bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological parameters of the leaf‐litter frog community of an Atlantic Rainforest area at Ilha Grande, Rio de Janeiro state, Brazil
Authors: Van SLUYS M. , VRCIBRADIC D. , ALVES M. A. S. , BERGALLO H. G. , ROCHA C. F. D.
Published: March 2007

Abstract  The Atlantic Rainforest originally covered much of the Brazilian coast and is now reduced to approximately only 7% of its original area. Data on abundance distribution and microhabitat characteristics of anuran amphibians living on the forest floor leaf litter in the Atlantic Rainforest are scarce. In this study, we analysed the effect of litter depth and structure on the abundance and species richness of leaf‐litter frogs in an area of Atlantic Rainforest at Ilha Grande, Rio de Janeiro State, south‐eastern Brazil. We performed monthly samples (nocturnal and diurnal) from August 1996 to October 1997 using small (2 m × 1 m) plots. We sampled 234 plots, totalling 468 m2 of forest leaf litter. We estimated leaf‐litter depth and the proportion of leaves in the plot and tested their effect on the total abundance of frogs and species richness using multiple regression analysis. We found 185 frogs from eight species: Brachycephalus (=Psyllophryne) didactylus (Izecksohn, 1971) (Brachycephalidae), Dendrophryniscus brevipollicatus Jiménez de la Espada 1871 (Bufonidae), Adenomera marmorata Steindachner 1867, Eleutherodactylus parvus (Girard 1853), Eleutherodactylus guentheri (Steindachner 1864), Eleutherodactylus binotatus (Spix 1824) and Zachaenus parvulus (Girard 1853) (Leptodactylidae), and Chiasmocleis sp. (Microhylidae). Brachycephalus didactylus was the most abundant species, with 91 individuals, whereas Dendrophryniscus brevipollicatus was the rarest, with two individuals. Mean litter depth and the proportion of leaves in the leaf litter were significantly related to frog abundance (R2 = 0.17; F2,107 = 10.779; P = 0.0001) and species richness (R2 = 0.11; F2,107 = 6.375; P =  0.002) indicating that microhabitat characteristics may affect local distribution and abundance of frogs in the forest floor.
Impacts of clearing, fragmentation and disturbance on the bird fauna of Eucalypt savanna woodlands in central Queensland, Australia
Authors: HANNAH D. , WOINARSKI J. C. Z. , CATTERALL C. P. , MCCOSKER J. C. , THURGATE N. Y. , FENSHAM R. J.
Published: March 2007

Abstract  This study reports on the responses of bird assemblages to woodland clearance, fragmentation and habitat disturbance in central Queensland Australia, a region exposed to very high rates of vegetation clearance over the last two to three decades. Many previous studies of clearing impacts have considered situations where there is a very sharp management contrast between uncleared lands and cleared areas: in this situation, the contrast is more muted, because both cleared lands and uncleared savanna woodlands are exposed to cattle grazing, invasion by the exotic grass Cenchrus ciliaris and similar fire management. Bird species richness (at the scale of a 1‐ha quadrat) was least in cleared areas (8.1 species), then regrowth areas (14.6 species), then uncleared woodlands (19.9 species). Richness at this scale was unrelated to woodland fragment size, connectivity or habitat condition; but declined significantly with increasing abundance of miners (interspecifically aggressive colonial honeyeaters). At whole of patch scale, richness increased with fragment size and decreased with abundance of miners. This study demonstrates complex responses of individual bird species to a regional management cocktail of disturbance elements. Of 71 individual bird species modelled for woodland fragment sites, the quadrat‐level abundance of 40 species was significantly related to at least one variable representing environmental position (across a rainfall gradient), fragment condition, fragment size and/or connectivity. This study suggests that priorities for conservation management include: cessation of broad‐scale clearing; increased protection for regrowth (particularly where this may bolster connectivity and/or size of woodland fragments); control of miners; maintenance of fallen woody debris in woodlands; increase in fire frequency; and reduction in the incidence of grazing and exotic pasture grass.
Controlling infestations of Parkinsonia aculeata in a riparian zone at the landscape scale
Authors: LAWES ROGER A. , GRICE ANTHONY C.
Published: March 2007

Abstract  To prioritize weed management activities it is necessary to predict the extent of future infestations of individual weed species. Management effort should focus on populations which are likely to spread and produce new satellite populations. Deciding which aspects of an invading population to manage, new emerging distant satellites or the existing core from which most seed originates has been the subject of much debate. We use extensive survey data to define the core and satellite populations and dispersal function of Parkinsonia aculeata in the semi‐arid rangelands of the Northern Territory of Australia. We described populations in terms of three size classes, classified on the basis of plant height (small (<0.4 m), medium (>0.4 and <2.5 m) and large (>2.5 m)). Data were recorded as a spatial point pattern and a dispersal function was derived from the distribution of the distance of each medium plant to the nearest P. aculeata neighbour that was greater than 2.5 m. All large and medium P. aculeata were classified as members of core or satellite populations. From these classifications, we tested critical assumptions of Moody and Mack's model, namely (i) the satellites form multiple disjunct foci that do not overlap; (ii) the system is homogenous and there are no abiotic or biotic restrictions to the weeds expansion enabling it to expand radially in any direction; (iii) the densities of all foci are uniform; (iv) there is no extinction through stochastic processes; and (v) there are no threshold effects. When the medium size class was considered, the population density and area occupied by the weed increased. Two satellite populations were comprised solely of medium plants, suggesting the number of satellites increased marginally from eight to 10 when data from both size classes were considered. Most individuals were part of the core population. The core population increased in density and we argue this core population is most likely to give rise to new satellites and should be managed in preference to emerging satellite populations. We suggest the invasion is behaving like a source‐sink system, where the core population is the source of most new medium plants.
Habitat selection of feral cats (Felis catus) on a temperate, forested island
Authors: HARPER GRANT A.
Published: March 2007

