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Selective Effects (selective + effects)
Selected AbstractsRegional and Selective Effects of Oestradiol and Progesterone on NMDA and AMPA Receptors in the Rat BrainJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2000We investigated the effect of 10 months ovariectomy and a correction therapy, 2 weeks before the rats were killed, of oestradiol, progesterone or their combination on NMDA and AMPA receptor binding in the hippocampus, dentate gyrus, striatum, nucleus accumbens and frontal cortex of the rat brain as well as on amino acid levels in frontal cortex. NMDA and AMPA binding densities were assayed by autoradiography using, respectively, l -[3H]glutamate and [3H]AMPA; amino acid concentrations were measured by high performance liquid chromatograhy (HPLC) coupled with UV detection. Ovariectomy was without effect on NMDA and AMPA binding density in all brain regions assayed except in the hippocampal CA1 region and dentate gyrus where it decreased NMDA binding density compared to intact rats values. Oestradiol restored and increased NMDA binding density in the CA1 subfield and the dentate gyrus of ovariectomized rats but, by contrast, it decreased binding density in the striatum and in the frontal cortex while having no effect in the CA2/3 subfield of the hippocampus and in the nucleus accumbens. Oestradiol was without effect on AMPA binding density in the hippocampus and the dentate gyrus but it reduced AMPA binding density in the striatum, the frontal cortex and the nucleus accumbens. Progesterone, and oestradiol combined with progesterone, decreased NMDA but not AMPA binding density in the frontal cortex of ovariectomized rats, and they were without effect on these receptors in the other brain regions assayed. Amino acid concentrations in the frontal cortex were unchanged after ovariectomy or steroid treatments. The effect of oestradiol in the hippocampus confirmed in the present study and our novel findings in the frontal cortex, striatum and nucleus accumbens may have functional significance for schizophrenia and neurodegenerative diseases. [source] Selective effects of Lactobacillus casei Shirota on T cell activation, natural killer cell activity and cytokine productionCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 2 2010H. Dong Summary Modulation of host immunity is an important potential mechanism by which probiotics confer health benefits. This study was designed to investigate the effects of a probiotic strain, Lactobacillus casei Shirota (LcS), on immune function using human peripheral blood mononuclear cells (PBMC) in vitro. In addition, the role of monocytes in LcS-induced immunity was also explored. LcS promoted natural killer (NK) cell activity and preferentially induced expression of CD69 and CD25 on CD8+ and CD56+ subsets in the absence of any other stimulus. LcS also induced production of interleukin (IL)-1,, IL-6, tumour necrosis factor (TNF)-,, IL-12 and IL-10 in the absence of lipopolysaccharide (LPS). In the presence of LPS, LcS enhanced IL-1, production but inhibited LPS-induced IL-10 and IL-6 production, and had no further effect on TNF-, and IL-12 production. Monocyte depletion reduced significantly the impact of LcS on lymphocyte activation, cytokine production and natural killer (NK) cell activity. In conclusion, LcS activated cytotoxic lymphocytes preferentially in both the innate and specific immune systems, which suggests that LcS could potentiate the destruction of infected cells in the body. LcS also induced both proinflammatory and anti-inflammatory cytokine production in the absence of LPS, but in some cases inhibited LPS-induced cytokine production. Monocytes play an important role in LcS-induced immunological responses. [source] WHEN SHOULD A TROPHICALLY TRANSMITTED PARASITE MANIPULATE ITS HOST?EVOLUTION, Issue 2 2009Geoffrey A. Parker We investigate evolution of two categories of adaptive host manipulation by trophically transmitted helminths: (1) predation suppression decreases the host's mortality before the helminth is capable of establishing in its next host; (2) predation enhancement increases the existing host's mortality after it can establish in its next host. If all parasite mortality is purely random (time-independent), enhancement must increase predation by the next host sufficiently more (depending on manipulative costs) than it increases the average for all forms of host mortality; thus if host and parasite die only through random predation, manipulation must increase the "right" predation more than the "wrong" predation. But if almost all parasites die in their intermediate host through reaching the end of a fixed life span, enhancement can evolve if it increases the right predation, regardless of how much it attracts wrong predators. Although enhancement is always most favorable when it targets the right host, suppression aids survival to the time when establishment in the next host is possible: it is most favorable if it reduces all aspects of host (and hence parasite) mortality. If constrained to have selective effects, suppression should reduce the commonest form of mortality. [source] MASKING INTERFERENCE AND THE EVOLUTION OF THE ACOUSTIC COMMUNICATION SYSTEM IN THE AMAZONIAN DENDROBATID FROG ALLOBATES FEMORALISEVOLUTION, Issue 9 2006Adolfo Amézquita Abstract The efficacy of communication relies on detection of species-specific signals against the background noise. Features affecting signal detection are thus expected to evolve under selective pressures represented by masking noise. Spectral partitioning between the auditory signals of co-occurring species has been interpreted as the outcome of the selective effects of masking interference. However, masking interference depends not only on signal's frequency but on receiver's range of frequency sensitivity; moreover, selection on signal frequency can be confounded by selection on body size, because these traits are often