402 research outputs found
Voltage-dependent block of anthrax toxin channels in planar phospholipid bilayer membranes by symmetric tetraalkylammonium ions. Effects on macroscopic conductance.
‘O sibling, where art thou?’ – a review of avian sibling recognition with respect to the mammalian literature
Avian literature on sibling recognition is rare compared to that developed by mammalian researchers. We compare avian and mammalian research on sibling recognition to identify why avian work is rare, how approaches differ and what avian and mammalian researchers can learn from each other. Three factors: (1) biological differences between birds and mammals, (2) conceptual biases and (3) practical constraints, appear to influence our current understanding. Avian research focuses on colonial species because sibling recognition is considered adaptive where ‘mixing potential’ of dependent young is high; research on a wider range of species, breeding systems and ecological conditions is now needed. Studies of acoustic recognition cues dominate avian literature; other types of cues (e.g. visual, olfactory) deserve further attention. The effect of gender on avian sibling recognition has yet to be investigated; mammalian work shows that gender can have important influences. Most importantly, many researchers assume that birds recognise siblings through ‘direct familiarisation’ (commonly known as associative learning or familiarity); future experiments should also incorporate tests for ‘indirect familiarisation’ (commonly known as phenotype matching). If direct familiarisation proves crucial, avian research should investigate how periods of separation influence sibling discrimination. Mammalian researchers typically interpret sibling recognition in broad functional terms (nepotism, optimal outbreeding); some avian researchers more successfully identify specific and testable adaptive explanations, with greater relevance to natural contexts. We end by reporting exciting discoveries from recent studies of avian sibling recognition that inspire further interest in this topic
Ejection Fraction, Biomarkers, and Outcomes and Impact of Vericiguat on Outcomes Across EF in VICTORIA
Background: Vericiguat reduced the risk of cardiovascular death (CVD) or hospitalization for heart failure (HF) in patients with worsening HF and reduced left ventricular ejection fraction (LVEF).Objectives: The authors assessed the association of LVEF with biomarker levels, risk of outcome, and whether the effect of vericiguat was homogeneous across LVEF in the VICTORIA (Vericiguat Global Study in Subjects with Heart Failure With Reduced Ejection Fraction) trial.Methods: Patients were grouped by LVEF tertiles (≤24%, 25%-33%, and >33%). Patient characteristics, clinical outcomes, and efficacy and safety of vericiguat were examined by tertile. Prespecified biomarkers including N-terminal pro–B-type natriuretic peptide, cardiac troponin T, growth differentiation factor 15, interleukin 6, high-sensitivity C-reactive protein, and cystatin C were examined.Results: The mean LVEF was 29% ± 8% (range: 5%-45%). A pattern of higher N-terminal pro–B-type natriuretic peptide, high-sensitivity C-reactive protein, and interleukin 6 was evident in patients in the lowest LVEF tertile vs the other tertiles. Patients with lower LVEF experienced higher rates of the composite outcome (41.7%, 36.3%, and 33.4% for LVEF ≤24, 25-33, and >33; P < 0.001). There was no significant treatment effect heterogeneity of vericiguat across LVEF groups (adjusted HR from lowest to highest tertiles: 0.79 [95% CI: 0.68-0.94]; 0.95 [95% CI: 0.82-1.11]; 0.94 [95% CI: 0.79-1.11]; P for interaction = 0.222), although the HR was numerically lower in the lowest tertile. There was also no heterogeneity of effect for CVD and HF hospitalization individually (P interaction for CVD = 0.964; HF hospitalization = 0.438). Discontinuation of treatment because of adverse events, symptomatic hypotension, or syncope was consistent across the range of LVEF.Conclusions: Patients with lower LVEF had a distinctive biomarker profile and a higher risk for adverse clinical outcomes vs those with a higher LVEF. There was no significant interaction for the benefit of vericiguat across LVEF tertiles, although the largest signal for benefit in both the primary outcome and HF hospitalizations was noted in tertile 1 (LVEF ≤24%).</p
Assessment of Biomarkers of Myocardial injury, Inflammation, and Renal Function in Heart Failure With Reduced Ejection Fraction:The VICTORIA Biomarker Substudy
Background: Circulating biomarkers may be useful in understanding prognosis and treatment efficacy in heart failure with reduced ejection fraction. In the VICTORIA (Vericiguat Global Study in Subjects with Heart Failure with Reduced Ejection Fraction) trial, vericiguat, a soluble guanylate cyclase stimulator, decreased the primary outcome of cardiovascular death or heart failure hospitalization in heart failure with reduced ejection fraction. We evaluated biomarkers of cardiac injury, inflammation, and renal function for associations with outcomes and vericiguat treatment effect. Methods and Results: High-sensitivity cardiac troponin T (hs-cTnT), growth differentiation factor-15 (GDF-15), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), and cystatin C were measured at baseline and 16 weeks. Associations of biomarkers with the primary outcome and its components were estimated. Interaction with study treatment was tested. Changes in biomarkers over time were examined by study treatment. One or more biomarkers were measured in 4652 (92%) of 5050 participants at baseline and 4063 (81%) at 16 weeks. After adjustment, higher values of hs-cTnT, growth differentiation factor-15, and interleukin-6 were associated with the primary outcome, independent of N-terminal pro-B-type natriuretic peptide. Higher hs-cTnT values were associated with a hazard ratio per log standard deviation of 1.21 (95% confidence interval 1.14–1.27). A treatment interaction with vericiguat was evident with hs-cTnT and cardiovascular death (P = .04), but not HF hospitalization (P = .38). All biomarkers except cystatin C decreased over 16 weeks and no relationship between treatment assignment and changes in biomarker levels was observed. Conclusions: hs-cTnT, growth differentiation factor-15, and interleukin-6 levels were associated with risk of the primary outcome in VICTORIA (Vericiguat Global Study in Subjects with Heart Failure with Reduced Ejection Fraction). Uniquely, lower hs-cTnT was associated with a lower rate of cardiovascular death but not HF hospitalization after treatment with vericiguat.</p
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Shifty salamanders: transient trophic polymorphism and cannibalism within natural populations of larval ambystomatid salamanders
INTRODUCTION: Many species of ambystomatid salamanders are dependent upon highly variable temporary wetlands
for larval development. High larval densities may prompt the expression of a distinct head morphology that may
facilitate cannibalism. However, few studies have characterized structural cannibalism within natural populations of
larval salamanders. In this study we used two species of larval salamanders, long-toed (Ambystoma macrodactylum)
and ringed salamanders (A. annulatum). Head morphometrics and stable isotopic values of carbon (δ¹³C) and
nitrogen (δ¹⁵N) were used to identify the presence or absence of structural cannibalism. Weather conditions were
also analyzed as a potential factor associated with the expression of cannibalistic morphology.