Abstract  Habitat selection of mammalian predators is known to be influenced by availability and distribution of prey. The habitat selection of feral cats on Stewart Island, southern New Zealand, was investigated using telemetry of radio‐tagged cats. Compositional analysis of the habitat selection of radio‐tagged cats showed they were using the available habitats non‐randomly. Feral cats avoided subalpine shrubland and preferentially selected podocarp‐broadleaf forest. The avoidance of subalpine shrubland by cats was probably due to a combination of the presence of a large aggressive prey species, Norway rats Rattus norvegicus, and the lack of rain‐impervious shelter there. Most cats also used subalpine shrubland more often in dry weather than in wet weather. Cats did not preferentially select all the other habitats with only smaller rat species, Rattus rattus and Rattus exulans, present however. Cats were probably further influenced by the availability of large trees, in podocarp‐broadleaf forest, that can provide shelter. Cats were also more active in dry rather than wet weather which supports this conclusion. Home ranges of feral cats on Stewart Island were some of the largest recorded, probably because of limited primary and alternative prey.
Landscape ecology of the burrowing bettong: Warren distribution and patch dynamics in semiarid eastern Australia
Authors: NOBLE JAMES C. , MÜLLER WARREN J. , DETLING JAMES K. , PFITZNER GILBERT H.
Published: March 2007

Abstract  In arid and semiarid Australia fossorial vertebrates have been a major component of the soil biota mediating many fundamental landscape processes. However, many species such as the burrowing bettong (Bettongia lesueur) have become seriously depleted following European pastoral settlement. As ‘landscape engineers’, they were responsible for creating and maintaining a high degree of surface heterogeneity that promoted a diverse and productive herbaceous understorey, particularly in ‘hard‐red’ communities dominated by mulga (Acacia aneura). While their regional extinction has had major impacts by contributing to desertification and loss of biodiversity, relict warrens ‘engineered’ by B. lesueur still remain in certain ecosystems and despite continual weathering, contribute significantly to herbage productivity and species diversity. This paper details the results obtained from a number of field studies aimed at determining the distribution of relict warrens at contrasting scales and their influence on landscape patch dynamics resulting from their impacts on soil nutrients, herbage composition and herbivory. Finally, the conservation implications following the continental extinction of this species and the resulting loss of fundamental ecosystem services, as well as cultural values, are discussed in the context of future re‐introduction efforts.
Functional and performance comparisons of invasive Hieracium lepidulum and co‐occurring species in New Zealand
Authors: RADFORD IAN J. , DICKINSON KATHARINE J. M. , LORD JANICE M.
Published: March 2007

Abstract  One of the key environmental factors affecting plant species abundance, including that of invasive exotics, is nutrient resource availability. Plant functional response to nutrient availability, and what this tells us about plant interactions with associated species, may therefore give us clues about underlying processes related to plant abundance and invasion. Patterns of abundance of Hieracium lepidulum, a European herbaceous invader of subalpine New Zealand, appear to be related to soil fertility/nutrient availability, however, abundance may be influenced by other factors including disturbance. In this study we compare H. lepidulum and field co‐occurring species for growth performance across artificial nutrient concentration gradients, for relative competitiveness and for response to disturbance, to construct a functional profile of the species. Hieracium lepidulum was found to be significantly different in its functional response to nutrient concentration gradients. Hieracium lepidulum had high relative growth rate, high yield and root plasticity in response to nutrient concentration dilution, relatively low absolute yield, low competitive yield and a positive response to clipping disturbance relative to other species. Based on overall functional response to nutrient concentration gradients, compared with other species found at the same field sites, we hypothesize that H. lepidulum invasion is not related to competitive domination. Relatively low tolerance of nutrient dilution leads us to predict that H. lepidulum is likely to be restricted from invading low fertility sites, including sites within alpine vegetation or where intact high biomass plant communities are found. Positive response to clipping disturbance and relatively high nutrient requirement, despite poor competitive performance, leads us to predict that H. lepidulum may respond to selective grazing disturbance of associated vegetation. These results are discussed in relation to published observations of H. lepidulum in New Zealand and possible tests for the hypotheses raised here.
Development of a model for evaluating the effects of environmental temperature and thermal behaviour on biological control of locusts and grasshoppers using pathogens
Authors: Klass Justine I. , Blanford Simon , Thomas Matthew B.
Published: March 2007

1 Recent years have seen an upsurge in locust and grasshopper populations in many parts of the world. Environmentally sustainable approaches to locust and grasshopper control may be possible through the use of biopesticides based on entomopathogenic fungi. Unfortunately, the performance of these biopesticides is highly variable with environmental temperature and host thermoregulatory behaviour critically determining the pattern and extent of mortality after applications. Here, we present a temperature‐dependent model that enables us to predict the field performance of Metarhizium anisopliae var. acridum, the key fungal pathogen used in locust biopesticides.

