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Extensive Evidence (extensive + evidence)
Selected AbstractsHistamine H3 receptor-mediated impairment of contextual fear conditioning and in-vivo inhibition of cholinergic transmission in the rat basolateral amygdalaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2001M. Beatrice Passani Abstract We investigated the effects of agents acting at histamine receptors on both, spontaneous release of ACh from the basolateral amygdala (BLA) of freely moving rats, and fear conditioning. Extensive evidence suggests that the effects of histamine on cognition might be explained by the modulation of cholinergic systems. Using the microdialysis technique in freely moving rats, we demonstrated that perfusion of the BLA with histaminergic compounds modulates the spontaneous release of ACh. The addition of 100 mm KCl to the perfusion medium strongly stimulated ACh release, whereas, 0.5 µm tetrodotoxin (TTX) inhibited spontaneous ACh release by more than 50%. Histaminergic H3 antagonists (ciproxifan, clobenpropit and thioperamide), directly administered to the BLA, decreased ACh spontaneous release, an effect fully antagonized by the simultaneous perfusion of the BLA with cimetidine, an H2 antagonist. Local administration of cimetidine alone increased ACh spontaneous release slightly, but significantly. Conversely, the administration of H1 antagonists failed to alter ACh spontaneous release. Rats receiving intra-BLA, bilateral injections of the H3 antagonists at doses similar to those inhibiting ACh spontaneous release, immediately after contextual fear conditioning, showed memory consolidation impairment of contextual fear conditioning. Post-training, bilateral injections of 50 µg scopolamine also had an adverse effect on memory retention. These observations provide the first evidence that histamine receptors are involved in the modulation of cholinergic tone in the amygdala and in the consolidation of fear conditioning. [source] A role for the Werner syndrome protein in epigenetic inactivation of the pluripotency factor Oct4AGING CELL, Issue 4 2010Johanna A. Smith Summary Werner syndrome (WS) is an autosomal recessive disorder, the hallmarks of which are premature aging and early onset of neoplastic diseases (Orren, 2006; Bohr, 2008). The gene, whose mutation underlies the WS phenotype, is called WRN. The protein encoded by the WRN gene, WRNp, has DNA helicase activity (Gray et al., 1997; Orren, 2006; Bohr, 2008; Opresko, 2008). Extensive evidence suggests that WRNp plays a role in DNA replication and DNA repair (Chen et al., 2003; Hickson, 2003; Orren, 2006; Turaga et al., 2007; Bohr, 2008). However, WRNp function is not yet fully understood. In this study, we show that WRNp is involved in de novo DNA methylation of the promoter of the Oct4 gene, which encodes a crucial stem cell transcription factor. We demonstrate that WRNp localizes to the Oct4 promoter during retinoic acid-induced differentiation of human pluripotent cells and associates with the de novo methyltransferase Dnmt3b in the chromatin of differentiating pluripotent cells. Depletion of WRNp does not affect demethylation of lysine 4 of the histone H3 at the Oct4 promoter, nor methylation of lysine 9 of H3, but it blocks the recruitment of Dnmt3b to the promoter and results in the reduced methylation of CpG sites within the Oct4 promoter. The lack of DNA methylation was associated with continued, albeit greatly reduced, Oct4 expression in WRN-deficient, retinoic acid-treated cells, which resulted in attenuated differentiation. The presented results reveal a novel function of WRNp and demonstrate that WRNp controls a key step in pluripotent stem cell differentiation. [source] Potential of Marine Reserves to Cause Community-Wide Changes beyond Their BoundariesCONSERVATION BIOLOGY, Issue 2 2007PAOLO GUIDETTI arrecifes rocosos templados; cambios a nivel comunitario; cascadas tróficas; estados comunitarios alternativos; exceso de pesca; reservas marinas Abstract:,Fishing and other human activities can alter the abundances, size structure, and behavior of species playing key roles in shaping marine communities (e.g., keystone predators), which may in turn cause ecosystem shifts. Despite extensive evidence that cascading trophic interactions can underlie community-wide recovery inside no-take marine reserves by protecting high-level predators, the spatial extent of these effects into adjacent fished areas is unknown. I examined the potential for community-wide changes (i.e., the transition from overgrazed coralline barrens to macroalgal beds) in