166 research outputs found
Recent interpretations of Plato's social philosophy as fascistic
Thesis (Ph.D.)--Boston UniversityThe purpose of this dissertation, stated in the first chapter, is to examine the recent interpretations of Plato's social philosophy as fascistic and to determine the validity of these interpretations relative to the whole structure of Plato's social thought. The term "recent" refers broadly to the period extending from the close of World War I to the close of World War II.
The second chapter presents an exegesis of Plato's Doctrine of Justice as the key to a general understanding of his social and political perspective. It is pointed out that what he has to say about psychology and anthropology represents a microcosmic picture of what he believes about politics and sociology. His aim to achieve harmony in the individual soul is matched by his desire to bring unity to the political community. The latter is not only patterned after the former but, as a social ideal, it is also derived from it and dependent on it. The ideal State comes into being and social justice is established when the rulers bring harmony to their souls by the rule of reason and each individual is assigned to the task for which he is best suited. Thus, the Doctrine of Justice presents political as well as psychological facets germane to the evaluation of Plato's social philosophy and the attacks made against it [TRUNCATED
Subcellular organization of UBE3A in human cerebral cortex.
BackgroundLoss of UBE3A causes Angelman syndrome, whereas excess UBE3A activity appears to increase the risk for autism. Despite this powerful association with neurodevelopmental disorders, there is still much to be learned about UBE3A, including its cellular and subcellular organization in the human brain. The issue is important, since UBE3A's localization is integral to its function.MethodsWe used light and electron microscopic immunohistochemistry to study the cellular and subcellular distribution of UBE3A in the adult human cerebral cortex. Experiments were performed on multiple tissue sources, but our results focused on optimally preserved material, using surgically resected human temporal cortex of high ultrastructural quality from nine individuals.ResultsWe demonstrate that UBE3A is expressed in both glutamatergic and GABAergic neurons, and to a lesser extent in glial cells. We find that UBE3A in neurons has a non-uniform subcellular distribution. In somata, UBE3A preferentially concentrates in euchromatin-rich domains within the nucleus. Electron microscopy reveals that labeling concentrates in the head and neck of dendritic spines and is excluded from the PSD. Strongest labeling within the neuropil was found in axon terminals.ConclusionsBy highlighting the subcellular compartments in which UBE3A is likely to function in the human neocortex, our data provide insight into the diverse functional capacities of this E3 ligase. These anatomical data may help to elucidate the role of UBE3A in Angelman syndrome and autism spectrum disorder
A Probabilistic View of Certain Weighted Fibonacci Sums
In this article, we pursue the reverse strategy of using probability to derive an and develop an exponential generating function for an in Section 3. In Section 4, we present a method for finding an exact, non-recursive, formula for an
Angelman syndrome: insights into genomic imprinting and neurodevelopmental phenotypes
Angelman syndrome (AS) is a severe genetic disorder caused by mutations or deletions of the maternally inherited UBE3A gene. UBE3A encodes an E3 ubiquitin ligase that is expressed biallelically in most tissues but is maternally expressed in almost all neurons. In this review, we describe recent advances in understanding the expression and function of UBE3A in the brain and the etiology of AS. We highlight current AS model systems, epigenetic mechanisms of UBE3A regulation, and the identification of potential UBE3A substrates in the brain. In the process, we identify major gaps in our knowledge that, if bridged, could move us closer to identifying treatments for this debilitating neurodevelopmental disorder
Loss of UBE3A from TH-expressing neurons suppresses GABA co-release and enhances VTA-NAc optical self-stimulation
Motivated reward-seeking behaviours are governed by dopaminergic ventral tegmental area projections to the nucleus accumbens. In addition to dopamine, these mesoaccumbal terminals co-release other neurotransmitters including glutamate and GABA, whose roles in regulating motivated behaviours are currently being investigated. Here we demonstrate that loss of the E3-ubiquitin ligase, UBE3A, from tyrosine hydroxylase-expressing neurons impairs mesoaccumbal, non-canonical GABA co-release and enhances reward-seeking behaviour measured by optical self-stimulation