correlated. To know whether geographic variation in communication traits agrees with predictions about masking interference effects, we tested the hypothesis that variation in the male-male communication system of the Amazonian frog, Allobates femoralis, is correlated with the occurrence of a single species calling within an overlapping frequency range, Epipedobates trivittatus. We studied frogs at eight sites, four where both species co-occur and four where A. femoralis occurs but E. trivittatus does not. To study the sender component of the communication system of A. femoralis and to describe the use of the spectral range, we analyzed the signal's spectral features of all coactive species at each site. To study the receiver component, we derived frequency-response curves from playback experiments conducted on territorial males of A. femoralis under natural conditions. Most geographic variation in studied traits was correlated with either call frequency or with response frequency range. The occurrence of E. trivittatus significantly predicted narrower and asymmetric frequency-response curves in A. femoralis, without concomitant differences in the call or in body size. The number of acoustically coactive species did not significantly predict variation in any of the studied traits. Our results strongly support that the receiver but not the sender component of the communication system changed due to masking interference by a single species. [source] Individual differences in the response to forgone payoffs: an examination of high functioning drug abusersJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 2 2005Eldad Yechiam Abstract This study evaluates the effect of forgone payoffs in decision-making tasks used for studying individual differences. We investigate whether the disclosure of forgone payoffs (defined as payoffs associated with un-chosen alternatives) has selective effects for drug abusers. Evidence suggests that drug abusers are hypersensitive to signals of positive reward. Accordingly, because the forgone payoffs of risky high-variability options include rewarding outcomes, this may create a distraction and lead drug abusers to make more risky choices. In a controlled experiment, we examined the behavior of high-functioning drug abusers and healthy controls using the Iowa gambling task. The results showed that in a forgone payoff condition, drug abusers made more risky choices. The results demonstrate that adding information about forgone payoffs can be useful for studying individual differences, and that studying individual differences can be valuable in evaluating the effects of forgone payoffs. Copyright © 2005 John Wiley & Sons, Ltd. [source] Differential selection of growth rate-related traits in wild barley, Hordeum spontaneum, in contrasting greenhouse nutrient environmentsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2004K. J. F. Verhoeven Abstract Across-species comparisons show that inherent variation in relative growth rate (RGR) and its underlying traits are correlated with habitat productivity. In this study, we test the hypothesis that growth rate-related traits confer differential selective effects in contrasting nutrient environments. We specifically test whether high RGR is targeted by selection in nutrient-rich environments whereas low values of traits that underlie RGR [specific leaf area (SLA), leaf mass fraction and leaf area ratio (LAR)] confer a direct fitness advantage in nutrient-poor environments, resulting in selection of low RGR as a correlated response. We measured RGR, its underlying component traits, and estimated fitness in a range of wild barley (Hordeum spontaneum) accessions grown under high and low nutrient conditions. Selection on component traits differed between the two environments, while total selection of RGR was not significant. Using multiple regression and path analysis to estimate direct fitness effects, a selective advantage of high LAR and SLA was demonstrated only under nutrient-rich conditions. While supporting the view that observed associations between habitat richness and some RGR-component traits reflect adaptation to differing nutrient regimes, our data suggest that direct selection targets component traits rather than RGR itself. [source] A review of the likely effects of climate change on anadromous Atlantic salmon Salmo salar and brown trout Salmo trutta, with particular reference to water temperature and flowJOURNAL OF FISH BIOLOGY, Issue 10 2009B. Jonsson The present paper reviews the effects of water temperature and flow on migrations, embryonic development, hatching, emergence, growth and life-history traits in light of the ongoing climate change with emphasis on anadromous Atlantic salmon Salmo salar and brown trout Salmo trutta. The expected climate change in the Atlantic is for milder and wetter winters, with more precipitation falling as rain and less as snow, decrease in ice-covered periods and frequent periods with extreme weather. Overall, thermal limits for salmonids are species specific. Scope for activity and growth and optimal temperature for growth increase with temperature to an optimal point before constrain by the oxygen content of the water. The optimal temperature for growth decreases with increasing fish size and varies little among populations within species, whereas the growth efficiency may be locally adapted to the temperature conditions of the home stream during the growth season. Indirectly, temperature influences age and size at smolting through its effect on growth. Time of spawning, egg hatching and emergence of the larvae vary with temperature and selective effects on time of first feeding. Traits such as age at first maturity, longevity and fecundity decrease with increasing temperature whilst egg size increases with temperature. Water flow influences the accessibility of rivers for returning adults and speed of both upstream and downstream migration. Extremes in water flow and temperature