bluuebunny/crossref_metadata_2025 huggingface dataset:
The President's Effect on Partisan Attitudes
Authors: Jacobson Gary C.
Published: October 2012

The link between the president's job approval ratings and aggregate election outcomes is well established, but the processes forging the connection have received comparatively little attention. A variety of data from diverse sources across multiple administrations indicates that popular assessments of the president strongly affect how his party is evaluated, perceived, and adopted as an object of identification, which, in turn, helps to account for the president's influence on the electoral fates of his party's candidates. The data also suggest that opinions of Barack Obama have so far had an even larger effect on attitudes toward the president's party than did opinions of his predecessors, including G. W. Bush.
Ex‐Presidential Approval: Retrospective Evaluations of Presidential Performance
Authors: Panagopoulos Costas
Published: October 2012

Political observers and presidents alike are preoccupied with the notion of presidential legacy. Speculation about how presidential actions will be viewed by future generations weighs heavily on the minds of chief executives as well as historians and analysts who seek to devise standards and techniques by which to measure the concept of legacy. In this article, I examine survey data on retrospective assessments about ex‐presidential performance to examine developments over time. I also develop and empirically test a series of hypotheses to explain level of ex‐presidential approval. I find that the public's retrospective evaluations of former presidential performance in office are linked to presidential approval during their administrations, incumbent presidential approval, whether or not they are deceased, and the length of time former presidents have been out of office.
Presidential Budgetary Duties
Authors: Fisher Louis
Published: October 2012

As an essential element of republican government,Congress possesses the power of the purse. It uses that authority to control presidents and executive agencies. From the start, however, there has always been tension between the two elected branches, with presidents insisting on exercising control over departments and agencies. A major collision occurred during the 1970s, whenPresidentNixon claimed constitutional authority to refuse to spend appropriated funds (the impoundment dispute). He lost that battle inCongress and in the courts. Other issues include covert spending,Gramm‐Rudman,Iran‐Contra, item vetoes, legislative vetoes, and efforts in recent decades to control the national debt.
The President's Economy: Parity in Presidential Party Performance
Authors: Campbell James E.
Published: October 2012

Have Democratic presidents since World War II had economic records that were superior to those of their Republican counterparts? In a previous study, I reported findings that there were no significant differences between the economic records of the presidential parties once the conditions of the economy they inherited from their predecessor were taken into account. Comiskey and Marsh challenged this finding with an analysis that controlled for business cycle effects. This article reexamines the issue and Comiskey and Marsh's analysis. The reexamination reaffirms my earlier findings that the presidential parties have not significantly differed in their economic records once the effects of inherited economic conditions are taken into account.
The Contemporary Presidency The Administrator as Outsider: James Jones as National Security Advisor
Authors: Marsh Kevin
Published: October 2012

This article examines the role of former National Security Advisor (NSA) James Jones in the Obama administration. I argue that Jones served as an administrator and failed to achieve a close advisory relationship with the president and ceded many aspects of coordination and management of the foreign policy‐making process to Deputy NSA Tom Donilon and other actors within the administration. The article then concludes with a discussion of the continued importance and influence of presidential management style on the role, power, and influence of the NSA in U.S. foreign policy making.
Polls and Elections Understanding Persuasion and Activation in Presidential Campaigns: The Random Walk and Mean Reversion Models
Authors: Kaplan Noah , Park David K. , Gelman Andrew
Published: October 2012

Political campaigns are commonly understood as random walks, during which, at any point in time, the level of support for any party or candidate is equally likely to go up or down. Each shift in the polls is then interpreted as the result of some combination of news and campaign strategies. A completely different story of campaigns is the mean reversion model in which the elections are determined by fundamental factors of the economy and partisanship; the role of the campaign is to give voters a chance to reach their predetermined positions. Using a new approach to analyze individual level poll data from recent presidential elections, we find that the fundamentals predict vote intention increasingly well as campaigns progress, which is consistent with the mean reversion model, at least at the time scale of months. We discuss the relevance of this finding to the literature on persuasion and activation effects.
Level of C‐Reactive Protein in Chronic Hemodialysis Patients: A Comparative Study Between Patients With Non‐Infected Catheters and Arteriovenous Fistula in a Large Saudi Hemodialysis Center
Authors: Al Saran Khalid , Sabry Alaa , Shalaby Medhat , Al Sherbeiny Sherrine , Abdelkader Mohamed
Published: October 2012

Central venous catheters are associated with infection and resultant higher C‐reactive protein levels (CRP), suggesting that catheters may be an important determinant of increased inflammatory response. The increased levels of markers such as CRP are associated with increased risk of premature death and hospitalization in end stage renal disease (ESRD) patients on regular hemodialysis (HD). In this prospective study the mean levels of the inflammatory marker CRP were measured every 2 months over a period of 6 months by using immunoturbidimetric assay in 70 ESRD patients on maintenance HD at Prince Salman Center For Kidney Diseases (PSCKD) who met our inclusion criteria, comparing those dialyzed using a non‐infected catheter (35 patients) to those using arteriovenous fistulas (35 patients). Seventy ESRD patients who had been on maintenance HD for more than 6 months were included in the study, with a mean age of 50.09 ± 15.61 years, 80% were males and 20% were females. Serial levels of mean CRP were statistically significantly higher in the group with non‐infected catheters (0.83, 0.82, 0.94 mg/dL) compared with those with arteriovenous fistula (0.31, 0.38 and 0.34 mg/dL) with P‐values of 0.000, 0.023 and 0.001, respectively. In our study we found no relationship between CRP level and age, sex, hemoglobin albumin, calcium, phosphorus and intact parathyroid hormone level in both groups. Our study shows that catheters might contribute to increased inflammation independent of infection, and support the avoidance of catheters and a timely conversion to fistulas with catheter removal.
Case series of equine pituitary pars intermedia dysfunction in a tropical climate
Authors: Spelta CW , Axon JE
Published: October 2012