Decreased Axon Caliber Underlies Loss of Fiber Tract Integrity, Disproportional Reductions in White Matter Volume, and Microcephaly in Angelman Syndrome Model Mice
Angelman syndrome (AS) is a debilitating neurodevelopmental disorder caused by loss of function of the maternally inherited UBE3A allele. It is currently unclear how the consequences of this genetic insult unfold to impair neurodevelopment. We reasoned that by elucidating the basis of microcephaly in AS, a highly penetrant syndromic feature with early postnatal onset, we would gain new insights into the mechanisms by which maternal UBE3A loss derails neurotypical brain growth and function. Detailed anatomical analysis of both male and female maternal Ube3a-null mice reveals that microcephaly in the AS mouse model is primarily driven by deficits in the growth of white matter tracts, which by adulthood are characterized by densely packed axons of disproportionately small caliber. Our results implicate impaired axon growth in the pathogenesis of AS and identify noninvasive structural neuroimaging as a potentially valuable tool for gauging therapeutic efficacy in the disorder
Allelic Specificity of Ube3a Expression in the Mouse Brain during Postnatal Development
Genetic alterations of the maternal UBE3A allele result in Angelman syndrome (AS), a neurodevelopmental disorder characterized by severe developmental delay, lack of speech, and difficulty with movement and balance. The combined effects of maternal UBE3A mutation and cell type-specific epigenetic silencing of paternal UBE3A are hypothesized to result in a complete loss of functional UBE3A protein in neurons. However, the allelic specificity of UBE3A expression in neurons and other cell types in the brain has yet to be characterized throughout development, including the early postnatal period when AS phenotypes emerge. Here we define maternal and paternal allele-specific Ube3a protein expression throughout postnatal brain development in the mouse, a species which exhibits orthologous epigenetic silencing of paternal Ube3a in neurons and AS-like behavioral phenotypes subsequent to maternal Ube3a deletion. We find that neurons downregulate paternal Ube3a protein expression as they mature and, with the exception of neurons born from postnatal stem cell niches, do not express detectable paternal Ube3a beyond the first postnatal week. By contrast, neurons express maternal Ube3a throughout postnatal development, during which time localization of the protein becomes increasingly nuclear. Unlike neurons, astrocytes and oligodendrotyes biallelically express Ube3a. Notably, mature oligodendrocytes emerge as the predominant Ube3a-expressing glial cell type in the cortex and white matter tracts during postnatal development. These findings demonstrate the spatiotemporal characteristics of allele-specific Ube3a expression in key brain cell types, thereby improving our understanding of the developmental parameters of paternal Ube3a silencing and the cellular basis of AS
GABAergic Neuron-Specific Loss of Ube3a Causes Angelman Syndrome-Like EEG Abnormalities and Enhances Seizure Susceptibility
Loss of maternal UBE3A causes Angelman syndrome (AS), a neurodevelopmental disorder associated with severe epilepsy. We previously implicated GABAergic deficits onto layer (L) 2/3 pyramidal neurons in the pathogenesis of neocortical hyperexcitability, and perhaps epilepsy, in AS model mice. Here we investigate consequences of selective Ube3a loss from either GABAergic or glutamatergic neurons, focusing on the development of hyperexcitability within L2/3 neocortex and in broader circuit and behavioral contexts. We find that GABAergic Ube3a loss causes AS-like increases in neocortical EEG delta power, enhances seizure susceptibility, and leads to presynaptic accumulation of clathrin-coated vesicles (CCVs) – all without decreasing GABAergic inhibition onto L2/3 pyramidal neurons. Conversely, glutamatergic Ube3a loss fails to yield EEG abnormalities, seizures, or associated CCV phenotypes, despite impairing tonic inhibition onto L2/3 pyramidal neurons. These results substantiate GABAergic Ube3a loss as the principal cause of circuit hyperexcitability in AS mice, lending insight into ictogenic mechanisms in AS
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