2 The model was constructed using mortality rate data generated across a range of temperatures in the laboratory and is driven by environmental temperature data linked through host body temperature models.

3 Model predictions were validated against empirical field data obtained for five species, Locustana pardalina, Oedaleus senegalensis, Zonocerus variegatus, Nomadacris septemfasciata and Chortoicetes terminifera. Mortality predictions were accurate to a 2‐day error in every 10 days. This level of resolution is satisfactory to guide operational use of the biopesticide.

4 The model was subsequently used for a prospective evaluation of the performance of M. anisopliae var. acridum against two additional pest species, Dociostaurus maroccanus and Calliptamus italicus in Spain. Results suggest that this pathogen would work reasonably well against these species as long as early instars are targeted.

5 The model could provide a useful tool to assist in interpreting effectiveness of control operations, develop improved application strategies to optimize the performance of the biopesticide and identify appropriate target species and environments.
Diversity of root‐associated fluorescent pseudomonads as affected by ferritin overexpression in tobacco
Authors: Robin Agnès , Mazurier Sylvie , Mougel Christophe , Vansuyt Gérard , Corberand Thérèse , Meyer Jean‐Marie , Lemanceau Philippe
Published: March 2007

A transgenic tobacco overexpressing ferritin (P6) was recently shown to accumulate more iron than the wild type (WT), leading to a reduced availability of iron in the rhizosphere and shifts in the pseudomonad community. The impact of the transgenic line on the community of fluorescent pseudomonads was assessed. The diversity of 635 isolates from rhizosphere soils, rhizoplane + root tissues, and root tissues of WT and P6, and that of 98 isolates from uncultivated soil was characterized. Their ability to grow under iron stress conditions was assessed by identifying their minimal inhibitory concentrations of 8‐hydroxyquinoline for each isolate, pyoverdine diversity by isoelectrofocusing and genotypic diversity by random amplified polymorphism DNA. The antagonistic activity of representative isolates and of some purified pyoverdines against a plant pathogen (Pythium aphanidermatum Op4) was tested in vitro. In overall, isolates taken from P6 tobacco showed a greater ability to grow in iron stress conditions than WT isolates. The antagonism by some of the representative isolates was only expressed under iron stress conditions promoting siderophore synthesis and their pyoverdines appeared to have a specific structure as assessed by mass spectrometry. For other isolates, antagonism was still expressed in the presence of iron, suggesting the involvement of metabolites other than siderophores. Altogether, these data indicate that the transgenic tobacco that over‐accumulates iron selected fluorescent pseudomonads, less susceptible to iron depletion and more antagonistic to the tested plant pathogen than those selected by the tobacco WT.
Protein kinase A‐dependent recruitment of RNA polymerase II, C/EBPβ and NF‐Y to the rat GTP cyclohydrolase I proximal promoter occurs without alterations in histone acetylation
Authors: Kapatos Gregory , Vunnava Prashanthi , Wu Yanning
Published: March 2007

Cyclic‐AMP stimulation of GTP cyclohydrolase I (GCH1) gene transcription was investigated in PC12 cells, the protein kinase A‐deficient PC12 cell line 126‐1B2 and C6 cells using transient transfection assays of proximal promoter reporter constructs and wild type or dominant negative proteins, chromatin immunoprecipitation and real‐time quantitative PCR. These studies show that protein kinase A is necessary and sufficient for cAMP‐dependent transcription conferred by both the cAMP regulatory element and the adjacent CCAAT‐box. In intact cells these cis‐elements were shown to bind cAMP response element binding protein, CCAAT‐enhancer binding protein beta and nuclear factor‐Y, with each protein controlling a different aspect of the cAMP response. Cyclic‐AMP acting through protein kinase A stimulated promoter recruitment of CCAAT‐enhancer binding protein beta, nuclear factor‐Y and RNA polymerase II while depleting the promoter of cyclic‐AMP response element binding protein. Stimulation of transcription by cAMP was not associated with increased acetylation of histones H3 and H4 at proximal promoter nucleosomes, indicating that histone acetyltransferases are not involved in this response. Nonetheless, pharmacological inhibition of histone deacetylase activity did increase histone H4 acetylation and the recruitment of RNA polymerase II, indicating that histone acetyltransferases are normally associated with the proximal promoter. Only in C6 cells, however, did inhibition of histone deacetylases stimulate transcription and synergize with cAMP. These experiments provide the first glimpse of the GCH1 gene promoter functioning within intact cells and supply evidence for the involvement of histone acetyltransferase‐containing complexes in GCH1 gene transcription.
Donepezil induces a cholinergic sprouting in basocortical degeneration
Authors: Ginestet Laure , Ferrario Juan E. , Raisman‐Vozari Rita , Hirsch Etienne C. , Debeir Thomas
Published: March 2007

