either anti-NGF antibodies or small interfering RNA against NGF displayed inhibited tumor growth and metastasis. Such treatments directed against NGF induced a decrease in cell proliferation with a concomitant increase in apoptosis of breast cancer cells and an inhibition of tumor angiogenesis. Together, these data indicate that targeting NGF in breast cancer may have therapeutic ramifications. [Cancer Res 2008;68(2):346–51]
Hyaluronic Acid Synthase-1 Expression Regulates Bladder Cancer Growth, Invasion, and Angiogenesis through CD44
Authors: Golshani Roozbeh , Lopez Luis , Estrella Veronica , Kramer Mario , Iida Naoko , Lokeshwar Vinata B.
Published: January 2008

Hyaluronic acid (HA) promotes tumor metastasis and is an accurate diagnostic marker for bladder cancer. HA is synthesized by HA synthases HAS1, HAS2, or HAS3. We have previously shown that HAS1 expression in tumor tissues is a predictor of bladder cancer recurrence and treatment failure. In this study, we stably transfected HT1376 bladder cancer cells with HAS1-sense (HAS1-S), HAS1-antisense (HAS1-AS), or vector cDNA constructs. Whereas HAS1-S transfectants produced ∼1.7-fold more HA than vector transfectants, HA production was reduced by ∼70% in HAS1-AS transfectants. HAS1-AS transfectants grew 5-fold slower and were ∼60% less invasive than vector and HAS1-S transfectants. HAS1-AS transfectants were blocked in G2-M phase of the cell cycle due to down-regulation of cyclin B1, cdc25c, and cyclin-dependent kinase 1 levels. These transfectants were also 5- to 10-fold more apoptotic due to the activation of the Fas-Fas ligand–mediated extrinsic pathway. HAS1-AS transfectants showed a ∼4-fold decrease in ErbB2 phosphorylation and down-regulation of CD44 variant isoforms (CD44-v3, CD44-v6, and CD44-E) both at the protein and mRNA levels. However, no decrease in RHAMM levels was observed. The decrease in CD44-v mRNA levels was not due to increased mRNA degradation. Whereas CD44 small interfering RNA (siRNA) transfection decreased cell growth and induced apoptosis in HT1376 cells, HA addition modestly increased CD44 expression and cell growth in HAS1-AS transfectants, which could be blocked by CD44 siRNA. In xenograft studies, HAS1-AS tumors grew 3- to 5-fold slower and had ∼4-fold lower microvessel density. These results show that HAS1 regulates bladder cancer growth and progression by modulating HA synthesis and HA receptor levels. [Cancer Res 2008;68(2):483–91]
Activating Transcription Factor 3 Is a Novel Repressor of the Nuclear Factor Erythroid-Derived 2–Related Factor 2 (Nrf2)–Regulated Stress Pathway
Authors: Brown Stephan L. , Sekhar Konjeti R. , Rachakonda Girish , Sasi Soumya , Freeman Michael L.
Published: January 2008

The transcription factor nuclear factor erythroid-derived 2–related factor 2 (Nrf2) regulates induction of an extensive cellular stress response network when complexed with the cAMP-responsive element binding protein (CBP) at antioxidant response elements (ARE) located in the promoter region of target genes. Activating transcription factor 3 (ATF3) can repress Nrf2-mediated signaling in a manner that is not well understood. Here, we show that ATF3-mediated suppression is a consequence of direct ATF3-Nrf2 protein-protein interactions that result in displacement of CBP from the ARE. This work establishes ATF3 as a novel repressor of the Nrf2-directed stress response pathway. [Cancer Res 2008;68(2):364–8]
Cyclooxygenase-2–Derived Prostaglandin E2 Activates β-Catenin in Human Cholangiocarcinoma Cells: Evidence for Inhibition of These Signaling Pathways by ω3 Polyunsaturated Fatty Acids
Authors: Lim Kyu , Han Chang , Xu Lihong , Isse Kumiko , Demetris Anthony J. , Wu Tong
Published: January 2008

