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991.
Mechanisms maintaining honesty of sexual signals are far from resolved, limiting our understanding of sexual selection and potential important parts of physiology. Carotenoid pigmented visual signals are among the most extensively studied sexual displays, but evidence regarding hypotheses on how carotenoids ensure signal honesty is mixed. Using a phylogenetically controlled meta-analysis of 357 effect sizes across 88 different species of birds, we tested two prominent hypotheses in the field: that carotenoid-dependent coloration signals i) immunocompetence and/or ii) oxidative stress state. Separate meta-analyses were performed for the relationships of trait coloration and circulating carotenoid level with different measures of immunocompetence and oxidative stress state. For immunocompetence we find that carotenoid levels (r = 0.20) and trait color intensity (r = 0.17) are significantly positively related to PHA response. Additionally we find that carotenoids are significantly positively related to antioxidant capacity (r = 0.10), but not significantly related to oxidative damage (r = −0.02). Thus our analyses provide support for both hypotheses, in that at least for some aspects of immunity and oxidative stress state the predicted correlations were found. Furthermore, we tested for differences in effect size between experimental and observational studies; a larger effect in observational studies would indicate that co-variation might not be causal. However, we detected no significant difference, suggesting that the relationships we found are causal. The overall effect sizes we report are modest and we discuss potential factors contributing to this, including differences between species. We suggest complementary mechanisms maintaining honesty rather than the involvement of carotenoids in immune function and oxidative stress and suggest experiments on how to test these. 相似文献
992.
993.
Movement patterns during songbird migration remain poorly understood despite their expected fitness consequences in terms of survival, energetic condition and timing of migration that will carry over to subsequent phases of the annual cycle. We took an experimental approach to test hypotheses regarding the influence of habitat, energetic condition, time of season and sex on the hour-by-hour, local movement decisions of a songbird during spring stopover. To simulate arrival of nocturnal migrants at unfamiliar stopover sites, we translocated and continuously tracked migratory red-eyed vireos (Vireo olivaceus) throughout spring stopover with and without energetic reserves that were released in two replicates of three forested habitat types. Migrants moved the most upon release, during which time they selected habitat characterized by greater food abundance and higher foraging attack rates. Presumably under pressure to replenish fuel stores necessary to continue migration in a timely fashion, migrants released in poorer energetic condition moved faster and further than migrants in better condition and the same pattern was true for migrants released late in spring relative to those released earlier. However, a migrant's energetic condition had less influence on their behavior when they were in poor quality habitat. Movement did not differ between sexes. Our study illustrates the importance of quickly finding suitable habitat at each stopover site, especially for energetically constrained migrants later in the season. If an initial period prior to foraging were necessary at each stop along a migrant's journey, non-foraging periods would cumulatively result in a significant energetic and time cost to migration. However, we suggest behavior during stopover is not solely a function of underlying resource distributions but is a complex response to a combination of endogenous and exogenous factors. 相似文献
994.
KM Verspoor KB Cohen A Lanfranchi C Warner HL Johnson C Roeder JD Choi C Funk Y Malenkiy M Eckert N Xue WA Baumgartner M Bada M Palmer LE Hunter 《BMC bioinformatics》2012,13(1):207-26
ABSTRACT: BACKGROUND: We introduce the linguistic annotation of a corpus of 97 full-text biomedical publications, known as the Colorado Richly Annotated Full Text (CRAFT) corpus. We further assess the performance of existing tools for performing sentence splitting, tokenization, syntactic parsing, and named entity recognition on this corpus. RESULTS: Many biomedical natural language processing systems demonstrated large differences between their previously published results and their performance on the CRAFT corpus when tested with the publicly available models or rule sets. Trainable systems differed widely with respect to their ability to build high-performing models based on this data. CONCLUSIONS: The finding that some systems were able to train high-performing models based on this corpus is additional evidence, beyond high inter-annotator agreement, that the quality of the CRAFT corpus is high. The overall poor performance of various systems indicates that considerable work needs to be done to enable natural language processing systems to work well when the input is full-text journal articles. The CRAFT corpus provides avaluable resource to the biomedical natural language processing community for evaluation and training of new models for biomedical full text publications. 相似文献
995.