One of the few currently approved therapies for Alzheimer’s disease (AD) consists in the administration of acetylcholinesterase inhibitors, which enhances the lifetime of the neurotransmitter acetylcholine. Despite numerous studies on the symptomatic effect of acetylcholinesterase inhibitors, there is as yet no direct morphological evidence to indicate that they have a neurorestorative action. We investigated the effect of the acetylcholinesterase inhibitor donepezil administered subcutaneously in a rat model of partial unilateral cortical devascularization that induces a loss of the cortical cholinergic terminal network and a retrograde degeneration of the cholinergic projections that originate in the nucleus basalis. For 6 weeks, lesioned and sham‐operated rats received a subcutaneous infusion of donepezil (2 mg/kg/day) or vehicle, delivered by osmotic minipumps implanted 2 weeks before the cortical devascularization. In lesioned rats, donepezil treatment increased the number and the size of vesicular acetylcholine transporter immunoreactive boutons in comparison to vehicle treatment. Donepezil had no observable effect on any of these parameters in sham‐operated animals. These results show that donepezil mitigates cholinergic neuronal degeneration in vivo. This suggests a neuroplastic activity of this drug and provides evidence for a potential use of donepezil as a disease modifier in neurodegenerative diseases such as AD.
Cdk5–p39 is a labile complex with the similar substrate specificity to Cdk5–p35
Authors: Yamada Mari , Saito Taro , Sato Yutaka , Kawai Yusei , Sekigawa Akio , Hamazumi Yuko , Asada Akiko , Wada Mitsuhito , Doi Hirofumi , Hisanaga Shin‐ichi
Published: March 2007

Cyclin‐dependent kinase 5 (Cdk5) is a proline‐directed Ser/Thr kinase that plays important roles in various neuronal activities, including neuronal migration, synaptic activity, and neuronal cell death. Cdk5 is activated by association with a neuron‐specific activator, p35 or its isoform p39, but little is known about the kinase activity of Cdk5–p39. In fact, kinase‐active Cdk5–p39 was not prepared from rat brain extracts nor from HEK293 cells expressing Cdk5 and p39 by immunoprecipitation in the presence of non‐ionic detergent, under conditions with which active Cdk5–p35 could be isolated. p39 dissociated from Cdk5 in the presence of detergent, indicating that p39 has a lower binding affinity for Cdk5 than p35. We developed a method for purifying kinase‐active Cdk5–p39 from Sf9 cells infected with baculovirus encoding Cdk5 and p39. The purified Cdk5–p39 complex showed similar substrate specificity to that of Cdk5–p35, but with opposite sensitivity to detergent. Cdk5–p39 was inactivated by Triton X‐100, whereas Cdk5–p35 was activated. The N‐terminal deletion from p35 and p39, the amino acid sequences of which are different, did not change the stability or substrate specificity of either Cdk5 complex. The different stability between Cdk5–p35 and Cdk5–p39 suggests their distinct roles under different regulation mechanisms in neurons.
Glutamate‐dependent transcriptional regulation of GLAST/EAAT1: a role for YY1
Authors: Rosas Sandra , Vargas Miguel A. , López‐Bayghen Esther , Ortega Arturo
Published: March 2007

Glutamate is the major excitatory transmitter in the vertebrate brain and its extracellular levels are tightly regulated to prevent excitotoxic effects. The Na+‐dependent glutamate/aspartate transporter GLAST/EAAT1 is regulated in the short and in the long term by glutamate. A receptors‐independent change in its membrane translocation rate, accounts for an acute modulation in GLAST/EAAT1 transport. In contrast, activation of the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate subtype of glutamate receptors represses the transcription of the chick glast gene. A glutamate responsive element has been mapped to the promoter region of this gene containing a bonafide binding site for the transcription factor Ying‐Yang 1. Using cultured chick cerebellar Bergmann glia cells, glutamate elicited a time and dose‐dependent increase in Ying‐Yang 1 DNA binding consistent with the negative response generated in a reporter gene construct controlled for Ying‐Yang 1. Over‐expression of this transcription factor leads to a substantial reduction in GLAST/EAAT1 transporter uptake and an important decrease in mRNA levels, all associated with the transcriptional repression of the chick glast promoter activity. These results provide evidence for an involvement of Ying‐Yang 1 in the transcriptional response to glutamate in glial cells and favor the notion of a relevant role of this factor in GLAST/EAAT1 transcriptional control.
Membrane topology of the Drosophila vesicular glutamate transporter
Authors: Fei Hao , Karnezis Tara , Reimer Richard J. , Krantz David E.
Published: March 2007

