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101.
Marianne Evju Rune Halvorsen Knut Rydgren Gunnar Austrheim Atle Mysterud 《Plant Ecology》2011,212(8):1299-1312
An improved understanding of population-level consequences of grazing on plants can be facilitated by an assessment of grazing
effects on all stages in the life-cycle. In this study, 6 years of demographic data for three populations of the perennial
herb Geranium sylvaticum were analysed. We examined the effects of sheep grazing (high sheep density, low sheep density and no sheep) and interannual
climatic variability on vital rates and population growth rates (λ). Grazing did not affect survival or flowering rates, but
reduced rates of growth and increased rates of clonal reproduction. At the population level, high contributions from retrogression
and clonal reproduction buffered reduced rates of growth and stasis, and no consistent differences in λ between populations
exposed to different sheep densities were found. Instead, large between-year variability in λ, independent of sheep density,
was detected, related to variation in the local summer climate. The results indicated, however, that grazing effects on λ
were more severe in unfavourable than in normal years. Our study highlights that increased clonal reproduction rates functioned
as a tolerance mechanism towards grazing in this herb, which forms a mechanism to explain how moderate population responses
to grazing in some herbs can arise. 相似文献
102.
Turhan Markussen Maria K. Dahle Torstein Tengs Marie L?voll ?ystein W. Finstad Christer R. Wiik-Nielsen S?ren Grove Silje Lauksund B?rre Robertsen Espen Rimstad 《PloS one》2013,8(7)
Piscine orthoreovirus (PRV) is associated with heart- and skeletal muscle inflammation (HSMI) of farmed Atlantic salmon (Salmo salar). We have performed detailed sequence analysis of the PRV genome with focus on putative encoded proteins, compared with prototype strains from mammalian (MRV T3D)- and avian orthoreoviruses (ARV-138), and aquareovirus (GCRV-873). Amino acid identities were low for most gene segments but detailed sequence analysis showed that many protein motifs or key amino acid residues known to be central to protein function are conserved for most PRV proteins. For M-class proteins this included a proline residue in μ2 which, for MRV, has been shown to play a key role in both the formation and structural organization of virus inclusion bodies, and affect interferon-β signaling and induction of myocarditis. Predicted structural similarities in the inner core-forming proteins λ1 and σ2 suggest a conserved core structure. In contrast, low amino acid identities in the predicted PRV surface proteins μ1, σ1 and σ3 suggested differences regarding cellular interactions between the reovirus genera. However, for σ1, amino acid residues central for MRV binding to sialic acids, and cleavage- and myristoylation sites in μ1 required for endosomal membrane penetration during infection are partially or wholly conserved in the homologous PRV proteins. In PRV σ3 the only conserved element found was a zinc finger motif. We provide evidence that the S1 segment encoding σ3 also encodes a 124 aa (p13) protein, which appears to be localized to intracellular Golgi-like structures. The S2 and L2 gene segments are also potentially polycistronic, predicted to encode a 71 aa- (p8) and a 98 aa (p11) protein, respectively. It is concluded that PRV has more properties in common with orthoreoviruses than with aquareoviruses. 相似文献
103.
Rita Vik Marco Busnelli Cinzia Parolini Bodil Bj?rndal Sverre Holm Pavol Bohov Bente Halvorsen Trond Brattelid Stefano Manzini Giulia S. Ganzetti Federica Dellera Ottar K. Nyg?rd P?l Aukrust Cesare R. Sirtori Giulia Chiesa Rolf K. Berge 《PloS one》2013,8(12)
Tetradecylthioacetic acid (TTA) is a hypolipidemic antioxidant with immunomodulating properties involving activation of peroxisome proliferator-activated receptors (PPARs) and proliferation of mitochondria. This study aimed to penetrate the effect of TTA on the development of atherosclerotic lesions in apolipoprotein (apo)-E-/- mice fed a high-fat diet containing 0.3% TTA for 12 weeks. These mice displayed a significantly less atherosclerotic development vs control. Plasma cholesterol was increased by TTA administration and triacylglycerol (TAG) levels in plasma and liver were decreased by TTA supplementation, the latter, probably due to increased mitochondrial fatty acid oxidation and reduced lipogenesis. TTA administration also changed the fatty acid composition in the heart, and the amount of arachidonic acid (ARA) and eicosapentaenoic acid (EPA) was reduced and increased, respectively. The heart mRNA expression of inducible nitric oxidase (NOS)-2 was decreased in TTA-treated mice, whereas the mRNA level of catalase was increased. Finally, reduced plasma levels of inflammatory mediators as IL-1α, IL-6, IL-17, TNF-α and IFN-γ were detected in TTA-treated mice. These data show that TTA reduces atherosclerosis in apoE-/- mice and modulates risk factors related to atherosclerotic disorders. TTA probably acts at both systemic and vascular levels in a manner independent of changes in plasma cholesterol, and triggers TAG catabolism through improved mitochondrial function. 相似文献
104.