temperate rocky reefs within and around a no-take marine reserve. For this purpose I assessed distribution patterns of predatory fishes, sea urchins, and barrens across the reserve boundaries. Predatory fishes were significantly more abundant within the reserve than in adjacent locations, with moderate spillover across the reserve edges. In contrast, community-wide changes of benthic assemblages were apparent well beyond the reserve boundaries, which is consistent with temporary movements of predatory fishes (e.g., foraging migration) from the reserve to surrounding areas. My results suggest that no-take marine reserves can promote community-wide changes beyond their boundaries. Resumen:,La pesca y otras actividades humanas pueden alterar la abundancia, tamaño, estructura y comportamiento de las especies que juegan papeles clave en el modelado de las comunidades marinas (e.g., depredadores clave), que a su vez pueden causar cambios en los ecosistemas. No obstante la evidencia extensiva de que las interacciones tróficas en cascada pueden subyacer en la recuperación de la comunidad dentro de reservas marinas que no permiten la pesca mediante la protección de depredadores de nivel alto, se desconoce la extensión espacial de estos efectos en áreas adyacentes. Examiné el potencial de los cambios a nivel comunidad (i.e., la transición de áreas coralinas sobre pastoreadas a lechos de microalgas) en arrecifes rocosos templados dentro y alrededor de una reserva marina sin pesca. Para este propósito, evalué los patrones de distribución de peces depredadores, erizos de mar y áreas sobre pastoreadas en los límites de la reserva. Los peces depredadores fueron significativamente más abundantes dentro de la reserva que en localidades adyacentes, con un excedente moderado en los bordes de la reserva. En contraste, los cambios a nivel de comunidad en los ensambles bénticos fueron aparentes más allá de los límites de la reserva, lo que es consistente con los movimientos temporales de los peces depredadores (e.g., migración de forrajeo) desde la reserva hacia las áreas circundantes. Mis resultados sugieren que las reservas que no permiten la pesca pueden promover cambios a nivel comunidad más allá de sus límites. [source] The sleep of co-sleeping infants when they are not co-sleeping: Evidence that co-sleeping is stressfulDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2002Melissa Hunsley Abstract Co-sleeping proponents consider the practice to be "natural" and a potential protection against sudden infant death syndrome (SIDS); others consider the practice of an infant sleeping in the parents' bed for prolonged periods at night to place an infant at risk for harm or death. For this study, co-sleeping was investigated from a different perspective, that is, as a significant early experience to investigate as it may have implications for the infant's development. The sleep of 101 normal, full-term infants was recorded nonintrusively in the home for 24 hr periods when they were 5 weeks and 6 months old. Infants were assigned to three groups: short-term co-sleepers, long-term co-sleepers, and non-co-sleepers. Their sleep states and wakefulness were compared at the two ages and over age. At 5 weeks and 6 months, the long-term co-sleeping infants differed significantly from the non-co-sleepers on a number of measures: At 5 weeks, they showed more quiet sleep and longer bouts of quiet sleep; and at 6 months, they also showed less active sleep, fewer arousals in active sleep, and less wakefulness. Each of these differences indicates a markedly lower arousal level in the long-term co-sleeping infants. This sleep pattern has been repeatedly found to be an indicator of stress. We infer that a major source of stress for these infants is the experience of sleep disturbance documented for infants when they were co-sleeping. Based on extensive evidence for long-term effects of early stress, we conclude that co-sleeping should have significant implications for infants' neurobehavioral development. © 2002 John Wiley & Sons, Inc. Dev Psychobiol 40: 14,22, 2002 [source] Transferring HR practices within multinational corporationsHUMAN RESOURCE MANAGEMENT JOURNAL, Issue 4 2007Ingmar Björkman There is extensive evidence that planned transfers of management practices by the headquarters of multinational corporations (MNCs) to foreign subsidiaries are not always successful. In this article, we outline a model of factors influencing the transfer of HR practices to MNC units abroad. The article has two main contributions. First, we develop a more holistic understanding of the outcome of