The clinical manifestations of equine pituitary pars intermedia dysfunction (PPID) in temperate climates are well described. The classic presentation is that of an older animal with hirsutism, laminitis, poor muscle tone, pendulous abdomen and weight loss. This case series highlights the additional clinical signs of anhidrosis and heat stress with secondary exercise intolerance that were seen as primary presenting problems in equids withPPIDin the hot, humid conditions of a tropical climate. The clinical signs resolved with medical treatment forPPID.
Sinus valsalva aneurysm on cardiac CT angiography: Assessment and detection
Authors: Troupis John M , Nasis Arthur , Pasricha Sundeep , Patel Mihir , Ellims Andris Harald , Seneviratne Sujith
Published: October 2012

After the advent of ECG gated cardiac CT angiography (CCTA) there has been significant improvement in image quality of the ascending aorta. As a result the sinuses of valsalva are readily assessable. Sinuses of valsalva aneurysm can cause significant dysfunction of the aortic root and annulus and can be congenital or acquired. The aneurysm most commonly originates from the right coronary sinus. Complications related to sinuses of valsalva aneurysm can cause chest pain and can be life threatening. The cardiac imager should actively assess the sinuses of valsalva in every CCTA study.
Balancing biodiversity with agriculture: Land sharing mitigates avian malaria prevalence
Authors: Mendenhall Chase D. , Archer Holly M. , Brenes Federico Oviedo , Sekercioglu Cagan H. , Sehgal Ravinder N. M.
Published: October 2012

Debate over balancing agricultural production and biodiversity conservation has generated two opposing strategies: a “land sparing” approach involving large‐scale nature reserves, versus a “land sharing” approach where agricultural areas support wildlife through fine‐scale conservation. As a result of this debate, studies focus almost exclusively on species diversity and food production, while ignoring other critical ecosystem processes such as disease dynamics. Here we quantify how tropical avian malaria in an abundant sedentary bird species responds at fine spatial scales in a “land sharing” system. We find the proportion and configuration of countryside forest elements within a radius of 400 m, proximity to the nearest river, and habitat type explains malaria prevalence across the region. We simulate “land sparing” and “land sharing” land use strategies and model malaria prevalence to find that land sharing mitigates malaria prevalence more effectively. With these analyses, we gain a better understanding of how biodiversity, ecosystem services, agricultural yield, and human well‐being intersect in complex ecosystems.
Thoracoscopic surgery for refractory cases of secondary spontaneous pneumothorax
Authors: Odaka Makoto , Akiba Tadashi , Mori Shohei , Asano Hisatoshi , Yamashita Makoto , Kamiya Noriki , Morikawa Toshiaki
Published: October 2012

Introduction

Secondary spontaneous pneumothorax (SSP) can be life threatening because patients often have severe lung disease with other coexisting diseases such as heart disease. In this study, we evaluate the feasibility of thoracoscopic surgery to treat SSP and discuss thoracoscopic techniques for managing complicated cases.

Methods

We retrospectively evaluated the outcome of thoracoscopic surgeries in 21 SSP patients.

Results

Fifteen patients had chronic emphysema, four had interstitial pneumonia, and two had inflammatory lung disease. All patients presented with persistent air leaks, and their median preoperative hospital stay was 11 days. All patients underwent thoracoscopic surgery. In 12 patients, the leaking bullae were excised by endoscopic stapling. Fibrin glue was used in 16 cases and polyglycolic acid sheets in 17. Polyglycolic acid sheets and fibrin glue without bullectomy were used in three cases. Air leaks were treated by simple stapling in four cases and by gelatin‐resorcin formaldehyde glue in five. Median postoperative hospital stay was 8 days. No patients required conversion to open surgery. Postoperative complications such as persistent air leaks, pneumonia, and acute respiratory failure were observed in six patients. Four recurrences of pneumothorax were observed during the median postoperative follow‐up period of 19.3 months.