can decrease recruitment and survival. There is reason to expect a northward movement of the thermal niche of anadromous salmonids with decreased production and population extinction in the southern part of the distribution areas, migrations earlier in the season, later spawning, younger age at smolting and sexual maturity and increased disease susceptibility and mortality. Future research challenges are summarized at the end of the paper. [source] Mechanisms of inflammation in spinal cord injuryJOURNAL OF NEUROCHEMISTRY, Issue 2002D. S. Rafati The inflammatory response initiated after spinal cord injury (SCI) is characterized by an increase in cytokines, notably IL-1,. Among its effects are the transcriptional control of cyclooxygenase 2 (COX-2) and the inducible form of nitric oxide synthase (iNOS). While they may ameliorate inflammation, they may also cause cellular damage via production of reactive oxygen species (O2 , ., OH·, NO·). The transcription factor NF-,B is a key intermediary in the signalling pathways leading from IL-1, expression to COX-2 and iNOS stimulation. Binding of NF-,B can be abrogated by the use of oligonucleotide ,decoys' that compete for the cognate endogenous NF-,B proteins. Using injections of fluorescent ,decoy' oligonucleotides into two-month-old-male rats after SCI into the site of injury, we found prompt, robust and transient uptake of labelled ,decoys' into both cytoplasm and nuclei of resident cells. Injection of ,decoys' containing the NF-,B binding sequences present in the COX-2 promoter region, together with a ,nonsense' sequence, showed selective effects on iNOS expression at the site of injury. These results are consistent with the hypothesis that NF-,B transcriptional regulation of COX-2 and iNOS are linked and may be an element in the pathophysiology and recovery of mammalian spinal cord after contusion injury. Acknowledgements:, Supported in part by NINDS Grant NS-39161 and Shriners Hospital Grant 8710. [source] White Adipose Tissue: Getting NervousJOURNAL OF NEUROENDOCRINOLOGY, Issue 11 2003E. Fliers Abstract Neuroendocrine research has altered the traditional perspective of white adipose tissue (WAT) as a passive store of triglycerides. In addition to fatty acids, WAT produces many hormones and can therefore be designated as a traditional endocrine gland actively participating in the integrative physiology of fuel and energy metabolism, eating behaviour and the regulation of hormone secretion and sensitivity. WAT is controlled by humoral factors, para- and intracrine factors and by neural regulation. Sympathetic nerve fibres innervate WAT and stimulate lipolysis, leading to the release of glycerol and free fatty acids. In addition, recent research in rats has clearly shown a functional parasympathetic innervation of WAT. There appears to be a distinct somatotopy within the parasympathetic nuclei: separate sets of autonomic neurones in the brain stem innervate either the visceral or the subcutaneous fat compartment. We therefore propose that the central nervous system (CNS) plays a major role in the hitherto unexplained regulation of body fat distribution. Parasympathectomy induces insulin resistance with respect to glucose and fatty acid uptake in the innervated fat depot and has selective effects on local hormone synthesis. Thus, the CNS is involved not only in the regulation of hormone production by WAT, but also in its hormone sensitivity. The developments in this research area are likely to increase our insights in the pathogenesis of metabolic disorders such as hypertriglyceridemia, diabetes mellitus type 2 and lipodystrophy syndromes. [source] Psychological Well-being: Evidence Regarding its Causes and Consequences,APPLIED PSYCHOLOGY: HEALTH AND WELL-BEING, Issue 2 2009Felicia A Huppert This review focuses on positive aspects of well-being, or flourishing. It examines evidence for the causes of positive well-being and also its consequences, including beneficial effects for many aspects of cognitive functioning, health, and social relationships. The neurobiological basis of psychological well-being is examined, and recent data on brain activation and neurochemical pathways are presented. Individuals vary widely in their habitual level of psychological well-being, and there is evidence for a seminal role of social factors and the early environment in this process. It is often assumed that the drivers of well-being are the same as (but in the opposite direction to) the drivers of ill-being, but while this is true for some drivers, others have more selective effects. Future developments in the science of well-being and its application require a fresh approach,beyond targeting the alleviation of disorder to a focus on personal and interpersonal flourishing. A universal intervention approach is outlined which may both increase population flourishing and reduce common mental health problems. [source] An analysis of the selective effects of NCR with punishment targeting problem behavior associated with positive affectBEHAVIORAL INTERVENTIONS, Issue 2 2001Karena S. Rush Among individuals with developmental disabilities and behavioral problems, self-injury and aggression are often associated with negative affect such as crying. In the current report, we present data on two children who displayed problem behaviors (screaming and self-injury) that were often associated with positive affect. In contrast to their other problem behaviors that were socially mediated, these behaviors were maintained independent of social consequences. One concern about treating problem behavior associated with positive affect is that the treatment may produce generalized reductions in positive affect. In both cases presented in the current study, the reductive effects of a treatment targeting these behaviors were highly selective, producing decreases in screaming and self-injury, while minimally affecting affect. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||||||||