Novel Situations (novel + situation)

Distribution by Scientific Domains

Selected Abstracts

Endothelium-derived hyperpolarizing factor as an in vivo back-up mechanism in the cutaneous microcirculation in old mice

Marie Line Gaubert
There is now strong evidence that an endothelium-derived hyperpolarizing factor (EDHF), other than nitric oxide (NO) or prostaglandin (PG), exists for dilating arteries and arterioles. In vitro studies on isolated vessels pointed out a role for EDHF as a back-up mechanism when the NO pathway is impaired, but there was a lack of in vivo studies showing a functional role for EDHF. Ageing has pronounced effects on vascular function and particularly on endothelium-dependent relaxation, providing a novel situation in which to assess the contributions of EDHF. The purpose of the present study was thus to determine if, in vivo, there was a functional role for EDHF as a back-up mechanism in the cutaneous microcirculation in the ageing process. We investigated in vivo the contribution of each endothelial factor (NO, PG and EDHF) in the cutaneous vasodilatation induced by iontophoretic delivery of acetylcholine and local pressure application in young adult (6,7 months) and old (22,25 months) mice, using pharmacological inhibitors. The cutaneous vasodilator responses induced by acetylcholine and local pressure application were dependent upon NO and PG pathways in young adult mice, whereas they were EDHF-dependent in old mice. EDHF appears to serve as a back-up mechanism when ageing reaches pathological states in terms of the ability for NO and PG to relax cutaneous microvessels, allowing for persistent cutaneous vasodilatator responses in old mice. However, as a back-up mechanism, EDHF did not completely restore cutaneous vasodilatation, since endothelial responses were reduced in old mice compared to young adult mice. [source]

Brain mechanisms underlying emotional alterations in the peripartum period in rats

Inga D. Neumann
Abstract In the period before and after parturition, i.e., in pregnancy and lactation, a variety of neuroendocrine alterations occur that are accompanied by marked behavioral changes, including emotional responsiveness to external challenging situations. On the one hand, activation of neuroendocrine systems (oxytocin, prolactin) ensures reproduction-related physiological processes, but in a synergistic manner also ensures accompanying behaviors necessary for the survival of the offspring. On the other hand, there is a dramatic reduction in the responsiveness of neuroendocrine systems to stimuli not relevant for reproduction, such as the hypothalamo-pituitary-adrenal (HPA) axis responses to physical or emotional stimuli in both pregnant and lactating rats. With CRH being the main regulator of the HPA axis, downregulation of the brain CRH system may result in various behavioral, in particular emotional, adaptations of the maternal organisms, including changes in anxiety-related behavior. In support of this, the lactating rat becomes less emotionally responsive to novel situations, demonstrating reduced anxiety, and shows a higher degree of aggressive behavior in the test for agonistic behavior as well as in the maternal defense test. These changes in emotionality are independent of the innate (pre-lactation) level of anxiety and are seen in both rats bred for high as well as low levels of anxiety. Both brain oxytocin and prolactin, highly activated at this time, play a significant role in these behavioral and possibly also neuroendocrine adaptations in the peripartum period. Depression and Anxiety 17:111,121, 2003. 2003 Wiley-Liss, Inc. [source]

The Transposition of EU Law: ,Post-Decisional Politics' and Institutional Autonomy

Dionyssis G. Dimitrakopoulos
The transposition of European Union (EU) law into national law is a significant part of the EU policy process. However, political scientists have not devoted to it the attention that it deserves. Here, transposition is construed as part of the wider process of policy implementation. Drawing on implementation theory from the field of public policy, the article outlines three sets of factors (institutional, political, and substantive) that affect transposition. Second, the article examines the manner in which eight member states transpose EU legislation, and identifies a European style of transposition. An institutionalist approach is employed to argue that this style is not the result of a process of convergence. Rather, it stems from the capacity of institutions to adapt to novel situations by means of their own standard operating procedures and institutional repertoires. It concludes by highlighting (a) the partial nature of efforts at EU level to improve transposition, themselves impaired by the politics of the policy process and (b) some ideas regarding future research. [source]

Genetic influences on behavioral inhibition and anxiety in juvenile rhesus macaques

J. Rogers
In humans and other animals, behavioral responses to threatening stimuli are an important component of temperament. Among children, extreme behavioral inhibition elicited by novel situations or strangers predicts the subsequent development of anxiety disorders and depression. Genetic differences among children are known to affect risk of developing behavioral inhibition and anxiety, but a more detailed understanding of genetic influences on susceptibility is needed. Nonhuman primates provide valuable models for studying the mechanisms underlying human behavior. Individual differences in threat-induced behavioral inhibition (freezing behavior) in young rhesus monkeys are stable over time and reflect individual levels of anxiety. This study used the well-established human intruder paradigm to elicit threat-induced freezing behavior and other behavioral responses in 285 young pedigreed rhesus monkeys. We examined the overall influence of quantitative genetic variation and tested the specific effect of the serotonin transporter promoter repeat polymorphism. Quantitative genetic analyses indicated that the residual heritability of freezing duration (behavioral inhibition) is h2 = 0.384 (P = 0.012) and of ,orienting to the intruder' (vigilance) is h2 = 0.908 (P = 0.00001). Duration of locomotion and hostility and frequency of cooing were not significantly heritable. The serotonin transporter polymorphism showed no significant effect on either freezing or orienting to the intruder. Our results suggest that this species could be used for detailed studies of genetic mechanisms influencing extreme behavioral inhibition, including the identification of specific genes that are involved in predisposing individuals to such behavior. [source]

The possible functions of involuntary autobiographical memories

Anne S. Rasmussen
Involuntary autobiographical memories are memories of personal experiences that come to mind spontaneously,that is with no preceding attempt at retrieval. We propose that such memories form a basic mode of remembering that is as frequent, common and functional as voluntary remembering but presumably evolutionarily earlier than the latter. In contrast to voluntary recall, the activation of involuntary memories involves little executive control. It typically depends on a distinct feature-overlap between the remembered and current situation, which favours the activation of specific episodic information. Involuntary remembering may serve the overarching function of providing a sense of continuity across time, thereby automatically updating our personal sense of existence. Furthermore, since involuntary memories yield fast access to memories of specific events with a distinctive content-overlap to the current situation, they may serve important directive functions in novel situations. Copyright 2009 John Wiley & Sons, Ltd. [source]

Recurring main-chain anion-binding motifs in short polypeptides: nests

E. James Milner-White
A novel tripeptide motif called a nest has recently been described in proteins with the function of binding anionic, or partially anionic, atoms such as carbonyl O atoms. In the present work, a search for nests in small polypeptides stored in the Cambridge Structural Database is reported. 37 unique examples were found: over half form part of hydrogen-bond arrangements resembling those in proteins, such as Schellman/paperclip loop motifs, various types of ,-turn and Asx-turns or Ser/Thr-turns, while a third are in novel situations, some involving binding to anionic groups from other molecules within the crystal complex. An example is the antibiotic vancomycin, which incorporates a prominent nest forming part of a peptide-binding site. This nest binds the carboxylate of the C-terminal d -alanine of the bacterial cell-wall precursor peptide, thereby inhibiting the final step of bacterial cell-wall synthesis. As in proteins, a number of nests occur in short peptides with an alternating glycine/l -amino-acid sequence but, uniquely to non-ribosomally synthesized short peptides, several nests within them are constructed from alternating d - and l -amino acids, and such sequences seem to specially favour nests. [source]