Conclusion

Our results suggest that thoracoscopic surgery is feasible and less invasive than open surgery for high‐risk patients, and it improves patient quality of life. Various techniques to stop air leaks enabled us to treat patients with refractory SSP.
A review of recent advances and current hypotheses on the pathogenesis of acute laminitis
Authors: Katz L. M. , Bailey S. R.
Published: October 2012

With the increasing number of studies being published on the different experimental models used to induce and study acute laminitis, the pathophysiological events associated with these various models (i.e. starch overload, oligofructose overload, black walnut extract and hyperinsulinaemia) can be compared more realistically. Within this review, the mechanisms for metabolic vs. inflammatory laminitis are discussed, and the question of how pasture laminitis may fit into any of the proposed mechanisms is addressed.
Respiratory responses to exercise in the horse
Authors: Franklin S. H. , Van Erck‐Westergren E. , Bayly W. M.
Published: October 2012

Horses are elite athletes when compared with other mammalian species. In the latter, performance is limited by cardiovascular or musculoskeletal performance whereas in athletic horses it is the respiratory system that appears to be rate limiting and virtually all horses exercising at high intensities become hypoxaemic and hypercapnoeic. This is due to both diffusion limitation and a level of ventilation inadequate for the metabolic level that enables horses to exercise at these intensities. In conjunction with these blood gas changes, total pulmonary resistance increases and the work of breathing rises exponentially and airflow eventually plateaus despite increases in inspiratory and expiratory intrapleural pressures. Horses breathe at comparatively high frequencies when galloping due to the tight 1:1 coupling of strides to breathing. Whether this effects gas exchange and, if so, to what extent, has not been fully elucidated.
Synthesis and Photoluminescence of a New Chlorogermanate Phosphor Ca8Mg(GeO4)4Cl2:Eu2+
Authors: Que Meidan , Ci ZhiPeng , Wang Yuhua , Zhu Ge , Liu Bitao , Zhang Jia , Shi YuRong , Wen Yan , Li Yao , Wang Qian
Published: October 2012

A new chlorogermanate compound Ca8Mg(GeO4)4Cl2 (CMGC) was synthesized via high‐temperature solid‐state reaction for the first time. The crystal structure of CMGC had been refined and determined from the XRD profiles by Rietveld refinement method, which belong to space group Fd‐3m with the lattice constants a = b = c = 15.1760(25) Å. Photoluminescence properties of CMGC:Eu2+ phosphors were investigated by absorption spectra, excitation, and emission spectra. The occupy situation and energy transfer were investigated by decay lifetimes and emission spectra under different excitation wavelengths. Thermal stability was also measured. The results show that the absorption spectra of CMGC:Eu2+ phosphors cover from 250 to 500 nm. Under 365 and 435 nm excitation, the emission spectra of CMGC:Eu2+ phosphors show blue‐green (centered at 425 and 510 nm) and green (centered at 510 nm) emission, respectively, which attributed to Eu2+ ions occupying different crystal sites. Our results indicated that CMGC:Eu2+ phosphors had a potential application use for white light‐emitting diodes.
Crystal Structure and Optical Performance of Al3+ and Ce3+ Codoped Ca3Sc2Si3O12 Green Phosphors for White LEDs
Authors: Wu Yun‐Fang , Chan Ya‐Han , Nien Yung‐Tang , Chen In‐Gann
Published: October 2012

Ca3Sc2Si3O12:Ce3+ (CSS:Ce) green phosphors used for white light‐emitting diodes (LEDs) are synthesized and codoped with Al3+ via a solid‐state reaction method. The crystal structure and vibrational modes are analyzed by X‐ray diffraction, Fourier transform infrared spectroscopy, and Raman scattering spectroscopy. The energy transfer behavior and optical performance are characterized by photoluminescence and excitation spectra, quantum efficiency, and time‐resolved photoluminescence. The incorporation of Al3+ into CSS:Ce can inhibit the formation of the impurity phases Sc2O3 and CeO2, improve crystallinity, and enhance the photoluminescence intensity as well as quantum efficiency. The substitution of Sc3+ with Al3+ increased the crystal field splitting of Ce3+ and resulted in the red shift of photoluminescence. The results show that Ca3Sc2−xAlxSi3O12:Ce3+ has high quantum efficiency, making it a promising green phosphor that can be collocated with a commercial 450 nm blue LED and a red phosphor for solid‐state lighting applications.
Linking ecological niche, community ecology and biogeography: insights from a mechanistic niche model
Authors: Cabral Juliano Sarmento , Kreft Holger
Published: October 2012

Aim

We present a mechanistic niche model that integrates the demography of competing plant species in a metabolic, stochastic framework. In order to explore the model's ability to generate multiple species and community patterns, we assessed trait composition, richness gradients and spatial distributions of species ranges and abundances of simulated communities.

Location

Hypothetical, sloped plane.

Methods

Stage‐structured populations of species differing in traits and habitat requirements competed for space in a grid‐based model. Demographic processes (recruitment, reproduction, mortality, dispersal) and resource competition were explicitly simulated. Demographic rates and carrying capacity followed metabolic constraints. We simulated 50 species pools until reaching stable communities. Species pools were initialized with 400 species that had random traits and habitat requirements. The habitat requirements generated potential distributions of richness, range and abundance, whereas the simulations yielded realized distributions.

Results

The communities assembled in the simulations consisted of species spread non‐randomly within trait space. Potential species richness peaked at mid‐elevations, whereas realized richness was slightly shifted towards higher elevations. For 11% of all species, the highest local abundances were found not in the most suitable habitat, but in suboptimal conditions. 53% of all species could not fill the climatically determined potential range. The ability to fill the potential range was significantly influenced by species traits (e.g. body mass and Allee effects) and species richness.