Gruzman A Elgart A Viskind O Billauer H Dotan S Cohen G Mishani E Hoffman A Cerasi E Sasson S 《Journal of cellular and molecular medicine》2012,16(3):594-604
We have recently generated lipophilic D-xylose derivatives that increase the rate of glucose uptake in cultured skeletal muscle cells in an AMP-activated protein kinase (AMPK)-dependent manner. The derivative 2,4:3,5-dibenzylidene-D-xylose-diethyl dithioacetal (EH-36) stimulated the rate of glucose transport by increasing the abundance of glucose transporter-4 in the plasma membrane of cultured myotubes. The present study aimed at investigating potential antihyperglycaemic effects of EH-36 in animal models of diabetes. Two animal models were treated subcutaneously with EH-36: streptozotocin-induced diabetes in C57BL/6 mice (a model of insulin-deficient type 1 diabetes), and spontaneously diabetic KKAy mice (Kuo Kondo rats carrying the A(y) yellow obese gene; insulin-resistant type 2 diabetes). The in vivo biodistribution of glucose in control and treated mice was followed with the glucose analogue 2-deoxy-2-[(18) F]-D-glucose; the rate of glucose uptake in excised soleus muscles was measured with [(3) H]-2-deoxy-D-glucose. Pharmacokinetic parameters were determined by non-compartmental analysis of the in vivo data. The effective blood EH-36 concentration in treated animals was 2 μM. It reduced significantly the blood glucose levels in both types of diabetic mice and also corrected the typical compensatory hyperinsulinaemia of KKAy mice. EH-36 markedly increased glucose transport in vivo into skeletal muscle and heart, but not to adipose tissue. This stimulatory effect was mediated by Thr(172) -phosphorylation in AMPK. Biochemical tests in treated animals and acute toxicological examinations showed that EH-36 was well tolerated and not toxic to the mice. These findings indicate that EH-36 is a promising prototype molecule for the development of novel antidiabetic drugs. 相似文献
996.
Background
The Xpert MTB/RIF test enables rapid detection of tuberculosis (TB) and rifampicin resistance. The World Health Organization recommends Xpert for initial diagnosis in individuals suspected of having multidrug-resistant TB (MDR-TB) or HIV-associated TB, and many countries are moving quickly toward adopting Xpert. As roll-out proceeds, it is essential to understand the potential health impact and cost-effectiveness of diagnostic strategies based on Xpert.Methods and Findings
We evaluated potential health and economic consequences of implementing Xpert in five southern African countries—Botswana, Lesotho, Namibia, South Africa, and Swaziland—where drug resistance and TB-HIV coinfection are prevalent. Using a calibrated, dynamic mathematical model, we compared the status quo diagnostic algorithm, emphasizing sputum smear, against an algorithm incorporating Xpert for initial diagnosis. Results were projected over 10- and 20-y time periods starting from 2012. Compared to status quo, implementation of Xpert would avert 132,000 (95% CI: 55,000–284,000) TB cases and 182,000 (97,000–302,000) TB deaths in southern Africa over the 10 y following introduction, and would reduce prevalence by 28% (14%–40%) by 2022, with more modest reductions in incidence. Health system costs are projected to increase substantially with Xpert, by US$460 million (294–699 million) over 10 y. Antiretroviral therapy for HIV represents a substantial fraction of these additional costs, because of improved survival in TB/HIV-infected populations through better TB case-finding and treatment. Costs for treating MDR-TB are also expected to rise significantly with Xpert scale-up. Relative to status quo, Xpert has an estimated cost-effectiveness of US$959 (633–1,485) per disability-adjusted life-year averted over 10 y. Across countries, cost-effectiveness ratios ranged from US$792 (482–1,785) in Swaziland to US$1,257 (767–2,276) in Botswana. Assessing outcomes over a 10-y period focuses on the near-term consequences of Xpert adoption, but the cost-effectiveness results are conservative, with cost-effectiveness ratios assessed over a 20-y time horizon approximately 20% lower than the 10-y values.Conclusions
Introduction of Xpert could substantially change TB morbidity and mortality through improved case-finding and treatment, with more limited impact on long-term transmission dynamics. Despite extant uncertainty about TB natural history and intervention impact in southern Africa, adoption of Xpert evidently offers reasonable value for its cost, based on conventional benchmarks for cost-effectiveness. However, the additional financial burden would be substantial, including significant increases in costs for treating HIV and MDR-TB. Given the fundamental influence of HIV on TB dynamics and intervention costs, care should be taken when interpreting the results of this analysis outside of settings with high HIV prevalence. Please see later in the article for the Editors'' Summary 相似文献997.