The vesicular glutamate transporters (VGLUTs) are responsible for packaging glutamate into synaptic vesicles, and are part of a family of structurally related proteins that mediate organic anion transport. Standard computer‐based predictions of transmembrane domains have led to divergent topological models, indicating the need for experimentally derived predictions. Here we present data on the topology of the VGLUT ortholog from Drosophila melanogaster (DVGLUT). Using immunofluorescence assays of DVGLUT transiently localized to the plasma membrane of heterologously transfected cells, we have determined the accessibility of epitope tags inserted into the lumenal/extracellular face of the protein. Using immunoisolation, we have identified complementary tagged sites that face the cytoplasm. Our data show that DVGLUT contains 10 hydrophobic regions that completely span the membrane (TMs 1–10) and that the amino and carboxyl termini are cytosolic. Importantly, between TMs 4 and 5 is an unforeseen cytosolic loop of some 50 residues. Other domains exposed to the cytosol include loops between TMs 6–7 and 8–9, and regions C‐terminal to TM2 and N‐terminal to TM3. Between TM2 and 3 is a potentially hydrophobic, but topologically ambiguous region. Lumenal domains include sequences between TMs 1–2, 3–4, 5–6, 7–8 and 9–10. These data provide a basis for determining structure‐function relationships for DVGLUT and other related proteins.
Mutations in LRRK2/dardarin associated with Parkinson disease are more toxic than equivalent mutations in the homologous kinase LRRK1
Authors: Greggio Elisa , Lewis Patrick A. , Van Der Brug Marcel P. , Ahmad Rili , Kaganovich Alice , Ding Jinhui , Beilina Alexandra , Baker Acacia K. , Cookson Mark R.
Published: March 2007

Several mutations have been found in the leucine‐rich repeat kinase 2 gene (LRRK2), encoding the protein dardarin, which are associated with autosomal dominant Parkinson disease. We have previously shown that mutant LRRK2/dardarin is toxic to neurons and neuron‐like cell lines in culture and that some mutations are also associated with an inclusion‐body phenotype. There is a homologous kinase, LRRK1, which has a similar domain structure but is not known to carry mutations causing Parkinson disease. In the current study, we introduced mutations at equivalent residues in both LRRK2 and LRRK1 to determine their effects in cells. We show that mutations in dardarin are more prone to form inclusion bodies in transfected cells and are more toxic than equivalent mutations in LRRK1. This work suggests that dardarin/LRRK2 is inherently more damaging than LRRK1.
Mammalian‐produced chondroitinase AC mitigates axon inhibition by chondroitin sulfate proteoglycans
Authors: Curinga Gabrielle M. , Snow Diane M. , Mashburn Charles , Kohler Katharina , Thobaben Rebecca , Caggiano Anthony O. , Smith George M.
Published: March 2007

Chondroitin sulfate proteoglycans (CSPGs) are up‐regulated following spinal cord injury and are partly responsible for failed regeneration. Experimental paradigms in vivo that degrade chondroitin sulfate glycosaminoglycan chains with the bacterial enzyme, chondroitinase, greatly enhance the ability of axons to regenerate through the glial scar. Unfortunately, enthusiasm for this treatment paradigm is diminished by the lack of a minimally invasive and sustained delivery method. To address these deficits, we have engineered a Tet‐On adenoviral vector encoding chondroitinase AC and have characterized its enzymatic function in vitro. U373 human astrocytoma cells were transduced with adenovirus and subsequently induced with doxycycline to secrete enzymatically active chondroitinase as detected by western blot and kinetic analyses. Enzymatic activity demonstrated biological relevance in studies where neurite outgrowth into and across CSPG‐adsorbed regions pre‐treated with conditioned media from chondroitinase secreting astrocytes was significantly increased compared with untreated controls (p < 0.0001). We also measured important parameters of enzyme activity including: pH, temperature, and enzyme stability that are fundamental to harnessing the true therapeutic potential of this approach. The use of resident cells for continuous secretion of CSPG‐degrading enzymes at the site of the glial scar promises to be of greater clinical relevance than contemporary methods.
Wild‐type superoxide dismutase acquires binding and toxic properties of ALS‐linked mutant forms through oxidation
Authors: Ezzi Samer Abou , Urushitani Makoto , Julien Jean‐Pierre
Published: March 2007

Recent studies suggest that superoxide dismutase (SOD1) may represent a major target of oxidative damage in neurodegenerative diseases. To test the possibility that oxidized species of wild‐type (WT) SOD1 might be involved in pathogenic processes, we analyzed the properties of the WT human SOD1 protein after its oxidation in vivo or in vitro by hydrogen peroxide (H2O2) treatment. Using transfected Neuro2a cells expressing WT or amyotrophic lateral sclerosis‐linked SOD1 species, we show that exposure to H2O2 modifies the properties of WT SOD1. Western blot analysis of immunoprecipitates from cell lysates revealed that, like mutant SOD1, oxidized WT SOD1 can be conjugated with poly‐ubiquitin and can interact with Hsp70. Chromogranin B, a neurosecretory protein that interacts with mutant SOD1 but not with WT SOD1, was co‐immunoprecipitated with oxidized WT SOD1 from lysates of Neuro2a cells treated with H2O2. Treatment of microglial cells (line BV2) with either oxidized WT SOD1 or mutant SOD1 recombinant proteins induced tumor necrosis factor‐α and inducible nitric oxide synthase. Furthermore, exposure of cultured motor neurons to oxidized WT SOD1 caused dose‐dependent cell death like mutant SOD1 proteins. These results suggest that WT SOD1 may acquire binding and toxic properties of mutant forms of SOD1 through oxidative damage.
Hepatitis B‐associated vasculitis in Alaska Natives: viral genotype, clinical and serologic outcome
Authors: Hurlburt Kathy J. , McMahon Brian J. , Simonetti Josephine P. , Livingston Stephen E. , Bulkow Lisa R. , Snowball Mary M. , Chulanov Vladimir P. , Nainan Omana P. , Williams James L.
Published: March 2007

Background: The highest incidence of hepatitis B virus (HBV)‐associated vasculitis in the world has been reported in Alaska Natives. We examined the incidence of HBV‐associated vasculitis before and after mass HBV vaccine immunization and the association between HBV genotype and vasculitis in a population‐based cohort study in Alaska natives chronically infected with HBV.

