Home About us Contact
|
Home About us Contact | ||
|
|
||
Many Arguments (many + argument)
Selected Abstracts,-cell development: the role of intercellular signalsDIABETES OBESITY & METABOLISM, Issue 2008R. Scharfmann Understanding in detail how pancreatic endocrine cells develop is important for many reasons. From a scientific point of view, elucidation of such a complex process is a major challenge. From a more applied point of view, this may help us to better understand and treat specific forms of diabetes. Although a variety of therapeutic approaches are well validated, no cure for diabetes is available. Many arguments indicate that the development of new strategies to cure diabetic patients will require precise understanding of the way ,-cells form during development. This is obvious for a future cell therapy using ,-cells produced from embryonic stem cells. This also holds true for therapeutic approaches based on regenerative medicine. In this review, we summarize our current knowledge concerning pancreatic development and focus on the role of extracellular signals implicated in ,-cell development from pancreatic progenitors. [source] A predator's perspective of nest predation: predation by red squirrels is learned, not incidentalOIKOS, Issue 5 2010Shawna A. Pelech Nest predation has been used to explain aspects of avian ecology ranging from nest site selection to population declines. Many arguments rely on specific assumptions regarding how predators find nests, yet these predatory mechanisms remain largely untested. Here we combine artificial nest experiments with behavioural observations of individual red squirrels Tamiasciurus hudsonicus to differentiate between two common hypotheses: predation is incidental versus learned. Specifically, we tested: 1) whether nest survival could be explained solely by a squirrel's activity patterns or habitat use, as predicted if predation was incidental; or 2) if predation increased as a squirrel gained experience preying on a nest, as predicted if predation was learned. We also monitored squirrel activity after predation to test for evidence of two search mechanisms: area-restricted searching and use of microhabitat search images. Contrary to incidental predation and in support of learning, squirrels did not find nests faster in areas with high use (e.g. forest edges). Instead, survival of artificial nests was strongly related to a squirrel's prior experience preying on artificial nests. Experience reduced nest survival times by over half and increased predation rates by 150,200%. Squirrels returned to and doubled their activity at the site of a previously preyed on nest. However, neither area-restricted searching nor microhabitat search images can explain how squirrels located artificial nests more readily with experience. Instead, squirrels likely used cues associated with the nests or eggs themselves. Learning implies that squirrels could be increasingly effective predators as the density or profitability of nests increases. Our results add support to the view that nest predation is complex and broadly influenced (e.g. by predator experience, motivation), and is unlikely to be predicted consistently by simple relationships with predator activity, abundance or habitat. [source] Review of animal models for autism: implication of thyroid hormoneCONGENITAL ANOMALIES, Issue 1 2006Miyuki Sadamatsu ABSTRACT,, Autism is a behaviorally defined disorder associated with characteristic impairments in social interactions and communication, as well as restricted and repetitive behaviors and interest. Its prevalence was once thought to be 2/10 000, but recently several large autism prevalence reviews revealed that the rate of occurrence was roughly 30/10 000. While it has been considered a developmental disorder, little is certain about its etiology. Neuroanatomical studies at the histological level in the brains of autistic patients provide many arguments in the etiology of autism. Results from postmortem and imaging studies have implicated many major structures of the brain including the limbic system, cerebellum, corpus callosum, basal ganglia and brainstem. There is no single biological or clinical marker for autism. While several promising candidate genes have been presented, the critical loci are yet unknown. Environmental influences such as rubella virus, valproic acid, and thalidomide exposure during pregnancy are also considered important, as concordance in monozygotic twins is less than 100% and the phenotypic expression of the disorder varies widely. It is thus hypothesized that non-genetic mechanisms contribute to the onset of autistic syndrome. In light of these ambiguities, hope is held that an animal model of autism may help elucidate matters. In this article, we overview most of the currently available animal models for autism, and propose the rat with mild and transient neonatal hypothyroidism as a novel model for autism. [source] Coming Down to Earth on Cloning: An Ecofeminist Analysis of Homophobia in the Current DebateHYPATIA, Issue 4 2006Victoria DavionArticle first published online: 9 JAN 200 In this essay, Davion argues that many arguments appealing to an "intuition" that reproductive cloning is morally wrong because it is "unnatural" rely upon an underlying moral assumption that only heterosexuality is "natural," an assumption that grounds extreme homophobia in America. Therefore, critics of cloning who are in favor of gay and lesbian equality have reasons to avoid prescriptive appeals to the so-called "natural" in making their arguments. Davion then suggests anticloning arguments that do not make such appeals. [source] VIII,An Argument Against Motivational InternalismPROCEEDINGS OF THE ARISTOTELIAN SOCIETY (HARDBACK), Issue 1part2 2008Elinor Mason I argue that motivational internalism should not be driving metaethics. I first show that many arguments for motivational internalism beg the question by resting on an illicit appeal to internalist assumptions about the nature of reasons. Then I make a distinction between weak internalism and the weakest form of internalism. Weak internalism allows that agents fail to act according to their normative judgments when they are practically irrational. I show that when we clarify the notion of practical irrationality it does not support motivational internalism. Weakest internalism only claims that agents are irrational if they entirely lack motivation to do what they judge they ought to. I do not argue against weakest internalism, but I argue that it is not an important view. [source] Oxidative stress: The special case of diabetesBIOFACTORS, Issue 1-2 2003N. F. Wiernsperger Abstract The implication of oxidative stress (OS) in diabetes is a major concern for the development of therapeutics aimed at improving the metabolic and/or vascular dysfunctions of this burdening disease. Ample evidence is available suggesting that OS is present in essentially all tissues and can even be observed in prediabetic states. This raises the question of the origin of OS and suggests that, although hyperglycemia is largely linked with free radical production, its role may mainly be the aggravation of a preexisting state. Indeed other factors are also causally linked to OS, such as hormones and lipids. The main debate is about the pertinence of antioxidant therapy since the large scale clinical trials performed recently have essentially failed to show any significant improvement in metabolic or vascular disturbances of diabetic patients. However this conclusion must be tempered by the fact that they have mainly been using vitamin E +/-C; indeed many arguments suggest that either the choice or the application modalities of these substances may have been inadequate. Potential reasons for the actual failure of antioxidant therapy in diabetes are discussed; the indisputable involvement of OS in this disease still leaves hope for alternative therapeutic approaches. [source] | |||||||||||||