RESULTS: Populations of salamander larvae did not consistently exhibit cannibalistic morphologies throughout
collection periods. Larval long-toed salamanders exhibited trophic polymorphisms when relatively lower precipitation
amounts were observed. Larval ringed salamanders were observed to be cannibalistic but did not exhibit polymorphisms
in this study.
CONCLUSIONS: Structural cannibalism may be transient in both species; however in long-toed salamanders this
morphology is necessary for cannibalism. Ringed salamanders can be cannibalistic without morphological adaptations;
however the cannibal morph may prolong the viable time period for cannibalism. Additionally, weather conditions may
alter pond hydroperiod, subsequently influencing head morphology and cannibalism.Keywords: Nitrogen-15, Trophic polymorphism, Carbon-13, Larval salamander, Stable isotope, Cannibalis
Grassroots Agency: Participation and Conflict in Buenos Aires Shantytowns seen through the Pilot Plan for Villa 7 (1971–1975)
open access articleIn 1971, after more than a decade of national and municipal policies aimed at the top-down removal of shantytowns, the Buenos Aires City Council approved the Plan Piloto para la Relocalización de Villa 7 (Pilot Plan for the Relocation of Shantytown 7; 1971–1975, referred to as the Pilot Plan hereinafter). This particular plan, which resulted in the construction of the housing complex, Barrio Justo Suárez, endures in the collective memory of Argentines as a landmark project regarding grassroots participation in state housing initiatives addressed at shantytowns. Emerging from a context of a housing shortage for the growing urban poor and intense popular mobilizations during the transition to democracy, the authors of the Pilot Plan sought to empower shantytown residents in novel ways by: 1) maintaining the shantytown’s location as opposed to eradication schemes that relocated the residents elsewhere, 2) formally employing some of the residents for the stage of construction, as opposed to “self-help” housing projects in which the residents contributed with unpaid labor, and 3) including them in the urban and architectural design of the of the new housing.
This paper will examine the context in which the Pilot Plan was conceived of as a way of re-assessing the roles of the state, the user, and housing-related professionals, often seen as antagonistic. The paper argues that residents’ fair participation and state intervention in housing schemes are not necessarily incompatible, and can function in specific social and political contexts through multiactor proposals backed by a political will that prioritizes grassroots agency
Effectiveness of multiple-capture live traps for field behavioral studies of microtine rodents
Progestin Receptor-Mediated Reduction of Anxiety-Like Behavior in Male Rats
BACKGROUND: It is well known progesterone can have anxiolytic-like effects in animals in a number of different behavioral testing paradigms. Although progesterone is known to influence physiology and behavior by binding to classical intracellular progestin receptors, progesterone's anxiety reducing effects have solely been attributed to its rapid non-genomic effects at the GABA A receptor. This modulation occurs following the bioconversion of progesterone to allopregnanolone. Seemingly paradoxical results from some studies suggested that the function of progesterone to reduce anxiety-like behavior may not be entirely clear; therefore, we hypothesized that progesterone might also act upon progestin receptors to regulate anxiety. METHODOLOGY/PRINCIPAL FINDINGS: To test this, we examined the anxiolytic-like effects of progesterone in male rats using the elevated plus maze, a validated test of anxiety, and the light/dark chamber in the presence or absence of a progestin receptor antagonist, RU 486. Here we present evidence suggesting that the anxiolytic-like effects of progesterone in male rats can be mediated, in part, by progestin receptors, as these effects are blocked by prior treatment with a progestin receptor antagonist. CONCLUSION/SIGNIFICANCE: This indicates that progesterone can act upon progestin receptors to regulate anxiety-like behavior in the male rat brain
Actions of Calcium on Smooth Muscle a
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72185/1/j.1749-6632.1988.tb33358.x.pd
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