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External Agents (external + agent)
Selected AbstractsFROM IDEAS TO CONCEPTS TO METAPHORS: THE GERMAN TRADITION OF INTELLECTUAL HISTORY AND THE COMPLEX FABRIC OF LANGUAGEHISTORY AND THEORY, Issue 2 2010ELÍAS JOSÉ PALTI ABSTRACT Recently, the diffusion of the so-called "new intellectual history" led to the dismissal of the old school of the "history of ideas" on the basis of its ahistorical nature (the view of ideas as eternal entities). This formulation is actually misleading, missing the core of the transformation produced in the field. It is not true that the history of ideas simply ignored the fact that the meaning of ideas changes over time. The issue at stake here is really not how ideas changed (the mere description of the semantic transformation they underwent historically), but rather why they do. The study of the German tradition of intellectual history serves in this essay as a basis to illustrate the meaning and significance of the recent turn from ideas as its object. In the process of trying to account for the source of contingency of conceptual formations, it will open our horizon to the complex nature of the ways by which we invest the world with meaning. That is, it will disclose the presence of different layers of symbolic reality lying beneath the surface level of "ideas," and analyze their differential nature and functions. It will also show the reasons for the ultimate failure of the "history of ideas" approach, why discourses can never achieve their vocation to constitute themselves as self-enclosed, rationally integrated systems, thereby expelling contingency from their realm. In sum, it will show why historicity is not merely something that comes to intellectual history from without (as a by-product of social history or as the result of the action of an external agent), as the history of ideas assumed, but is a constitutive dimension of it. [source] Environmental carcinogens and p53 tumor-suppressor gene interactions in a transgenic mouse model for mammary carcinogenesisENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2-3 2002Daniel Medina Abstract Mouse mammary tumorigenesis is greatly influenced by a variety of exogenous agents, such as MMTV, chemical carcinogens (i.e., polycyclic aromatic hydrocarbons), and radiation, as well as by endogenous/physiological factors, such as steroid hormones, tumor-suppressor genes (i.e., Brca1/2,p53), and gene products of modifier genes. In the mouse model, the most frequently used chemical carcinogen has been 7,12-dimethylbenz[a]anthracene (DMBA), which activates the Ha- ras gene but does not alter the p53 tumor-suppressor gene. However, on an existing background of p53 gene alteration, low doses of DMBA are strongly cocarcinogenic. Using a transgenic model system, in which the p53 gene was deleted in the mammary gland, we examined the carcinogenic effects of a variety of external agents and internal factors given at either low doses or physiological doses. These agents/factors included DMBA, ,-radiation, Brca2 heterozygosity, and steroid hormones. All agents/factors increased the tumorigenic response of the p53 null mammary cells, even under conditions where no tumorigenic response was observed in the p53 wildtype mammary cell. The strongest cocarcinogenic effect was observed with the steroid hormone progesterone. The majority of tumors were highly aneuploid and composed of nuclear igh-grade cells. The mechanism for the aneuploidy and secondary events associated with high tumorigenicity were examined using array technology. These results demonstrate that, on a background of underlying genetic instability, very low doses of environmental mutagens and mitogens can produce strong cocarcinogenic effects. Environ. Mol. Mutagen. 39:178,183, 2002. © 2002 Wiley-Liss, Inc. [source] Characterization of 1H NMR detectable mobile lipids in cells from human adenocarcinomasFEBS JOURNAL, Issue 5 2009Anna Maria Luciani Magnetic resonance spectroscopy studies are often carried out to provide metabolic information on tumour cell metabolism, aiming for increased knowledge for use in anti-cancer treatments. Accordingly, the presence of intense lipid signals in tumour cells has been the subject of many studies aiming to obtain further insight on the reaction of cancer cells to external agents that eventually cause cell death. The present study explored the relationship between changes in neutral lipid signals during cell growth and after irradiation with gamma rays to provide arrest in cell cycle and cell death. Two cell lines from human tumours were used that were differently prone to apoptosis following irradiation. A