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https://www.readbyqxmd.com/read/28096430/testing-hypotheses-about-individual-variation-in-plasma-corticosterone-in-free-living-salamanders
#1
Jessica R Thomas, Andrew J Magyan, Peter E Freeman, Sarah K Woodley
In vertebrates, many responses to stress as well as homeostatic maintenance of basal metabolism are regulated by plasma glucocorticoid hormones (GCs). Despite having crucial functions, levels of GCs are typically variable among individuals. We examined the contribution of several physiological factors to individual variation in plasma corticosterone (CORT) and the number of corticotropin-releasing hormone (CRH) neurons in the magnocellular preoptic area of the brain in free-living Allegheny Mountain dusky salamanders...
January 17, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28092408/network-structure-and-local-adaptation-in-coevolving-bacteria-phage-interactions
#2
James Gurney, Lafi Aldakak, Alex Betts, Claire Gougat-Barbera, Timothée Poisot, Oliver Kaltz, Michael E Hochberg
Numerous theoretical and experimental studies have investigated antagonistic coevolution between parasites and their hosts. Although experimental tests of theory from a range of biological systems are largely concordant regarding the influence of several driving processes, we know little as to how mechanisms acting at the smallest scales (individual molecular and phenotypic changes) may result in the emergence of structures at larger scales, such as coevolutionary dynamics and local adaptation. We capitalized on methods commonly employed in community ecology to quantify how the structure of community interaction matrices, so called 'bipartite networks', reflected observed coevolutionary dynamics, and how phages from these communities may or may not have adapted locally to their bacterial hosts...
January 16, 2017: Molecular Ecology
https://www.readbyqxmd.com/read/28092219/the-21st-century-cures-act-pharmacoeconomic-boon-or-bane
#3
Roger Lee Mendoza
Barriers to entry in healthcare markets constitute one of the overriding concerns of health economists. The recent enactment of the 21st Century Cures Act in the United States is one landmark legislation that reduces statutory entry barriers to the discovery, development, testing and licensing of drugs and medical devices. However, it brings with it many critical challenges concerning the safety, efficacy and value of drugs and devices, along with novel opportunities for medical innovation and faster treatment of diseases...
January 16, 2017: Journal of Medical Economics
https://www.readbyqxmd.com/read/28091822/does-the-growth-differentiation-balance-hypothesis-explain-allocation-to-secondary-metabolites-in-combretum-apiculatum-an-african-savanna-woody-species
#4
Dawood Hattas, Peter F Scogings, Riitta Julkunen-Tiitto
The growth differentiation balance hypothesis (GDBH) provides a framework that predicts a trade-off between costs of secondary metabolites (SMs) relative to the demand for photosynthate by growth. However, this hypothesis was developed using empirical evidence from plant species in northern boreal and temperate systems, leaving its applicability to species under different abiotic and biotic conditions questionable and generalizations problematic. The objective of this study was to investigate whether the GDBH explains allocation to SMs in the deciduous African savanna woody species C...
January 14, 2017: Journal of Chemical Ecology
https://www.readbyqxmd.com/read/28089543/optimal-regulatory-circuit-topologies-for-fold-change-detection
#5
Miri Adler, Pablo Szekely, Avi Mayo, Uri Alon
Evolution repeatedly converges on only a few regulatory circuit designs that achieve a given function. This simplicity helps us understand biological networks. However, why so few circuits are rediscovered by evolution is unclear. We address this question for the case of fold-change detection (FCD): a response to relative changes of input rather than absolute changes. Two types of FCD circuits recur in biological systems-the incoherent feedforward and non-linear integral-feedback loops. We performed an analytical screen of all three-node circuits in a class comprising ∼500,000 topologies...
January 10, 2017: Cell Systems
https://www.readbyqxmd.com/read/28089490/dynamic-plant-plant-herbivore-interactions-govern-plant-growth-defence-integration
#6
REVIEW
Jorad de Vries, Jochem B Evers, Erik H Poelman
Plants downregulate their defences against insect herbivores upon impending competition for light. This has long been considered a resource trade-off, but recent advances in plant physiology and ecology suggest this mechanism is more complex. Here we propose that to understand why plants regulate and balance growth and defence, the complex dynamics in plant-plant competition and plant-herbivore interactions needs to be considered. Induced growth-defence responses affect plant competition and herbivore colonisation in space and time, which has consequences for the adaptive value of these responses...
January 12, 2017: Trends in Plant Science
https://www.readbyqxmd.com/read/28088842/unbiased-split-variable-selection-for-random-survival-forests-using-maximally-selected-rank-statistics
#7
Marvin N Wright, Theresa Dankowski, Andreas Ziegler
The most popular approach for analyzing survival data is the Cox regression model. The Cox model may, however, be misspecified, and its proportionality assumption may not always be fulfilled. An alternative approach for survival prediction is random forests for survival outcomes. The standard split criterion for random survival forests is the log-rank test statistic, which favors splitting variables with many possible split points. Conditional inference forests avoid this split variable selection bias. However, linear rank statistics are utilized by default in conditional inference forests to select the optimal splitting variable, which cannot detect non-linear effects in the independent variables...