The MIAmaxent R package: Variable transformation and model selection for species distribution models
The widely used “Maxent” software for modeling species distributions from presence‐only data (Phillips et al., Ecological Modelling, 190, 2006, 231) tends to produce models with high‐predictive performance but low‐ecological interpretability, and implications of Maxent's statistical approach to variable transformation, model fitting, and model selection remain underappreciated. In particular, Maxent's approach to model selection through lasso regularization has been shown to give less parsimonious distribution models—that is, models which are more complex but not necessarily predictively better—than subset selection. In this paper, we introduce the MIAmaxent R package, which provides a statistical approach to modeling species distributions similar to Maxent's, but with subset selection instead of lasso regularization. The simpler models typically produced by subset selection are ecologically more interpretable, and making distribution models more grounded in ecological theory is a fundamental motivation for using MIAmaxent. To that end, the package executes variable transformation based on expected occurrence–environment relationships and contains tools for exploring data and interrogating models in light of knowledge of the modeled system. Additionally, MIAmaxent implements two different kinds of model fitting: maximum entropy fitting for presence‐only data and logistic regression (GLM) for presence–absence data. Unlike Maxent, MIAmaxent decouples variable transformation, model fitting, and model selection, which facilitates methodological comparisons and gives the modeler greater flexibility when choosing a statistical approach to a given distribution modeling problem. 相似文献
105.
Measuring interactions between biological molecules is vitally important to both basic and applied research as well as development of pharmaceuticals. Although a wide and growing range of techniques is available to measure various kinetic and thermodynamic properties of interacting biomolecules, it can be difficult to compare data across techniques of different laboratories and personnel or even across different instruments using the same technique. Here we evaluate relevant biological interactions based on complementary DNA and RNA oligonucleotides that could be used as reference standards for many experimental systems. We measured thermodynamics of duplex formation using isothermal titration calorimetry, differential scanning calorimetry, and ultraviolet–visible (UV–vis) monitored denaturation/renaturation. These standards can be used to validate results, compare data from disparate techniques, act as a teaching tool for laboratory classes, or potentially to calibrate instruments. The RNA and DNA standards have many attractive features, including low cost, high purity, easily measurable concentrations, and minimal handling concerns, making them ideal for use as a reference material. 相似文献
106.
107.
108.
Silje Halvorsen Sveaas Inger Jorid Berg Sella Aarrestad Provan Anne Grete Semb K?re Birger Hagen Nina V?llestad Camilla Fongen Inge C. Olsen Annika Michelsen Thor Ueland P?l Aukrust Tore K. Kvien Hanne Dagfinrud 《PloS one》2014,9(9)
Background
Physical therapy is recommended for the management of axial spondyloarthritis (axSpA) and flexibility exercises have traditionally been the main focus. Cardiovascular (CV) diseases are considered as a major health concern in axSpA and there is strong evidence that endurance and strength exercise protects against CV diseases. Therefore, the aim of this study was to investigate the efficacy of high intensity endurance and strength exercise on disease activity and CV health in patients with active axSpA.Methods
In a single blinded randomized controlled pilot study the exercise group (EG) performed 12 weeks of endurance and strength exercise while the control group (CG) received treatment as usual. The primary outcome was the Ankylosing Spondylitis (AS) Disease Activity Score (ASDAS). Secondary outcomes included patient reported disease activity (Bath AS Disease Activity Index [BASDAI]), physical function (Bath AS Functional Index [BASFI]), and CV risk factors measured by arterial stiffness (Augmentation Index [Alx]) and Pulse Wave Velocity [PWV]), cardiorespiratory fitness (VO2 peak) and body composition. ANCOVA on the post intervention values with baseline values as covariates was used to assess group differences, and Mann Whitney U-test was used for outcomes with skewed residuals.Results
Twenty-eight patients were included and 24 (EG, n = 10, CG, n = 14) completed the study. A mean treatment effect of −0.7 (95%CI: −1.4, 0.1) was seen in ASDAS score. Treatment effects were also observed in secondary outcomes (mean group difference [95%CI]): BASDAI: −2.0 (−3.6, −0.4), BASFI: −1.4 (−2.6, −0.3), arterial stiffness (estimated median group differences [95% CI]): AIx (%): −5.3 (−11.0, −0.5), and for PVW (m/s): −0.3 (−0.7, 0.0), VO2 peak (ml/kg/min) (mean group difference [95%CI]: 3.7 (2.1, 5.2) and trunk fat (%): −1.8 (−3.0, −0.6). No adverse events occurred.Conclusion
High intensity exercise improved disease activity and reduced CV risk factors in patients with active axSpA. These effects will be further explored in a larger trial.Trial Registration
ClinicalTrials.gov NCT01436942相似文献109.
