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Physiological Situations (physiological + situation)
Selected AbstractsSex Hormones and Sexual DesireJOURNAL FOR THE THEORY OF SOCIAL BEHAVIOUR, Issue 1 2008JAMES GILES ABSTRACT Some scholars attempt to explain sexual desire biologically by claiming that sex hormones play a necessary causal role in sexual desire. This can be claimed even if sexual desire is seen to be an experience. Yet the evidence for such biological essentialism is inadequate. With males the loss of sexual desire following hormonal changes can easily be explained in terms of social stigmas that are attached to the physiological situation. Concerning females, the relevance of sex hormones here is even more unclear. Although some women seem to have fluctuations in sexual desire during hormonal changes, other women do not. Even where there are such fluctuations these can be explained by responses to other physiological changes or the meanings that are attached to the situation. Research with non-human primates supports this view of the non-essential relation of sex hormones to sexual desire. A phenomenology of sex hormones is given that shows a possible non-essential relation between sex hormones and sexual desire. Here hormone induced excitations in the genitals may or may not lead to sexual desire depending on the meaning they are given within awareness. This suggests that sexual desire has its origin in the meanings we give our biology and not in our biology itself. [source] A mathematical model of immune competition related to cancer dynamicsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 6 2010Ilaria Brazzoli Abstract This paper deals with the qualitative analysis of a model describing the competition among cell populations, each of them expressing a peculiar cooperating and organizing behavior. The mathematical framework in which the model has been developed is the kinetic theory for active particles. The main result of this paper is concerned with the analysis of the asymptotic behavior of the solutions. We prove that, if we are in the case when the only equilibrium solution if the trivial one, the system evolves in such a way that the immune system, after being activated, goes back toward a physiological situation while the tumor cells evolve as a sort of progressing travelling waves characterizing a typical equilibrium/latent situation. Copyright © 2009 John Wiley & Sons, Ltd. [source] Assessment of CD8 involvement in T,cell clone avidity by direct measurement of HLA-A2/Mage3 complex density using a high-affinity TCR like monoclonal antibodyEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2005Karine Bernardeau Abstract Peptide affinity for MHC molecules determines the number of MHC/peptide complexes stabilized at the cell surface in in vitro tests or in vaccination protocols. We isolated a high affinity monoclonal antibody specific for the HLA-A2/Mage3 complex that enables an equilibrium binding assay to be performed on T2 cell line loaded with a range of Mage3 peptides. Binding of Mage3 to the HLA-A2 molecule can be modeled by a standard receptor-ligand interaction characterized by an affinity constant. This model enables the measurement of the affinity of other immunogenic peptides for HLA-A2 by a competition test and the calculation of the density of complexes stabilized at the T2 cell surface for all peptide concentrations. Quantification of the HLA-A2/Mage3 complexes at target cell surfaces was used to estimate the number of complexes required to reach cytotoxicity ED50 of human T,cell clones sorted from an unprimed repertoire. We confirm with this antibody the direct relationship between clone avidity and TCR affinity, and the moderate contribution of the CD8 co-receptor in the reinforcement of TCR-MHC/peptide contact. Nevertheless, CD8 plays a critical role in the amplification of the specific signal to establish an efficient T,cell response at low specific complex densities found in physiological situations. [source] Mast cells and their role in the neuro-immune-endocrine axisEXPERIMENTAL DERMATOLOGY, Issue 9 2004J. Bienenstock It has become clear that the immune and nervous systems communicate constantly to maintain homeostasis and a coordinated and continuing adaptive response to an ever-changing environment. Evidence from mast cell nerve communication, as an example of this interaction, has been obtained in a variety of tissues and circumstances, most especially in the intestine and skin. Bidirectional communication has been shown in vivo, ex vivo, in vitro and in coculture experiments involving the two cell types. Examples will be given of these various situations and involve normal physiological situations and those involved in response to infection and inflammation as well as in response to ultraviolet light. More recent