January 15, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/28088064/improved-cognition-while-cycling-in-parkinson-s-disease-patients-and-healthy-adults
#8
Audrey A Hazamy, Lori J P Altmann, Elizabeth Stegemöller, Dawn Bowers, Hyo Keun Lee, Jonathan Wilson, Michael S Okun, Chris J Hass
Persons with Parkinson's disease (PD) are typically more susceptible than healthy adults to impaired performance when two tasks (dual task interference) are performed simultaneously. This limitation has by many experts been attributed to limitations in cognitive resources. Nearly all studies of dual task performance in PD employ walking or balance-based motor tasks, which are commonly impaired in PD. These tasks can be performed using a combination of one or two executive function tasks. The current study examined whether persons with PD would demonstrate greater dual task effects (DTEs) on cognition compared to healthy older adults (HOAs) during a concurrent cycling task...
January 11, 2017: Brain and Cognition
https://www.readbyqxmd.com/read/28087658/are-winter-and-summer-dormancy-symmetrical-seasonal-adaptive-strategies-the-case-of-temperate-herbaceous-perennials
#9
REVIEW
Lauren M Gillespie, Florence A Volaire
BACKGROUND: Dormancy in higher plants is an adaptive response enabling plant survival during the harshest seasons and has been more explored in woody species than in herbaceous species. Nevertheless, winter and summer shoot meristem dormancy are adaptive strategies that could play a major role in enhancing seasonal stress tolerance and resilience of widespread herbaceous plant communities. SCOPE: This review outlines the symmetrical aspects of winter and summer dormancy in order to better understand plant adaptation to severe stress, and highlight research priorities in a changing climate...
January 13, 2017: Annals of Botany
https://www.readbyqxmd.com/read/28086968/microbiota-fingerprints-lose-individually-identifying-features-over-time
#10
David Wilkins, Marcus H Y Leung, Patrick K H Lee
BACKGROUND: Humans host individually unique skin microbiota, suggesting that microbiota traces transferred from skin to surfaces could serve as forensic markers analogous to fingerprints. While it is known that individuals leave identifiable microbiota traces on surfaces, it is not clear for how long these traces persist. Moreover, as skin and surface microbiota change with time, even persistent traces may lose their forensic potential as they would cease to resemble the microbiota of the person who left them...
January 9, 2017: Microbiome
https://www.readbyqxmd.com/read/28081069/photoacoustic-imaging-of-sub-diffraction-objects-with-spectral-contrast
#11
Sophinese Iskander-Rizk, Pieter Kruizinga, Geert Springeling, Hendrik J Vos, Antonius F W van der Steen, Gijs van Soest
Photoacoustic imaging couples the chemical specificity of optical absorption with the viewing depth of ultrasound. Systems based on linear array transducers have the versatility to be applied in various (pre-) clinical scenarios but face a trade-off between viewing depth and image resolution depending on transducer frequency and aperture. We propose here a method to disentangle, with precision, small, closely spaced targets with optical spectral contrast, without impairing the imaging depth. Photoacoustic data sets were recorded at two different optical wavelengths...
January 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28079264/electromagnetic-computation-and-modeling-in-mri
#12
REVIEW
Xin Chen, Michael Steckner
Electromagnetic (EM) computational modeling is used extensively during the development of a Magnetic Resonance Imaging (MRI) scanner, its installation, and use. MRI, which relies on interactions between nuclear magnetic moments and the applied magnetic fields, uses a range of EM tools to optimize all of the magnetic fields required to produce the image. The main field magnet is designed to exacting specifications but challenges in manufacturing, installation, and use require additional tools to maintain target operational performance...
January 12, 2017: Medical Physics
https://www.readbyqxmd.com/read/28078461/cost-effectiveness-of-prophylactic-appendectomy-a-markov-model
#13
Karina Newhall, Benjamin Albright, Anna Tosteson, Elissa Ozanne, Thadeus Trus, Philip P Goodney
BACKGROUND: Appendectomy is the most common emergency surgery performed in the USA. Removal of a non-inflamed appendix during unrelated abdominal surgery (prophylactic or incidental appendectomy) can prevent the downstream risks and costs of appendicitis. It is unknown whether such a strategy could be cost saving for the health system. METHODS: We considered hypothetical patient cohorts of varying ages from 18 to 80, undergoing elective laparoscopic abdominal and pelvic procedures...
January 11, 2017: Surgical Endoscopy
https://www.readbyqxmd.com/read/28077781/effects-of-an-unusual-poison-identify-a-lifespan-role-for-topoisomerase-2-in-saccharomyces-cerevisiae
#14
Gregory Tombline, Jonathan I Millen, Bogdan Polevoda, Matan Rapaport, Bonnie Baxter, Michael Van Meter, Matthew Gilbertson, Joe Madrey, Gary A Piazza, Lynn Rasmussen, Krister Wennerberg, E Lucile White, John L Nitiss, David S Goldfarb
A progressive loss of genome maintenance has been implicated as both a cause and consequence of aging. Here we present evidence supporting the hypothesis that an age-associated decay in genome maintenance promotes aging in Saccharomyces cerevisiae (yeast) due to an inability to sense or repair DNA damage by topoisomerase 2 (yTop2). We describe the characterization of LS1, identified in a high throughput screen for small molecules that shorten the replicative lifespan of yeast. LS1 accelerates aging without affecting proliferative growth or viability...
