154 research outputs found
Recommended from our members
Indirect effect of financial strain on daily cortisol output through daily negative to positive affect index in the Coronary Artery Risk Development in Young Adults Study
Daily affect is important to health and has been linked to cortisol. The combination of high negative affect and low positive affect may have a bigger impact on increasing HPA axis activity than either positive or negative affect alone. Financial strain may both dampen positive affect as well as increase negative affect, and thus provides an excellent context for understanding the associations between daily affect and cortisol. Using random effects mixed modeling with maximum likelihood estimation, we examined the relationship between self-reported financial strain and estimated mean daily cortisol level (latent cortisol variable), based on six salivary cortisol assessments throughout the day, and whether this relationship was mediated by greater daily negative to positive affect index measured concurrently in a sample of 776 Coronary Artery Risk Development in Young Adults (CARDIA) Study participants. The analysis revealed that while no total direct effect existed for financial strain on cortisol, there was a significant indirect effect of high negative affect to low positive affect, linking financial strain to elevated cortisol. In this sample, the effects of financial strain on cortisol through either positive affect or negative affect alone were not significant. A combined affect index may be a more sensitive and powerful measure than either negative or positive affect alone, tapping the burden of chronic financial strain, and its effects on biology
Recommended from our members
Indirect effect of financial strain on daily cortisol output through daily negative to positive affect index in the Coronary Artery Risk Development in Young Adults Study
Daily affect is important to health and has been linked to cortisol. The combination of high negative affect and low positive affect may have a bigger impact on increasing HPA axis activity than either positive or negative affect alone. Financial strain may both dampen positive affect as well as increase negative affect, and thus provides an excellent context for understanding the associations between daily affect and cortisol. Using random effects mixed modeling with maximum likelihood estimation, we examined the relationship between self-reported financial strain and estimated mean daily cortisol level (latent cortisol variable), based on six salivary cortisol assessments throughout the day, and whether this relationship was mediated by greater daily negative to positive affect index measured concurrently in a sample of 776 Coronary Artery Risk Development in Young Adults (CARDIA) Study participants. The analysis revealed that while no total direct effect existed for financial strain on cortisol, there was a significant indirect effect of high negative affect to low positive affect, linking financial strain to elevated cortisol. In this sample, the effects of financial strain on cortisol through either positive affect or negative affect alone were not significant. A combined affect index may be a more sensitive and powerful measure than either negative or positive affect alone, tapping the burden of chronic financial strain, and its effects on biology
What can we really learn from positron flux 'anomalies'?
We present a critical analysis of the observational constraints on, and of
the theoretical modeling of, aspects of cosmic ray (CR) generation and
propagation in the Galaxy, which are relevant for the interpretation of recent
positron and anti-proton measurements. We give simple, analytic, model
independent expressions for the secondary pbar flux, and an upper limit for the
secondary e+ flux, obtained by neglecting e+ radiative losses, e+/(e+ +
e-)<0.2\pm0.1 up to ~300 GeV. These expressions are completely determined by
the rigidity dependent grammage, which is measured from stable CR secondaries
up to ~150 GeV/nuc, and by nuclear cross sections measured in the laboratory.
pbar and e+ measurements, available up to ~100 GeV, are consistent with these
estimates, implying that there is no need for new, non-secondary, pbar or e+
sources. The radiative loss suppression factor f_{s,e+} of the e+ flux depends
on the e+ propagation in the Galaxy, which is not understood theoretically. A
rough, model independent estimate of f_{s,e+} 1/3 can be obtained at a single
energy, E\sim20 GeV, from unstable secondary decay and is found to be
consistent with e+ measurements, including the positron fraction measured by
PAMELA. We show that specific detailed models, that agree with compositional CR
data, agree with our simple expressions for the e+ and pbar flux, and that the
claims that the positron fraction measured by PAMELA requires new primary e+
sources are based on assumptions, that are not supported by observations. If
PAMELA results are correct, they suggest that f_{s,e+} is slightly increasing
with energy, which provides an interesting constraint on CR propagation models.
We argue that measurements of the e+ to pbar ratio are more useful for
challenging secondary production models than the positron fraction.Comment: 16 pages, 10 figures, minor revisions, accepted for publication in
MNRA
Local enrichment and its nonlocal consequences for victim-exploiter metapopulations
The stabilizing effects of local enrichment are revisited. Diffusively
coupled host-parasitoid and predator-prey metapopulations are shown to admit a
stable fixed point, limit cycle or stable torus with a rich bifurcation
structure. A linear toy model that yields many of the basic qualitative
features of this system is presented. The further nonlinear complications are
analyzed in the framework of the marginally stable Lotka-Volterra model, and
the continuous time analog of the unstable, host-parasitoid Nicholson-Bailey
model. The dependence of the results on the migration rate and level of spatial
variations is examined, and the possibility of "nonlocal" effect of enrichment,
where local enrichment induces stable oscillations at a distance, is studied. A
simple method for basic estimation of the relative importance of this effect in
experimental systems is presented and exemplified.Comment: 25 pages, 13 figures, to appear physica D 200
Chronic psychosocial and financial burden accelerates 5-year telomere shortening: findings from the Coronary Artery Risk Development in Young Adults Study.