examples of the importance of mast cells in the regulation of central nervous activity including the secretion of hormones by the pituitary gland, and thereby the regulation of the HPA axis as well as involvement in behavioural change will be addressed. Through its potential communication with the nervous system, the mast cell can be regarded as a sentinel cell or receptor, especially located at surfaces exposed to the environment, which specifically and non-specifically react to molecules and substances, foreign to the organism, so as to help orchestrate the complex and integrated responses required to maintain homeostasis. [source] Gene activation cascade triggered by a single photoperiodic cycle inducing flowering in Sinapis albaTHE PLANT JOURNAL, Issue 6 2009Maria D'Aloia Summary Molecular genetic analyses in Arabidopsis disclosed a genetic pathway whereby flowering is induced by the photoperiod. This cascade is examined here within the time course of floral transition in the long-day (LD) plant Sinapis alba induced by a single photoperiodic cycle. In addition to previously available sequences, the cloning of CONSTANS (SaCO) and FLOWERING LOCUS T (SaFT) homologues allowed expression analyses to be performed to follow the flowering process step by step. A diurnal rhythm in SaCO expression in the leaves was observed and transcripts of SaFT were detected when light was given in phase with SaCO kinetics only. This occurred when day length was extended or when a short day was shifted towards a ,photophile phase'. The steady-state level of SaFT transcripts in the various physiological situations examined was found to correlate like a rheostat with floral induction strength. Kinetics of SaFT activation were also consistent with previous estimations of translocation of florigen out of leaves, which could actually occur after the inductive cycle. In response to one 22-h LD, initiation of floral meristems by the shoot apical meristem (SAM) started about 2 days after activation of SaFT and was marked by expression of APETALA1 (SaAP1). Meanwhile, LEAFY (SaLFY) was first up-regulated in leaf primordia and in the SAM. FRUITFULL (SaFUL) was later activated in the whole SAM but excluded from floral meristems. These patterns are integrated with previous observations concerning upregulation of SUPPRESSOR OF OVEREXPRESSION OF CO1 (SaSOC1) to provide a temporal and spatial map of floral transition in Sinapis. [source] Changes in Vein Dynamics Ranging from Low to High Pressure Levels as a Determinant of the Differences in Vein Adaptation to Arterial Hemodynamic ConditionsARTIFICIAL ORGANS, Issue 7 2007Yanina Zócalo Abstract:, The causes of the regional differences in venous grafts patency rates are partially understood. Differences in vein dynamics during physiological situations could determine differences in veins' capability to face arterial conditions and could contribute to the dissimilar performance of veins as arterial grafts. In vitro pressure and diameter were measured in four different veins during physiological and arterial (graft) pressure conditions. A diameter,pressure transfer function was designed. Compliance, viscous and inertial properties; circumferential stresses and deformation; and buffering function were calculated. Regional differences in veins' dynamics, but not in buffering function were found during physiological and arterial conditions. The back vein (femoral) showed the least changes when submitted to arterial conditions. Arterial conditions represent different changes in vein dynamics depending on the segment considered. The regional differences in vein dynamics, both at physiological and graft conditions, could contribute to explain the dissimilar results of venous grafts. [source] Expanding roles for AMP-activated protein kinase in neuronal survival and autophagyBIOESSAYS, Issue 9 2009Jeroen Poels Abstract AMP-activated protein kinase (AMPK) is an evolutionarily conserved cellular switch that activates catabolic pathways and turns off anabolic processes. In this way, AMPK activation can restore the perturbation of cellular energy levels. In physiological situations, AMPK senses energy deficiency (in the form of an increased AMP/ATP ratio), but it is also activated by metabolic insults, such as glucose or oxygen deprivation. Metformin, one of the most widely prescribed anti-diabetic drugs, exerts its actions by AMPK activation. However, while the functions of AMPK as a metabolic regulator are fairly well understood, its actions in neuronal cells only recently gained attention. This review will discuss newly emerged functions of AMPK in neuroprotection and neurodegeneration. Additionally, recent views on the role of AMPK in autophagy, an important catabolic process that is also involved in neurodegeneration and cancer, will be highlighted. [source] | |||||||||||||