Main conclusions

Spatial and trait properties of surviving species and of equilibrium communities diverged from the potential distributions. Realized richness gradients were consistent both with patterns observed in nature and those expected from null models based on geometrical constraints. However, the divergences between potential and realized patterns of richness, ranges and abundances indicate the importance of demography and biotic interaction for generating patterns at species and community levels. Consequently, bias in correlative habitat models and single‐species mechanistic models may arise if competition and demography are neglected. Additionally, competitive exclusion provides a mechanistic explanation for the low transferability of single‐species niche models. These results confirm the usefulness of mechanistic niche models for guiding further research integrating ecological niche, community ecology and biogeography.
Rheological Characteristics of Sour Cherries in Gels Containing Waxy Maize and Cassava Starches
Authors: Pająk Paulina , Fortuna Teresa , Gałkowska Dorota
Published: October 2012

Eight gels composed of sour cherries, starch ingredient, sucrose, potassium sorbate and citric acid were prepared using the same recipe. The starch component was waxy maize (WM) or cassava (CA) starch or their blends with cold water swelling (CWS) starches. The gels varied only in the origin and type of chemical modification of starch (acetylated distarch adipate, hydroxypropylated distarch phosphate). Rheological properties of the gels were studied. Flow tests showed that all samples were pseudoplastic and exhibited shear thinning behavior with tendency to yield stress. The structural recovery of the cherry gels was above 55% and was clearly dominated by the origin of the starch. Linear viscoelastic data showed that all fruit gels exhibited weak gel‐like structure. Classification of gels into two different types was confirmed both in results of steady flow and low amplitude oscillatory tests. Cherry gels containing modified WM starches showed very good heat and rheological stability, whereas gels based on CA starches and their blends with CWS WM starches were more susceptible to shear rates and increased temperature.

Practical Applications

Fruit gels are popular low‐level sugar products used mainly in confectionery. It is very important to provide appropriate viscosity of this product (thick or thin, depending on its usage). Starch is commonly used in production of modern food, mainly to modify its texture and to improve food stability during storage. This research was developed to study the effect of starch addition on the rheological properties of cherry gels. Published works provide information for researchers on this area of study and enable producers to make fruit gels of great consumer's acceptability.
Effect of Seabuckthorn Leaf Extract on Microbiological Quality of Raw Chicken during Extended Periods of Storage
Authors: Dhanze Himani , Khurana S.K. , Mane B.G.
Published: October 2012

Seabuckthorn, a magical herb, is well known for its various valuable properties and is found in abundance in the Himalayan region of Leh districts (Jammu and Kashmir) and Lahaul and Spiti districts (Himachal Pradesh) of India. In the present study, the effect of three different concentrations (1, 2 and 3%) of aqueous extract of seabuckthorn leaves was observed on sensory and microbiological quality of chicken legs at days 0, 1, 3, 5 and 7. No significant difference (P < 0.05) was observed for sensory attributes in the control and treated groups; however, scores were higher for the treated groups compared with the control group. All three concentrations of aqueous extract of seabuckthorn leaves lowered the (P < 0.05) standard plate count (SPC), psychrophilic count (PC), coliform count (CC), and yeast and mold count (YMC) significantly on chicken leg as compared with the control. The 3% seabuckthorn leaf extract treatment resulted in significant (P < 0.05) lowering of SPC, PC, CC and YMC through 7 days. The results of this study revealed the antibacterial and antifungal properties for the seabuckthorn leaf extract. The study also suggested the possibility of using seabuckthorn leaf extract as a decontaminant and preservative for fresh chicken meat.

Practical Applications

The results of the present study indicate the possibility of using seabuckthorn leaf extract as a decontaminant and/or preservative for fresh meat through overall reduction of microbial loads to extend the shelf life without any adverse effect on the sensory quality.
Blueschist‐facies metapelites from the Malpica–Tui Unit (NW Iberian Massif): phase equilibria modelling and H2O and Fe2O3 influence in high‐pressure assemblages
Authors: LÓPEZ‐CARMONA A. , PITRA P. , ABATI J.
Published: October 2012

The Malpica–Tui Unit (Galicia, NW Spain) records eclogite‐ and blueschist‐facies metamorphism during the onset of the Variscan orogeny in Europe. Petrological analysis involving pseudosections calculated using thermocalc shows that the Upper Sheet of this unit, the Ceán Schists, recorded a three‐stage metamorphic evolution involving (i) Early subduction‐related medium‐pressure/low‐temperature metamorphism (M1) constrained at ∼350–380 °C, 12–14 kbar, which is only recorded in the basal part (lower metapelites, LM) of the Ceán Schists. (ii) Subduction‐related blueschist facies prograde metamorphism (M2) going from ∼19 kbar, 420 °C to 21 kbar, 460 °C in the LM, and from 16 kbar 430 °C to 21–22 kbar, 520 °C in the structurally upper metapelites (UM). (iii) Exhumation‐related metamorphism (M3) is characterized by a decompression to 8–10 kbar, 470–490 °C in the LM. This decompression is also recorded in the UM, but it was not possible to estimate precise P–T conditions. The calculations indicate that (i) the prograde evolution in subduction zones may occur in fluid‐undersaturated conditions due to the crystallization of lawsonite, even in metapelitic rocks. This significantly influences phase equilibria and hence the P–T estimates. (ii) The proportion of ferric iron also has a strong influence on phase equilibria, even in metapelites. However, the analysed values of Fe2O3 may not reflect the oxidation state during the main metamorphic evolution and are probably easily modified by superficial alteration even in apparently fresh samples. The use of P–T–X(Fe2O3) pseudosections together with petrographic observations is then necessary to estimate the real oxidation state of the rocks and correctly evaluate the P–T conditions.
Retracted: Expression of angiotensin II and its receptors in cyclosporine‐induced gingival overgrowth
Authors: Subramani T. , Senthilkumar K. , Periasamy S. , Rao S.
Published: October 2012