Cholangiocarcinoma is a highly malignant neoplasm of the biliary tree. It has a high rate of mortality, and currently, there is no effective chemoprevention and treatment. This study was designed to investigate the potential effect of ω3 polyunsaturated fatty acids (ω3-PUFA) on human cholangiocarcinoma cell growth and to determine their mechanisms of actions. Treatment of three human cholangiocarcinoma cells (CCLP1, HuCCT1, SG231) with two ω3-PUFAs, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), for 12 to 72 h resulted in a dose- and time-dependent inhibition of cell growth; in contrast, arachidonic acid, a ω6-PUFA, had no significant effect. The ω3-PUFA effect is due to the induction of apoptosis, given that DHA induced the cleaved form of PARP, caspase-3, and caspase-9. DHA and EPA treatment caused dephosphorylation (and hence, the activation) of glycogen synthase kinase-3β (GSK-3β) with a decline of β-catenin protein. Accordingly, DHA treatment also decreased the β-catenin–mediated T cell factor/lymphoid enhancer factor (TCF/LEF) reporter activity, and inhibited the expression of c-Met, a β-catenin–controlled downstream gene implicated in cholangiocarcinogenesis. The GSK-3β inhibitor, SB216763, partially prevented DHA-induced reduction of β-catenin protein and TCF/LEF reporter activity, and restored cell growth, suggesting the involvement of GSK-3β dephosphorylation in ω3-PUFA–induced β-catenin degradation. In parallel, DHA treatment also induced the formation of the β-catenin/Axin/GSK-3β binding complex, further leading to β-catenin degradation. Moreover, DHA inhibited the expression of cyclooxygenase-2 (COX-2) and enhanced the expression of 15-hydroxyprostaglandin dehydrogenase, a physiologic COX-2 antagonist, in human cholangiocarcinoma cells. These findings suggest that ω3-PUFAs block cholangiocarcinoma cell growth at least in part through inhibition of Wnt/β-catenin and COX-2 signaling pathways. Thus, utilization of ω3-PUFAs may represent an effective and safe therapeutic approach for the chemoprevention and treatment of human cholangiocarcinoma. [Cancer Res 2008;68(2):553–60]
Impact of Common Epidermal Growth Factor Receptor and HER2 Variants on Receptor Activity and Inhibition by Lapatinib
Authors: Gilmer Tona M. , Cable Louann , Alligood Krystal , Rusnak David , Spehar Glenn , Gallagher Kathleen T. , Woldu Ermias , Carter H. Luke , Truesdale Anne T. , Shewchuk Lisa , Wood Edgar R.
Published: January 2008

The goal of this study was to characterize the effects of non–small cell lung carcinoma (NSCLC)-associated mutations in epidermal growth factor receptor (EGFR/ErbB1) and HER2 (ErbB2) on interactions with the dual tyrosine kinase inhibitor lapatinib. Biochemical studies show that commonly observed variants of EGFR [G719C, G719S, L858R, L861Q, and Δ746–750 (del15)] are enzyme activating, increasing the tyrosine kinase Vmax and increasing the Km(app) for ATP. The point mutations G719C and L861Q had minor effects on lapatinib Kis, whereas EGFR mutations L858R and del15 had a higher Ki for lapatinib than wild-type EGFR. Structural analysis of wild-type EGFR-lapatinib complexes and modeling of the EGFR mutants were consistent with these data, suggesting that loss of structural flexibility and possible stabilization of the active-like conformation could interfere with lapatinib binding, particularly to the EGFR deletion mutants. Furthermore, EGFR deletion mutants were relatively resistant to lapatinib-mediated inhibition of receptor autophosphorylation in recombinant cells expressing the variants, whereas EGFR point mutations had a modest or no effect. Of note, EGFR T790M, a receptor variant found in patients with gefitinib-resistant NSCLC, was also resistant to lapatinib-mediated inhibition of receptor autophosphorylation. Two HER2 insertional variants found in NSCLC were less sensitive to lapatinib inhibition than two HER2 point mutants. The effects of lapatinib on the proliferation of human NSCLC tumor cell lines expressing wild-type or variant EGFR and HER2 cannot be explained solely on the basis of the biochemical activity or receptor autophosphorylation in recombinant cells. These data suggest that cell line genetic heterogeneity and/or multiple determinants modulate the role played by EGFR/HER2 in regulating cell proliferation. [Cancer Res 2008;68(2):571–9]
Mammalian Target of Rapamycin Is the Key Effector of Phosphatidylinositol-3-OH–Initiated Proliferative Signals in the Thyroid Follicular Epithelium
Authors: Yeager Nicole , Brewer Charlene , Cai Kathy Qi , Xu Xiang-Xi , Di Cristofano Antonio
Published: January 2008