January 5, 2017: Aging
https://www.readbyqxmd.com/read/28077771/the-correlated-evolution-of-antipredator-defences-and-brain-size-in-mammals
#15
Theodore Stankowich, Ashly N Romero
Mammals that possess elaborate antipredator defences such as body armour, spines and quills are usually well protected, intermediate in size, primarily insectivorous and live in simple open environments. The benefits of such defences seem clear and may relax selection on maintaining cognitive abilities that aid in vigilance and predator recognition, and their bearers may accrue extensive production and maintenance costs. Here, in this comparative phylogenetic analysis of measurements of encephalization quotient and morphological defence scores of 647 mammal species representing nearly every order, we found that as lineages evolve stronger defences, they suffer a correlated reduction in encephalization...
January 11, 2017: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/28076409/an-efficient-antioxidant-system-in-a-long-lived-termite-queen
#16
Eisuke Tasaki, Kazuya Kobayashi, Kenji Matsuura, Yoshihito Iuchi
The trade-off between reproduction and longevity is known in wide variety of animals. Social insect queens are rare organisms that can achieve a long lifespan without sacrificing fecundity. The extended longevity of social insect queens, which contradicts the trade-off, has attracted much attention because it implies the existence of an extraordinary anti-aging mechanism. Here, we show that queens of the termite Reticulitermes speratus incur significantly lower oxidative damage to DNA, protein and lipid and have higher activity of antioxidant enzymes than non-reproductive individuals (workers and soldiers)...
2017: PloS One
https://www.readbyqxmd.com/read/28076353/a-topological-criterion-for-filtering-information-in-complex-brain-networks
#17
Fabrizio De Vico Fallani, Vito Latora, Mario Chavez
In many biological systems, the network of interactions between the elements can only be inferred from experimental measurements. In neuroscience, non-invasive imaging tools are extensively used to derive either structural or functional brain networks in-vivo. As a result of the inference process, we obtain a matrix of values corresponding to a fully connected and weighted network. To turn this into a useful sparse network, thresholding is typically adopted to cancel a percentage of the weakest connections...
January 11, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28074860/sex-and-age-dependent-patterns-of-survival-and-breeding-success-in-a-long-lived-endangered-avian-scavenger
#18
Ana Sanz-Aguilar, Ainara Cortés-Avizanda, David Serrano, Guillermo Blanco, Olga Ceballos, Juan M Grande, José L Tella, José A Donázar
In long-lived species, the age-, stage- and/or sex-dependent patterns of survival and reproduction determine the evolution of life history strategies, the shape of the reproductive value, and ultimately population dynamics. We evaluate the combined effects of age and sex in recruitment, breeder survival and breeding success of the globally endangered Egyptian vulture (Neophron percnopterus), using 31-years of exhaustive data on marked individuals in Spain. Mean age of first reproduction was 7-yrs for both sexes, but females showed an earlier median and a larger variance than males...
January 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28073820/predicting-6-month-mortality-risk-of-patients-commencing-dialysis-treatment-for-end-stage-kidney-disease
#19
Sara E Ivory, Kevan R Polkinghorne, Yeasmin Khandakar, Jessica Kasza, Sophia Zoungas, Retha Steenkamp, Paul Roderick, Rory Wolfe
BACKGROUND: There is evidence that end-stage kidney disease patients who are older or with more comorbidity may have a poor trade-off between benefits of dialysis and potential harms. We aimed to develop a tool for predicting patient mortality in the early stages of receiving dialysis. METHODS: In 23 658 patients aged 15+ years commencing dialysis between 2000 and 2009 in Australia and New Zealand a point score tool was developed to predict 6-month mortality based on a logistic regression analysis of factors available at dialysis initiation...
January 10, 2017: Nephrology, Dialysis, Transplantation
https://www.readbyqxmd.com/read/28073538/margalef-revisited-a-new-phytoplankton-mandala-incorporating-twelve-dimensions-including-nutritional-physiology
#20
Patricia M Glibert
Building on the classic depiction of the progression from a diatom to a dinoflagellate bloom as a function of nutrients and turbulence, known as the "Margalef mandala", a new conceptual model or mandala is presented here. The new mandala maps twelve response or effects traits, or environmental characteristics, related to different phytoplankton functional types: (1) relative preference for chemically reduced vs chemically oxidized forms of nitrogen; (2) relative availability of inorganic nitrogen and phosphorus; (3) adaptation to high vs low light and the tendency to be autotrophic vs mixotrophic; (4) cell motility; (5) environmental turbulence; (6) pigmentation quality; (7) temperature; (8) cell size; (9) relative growth rate; (10) relative production of bioactive compounds such as toxins or reactive oxygen species (ROS); (11) r vs K strategy; and (12) fate of the production in terms of grazing...
May 2016: Harmful Algae
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