Background and Objectives

The renin–angiotensin system (RAS) is considered as a hormonal circulatory system involved in maintaining blood pressure, electrolyte and fluid homeostasis. RAS components can be synthesized in local tissues and are found to play a role in gingival overgrowth. The drug‐induced gingival overgrowth (DIGO) is a fibrotic condition, which is associated with multiple factors, including inflammation and adverse drug effects such as cyclosporine A. This study was directed forward to the identification of the angiotensinogen, angiotensin II (Ang II) and its receptors AT1/AT2 expression in DIGO tissues and cyclosporine‐treated human gingival fibroblast cells.

Material and Methods

Gingival samples were obtained from patients with cyclosporine‐induced gingival overgrowth, chronic periodontitis and normal healthy subjects. The total RNA was isolated and reverse transcription–polymerase chain reaction was performed for angiotensinogen, Ang II and AT1/AT2 receptor. Ang II protein was estimated from tissue by enzyme immunoassay. The expression of Ang II and its receptors were also examined in gingival fibroblast cells treated with cyclosporine.

Results

Ang II mRNA and protein expression was significantly higher in patients with DIGO than in patients with periodontitis and healthy subjects. The AT1 mRNA was expressed more than AT2 in all examined tissues. In gingival fibroblasts, Ang II and AT1 expressions were increased with cyclosporine incorporation compared to controls.

Conclusion

These results suggest that cyclosporine can modulate local expression of RAS components such as angiotensinogen, Ang II and its receptors in gingival tissues and gingival fibroblast cells.
Effects of cranberry components on human aggressive periodontitis gingival fibroblasts
Authors: Tipton D. A. , Babu J. P. , Dabbous M. Kh.
Published: October 2012

Background and Objective

Aggressive periodontitis (AgP) causes rapid periodontal breakdown involving AgP gingival fibroblast production of cytokines [i.e. interleukin (IL)‐6, a bone metabolism regulator], and matrix metalloproteinase (MMP)‐3. Lipopolysaccharide upregulates fibroblast IL‐6 and MMP‐3, via transcription factors (i.e. NF‐κB). Cranberry (Vaccinium macrocarpon) inhibits lipopolysaccharide‐stimulated macrophage and normal gingival fibroblast activities, but little is known of its effects on AgP fibroblasts. Objectives of this study are to use AgP fibroblasts, to determine cytotoxicity of cranberry components or periodontopathogen (Fusobacterium nucleatum, Porphyromonas gingivalis) lipopolysaccharide ± cranberry components, and effects of cranberry components on lipopolysaccharide‐stimulated NF‐κB activation and IL‐6 and MMP‐3 production.

Material and Methods

AgP fibroblasts were incubated ≤ 6 d with high molecular weight non‐dialyzable material (NDM) (derived from cranberry juice (1–500 μg/mL) or lipopolysaccharide (1 μg/mL) ± NDM. Membrane damage and viability were assessed by enzyme activity released into cell supernatants and activity of a mitochondrial enzyme, respectively. Secreted IL‐6 and MMP‐3 were measured by ELISA. NF‐κB p65 was measured via binding to an oligonucleotide containing the NF‐κB consensus site. Data were analyzed using analysis of variance and Scheffe's F procedure for post hoc comparisons.

Results

Short‐term exposure to NDM, or lipopolysaccharide ± NDM caused no membrane damage. NDM (≤ 100 μg/mL) or lipopolysaccharide ± NDM had no effect on viability ≤ 7 d exposure. NDM (50 μg/mL) inhibited lipopolysaccharide‐stimulated p65 (P ≤ 0.003) and constitutive or lipopolysaccharide‐stimulated MMP‐3 (P ≤ 0.02). NDM increased AgP fibroblast constitutive or lipopolysaccharide‐stimulated IL‐6 (P ≤ 0.0001), but inhibited normal human gingival fibroblast IL‐6 (P ≤ 0.01).

Conclusion

Lack of toxicity of low NDM concentrations, and its inhibition of NF‐κB and MMP‐3, suggest that cranberry components may regulate AgP fibroblast inflammatory responses. Distinct effects of NDM on AgP and gingival fibroblast production of IL‐6 (which can have both positive and negative effects on bone metabolism) may reflect phenotypic differences in IL‐6 regulation in the two cell types.
Improving the prediction of plant species distribution and community composition by adding edaphic to topo‐climatic variables
Authors: Dubuis Anne , Giovanettina Sara , Pellissier Loïc , Pottier Julien , Vittoz Pascal , Guisan Antoine
Published: October 2012

Questions

Soil properties have been widely shown to influence plant growth and distribution. However, the degree to which edaphic variables can improve models based on topo‐climatic variables is still unclear. In this study, we tested the roles of seven edaphic variables, namely (1) pH; (2) the content of nitrogen and of (3) phosphorus; (4) silt; (5) sand; (6) clay and (7) carbon‐to‐nitrogen ratio, as predictors of species distribution models in an edaphically heterogeneous landscape. We also tested how the respective influence of these variables in the models is linked to different ecological and functional species characteristics.