Methods: Genotyping was performed in vasculitis cases and 644 hepatitis B‐positive controls without vasculitis using polymerase chain reaction and sequencing of the S gene. Occurrence of HBV vasculitis from 1974 to 2004 was calculated. HBV vasculitis patients and controls were also tested for basal core promoter and precore mutations.

Results: Fifteen cases of HBV‐associated vasculitis were identified: 13 (86%) had genotype D and one each genotype A and F. Genotype D was more commonly found in patients with vasculitis than controls [odd ratio (OR)=5.9, confidence interval (95% CI) 1.2, 21.8; P<0.015).

Conclusions: HBV‐associated vasculitis was associated with genotype D.
Analysis of the core gene of hepatitis B virus in Korean patients
Authors: Kim Hyung Joon , Lee Dong Ho , Gwak Geum‐Youn , Choi Moon Seok , Lee Joon Hyeok , Koh Kwang Cheol , Paik Seung Woon , Yoo Byung Chul
Published: March 2007

Background/Aims: As the core gene of hepatitis B virus (HBV) is a major immunological target, its mutation may evoke or evade immune clearance. We investigated the frequency and location of HBV core gene substitutions according to hepatitis B e antigen (HBeAg) status and viral replication status, and evaluated the association of these substitutions with the different stages of chronic HBV infection in Korean patients.

Methods: The study population included 45 HBeAg‐positive/DNA‐positive patients (group I), 49 HBeAg‐negative/DNA‐positive patients (II) and 50 HBeAg‐negative/DNA‐negative patients (III). The HBV core gene was analysed by polymerase chain reaction (PCR) and sequencing.

Results: The frequency of core gene substitutions increased from group I to group III. Substitutions were commonly detected at codons 87, 97, 112 and 130. The frequency of substitutions at codons 87 and 112 was higher in groups II/III than in group I. The frequency of the codon I97F substitutions was the highest in group III. However, the codon 130 substitution was more frequently found in groups I/II than in group III.

Conclusion: Core gene substitutions were more frequently detected in HBeAg‐negative and/or HBV DNA‐negative patients. The substitutional hot spots were codons 87, 97, 112 and 130; substitutions at these codons might play a role in immune‐modulation during the course of chronic HBV infection.
Robust Resource Allocation Decisions in Resource‐Constrained Projects*
Authors: Deblaere Filip , Demeulemeester Erik , Herroelen Willy , Van de Vonder Stijn
Published: March 2007

The well‐known deterministic resource‐constrained project scheduling problem involves the determination of a predictive schedule (baseline schedule or pre‐schedule) of the project activities that satisfies the finish–start precedence relations and the renewable resource constraints under the objective of minimizing the project duration. This baseline schedule serves as a baseline for the execution of the project. During execution, however, the project can be subject to several types of disruptions that may disturb the baseline schedule. Management must then rely on a reactive scheduling procedure for revising or reoptimizing the baseline schedule. The objective of our research is to develop procedures for allocating resources to the activities of a given baseline schedule in order to maximize its stability in the presence of activity duration variability. We propose three integer programming–based heuristics and one constructive procedure for resource allocation. We derive lower bounds for schedule stability and report on computational results obtained on a set of benchmark problems.
Decision Sciences Research in China: Current Status, Opportunities, and Propositions for Research in Supply Chain Management, Logistics, and Quality Management*
Authors: Zhao Xiande , Flynn Barbara B. , Roth Aleda V.
Published: March 2007

As China becomes increasingly important to the global economy, it is critical to conduct high‐quality research on important decision sciences issues there. This article provides an extensive review and critique of the extant China‐based literature on supply chain management, logistics, and quality management, based on the foundation established by Zhao, Flynn, and Roth (2006). In general, decision sciences research in China is in its infancy. Although there have been some very interesting and well‐executed articles, the majority are descriptive and focus on status updates. We provide a set of propositions to guide future research in logistics, supply chain management, and quality management in China, as well as guidelines for dealing with some of the unique challenges of conducting empirical research in China.
The Severity of Supply Chain Disruptions: Design Characteristics and Mitigation Capabilities
Authors: Craighead Christopher W. , Blackhurst Jennifer , Rungtusanatham M. Johnny , Handfield Robert B.
Published: March 2007

Supply chain disruptions and the associated operational and financial risks represent the most pressing concern facing firms that compete in today's global marketplace. Extant research has not only confirmed the costly nature of supply chain disruptions but has also contributed relevant insights on such related issues as supply chain risks, vulnerability, resilience, and continuity. In this conceptual note, we focus on a relatively unexplored issue, asking and answering the question of how and why one supply chain disruption would be more severe than another. In doing so, we argue, de facto, that supply chain disruptions are unavoidable and, as a consequence, that all supply chains are inherently risky. Employing a multiple‐method, multiple‐source empirical research design, we derive novel insights, presented as six propositions that relate the severity of supply chain disruptions (i) to the three supply chain design characteristics of density, complexity, and node criticality and (ii) to the two supply chain mitigation capabilities of recovery and warning. These findings not only augment existing knowledge related to supply chain risk, vulnerability, resilience, and business continuity planning but also call into question the wisdom of pursuing such practices as supply base reduction, global sourcing, and sourcing from supply clusters.
Student Perceptions of the Insurance Profession
Authors: Cory Suzanne N. , Kerr Dana , Todd Jerry D.
Published: March 2007

