The G protein-coupling specificity of D2-like dopamine receptors

The G-protein coupling specificity of D2-like dopamine receptors was investigated using both receptor-G protein fusions and membranes of cells in which pertussis toxin-resistant mutants of individual Gi-family G proteins could be expressed in an inducible fashion. A range of ligands displayed agonism at the long isoform of the human dopamine D2 receptor. However, varying degrees of efficacy were observed for individual ligands as monitored by their capacity to load [35S] GTPγS onto each of Gi1, Gi2, Gi3 and Go1. By contrast, S-(-)-3-(3-hydroxyphenyl)-N-propylpiperidine (S-(-)-3PPP) was a partial agonist when Go1 was the target G protein but an antagonist/inverse agonist at Gi1, Gi2, Gi3. In ligand binding assays dopamine identified both high and low affinity states at each of the dopamine D2 receptor-G protein fusion proteins and the high affinity state was eliminated by guanine nucleotide. S-(-)-3PPP bound to an apparent single state of the constructs where the D2 receptor was fused to Gi1, Gi2 or Gi3. However, it bound to distinct high and low affinity states of the D2 receptor-Go1 fusion with the high affinity state being eliminated by guanine nucleotide. Similarly, although dopamine identified guanine nucleotide-sensitive high affinity states of the D2 receptor when expression of pertussis toxin-resistant forms of either Gi2 or Go1 was induced, S-(-)-3PPP identified a high affinity site only in the presence of Go1. These results demonstrate S-(-)-3PPP to be a protean agonist at the D2l receptor and may explain in vivo actions of this ligand. Furthermore, in agreement with previous studies, the ability of the dopamine D2l receptor to couple promiscuously to Gαi1-3, and Gαo1 was demonstrated. However, despite high homology between dopamine D2l and D3 receptors, the G protein-coupling specificity of the D3 receptor has not been well characterised. Again using both receptor-G protein fusions and membranes of cells in which pertussis toxin-resistant mutants of individual Gi-family G proteins could be expressed in an inducible fashion, we confirmed the selective coupling of the D3 receptor to Gαo1. A range of ligands displayed agonism at the D2l receptor and the D3 receptor when coupled to Gαo1. As a general trend, agonists, including dopamine, displayed a higher potency at the D3 receptor. This perhaps reflects the role of D3 as an autoreceptor. Of particular interest was the demonstration that S-(-)-3PPP has both a higher efficacy and potency at the D3 receptor when coupled to Gαo1. The investigations into dopamine receptor-G protein coupling highlighted the utility of the [35S]GTPγS binding assay as a method of directly measuring receptor catalysed nucleotide exchange on the α subunit of G proteins. However, the expense associated with the use of radiolabels makes this assay less attractive, particularly for high-throughput screening programmes. In an attempt to develop a non-radioactive assay equivalent to the [35S] GTPγS assay an immunisation programme was initiated to generate antibodies selective against the active (GTP bound) conformation of G proteins. 4 way primary screening of 1632 hybridomas generated from mice immunized with GTPS-loaded Gi1 and isolated using an automated robotic colony picker, identified 3 antibodies that interacted with the constitutively active Q204L but neither the constitutively inactive G203A nor wild type form of Gi1. This profile extended to other closely related Gi-family G proteins but not to the less closely related Gs and Gq/G11 families. Each of these antibodies was, however, also able to identify wild type, GDP-bound Gi- family G proteins in the presence of AlF4- which mimics the presence of the terminal phosphate of GTP and hence generates an active conformation of the G protein. Stimulation of cells co-expressing a wild type Gisubunit and the dopamine D2 receptor with the agonist ligand nor-apomorphine also allowed these conformation selective antibodies to bind the G protein. Such reagents allow the development of label- free assays for G protein-coupled receptor-mediated activation of Gi- family G proteins

High-resolution numerical modelling of flow-vegetation interactions

In this paper, we present and apply a new three-dimensional model for the prediction of canopy-flow and turbulence dynamics in open-channel flow. The approach uses a dynamic immersed boundary technique that is coupled in a sequentially staggered manner to a large eddy simulation. Two different biomechanical models are developed depending on whether the vegetation is dominated by bending or tensile forces. For bending plants, a model structured on the Euler–Bernoulli beam equation has been developed, whilst for tensile plants, an N-pendula model has been developed. Validation against flume data shows good agreement and demonstrates that for a given stem density, the models are able to simulate the extraction of energy from the mean flow at the stem-scale which leads to the drag discontinuity and associated mixing layer

Mississippian stratotypes

Working Group on the Mississippian of the U.S.A.Ope

On ordinal utility, cardinal utility, and random utility

Though the Random Utility Model (RUM) was conceived  entirely in terms of ordinal utility, the apparatus throughwhich it is widely practised exhibits properties of  cardinal utility.  The adoption of cardinal utility as a  working operation of ordinal is perfectly valid, provided  interpretations drawn from that operation remain faithful  to ordinal utility.  The paper considers whether the latterrequirement holds true for several measurements commonly  derived from RUM.  In particular it is found that  measurements of consumer surplus change may depart from  ordinal utility, and exploit the cardinality inherent in  the practical apparatus.