Location

The Western Alps, Switzerland.

Methods

With four different modelling techniques, we built models for 115 plant species using topo‐climatic variables alone and then topo‐climatic variables plus each of the seven edaphic variables, one at a time. We evaluated the contribution of each edaphic variable by assessing the change in predictive power of the model. In a second step, we evaluated the importance of the two edaphic variables that yielded the largest increase in predictive power in one final set of models for each species. Third, we explored the change in predictive power and the importance of variables across plant functional groups. Finally, we assessed the influence of the edaphic predictors on the prediction of community composition by stacking the models for all species and comparing the predicted communities with the observed community.

Results

Among the set of edaphic variables studied, pH and nitrogen content showed the highest contributions to improvement of the predictive power of the models, as well as the predictions of community composition. When considering all topo‐climatic and edaphic variables together, pH was the second most important variable after degree‐days. The changes in model results caused by edaphic predictors were dependent on species characteristics. The predictions for the species that have a low specific leaf area, and acidophilic preferences, tolerating low soil pH and high humus content, showed the largest improvement by the addition of pH and nitrogen in the model.

Conclusions

pH was an important predictor variable for explaining species distribution and community composition of the mountain plants considered in our study. pH allowed more precise predictions for acidophilic species. This variable should not be neglected in the construction of species distribution models in areas with contrasting edaphic conditions.
Temporal changes in abundance–occupancy relationships within and between communities after disturbance
Authors: Guedo Digit D. , Lamb Eric G.
Published: October 2012

Questions

A positive relationship between abundance and occupancy of species (AOR) is commonly observed in ecological communities, but the mechanisms driving this pattern are elusive. Succession after disturbance is an important factor structuring many plant communities, yet little is known about how and if this may shape AORs, and if AORs change over time within and between plant communities. Do AORs change through time as a plant community recovers from disturbance? Do patterns in AOR differ between plant communities?

Location

Prince Albert National Park, Saskatchewan, Canada.

Methods

Changes in AOR were evaluated through time following prescribed burning of fescue grassland and adjacent forest transition plant communities invaded by Populus tremuloides Michx. using a 35‐yr data set. Species presence data were used as a frequency measure of abundance and mean species cover was used as a relative measure for abundance. Species data used for the abundance and occupancy measures were collected in permanent sampling plots prior to burning in 1975, and after burning in 1983, 1995 and 2010.

Results

Changes in grassland AORs based on the frequency were shown through time since disturbance, as an increase in abundance relative to occupancy occurred in 1983 and 2010. There was no significant change in grassland AORs when the relative abundance data were used. The forest transition AOR based on frequency showed the 1983 post‐burn AOR had lower abundance relative to occupancy, while the relative abundance measure showed the pre‐burn 1975 AOR had lower abundance relative to occupancy. The removal of litter, changes in soil resources and increase in trembling aspen suckering after fire may have caused changes to plant community structure after burning, explaining differing AOR patterns in the grassland and forest transition plant communities.

Conclusions

Although exact mechanisms behind the observed changes in AOR are hard to determine, the phenomenon of change within and between communities over time since disturbance has not previously been documented. The observed differences in AOR between frequency and relative abundance indicate that measures of abundance should be chosen cautiously. Post‐disturbance succession should be considered as a mechanism influencing AORs in communities impacted by disturbance.
CC genotype donors for the interleukin‐28B single nucleotide polymorphism are associated with better outcomes in hepatitis C after liver transplant
Authors: Firpi Roberto J. , Dong Huijia , Clark Virginia C. , Soldevila‐Pico Consuelo , Morelli Giuseppe , Cabrera Roniel , Norkina Oxana , Shuster Jonathan J. , Nelson David R. , Liu Chen
Published: October 2012

Background/Aims

Interleukin‐28B (IL‐28B) polymorphism is the strongest pretreatment predictor of viral clearance in the hepatitis C (HCV) population. Donor and recipient IL‐28B genomic background may play an important role in post‐transplant HCV recurrence. We sought to examine the role of IL‐28B polymorphisms of donor and recipients in liver transplant patients with recurrent HCV and its impact on the response to interferon‐based therapy.

Methods

The cohort study consisted of 135 adult liver transplant patients who received interferon‐based therapy for recurrent HCV between 1996 and 2005 at the University of Florida. IL‐28B single nucleotide polymorphism (rs. 12979860) was characterized using liver tissue from all donors and recipients.

Results

The CC genotype was observed in approximately 30% of donors and recipients. Sustained viral response (SVR) to HCV therapy was 100% if both recipient and donor were CC genotype, while the SVR was only 25% if neither donor nor recipient had a CC genotype. (Recipient, P = 0.025, Donor, P < 0.001). Recipients and donors with CC genotype had less fibrosis than recipients with genotypes CT and TT, but the difference was not statistically significant. IL‐28B genotype did not seem to play a role in the overall survival in these patients.