Abstract

To attract students to the risk management and insurance profession, strategies need to be developed to overcome biases in their perceptions of the profession. This study attempts to determine some of those perceptions of students—specifically a group of business career high school students and a group of college students enrolled in an introduction to business course—about the personality traits of insurance professionals. A Personality Factor Questionnaire previously used extensively in other research was used to measure differences in student perceptions of personality profiles of different professions. We also measured how student characteristics such as age, sex, and expected college major influence student perceptions of these traits. The overall general conclusion was that perceptions of the profession are not as negative as many imagine, but do require some substantive work to improve, even among students seeking business careers.
Transcription factor dynamics in pineal gland and liver of the Syrian hamster (Mesocricetus auratus) adapts to prevailing photoperiod
Authors: Maronde Erik , Pfeffer Martina , Glass Yuri , Stehle Jörg H.
Published: March 2007

Abstract:  The anticipation of day length and duration of darkness is necessary and advantageous for animals to survive and requires a photoperiodic memory. In the Syrian hamster this adaptation to photoperiod is mirrored by seasonal changes in the animal's reproductive state and its liver metabolism. Both events are linked to season‐dependent alterations of the nocturnally elevated synthesis of the pineal hormone melatonin. To decipher molecules that are involved in this temporal gating, hamsters were exposed to long photoperiod (16 hr light:8 hr darkness; LP), or short photoperiod (8 hr light:16 hr darkness; SP). Dynamics in gene expression was investigated in the pineal gland [inducible cAMP early repressor (ICER)], and in the liver (ICER; C/EBPδ; clock genes) using immunochemistry and reverse transcriptase PCR. While in the pineal, ICER rhythms tightly follow the prior duration of light and dark with decreasing levels at the beginning of the dark period in both LP and SP, ICER is not rhythmic in liver. In the liver, clock genes and their protein products reflect differences in photoperiodic history, with enhanced rhythm amplitudes of PER, CRY, CLOCK, and BMAL1 under SP conditions. Thus, in the Syrian hamster transcription factor expression patterns lock onto the prevailing photoperiod in two peripheral oscillators, the pineal gland and the liver, to function as mediators of suprachiasmatic nucleus‐derived information on environmental light and dark. This tissue‐specific gating in gene transcription represents a strategy to ameliorate consequences of altering environmental lighting conditions on endocrine and metabolic parameters that endow a strong circadian bias.
The presence of melatonin receptors and inhibitory effect of melatonin on hydrogen peroxide‐induced endothelial nitric oxide synthase expression in bovine cerebral blood vessels
Authors: Chucharoen Prapapun , Chetsawang Banthit , Putthaprasart Chorkaew , Srikiatkhachorn Anan , Govitrapong Piyarat
Published: March 2007

Abstract:  Melatonin plays a key role in a variety of important physiological functions including influencing cerebral blood vessels. Therefore, in the present study, we have identified the existence of melatonin receptors and test the effect of melatonin on hydrogen peroxide‐induced endothelial nitric oxide synthase (eNOS) expression in bovine cerebral arteries. The results indicate that mt1A melatonin receptor mRNA is expressed in bovine cerebral arteries. The relative levels of mt1A melatonin receptor mRNA expression in anterior, posterior, middle and vertebral cerebral arteries were compared. The data show the highest and lowest levels of mRNA expressions in the middle and vertebral cerebral arteries, respectively. The maximal number (Bmax) of different types of melatonin receptors in various regions of cerebral arteries were identified and further characterized by using the selective 2‐[125I] iodomelatonin binding assay. Saturation studies revealed that the binding represented a single site of high affinity binding for the melatonin receptor with the highest and lowest binding capacities in the middle and vertebral arteries, respectively. In order to elaborate the functional significance of melatonin in cerebral blood vessels, hydrogen peroxide‐ induced induction in eNOS protein level and phosphorylation of calcium/calmodulain‐dependent protein kinase II (phospho‐CaMKII) were demonstrated in the bovine isolated cerebral arteries with these effect being abolished by melatonin. This is the first evidence showing expression of mt1A melatonin receptor in the bovine cerebral arteries. However, further studies are necessary to delineate the role of melatonin and its receptors in regulating physiology of the cerebral vessels.
Immigrant Motherhood and Transnationality in Jhumpa Lahiri's Fiction
Authors: Alfonso‐Forero Ann Marie
Published: March 2007

This essay won the 2006 Literature Compass Graduate Essay Prize, Twentieth Century & Contemporary Section.