Michail S. Lionakis Brett G. Fischer Jean K. Lim Muthulekha Swamydas Wuzhou Wan Chyi-Chia Richard Lee Jeffrey I. Cohen Phillip Scheinberg Ji-Liang Gao Philip M. Murphy 《PLoS pathogens》2012,8(8)
Invasive candidiasis is the 4th leading cause of nosocomial bloodstream infection in the US with mortality that exceeds 40% despite administration of antifungal therapy; neutropenia is a major risk factor for poor outcome after invasive candidiasis. In a fatal mouse model of invasive candidiasis that mimics human bloodstream-derived invasive candidiasis, the most highly infected organ is the kidney and neutrophils are the major cellular mediators of host defense; however, factors regulating neutrophil recruitment have not been previously defined. Here we show that mice lacking chemokine receptor Ccr1, which is widely expressed on leukocytes, had selectively impaired accumulation of neutrophils in the kidney limited to the late phase of the time course of the model; surprisingly, this was associated with improved renal function and survival without affecting tissue fungal burden. Consistent with this, neutrophils from wild-type mice in blood and kidney switched from Ccr1lo to Ccr1high at late time-points post-infection, when Ccr1 ligands were produced at high levels in the kidney and were chemotactic for kidney neutrophils ex vivo. Further, when a 1∶1 mixture of Ccr1+/+ and Ccr1−/− donor neutrophils was adoptively transferred intravenously into Candida-infected Ccr1+/+ recipient mice, neutrophil trafficking into the kidney was significantly skewed toward Ccr1+/+ cells. Thus, neutrophil Ccr1 amplifies late renal immunopathology and increases mortality in invasive candidiasis by mediating excessive recruitment of neutrophils from the blood to the target organ. 相似文献
998.
In��s Vigan-Womas Micheline Guillotte Alexandre Juillerat Audrey Hessel Bertrand Raynal Patrick England Jacques H. Cohen Olivier Bertrand Thierry Peyrard Graham A. Bentley Anita Lewit-Bentley Odile Mercereau-Puijalon 《PLoS pathogens》2012,8(7)
The ABO blood group influences susceptibility to severe Plasmodium falciparum malaria. Recent evidence indicates that the protective effect of group O operates by virtue of reduced rosetting of infected red blood cells (iRBCs) with uninfected RBCs. Rosetting is mediated by a subgroup of PfEMP1 adhesins, with RBC binding being assigned to the N-terminal DBL1α1 domain. Here, we identify the ABO blood group as the main receptor for VarO rosetting, with a marked preference for group A over group B, which in turn is preferred to group O RBCs. We show that recombinant NTS-DBL1α1 and NTS-DBL1α1-CIDR1γ reproduce the VarO-iRBC blood group preference and document direct binding to blood group trisaccharides by surface plasmon resonance. More detailed RBC subgroup analysis showed preferred binding to group A1, weaker binding to groups A2 and B, and least binding to groups Ax and O. The 2.8 Å resolution crystal structure of the PfEMP1-VarO Head region, NTS-DBL1α1-CIDR1γ, reveals extensive contacts between the DBL1α1 and CIDR1γ and shows that the NTS-DBL1α1 hinge region is essential for RBC binding. Computer docking of the blood group trisaccharides and subsequent site-directed mutagenesis localized the RBC-binding site to the face opposite to the heparin-binding site of NTS-DBLα1. RBC binding involves residues that are conserved between rosette-forming PfEMP1 adhesins, opening novel opportunities for intervention against severe malaria. By deciphering the structural basis of blood group preferences in rosetting, we provide a link between ABO blood grouppolymorphisms and rosette-forming adhesins, consistent with the selective role of falciparum malaria on human genetic makeup. 相似文献
999.
J Pan Q Chen D Willenbring D Mowrey XP Kong A Cohen CB Divito Y Xu P Tang 《Structure (London, England : 1993)》2012,20(9):1463-1469
Highlights? The structure of ketamine-bound GLIC reveals an anesthetic binding site ? The study provides compelling evidence for allosteric inhibition by anesthetics ? Ketamine inhibition on GLIC is similar to competitive antagonist action on nAChRs ? Ketamine directly acts on pLGICs in addition to NMDA receptors 相似文献
1000.
Populations vary in time and in space, and temporal variation may differ from spatial variation. Yet, in the past half century, field data have confirmed both the temporal and spatial forms of Taylor's power Law, a linear relationship between log(variance) and log(mean) of population size. Recent theory predicted that competitive species interactions should reduce the slope of the temporal version of Taylor's Law. We tested whether this prediction applied to the spatial version of Taylor's Law using simple, well-controlled laboratory populations of two species of bacteria that were cultured either separately or together for 24 h in media of widely varying nutrient richness. Experimentally, the spatial form of Taylor's Law with a slope of 2 held for these simple bacterial communities, but competitive interactions between the two species did not reduce the spatial Taylor's Law slope. These results contribute to the widespread usefulness of Taylor's Law in population ecology, epidemiology and pest control. 相似文献