Proceedings of the National Academy of Sciences of the United States of America
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Proc. Natl. Acad. Sci. U.S.A. · Aug 2012
Bodywide skipping of exons 45-55 in dystrophic mdx52 mice by systemic antisense delivery.
Duchenne muscular dystrophy (DMD), the commonest form of muscular dystrophy, is caused by lack of dystrophin. One of the most promising therapeutic approaches is antisense-mediated elimination of frame-disrupting mutations by exon skipping. However, this approach faces two major hurdles: limited applicability of each individual target exon and uncertain function and stability of each resulting truncated dystrophin. ⋯ Encouragingly, with mixtures of 10 AOs, we demonstrated skipping of all 10 exons in vitro, in H2K-mdx52 myotubes and on intramuscular injection into mdx52 mice. Moreover, in mdx52 mice in vivo, systemic injections of 10 AOs induced extensive dystrophin expression at the subsarcolemma in skeletal muscles throughout the body, producing up to 15% of wild-type dystrophin protein levels, accompanied by improved muscle strength and histopathology without any detectable toxicity. This is a unique successful demonstration of effective rescue by exon 45-55 skipping in a dystrophin-deficient animal model.
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Proc. Natl. Acad. Sci. U.S.A. · Aug 2012
Hypoxia suppresses conversion from proliferative arrest to cellular senescence.
Unlike reversible quiescence, cellular senescence is characterized by a large flat cell morphology, β-gal staining and irreversible loss of regenerative (i.e., replicative) potential. Conversion from proliferative arrest to irreversible senescence, a process named geroconversion, is driven in part by growth-promoting pathways such as mammalian target of rapamycin (mTOR). During cell cycle arrest, mTOR converts reversible arrest into senescence. ⋯ Also hypoxia suppressed geroconversion in cells treated with nutlin-3a, a nongenotoxic inducer of p53, in cell lines susceptible to nutlin-3a-induced senescence (MEL-10, A172, and NKE). Thus, in normal and cancer cell lines, hypoxia suppresses geroconversion caused by diverse stimuli. Physiological and clinical implications of the present findings are discussed.
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Proc. Natl. Acad. Sci. U.S.A. · Aug 2012
Comparative StudyVariation in neural development as a result of exposure to institutionalization early in childhood.
We used structural MRI and EEG to examine brain structure and function in typically developing children in Romania (n = 20), children exposed to institutional rearing (n = 29), and children previously exposed to institutional rearing but then randomized to a high-quality foster care intervention (n = 25). In so doing, we provide a unique evaluation of whether placement in an improved environment mitigates the effects of institutional rearing on neural structure, using data from the only existing randomized controlled trial of foster care for institutionalized children. Children enrolled in the Bucharest Early Intervention Project underwent a T1-weighted MRI protocol. ⋯ We were also able to explain previously reported reductions in EEG α-power among institutionally reared children compared with children raised in families using these MRI data. As hypothesized, the association between institutionalization and EEG α-power was partially mediated by cortical white matter volume for children not randomized to foster care. The increase in white matter among children randomized to an improved rearing environment relative to children who remained in institutional care suggests the potential for developmental "catch up" in white matter growth, even following extreme environmental deprivation.