HR practice transfer as encompassing three dimensions: implementation, internalisation and integration. Second, we expand current explanations of transfers of practices to foreign units. We argue that transfer of HR practices is a social process where the governance mechanisms used by the MNC, characteristics of the subsidiary HR systems, the social relationship between the subsidiary and MNC headquarters, and the transfer approach taken by headquarters management will influence the outcome of the process. [source] Social Presence and Children: Praise, Intrinsic Motivation, and Learning With ComputersJOURNAL OF COMMUNICATION, Issue 1 2004Cheryl Campanella Bracken The computers are social actors (CASA) paradigm asserts that human computer users interact socially with computers, and the paradigm has provided extensive evidence that this is the case for adults. This experiment examined whether or not children have similar reactions to computers by comparing children's predictable responses to praise from a teacher to their responses to praise from a computer. Eight- to 10-year-old participants (N= 42) received either praise or neutral feedback from a computer. Independent variables were the feedback (praise or neutral), and participants' age and gender. Dependent variables measured via a paper-and-pencil questionnaire were learning (recall and recognition memory), perceived ability, and intrinsic motivation. Results provide evidence that children do have social responses to computers and that such social responses can lead to increases in learning (recall and recognition) in young children. [source] Schlieren formation in diatexite migmatite: examples from the St Malo migmatite terrane, FranceJOURNAL OF METAMORPHIC GEOLOGY, Issue 4 2003I. Milord Abstract Schlieren are trains of platy or blocky minerals, typically the ferromagnesian minerals and accessory phases, that occur in granites and melt-rich migmatites, such as diatexites. They have been considered as: (1) unmelted residue from xenoliths or the source region; (2) mineral accumulations formed during magma flow; (3) compositional layering; and (4) sites of melt loss. In order to help identify schlieren-forming processes in the diatexites at St Malo, differences in the size, shape, orientation, distribution and composition of the biotite from schlieren and from their hosts have been investigated. Small biotite grains are much less abundant in the schlieren than in their hosts. Schlieren biotite grains are generally larger, have greater aspect ratios and have, except in hosts with low (< 10%) biotite contents, a much stronger shape preferred orientation than host biotite. The compositional ranges of host and schlieren biotite are similar, but schlieren biotite defines tighter, sharper peaks on composition-frequency plots. Hosts show magmatic textures such as imbricated (tiled), unstrained plagioclase. Some schlieren show only magmatic textures (tiled biotite, no crystal-plastic strain features), but many have textures indicating submagmatic and subsolidus deformation (e.g. kinked grains) and these schlieren show the most extensive evidence for recrystallization. Magmas at St Malo initially contained a significant fraction of residual biotite and plagioclase crystals; smaller biotite grains were separated from the larger plagioclase crystals during magma flow. Since plagioclase was also the major, early crystallizing phase, the plagioclase-rich domains developed rapidly and reached the rigid percolation threshold first, forcing further magma flow to be concentrated into narrowing melt-rich zones where the biotite had accumulated, hence increasing shear strain and the degree of shape preferred orientation in these domains. Schlieren formed in these domains as a result of grain contacts and tiling in the grain inertia-regime. Final amalgamation of the biotite aggregates into schlieren involved volume loss as melt trapped between grains was expelled after the rigid percolation threshold was reached in the biotite-rich layers. [source] Epigenetics and the embodiment of race: Developmental origins of US racial disparities in cardiovascular healthAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2009Christopher W. Kuzawa The relative contribution of genetic and environmental influences to the US black-white disparity in cardiovascular disease (CVD) is hotly debated within the public health, anthropology, and medical communities. In this article, we review evidence for developmental and epigenetic pathways linking early life environments with CVD, and critically evaluate their possible role in the