This article argues that Jhumpa Lahiri's novel The Namesake offers motherhood as a site of agency for negotiating a transnational identity for the postcolonial female subject in diaspora. Lahiri shows how traditional gender roles – often considered subordinate in the postcolonial context in their appropriation by nationalist agendas – can be read as a source of empowerment when translated into the context of middle class immigrant life in America. The Namesake depicts the cultural and national fluidity offered by this status: the immigrant mother, a central character in this novel, is able to preserve the Indian traditions that link her to her homeland while simultaneously benefiting from the privileges afforded by American citizenship in order to ensure a successful future for her American‐born children. An Indian matriarch living in the suburbs of Boston, she does so through the careful negotiations she makes for her family on a daily basis in response to the often conflicting demands of traditional Bengali culture and the pressure to become an assimilated American. Although in the context of Western feminism it may seem contradictory that it is through the role of wife and mother that a subjectivity which transcends any fixed national identity is achieved, this reading of Lahiri's novel is informed by the arguments of transnational feminists who resist any essentializing understanding of female emancipation. This article concludes that immigrant women from the so‐called ‘third world’ need to be understood not only in the context of their particular national histories, but also through the manner in which they appropriate these histories in forging individual identities in America. Lahiri's The Namesake provides the occasion for such a discussion within ethnic American literary studies, especially as this field continues to engage with postcolonial and transnational paradigms.
‘Rank Imposture’ and ‘Mimic Goblinry’ in Scott's Doom of Devorgoil: A Genre Politics of National Drama
Authors: Van Kooy Dana
Published: March 2007

This essay won the 2006 Literature Compass Graduate Essay Prize, Romanticism Section.

Scholars seldom associate Sir Walter Scott with nineteenth‐century drama or with the commercial interests of the theatre, including those of playwrights and publishers. However, Scott's dramas reveal his keen interest in dramatic traditions as well as an astute comprehension of the theatre as a commercial institution subject to the complex politics of nation and empire. The Doom of Devorgoil, as an authorial masquerade, exposes Scott's willingness to transgress and manipulate cultural constructions of personal and national identity. However, as a dramatic production created to conform to the templates of the theatre as a culture industry, it unveils a symptomatic and disturbing affiliation between the formation and practices of the so‐called national drama as a melodramatic form and the dramatic reproduction of national identity. A performance and a critique of ‘rank imposture’, The Doom of Devorgoil underscores the critical importance of understanding the production of genre politics on stage and within dramatic discourses of the period.
Nonlinear Rotordynamics of Automotive Turbochargers: Predictions and
Comparisons to Test Data
Authors: San Andrés Luis , Rivadeneira Juan Carlos , Chinta Murali , Gjika Kostandin , LaRue Gerry
Published: March 2007

Passenger vehicle turbochargers (TCs) offer increased engine power and efficiency in an ever-competitive marketplace. Turbochargers operate at high rotational speeds and use engine oil to lubricate fluid-film-bearing supports (radial and axial). However, TCs are prone to large amplitudes of subsynchronous shaft motion over wide ranges of their operating speed. Linear rotordynamic tools cannot predict the amplitudes and multiple frequency shaft motions. A comprehensive nonlinear rotordynamics model coupled to a complete fluid-film-bearing model solves in real time the dynamics of automotive turbochargers. The computational design tool predicts the limit cycle response for several inner and outer film clearances and operating conditions including rotor speed and lubricant feed pressure. Substantial savings in product development and prototype testing are the benefits of the present development. The paper presents predictions of the linear and nonlinear shaft motion of an automotive turbocharger supported on a semi-floating ring bearing. The shaft motion predictions are compared to measurements of shaft motion at the compressor nose for speeds up to 240krpm, and for lubricant inlet pressure of 4bar at 150°C. Linear and nonlinear rotordynamic models reproduce very well the test data for synchronous response to imbalance. The nonlinear results show two subsynchronous whirl frequencies whose large magnitudes agree well with the measurements. A large side load predicted for this turbocharger must be considered for accurate prediction of the rotordynamic response.
Structural Stiffness, Dry Friction Coefficient, and Equivalent Viscous Damping in a Bump-Type Foil Gas Bearing
Authors: Rubio Dario , San Andres Luis
Published: March 2007

High performance oil-free turbomachinery implements gas foil bearings (FBs) to improve mechanical efficiency in compact units. FB design, however, is still largely empirical due to its mechanical complexity. The paper provides test results for the structural parameters in a bump-type foil bearing. The stiffness and damping (Coulomb or viscous type) coefficients characterize the bearing compliant structure. The test bearing, 38.1mm in diameter and length, consists of a thin top foil supported on bump-foil strips. A prior investigation identified the stiffness due to static loads. Presently, the test FB is mounted on a non-rotating stiff shaft and a shaker exerts single frequency loads on the bearing. The dynamic tests are conducted at shaft surface temperatures from 25to75°C. Time and frequency domain methods are implemented to determine the FB parameters from the recorded periodic load and bearing motions. Both methods deliver identical parameters. The dry friction coefficient ranges from 0.05 to 0.20, increasing as the amplitude of load increases. The recorded motions evidence a resonance at the system natural frequency, i.e., null damping. The test derived equivalent viscous damping is inversely proportional to the motion amplitude and excitation frequency. The characteristic stick-slip of dry friction is dominant at small amplitude dynamic loads leading to a hardening effect (stiffening) of the FB structure. The operating temperature produces shaft growth generating a bearing preload. However, the temperature does not significantly affect the identified FB parameters, albeit the experimental range was too small considering the bearings intended use in industry.