Proceedings of the National Academy of Sciences of the United States of America
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Proc. Natl. Acad. Sci. U.S.A. · Jul 2012
Early-onset binocularity in preterm infants reveals experience-dependent visual development in humans.
Although there is a great deal of knowledge regarding the phylo- and ontogenetic plasticity of the neocortex, the precise nature of environmental impact on the newborn human brain is still one of the most controversial issues of neuroscience. The leading model-system of experience-dependent brain development is binocular vision, also called stereopsis. Here, we show that extra postnatal visual experience in preterm human neonates leads to a change in the developmental timing of binocular vision. ⋯ Despite the immaturity of the visual pathway, clearly demonstrated by the PR-VEP latencies, our DRCD-VEP data show that the visual cortex is remarkably ready to accept environmental stimulation right after birth. This early plasticity makes full use of the available extra stimulation time in preterm human infants and results in an early onset of cortical binocularity. According to our data, the developmental processes preceding the onset of binocular function are not preprogrammed, and the mechanisms turning on stereopsis are extremely experience-dependent in humans.
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Proc. Natl. Acad. Sci. U.S.A. · Jun 2012
ReviewIntegration of faces and vocalizations in ventral prefrontal cortex: implications for the evolution of audiovisual speech.
The integration of facial gestures and vocal signals is an essential process in human communication and relies on an interconnected circuit of brain regions, including language regions in the inferior frontal gyrus (IFG). Studies have determined that ventral prefrontal cortical regions in macaques [e.g., the ventrolateral prefrontal cortex (VLPFC)] share similar cytoarchitectonic features as cortical areas in the human IFG, suggesting structural homology. ⋯ Although bimodal responses may be found across a wide region of prefrontal cortex, vocalization responsive cells, which also respond to faces, are mainly found in anterior VLPFC. This suggests that VLPFC may be specialized to process and integrate social communication information, just as the IFG is specialized to process and integrate speech and gestures in the human brain.
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Proc. Natl. Acad. Sci. U.S.A. · Jun 2012
Pathogenesis of emerging severe fever with thrombocytopenia syndrome virus in C57/BL6 mouse model.
The discovery of an emerging viral disease, severe fever with thrombocytopenia syndrome (SFTS), caused by SFTS virus (SFTSV), has prompted the need to understand pathogenesis of SFTSV. We are unique in establishing an infectious model of SFTS in C57/BL6 mice, resulting in hallmark symptoms of thrombocytopenia and leukocytopenia. Viral RNA and histopathological changes were identified in the spleen, liver, and kidney. ⋯ Moreover, the number of macrophages and platelets were largely increased in the spleen, and SFTSV colocalized with platelets in cytoplasm of macrophages in the red pulp of the spleen. In vitro cellular assays further revealed that SFTSV adhered to mouse platelets and facilitated the phagocytosis of platelets by mouse primary macrophages, which in combination with in vivo findings, suggests that SFTSV-induced thrombocytopenia is caused by clearance of circulating virus-bound platelets by splenic macrophages. Thus, this study has elucidated the pathogenic mechanisms of thrombocytopenia in a mouse model resembling human SFTS disease.
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Proc. Natl. Acad. Sci. U.S.A. · Jun 2012
Model for MLL translocations in therapy-related leukemia involving topoisomerase IIβ-mediated DNA strand breaks and gene proximity.
Topoisomerase poisons such as the epipodophyllotoxin etoposide are widely used effective cytotoxic anticancer agents. However, they are associated with the development of therapy-related acute myeloid leukemias (t-AMLs), which display characteristic balanced chromosome translocations, most often involving the mixed lineage leukemia (MLL) locus at 11q23. ⋯ We show that most etoposide-induced chromosome breaks in the MLL locus and the overall genotoxicity of etoposide are dependent on topoisomerase IIβ, but that topoisomerase IIα and -β occupancy and etoposide-induced DNA cleavage data suggest factors other than local topoisomerase II concentration determine specific clustering of MLL translocation breakpoints in t-AML. We propose a model where DNA double-strand breaks (DSBs) introduced by topoisomerase IIβ into pairs of genes undergoing transcription within a common transcription factory become stabilized by antitopoisomerase II drugs such as etoposide, providing the opportunity for illegitimate end joining and translocation.
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Proc. Natl. Acad. Sci. U.S.A. · May 2012
Historical ArticleQuantitative patterns of stylistic influence in the evolution of literature.
Literature is a form of expression whose temporal structure, both in content and style, provides a historical record of the evolution of culture. In this work we take on a quantitative analysis of literary style and conduct the first large-scale temporal stylometric study of literature by using the vast holdings in the Project Gutenberg Digital Library corpus. ⋯ Within a given time period we also find evidence for stylistic coherence with a given literary topic, such that writers in different fields adopt different literary styles. This study gives quantitative support to the notion of a literary "style of a time" with a strong trend toward increasingly contemporaneous stylistic influence.