Silje Skrede Johan Fern? Bodil Bj?rndal Wenche R?dseth Brede Pavol Bohov Rolf Kristian Berge Vidar Martin Steen 《PloS one》2012,7(11)
Background
Psychiatric patients often require chronic treatment with antipsychotic drugs, and while rats are frequently used to study antipsychotic-induced metabolic adverse effects, long-term exposure has only partially mimicked the appetite-stimulating and weight-inducing effects found in the clinical setting. Antipsychotic-induced effects on serum lipids are also inconsistent in rats, but in a recent study we demonstrated that subchronic treatment with the orexigenic antipsychotic olanzapine resulted in weight-independent increase in serum triglycerides and activation of lipogenic gene expression in female rats. In addition, a recent long-term study in male rats showed that chronic treatment with antipsychotic drugs induced dyslipidemic effects, despite the lack of weight gain.Aims
In the current study, we sought to examine long-term effects of antipsychotic drugs on weight gain, lipid levels and lipid composition after twice-daily administration of antipsychotics to female rats, and to investigate potential beneficial effects of the lipid-lowering agent tetradecylthioacetic acid (TTA), a modified fatty acid.Methods
Female rats were exposed to orexigenic antipsychotics (olanzapine or clozapine), metabolically neutral antipsychotics (aripiprazole or ziprasidone), or TTA for 8 weeks. Separate groups received a combination of clozapine and TTA or olanzapine and TTA. The effects of TTA and the combination of olanzapine and TTA after 2 weeks were also investigated.Results
The antipsychotic-induced weight gain and serum triglyceride increase observed in the subchronic setting was not present after 8 weeks of treatment with antipsychotics, while lipid-lowering effect of TTA was much more pronounced in the chronic than in the subchronic setting, with concomitant upregulation of key oxidative enzymes in the liver. Unexpectedly, TTA potentiated weight gain in rats treated with antipsychotics.Conclusion
TTA is a promising candidate for prophylactic treatment of antipsychotic-induced dyslipidemic effects, but a more valid long-term rat model for antipsychotic-induced metabolic adverse effects is required. 相似文献110.
Elisabeth Astrup Tove Lekva Giovanni Davì Kari Otterdal Francesca Santilli Erik ?ie Bente Halvorsen Jan Kristian Dam?s Didier Raoult Giustina Vitale Juan P. Olano Thor Ueland P?l Aukrust 《PloS one》2012,7(9)
The pathophysiological hallmark of spotted fever group rickettsioses comprises vascular inflammation. Based on the emerging importance of the wingless (Wnt) pathways in inflammation and vascular biology, we hypothesized that Dickkopf-1 (DKK-1), as a major modulator of Wnt signaling, could be involved in the pathogenesis in rickettsial infections. Our major findings were: (i) While baseline concentration of DKK-1 in patients with R. conorii infection (n = 32) were not different from levels in controls (n = 24), DKK-1 rose significantly from presentation to first follow-up sample (median 7 days after baseline). (ii) In vitro experiments in human umbilical vein endothelial cells (HUVECs) showed that while heat-inactivated R. conorii enhanced the release of interleukin-6 (IL-6) and IL-8, it down-regulated the release of endothelial-derived DKK-1 in a time- and dose-dependent manner. (iii) Silencing of DKK-1 attenuated the release of IL-6, IL-8 and growth-related oncogene (GRO)α in R. conorii-exposed HUVECs, suggesting inflammatory effects of DKK-1. (iv) Silencing of DKK-1 attenuated the expression of tissue factor and enhanced the expression of thrombomodulin in R. conorii-exposed HUVECs suggesting pro-thrombotic effects of DKK-1. The capacity of R. conorii to down-regulate endothelial-derived DKK-1 and the ability of silencing DKK-1 to attenuate R. conorii-induced inflammation in endothelial cells could potentially reflect a novel mechanism by which R. conorii escapes the immune response at the site of infection. 相似文献