Conclusion

In conclusion, recipient and donor CC genotype is associated with a better treatment response to interferon‐based therapy after liver transplant. Our study suggests that using CC genotype donor livers for HCV patients may improve the overall clinical outcome after liver transplantation.
Adding adefovir vs. switching to entecavir for lamivudine‐resistant chronic hepatitis B (ACE study): a 2‐year follow‐up randomized controlled trial
Authors: Yim Hyung Joon , Seo Yeon Seok , Yoon Eileen L. , Kim Chang Wook , Lee Chang Don , Park Sang Hoon , Lee Myung Seok , Park Choong Kee , Chae Hee Bok , Kim Moon Young , Baik Soon Koo , Kim Yun Soo , Kim Ju Hyun , Lee Jung Il , Lee Jin Woo , Hong Sun Pyo , Um Soon Ho
Published: October 2012

Background

Management of lamivudine‐resistant chronic hepatitis B (CHB) remains challenging, as inappropriate choice of treatment may cause multidrug resistance. Until now, randomized trials directly comparing adding adefovir and switching to entecavir monotherapy have not been reported.

Aims

This multicentre prospective randomized study was designed to compare the efficacy of these two strategies.

Methods

Two hundred and nineteen lamivudine‐resistant CHB patients were randomized to either adefovir–lamivudine combination group or entecavir monotherapy group (n = 110 vs. 109), and followed up for 24 months.

Results

One hundred and eighty patients completed this study. At month 24, virological response rate [hepatitis B virus (HBV) DNA <60 IU/ml] was higher in the adefovir–lamivudine combination group compared with entecavir group (56.7% vs. 40%, P = 0.025), although biochemical and serological response rates were not significantly different. Genotypic resistance (9.2% vs. 24.6%, P = 0.005) and combined viral breakthrough (2.0% vs. 17.6%, P < 0.001) were more frequent in the entecavir group.

However, by subgroup analysis, virological response rates were not significantly different between the two therapies in HBeAg‐positive patients (44.9% vs. 35.7%, P = 0.268) or in patients with high baseline HBV DNA (≥7 log IU/ml) (40.7% vs. 31.3%, P = 0.320) at month 24.

Conclusion

This study showed that adefovir–lamivudine combination provides significantly higher antiviral efficacy and the lower resistance rate compared with the entecavir monotherapy in the management of lamivudine‐resistant CHB. However, it had limited efficacy in HBeAg‐positive patients or in patients with high baseline HBV DNA.
Transcriptome‐wide polymorphisms of red abalone (Haliotis rufescens) reveal patterns of gene flow and local adaptation
Authors: De Wit Pierre , Palumbi Stephen R.
Published: October 2012

Global climate change is projected to accelerate during the next century, altering oceanic patterns in temperature, pH and oxygen concentrations. Documenting patterns of genetic adaptation to these variables in locations that currently experience geographic variation in them is an important tool in understanding the potential for natural selection to allow populations to adapt as climate change proceeds. We sequenced the mantle transcriptome of 39 red abalone (Haliotis rufescens) individuals from three regions (Monterey Bay, Sonoma, north of Cape Mendocino) distinct in temperature, aragonite saturation, exposure to hypoxia and disease pressure along the California coast. Among 1.17 × 106 Single Nucleotide Polymorphisms (SNPs) identified in this study (1.37% of the transcriptome), 21 579 could be genotyped for all individuals. A principal components analysis concluded that the vast majority of SNPs show no population structure from Monterey, California to the Oregon border, in corroboration with several previous studies. In contrast, an FST outlier analysis indicated 691 SNPs as exhibiting significantly higher than expected differentiation (experiment‐wide P < 0.05). From these, it was possible to identify 163 genes through BLAST annotation, 34 of which contained more than one outlier SNP. A large number of these genes are involved in biomineralization, energy metabolism, heat‐, disease‐ or hypoxia‐tolerance. These genes are candidate loci for spatial adaptation to geographic variation that is likely to increase in the future.
A free lunch? No cost for acquiring defensive plant pyrrolizidine alkaloids in a specialist arctiid moth (Utetheisa ornatrix)
Authors: Cogni Rodrigo , Trigo José R. , Futuyma Douglas J.
Published: October 2012

Many herbivorous insects sequester defensive chemicals from their host plants. We tested sequestration fitness costs in the specialist moth Utetheisa ornatrix (Lepidoptera: Arctiidae). We added pyrrolizidine alkaloids (PAs) to an artificial diet at different concentrations. Of all the larval and adult fitness components measured, only development time was negatively affected by PA concentration. These results were repeated under stressful laboratory conditions. On the other hand, the amount of PAs sequestered greatly increased with the diet PA concentration. Absence of a detectable negative effect does not necessarily imply a lack of costs if all individuals express the biochemical machinery of detoxification and sequestration constitutively. Therefore, we used qPCR to show that expression of the gene used to detoxify PAs, pyrrolizidine‐alkaloid‐N‐oxygenase (pno), increased 41‐fold in our highest PA treatment. Nevertheless, fitness components were affected only slightly or not at all, suggesting that sequestration in this species does not incur a strong cost. The apparent lack of costs has important implications for our understanding of the evolution of ecological interactions; for example, it implies that selection by specialist herbivores may decrease the levels of certain chemical defences in plant populations.
Intentions and Unified Agency: Insights from the Split‐brain Phenomenon
Authors: Schechter Elizabeth
Published: October 2012