Leukocyte telomere length, a marker of immune system function, is sensitive to exposures such as psychosocial stressors and health-maintaining behaviors. Past research has determined that stress experienced in adulthood is associated with shorter telomere length, but is limited to mostly cross-sectional reports. We test whether repeated reports of chronic psychosocial and financial burden is associated with telomere length change over a 5-year period (years 15 and 20) from 969 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a longitudinal, population-based cohort, ages 18-30 at time of recruitment in 1985. We further examine whether multisystem resiliency, comprised of social connections, health-maintaining behaviors, and psychological resources, mitigates the effects of repeated burden on telomere attrition over 5 years. Our results indicate that adults with high chronic burden do not show decreased telomere length over the 5-year period. However, these effects do vary by level of resiliency, as regression results revealed a significant interaction between chronic burden and multisystem resiliency. For individuals with high repeated chronic burden and low multisystem resiliency (1 SD below the mean), there was a significant 5-year shortening in telomere length, whereas no significant relationships between chronic burden and attrition were evident for those at moderate and higher levels of resiliency. These effects apply similarly across the three components of resiliency. Results imply that interventions should focus on establishing strong social connections, psychological resources, and health-maintaining behaviors when attempting to ameliorate stress-related decline in telomere length among at-risk individuals
The Power of Exercise: Buffering the Effect of Chronic Stress on Telomere Length
Background: Chronic psychological stress is associated with detrimental effects on physical health, and may operate in part through accelerated cell aging, as indexed by shorter telomeres at the ends of chromosomes. However, not all people under stress have distinctly short telomeres, and we examined whether exercise can serve a stress-buffering function. We predicted that chronic stress would be related to short telomere length (TL) in sedentary individuals, whereas in those who exercise, stress would not have measurable effects on telomere shortening. Methodology and Principal Findings: 63 healthy post-menopausal women underwent a fasting morning blood draw for whole blood TL analysis by a quantitative polymerase chain reaction method. Participants completed the Perceived Stress Scale (Cohen et al., 1983), and for three successive days reported daily minutes of vigorous activity. Participants were categorized into two groups-sedentary and active (those getting Centers for Disease Control-recommended daily amount of activity). The likelihood of having short versus long telomeres was calculated as a function of stress and exercise group, covarying age, BMI and education. Logistic regression analyses revealed a significant moderating effect of exercise. As predicted, among non-exercisers a one unit increase in the Perceived Stress Scale was related to a 15-fold increase in the odds of having short telomeres (p,.05), whereas in exercisers, perceived stress appears to be unrelated to TL (B = 2.59, SE =.78, p =.45)
Probenecid Inhibits the Human Bitter Taste Receptor TAS2R16 and Suppresses Bitter Perception of Salicin
Bitter taste stimuli are detected by a diverse family of G protein-coupled receptors (GPCRs) expressed in gustatory cells. Each bitter taste receptor (TAS2R) responds to an array of compounds, many of which are toxic and can be found in nature. For example, human TAS2R16 (hTAS2R16) responds to β-glucosides such as salicin, and hTAS2R38 responds to thiourea-containing molecules such as glucosinolates and phenylthiocarbamide (PTC). While many substances are known to activate TAS2Rs, only one inhibitor that specifically blocks bitter receptor activation has been described. Here, we describe a new inhibitor of bitter taste receptors, p-(dipropylsulfamoyl)benzoic acid (probenecid), that acts on a subset of TAS2Rs and inhibits through a novel, allosteric mechanism of action. Probenecid is an FDA-approved inhibitor of the Multidrug Resistance Protein 1 (MRP1) transporter and is clinically used to treat gout in humans. Probenecid is also commonly used to enhance cellular signals in GPCR calcium mobilization assays. We show that probenecid specifically inhibits the cellular response mediated by the bitter taste receptor hTAS2R16 and provide molecular and pharmacological evidence for direct interaction with this GPCR using a non-competitive (allosteric) mechanism. Through a comprehensive analysis of hTAS2R16 point mutants, we define amino acid residues involved in the probenecid interaction that result in decreased sensitivity to probenecid while maintaining normal responses to salicin. Probenecid inhibits hTAS2R16, hTAS2R38, and hTAS2R43, but does not inhibit the bitter receptor hTAS2R31 or non-TAS2R GPCRs. Additionally, structurally unrelated MRP1 inhibitors, such as indomethacin, fail to inhibit hTAS2R16 function. Finally, we demonstrate that the inhibitory activity of probenecid in cellular experiments translates to inhibition of bitter taste perception of salicin in humans. This work identifies probenecid as a pharmacological tool for understanding the cell biology of bitter taste and as a lead for the development of broad specificity bitter blockers to improve nutrition and medical compliance
An overview of progress in electrolytes for secondary zinc-air batteries and other storage systems based on zinc
The revived interest and research on the development of novel energy storage systems with exceptional inherent
safety, environmentally benign and low cost for integration in large scale electricity grid and electric
vehicles is now driven by the global energy policies. Within various technical challenges yet to be resolved
and despite extensive studies, the low cycle life of the zinc anode is still hindering the implementation of
rechargeable zinc batteries at industrial scale. This review presents an extensive overview of electrolytes for
rechargeable zinc batteries in relation to the anode issues which are closely affected by the electrolyte nature.
Widely studied aqueous electrolytes, from alkaline to acidic pH, as well as non-aqueous systems including
polymeric and room temperature ionic liquids are reported. References from early rechargeable Zn-air research
to recent results on novel Zn hybrid systems have been analyzed. The ambition is to identify the challenges
of the electrolyte system and to compile the proposed improvements and solutions. Ultimately, all the
technologies based on zinc, including the more recently proposed novel zinc hybrid batteries combining the
strong points of lithium-ion, redox-flow and metal-air systems, can benefit from this compilation in order to
improve secondary zinc based batteries performance.Basque Country University
(ZABALDUZ2012 program), and the Basque Country Government
(Project: CIC energiGUNÉ16 of the ELKARTEK program) and the
European Commission through the project ZAS: “Zinc Air Secondary
innovative nanotech based batteries for efficient energy storage”
(Grant Agreement 646186
- …