Activation of the phosphatidylinositol-3-OH kinase (PI3K) signaling cascade is becoming increasingly recognized as a common feature of thyroid follicular neoplasms. We have recently shown that conditional loss of Pten in the mouse thyroid follicular cells is sufficient to stimulate continuous autonomous growth, leading to a homogeneously hyperplastic gland and to the development of follicular adenomas. Because the PI3K/AKT cascade can activate a plethora of different signaling pathways, it is still unclear which of these may represent the key mitogenic output of PI3K-initiated signaling. Here, we show that the in vivo proliferative response to chronic PI3K activation profoundly relies on the activation of the mammalian target of rapamycin (mTOR)/S6K1 axis, and that mTOR inhibition in Pten mutant mice and cells restores virtually normal proliferation rates, despite the presence of still elevated Akt activity, at least in part by down-regulating cyclins D1 and D3, and without affecting cell survival. [Cancer Res 2008;68(2):444–9]
Indirect Macrophage Responses to Ionizing Radiation: Implications for Genotype-Dependent Bystander Signaling
Authors: Coates Philip J. , Rundle Jana K. , Lorimore Sally A. , Wright Eric G.
Published: January 2008

In addition to the directly mutagenic effects of energy deposition in DNA, ionizing radiation is associated with a variety of untargeted and delayed effects that result in ongoing bone marrow damage. Delayed effects are genotype dependent with CBA/Ca mice, but not C57BL/6 mice, susceptible to the induction of damage and also radiation-induced acute myeloid leukemia. Because macrophages are a potential source of ongoing damaging signals, we have determined their gene expression profiles and we show that bone marrow–derived macrophages show widely different intrinsic expression patterns. The profiles classify macrophages derived from CBA/Ca mice as M1-like (pro-inflammatory) and those from C57BL/6 mice as M2-like (anti-inflammatory); measurements of NOS2 and arginase activity in normal bone marrow macrophages confirm these findings. After irradiation in vivo, but not in vitro, C57BL/6 macrophages show a reduction in NOS2 and an increase in arginase activities, indicating a further M2 response, whereas CBA/Ca macrophages retain an M1 phenotype. Activation of specific signal transducer and activator of transcription signaling pathways in irradiated hemopoietic tissues supports these observations. The data indicate that macrophage activation is not a direct effect of radiation but a tissue response, secondary to the initial radiation exposure, and have important implications for understanding genotype-dependent responses and the mechanisms of the hemotoxic and leukemogenic consequences of radiation exposure. [Cancer Res 2008;68(2):450–6]
Vascular Endothelial Growth Factor–Mediated Decrease in Plasma Soluble Vascular Endothelial Growth Factor Receptor-2 Levels as a Surrogate Biomarker for Tumor Growth
Authors: Ebos John M.L. , Lee Christina R. , Bogdanovic Elena , Alami Jennifer , Van Slyke Paul , Francia Giulio , Xu Ping , Mutsaers Anthony J. , Dumont Daniel J. , Kerbel Robert S.
Published: January 2008

Vascular endothelial growth factor (VEGF) is a potent proangiogenic protein that activates VEGF receptor (VEGFR) tyrosine kinases expressed by vascular endothelial cells. We previously showed that one of these receptors, VEGFR-2, has a truncated soluble form (sVEGFR-2) that can be detected in mouse and human plasma. Because activation of VEGFR-2 plays an important role in tumor angiogenesis, clinical interest in monitoring plasma sVEGFR-2 levels in cancer patients has focused on its potential exploitation as a surrogate biomarker for disease progression as well as assessing efficacy/activity of antiangiogenic drugs, particularly those that target VEGF or VEGFR-2. However, no preclinical studies have been done to study sVEGFR-2 during tumor growth or the mechanisms involved in its modulation. Using spontaneously growing tumors and both localized and metastatic human tumor xenografts, we evaluated the relationship between sVEGFR-2 and tumor burden as well as underlying factors governing protein level modulation in vivo. Our results show an inverse relationship between the levels of sVEGFR-2 and tumor size. Furthermore, using various methods of VEGF overexpression in vivo, including cell transfection and adenoviral delivery, we found plasma sVEGFR-2 decreases to be mediated largely by tumor-derived VEGF. Finally, in vitro studies indicate VEGF-mediated sVEGFR-2 modulation is the result of ligand-induced down-regulation of the VEGFR-2 from the cell surface. Taken together, these findings may be pertinent to further clinical exploitation of plasma sVEGFR-2 levels as a surrogate biomarker of VEGF-dependent tumor growth as well as an activity indicator of antiangiogenic drugs that target the VEGFR system. [Cancer Res 2008;68(2):521–9]