Under experimental conditions, behavior suggesting dual agency is easily elicited from split‐brain subjects who usually behave in an unremarkable fashion. This article presents a model of split‐brain agency that accounts for this apparent tension. Right and left hemisphere are associated with distinct agents, R and L, each of whose unity is grounded in the special inferential and experiential relations that its mental states bear to each other. These same relations do not hold interhemispherically; rather, unified behavior is largely the result of a split‐brain subject's having a single body, much of whose coordination in action is maintained by forces operating downstream of reasons and intentions and conscious experiences. The split‐brain subject as a whole is still a unified agent as well, however, in virtue of R's and L's intentions bearing, with respect to one and the same body, those special causal powers that an individual's intentions (and hers alone) bear to her body (and to her body alone).
Streptokinase variants from Streptococcus pyogenes isolates display altered plasminogen activation characteristics – implications for pathogenesis
Authors: Cook Simon M. , Skora Amanda , Gillen Christine M. , Walker Mark J. , McArthur Jason D.
Published: October 2012

Streptococcus pyogenes (group A streptococcus, GAS) secretes streptokinase, a potent plasminogen activating protein. Among GAS isolates, streptokinase gene sequences (ska) are polymorphic and can be grouped into two distinct sequence clusters (termed cluster type‐1 and cluster type‐2) with cluster type‐2 being further divided into sub‐clusters type‐2a and type‐2b. In this study, far‐UV circular dichroism spectroscopy indicated that purified streptokinase variants of each type displayed similar secondary structure. Type‐2b streptokinase variants could not generate an active site in Glu‐plasminogen through non‐proteolytic mechanisms while all other variants had this capability. Furthermore, when compared with other streptokinase variants, type‐2b variants displayed a 29‐ to 35‐fold reduction in affinity for Glu‐plasminogen. All SK variants could activate Glu‐plasminogen when an activator complex was preformed with plasmin; however, type‐2b and type‐1 complexes were inhibited by α2‐antiplasmin. Exchanging skatype‐2a in the M1T1 GAS strain 5448 with skatype‐2b caused a reduction in virulence while exchanging skatype‐2a with skatype‐1 into 5448 produced an increase in virulence when using a mouse model of invasive disease. These findings suggest that streptokinase variants produced by GAS isolates utilize distinct plasminogen activation pathways, which directly affects the pathogenesis of this organism.
The fungal α‐aminoadipate pathway for lysine biosynthesis requires two enzymes of the aconitase family for the isomerization of homocitrate to homoisocitrate
Authors: Fazius Felicitas , Shelest Ekaterina , Gebhardt Peter , Brock Matthias
Published: October 2012

Fungi produce α‐aminoadipate, a precursor for penicillin and lysine via the α‐aminoadipate pathway. Despite the biotechnological importance of this pathway, the essential isomerization of homocitrate via homoaconitate to homoisocitrate has hardly been studied. Therefore, we analysed the role of homoaconitases and aconitases in this isomerization. Although we confirmed an essential contribution of homoaconitases from Saccharomyces cerevisiae and Aspergillus fumigatus, these enzymes only catalysed the interconversion between homoaconitate and homoisocitrate. In contrast, aconitases from fungi and the thermophilic bacterium Thermus thermophilus converted homocitrate to homoaconitate. Additionally, a single aconitase appears essential for energy metabolism, glutamate and lysine biosynthesis in respirating filamentous fungi, but not in the fermenting yeast S. cerevisiae that possesses two contributing aconitases. While yeast Aco1p is essential for the citric acid cycle and, thus, for glutamate synthesis, Aco2p specifically and exclusively contributes to lysine biosynthesis. In contrast, Aco2p homologues present in filamentous fungi were transcribed, but enzymatically inactive, revealed no altered phenotype when deleted and did not complement yeast aconitase mutants. From these results we conclude that the essential requirement of filamentous fungi for respiration versus the preference of yeasts for fermentation may have directed the evolution of aconitases contributing to energy metabolism and lysine biosynthesis.
Hyphal heterogeneity in Aspergillus oryzae is the result of dynamic closure of septa by Woronin bodies
Authors: Bleichrodt Robert‐Jan , van Veluw G. Jerre , Recter Brand , Maruyama Jun‐ichi , Kitamoto Katsuhiko , Wösten Han A. B.
Published: October 2012

Hyphae of higher fungi are compartmentalized by septa. These septa contain a central pore that allows for inter‐compartmental and inter‐hyphal cytoplasmic streaming. The cytoplasm within the mycelium is therefore considered to be a continuous system. In this study, however, we demonstrate by laser dissection that 40% of the apical septa of exploring hyphae of Aspergillus oryzae are closed. Closure of septa correlated with the presence of a peroxisome‐derived organelle, known as Woronin body, near the septal pore. The location of Woronin bodies in the hyphae was dynamic and, as a result, plugging of the septal pore was reversible. Septal plugging was abolished in a ΔAohex1 strain that cannot form Woronin bodies. Notably, hyphal heterogeneity was also affected in the ΔAohex1 strain. Wild‐type strains of A. oryzae showed heterogeneous distribution of GFP between neighbouring hyphae at the outer part of the colony when the reporter was expressed from the promoter of the glucoamylase gene glaA or the α‐glucuronidase gene aguA. In contrast, GFP fluorescence showed a normal distribution in the case of the ΔAohex1 strain. Taken together, it is concluded that Woronin bodies maintain hyphal heterogeneity in a fungal mycelium by impeding cytoplasmic continuity.