sub-G1 peak was present only in the radiosensitive HeLa cells. Different patterns of neutral lipids changes were observed in spectra from intact cells, either during unperturbed cell growth in culture or after radiation-induced growth arrest. The intensities of triglyceride signals in the spectra from extracted total lipids changed concurrently. The increase in lipid peak intensities did not correlate with the apoptotic fate. Modelling to fit the experimental data revealed a dynamic equilibrium between the production and depletion of neutral lipids. This is observed for the first time in cells that are different from adipocytes. [source] Dispersal of freshwater invertebrates by large terrestrial mammals: a case study with wild boar (Sus scrofa) in Mediterranean wetlandsFRESHWATER BIOLOGY, Issue 11 2008BRAM VANSCHOENWINKEL Summary 1.,Many invertebrates inhabiting insular aquatic habitats rely on external agents or vectors to disperse. Besides water connections and wind, waterfowl and amphibians are known to mediate passive dispersal of freshwater invertebrates. However, the possibility of dispersal by terrestrial mammals has been largely overlooked. 2.,We investigated the potential of both external and internal zoochorous dispersal of aquatic invertebrates by the wild boar (Sus scrofa) in Mediterranean wetlands in the Camargue (France). As wild boar frequently visit wetlands for feeding and wallowing purposes, we hypothesized that they may be important passive dispersal vectors of aquatic invertebrates at a local scale. Dried mud was collected from selected ,rubbing trees' used by boars to dispose of parasites. Additionally, faecal pellets were collected from different locations in the wetland area. 3.,Seventeen freshwater invertebrate taxa including rotifers, cladocerans, copepods and ostracods hatched from sediment obtained from ,rubbing trees', while invertebrates hatching from dried faeces (10 taxa) were mainly rotifers. Dispersing invertebrates were collected up to 318 m from a nearest potential dispersal source. Both abundance and richness of invertebrates significantly decreased with dispersal distance. 4.,Our results demonstrate that large mammals such as wild boar can act as dispersal vectors of aquatic invertebrates at a local scale in the wetland area of the Camargue and suggest that external transport may be quantitatively more important than internal transport. As wallowing (mud bathing) is common in many terrestrial mammals, this mode of dispersal may be quite widespread. [source] Exploring social capital in rural settlements of an islander region in GreeceJOURNAL OF COMMUNITY & APPLIED SOCIAL PSYCHOLOGY, Issue 2 2010Anastasia Zissi Abstract This paper reports on a large scale cross-sectional study examining subjective perceptions of community social life held by a randomly selected sample of residents (n,=,428) in all small rural settings (n,=,89) of the region of North Aegean Sea. The notion of social capital was used as a conceptual tool in order to explore different aspects of the relational life of contemporary rural communities. This study has two aims: First to provide an account of rural residents' perceptions of village life in terms of interpersonal support, mutual aid, trust, social cohesion and community competence, and second to examine the suitability of the social capital notion within the specific cultural context. A combination of data collection procedures and a range of sources were employed, such as key informants, rural residents and researchers' field observations. The findings indicate that small farming communities of high devotion with deep roots and strong sense of belonging face severe demographic imbalance and experience low civic power given the limited links with external agents. The mainstream notion of social capital as an unconditionally beneficial factor is thus questioned. The findings call for revisiting its relevance across communities with varying capacities and needs. Copyright © 2009 John Wiley & Sons, Ltd. [source] Photosensitivity skin disorders in childhoodPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 2 2008Irene Horkay Summary Photosensitivity in childhood is caused by a diverse group of diseases. It usually indicates idiopathic photodermatoses, first of all polymorphic light eruption. It may be an early symptom of genetic disorders such as porphyria or very rare genophotodermatoses. Photosensitivity secondary to topical or systemic external agents as well as photoexacerbated dermatoses is not so frequent in childhood. Here we present our experience with childhood photosensitivity skin diseases collected over a 40-year period. [source] | ||||||||||