Prolonged non-metabolic heart rate variability reduction as a physiological marker of psychological stress in daily life

BACKGROUND\nProlonged cardiac activity that exceeds metabolic needs can be detrimental for somatic health. Psychological stress could result in such "additional cardiac activity."\nPURPOSE\nIn this study, we examined whether prolonged additional reductions in heart rate variability (AddHRVr) can be measured in daily life with an algorithm that filters out changes in HRV that are purely due to metabolic demand, as indexed by movement, using a brief calibration procedure. We tested whether these AddHRVr periods were related to worry, stress, and negative emotions.\nMETHODS\nMovement and the root of the mean square of successive differences (RMSSD) in heart rate were measured during a calibration phase and the subsequent 24 h in 32 participants. Worry, stress, explicit and implicit emotions were assessed hourly using smartphones. The Levels of Emotional Awareness Scale and resting HRV were used to account for individual differences. During calibration, person-specific relations between movement and RMSSD were determined. The 24-h data were used to detect prolonged periods (i.e., 7.5 min) of AddHRVr.\nRESULTS\nAddHRVr periods were associated with worrying, with decreased explicit positive affect, and with increased tension, but not with the frequency of stressful events or implicit emotions. Only in people high in emotional awareness and high in resting HRV did changes in AddHRVr covary with changes in explicit emotions.\nCONCLUSIONS\nThe algorithm can be used to capture prolonged reductions in HRV that are not due to metabolic needs. This enables the real-time assessment of episodes of potentially detrimental cardiac activity and its psychological determinants in daily life.FSW - Self-regulation models for health behavior and psychopathology - ou

Investigating the autonomic nervous system and cognitive functions as potential mediators of an association between cardiovascular disease and driving performance

Abstract: Cardiovascular disease (CVD) impacts the autonomic nervous system and cognitive functions related to activities of daily living, including driving an automobile. Although CVD has been linked to unsafe driving, mechanisms underlying this relationship remain elusive. The aim of this study was to examine the role of cognitive functions and the autonomic nervous system as potential mediators of driving performance. Nineteen individuals having recently suffered a cardiac event and sixteen individuals with no history of CVD completed a simulated drive using a STISIM simulator to assess driving performance. Heart rate was recorded throughout testing using a Polar RS800CX heart rate monitor and measures of executive, orienting and alerting functions were obtained through the Attention Network Test. We used the Baron and Kenny analysis method to assess potential mediating effects of the relationship between CVD and driving performance. Executive function was the only potential mediator investigated to be associated with driving (p < 0.01) and CVD (p < 0.05), however, it did not appear to play a mediating role (p = 0.28). These results suggest that individuals with CVD exhibit decrements in complex cognitive tasks such as driving and that further research is needed to better understand the mechanisms underlying this relationship

Ecological momentary assessment of emotional awareness: preliminary evaluation of psychometric properties

Stress and Psychopatholog

Inducing unconscious stress: subliminal anger and relax primes show similar cardiovascular activity patterns

Stress-related stimuli may be presented outside of awareness and may ultimately influence health by causing repetitive increases in physiological parameters, such as blood pressure (BP). In this study, we aimed to corroborate previous studies that demonstrated BP effects of subliminally presented stress-related stimuli. This would add evidence to the hypothesis that unconscious manifestations of stress can affect somatic health. Additionally, we suggest that these findings may be extended by measuring affective changes relating to these physiological changes, using measures for self-reported and implicit positive and negative affectivity. Using a repeated measures between-subject design, we presented either the prime word “angry” (n = 26) or “relax” (n = 28) subliminally (17 ms) for 100 trials to a student sample and measured systolic and diastolic BP, heart rate (HR), and affect. The “angry” prime, compared to the “relax” prime, did not affect any of the outcome variables. During the priming task, a higher level of implicit negative affect (INA) was associated with a lower systolic BP and diastolic BP. No association was found with HR. Self-reported affect and implicit positive affect were not related to the cardiovascular (CV) activity. In sum, anger and relax primes elicited similar CV activity patterns, but implicit measures of affect may provide a new method to examine the relationship between (unconscious) stress and health.Health and self-regulatio

Ecological momentary assessment of emotional awareness: preliminary evaluation of psychometric properties

The Levels of Emotional Awareness Scale (LEAS) is a well-validated performance measure of trait emotional awareness (EA), which is associated with psychological and physical problems. EA is, however, expected to vary over time and we aimed to adapt the LEAS to permit the measurement of EA in daily life as a function of momentary state. Twenty-five students completed 12 ecological momentary assessments (EMAs) of EA across 2 days. The correlation between the mean EMAs of EA and trait EA, and the change over time in EA, was also examined. Findings revealed a significant positive correlation between state and trait EA. The within-person reliability was substantial, suggesting that EMAs can reliably assess EA over time across individuals. Importantly, latent state-trait analysis showed that about 50% of EA variability was due to state variance whereas only 2% of EA variability was due to trait variance. Preliminary psychometric properties suggest that the developed method allows for the measurement of EA in daily life and supports the claim that EA can be measured using both hypothetical (as in the LEAS) and real-life (using EMAs) scenarios.Prevention, Population and Disease management (PrePoD)Public Health and primary car

The Green, Green Grass of Home: an archaeo-ecological approach to pastoralist settlement in central Kenya

© 2016 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This paper considers the ecological residues of pastoralist occupation at the site of Maili Sita in Laikipia, central Kenya, drawing links with the archaeological record so as to contribute a fresh approach to the ephemeral settlement sites of mobile herding communities, a methodological aspect of African archaeology that remains problematic. Variations in the geochemical and micromorphological composition of soils along transects across the site are compared with vegetation distributions and satellite imagery to propose an occupation pattern not dissimilar to contemporary Cushitic-speaking groups further north. We argue that Maili Sita exemplifies the broad migratory and cultural exchange networks in place during the mid- to late second millennium AD, with pastoralist occupants who were both physically and culturally mobile.British Academy (2002-5 Funding) European Union - Marie Curie Initiatives (EXT grant 2007-11