origins of these racial health disparities. African Americans not only suffer from a disproportionate burden of CVD relative to whites, but also have higher rates of the perinatal health disparities now known to be the antecedents of these conditions. There is extensive evidence for a social origin to prematurity and low birth weight in African Americans, reflecting pathways such as the effects of discrimination on maternal stress physiology. In light of the inverse relationship between birth weight and adult CVD, there is now a strong rationale to consider developmental and epigenetic mechanisms as links between early life environmental factors like maternal stress during pregnancy and adult race-based health disparities in diseases like hypertension, diabetes, stroke, and coronary heart disease. The model outlined here builds upon social constructivist perspectives to highlight an important set of mechanisms by which social influences can become embodied, having durable and even transgenerational influences on the most pressing US health disparities. We conclude that environmentally responsive phenotypic plasticity, in combination with the better-studied acute and chronic effects of social-environmental exposures, provides a more parsimonious explanation than genetics for the persistence of CVD disparities between members of socially imposed racial categories. Am. J. Hum. Biol., 2009. © 2008 Wiley-Liss, Inc. [source] A Prospective Study of p53 Expression and Its Correlation With Clinical Response of Radiotherapy in Nasopharyngeal Carcinoma,THE LARYNGOSCOPE, Issue 1 2001Kuen-Yao Ho MD Abstract Objectives/Hypothesis Nasopharyngeal carcinoma (NPC) is a common malignant neoplasm of the head and neck that occurs in people in the southeastern Asian area, including Taiwan. The significant association of p53 expression in NPC suggested that p53 overexpression seemed to occur at an early stage in the development of NPC. Alterations of p53 status were probably the most commonly encountered in head and neck carcinomas, and there was extensive evidence that p53 status might determine tumor response to therapy. Ionizing radiation was studied extensively for the relationship between its damaging effect and p53 status in human cancer cells. Study Design This study was carried out to investigate whether there was any correlation between overexpression of p53 protein and locoregional tumor response in patients with NPC treated with 7000 cGy of radiotherapy. Methods Sixty-eight patients (50 males, 18 females) with NPC who were diagnosed and treated with radiotherapy were studied prospectively. Before they had received a radiation dose of 7000 cGy in 35 fractions, five fractions a week, p53 status from a nasopharyngeal biopsy was studied using immunohistochemical staining (IHC). Results The locoregional response rate of primary tumor was analyzed statistically. Forty-seven patients (69.1%) showed positive p53 staining in their tumors. There were 5 positive stains in 6 squamous cell carcinomas (SCC; 83.3%), 34 positive in 53 non-keratinizing carcinomas (NKC; 64.2%), and 8 positive in 9 undifferentiated carcinomas (UC; 88.9%). The mean ages for patients with three different histopathologies were 48.5, 46.1, and 61.1 years. There were 8 patients (7 positive stains, 1 negative stain) with residual tumor after radiotherapy and all were NKC (6 males, 2 females). Therefore, the clinical response rate of primary tumor was 85.1% in positive p53 immunostaining (40 of 47 cases), 95.2% in those with no immunostaining (20 of 21 cases); the former was poorer in locoregional tumor response than the latter, but there was no significant difference (P >.05, ,2 test). Conclusions We conclude that there is no statistically significant correlation in locoregional response of primary tumor between p53 overexpression and radiotherapy in patients with NPC (P >.05, Fisher exact test). [source] Multi-disciplinary research on the past human ecology of the east Arabian coast: excavations at Hamriya and Tell Abraq (Emirate of Sharjah, United Arab Emirates)ARABIAN ARCHAEOLOGY AND EPIGRAPHY, Issue 1 2009Peter Magee The results of two seasons of research at Hamriya and Tell Abraq (Sharjah, UAE) by an international team of researchers are presented. The research has revealed extensive evidence for occupation from c. 5000 BC to the recent past adjoining lagoon areas that face the Arabian Gulf. C14 analysis of shells has contributed to understanding the chronology of settlement and also assisted our understanding of species-specific deviation from the global reservoir effect. [source] | |||||||||||||