Wnt/β-catenin controls follistatin signalling to regulate satellite cell myogenic potential.

Background: Adult skeletal muscle regeneration is a highly orchestrated process involving the activation and proliferation of satellite cells, an adult skeletal muscle stem cell. Activated satellite cells generate a transient amplifying progenitor pool of myoblasts that commit to differentiation and fuse into multinucleated myotubes. During regeneration, canonical Wnt signalling is activated and has been implicated in regulating myogenic lineage progression and terminal differentiation.

Raman spectroscopy of uranium compounds and the use of multivariate analysis for visualization and classification.

Raman spectroscopy was used on 95 samples comprising mainly of uranium ore concentrates as well as some UF4 and UO2 samples, in order to classify uranium compounds for nuclear forensic purposes, for the first time. This technique was selected as it is non-destructive and rapid. The spectra obtained from 9 different classes of chemical compounds were subjected to multivariate data analysis such as principal component analysis (PCA), partial least square-discriminant analysis (PLS-DA) and Fisher Discriminant Analysis (FDA).

Classification of spent reactor fuel for nuclear forensics.

In this paper we demonstrate the use of pattern recognition and machine learning techniques to determine the reactor type from which spent reactor fuel has originated. This has been done using the isotopic and elemental measurements of the sample and proves to be very useful in the field of nuclear forensics. Nuclear materials contain many variables (impurities and isotopes) that are very difficult to consider individually.

Pax7 is critical for the normal function of satellite cells in adult skeletal muscle.

Extensive analyses of mice carrying null mutations in paired box 7 (Pax7) have confirmed the progressive loss of the satellite cell lineage in skeletal muscle, resulting in severe muscle atrophy and death. A recent study using floxed alleles and tamoxifen-induced inactivation concluded that after 3 wk of age, Pax7 was entirely dispensable for satellite cell function. Here, we demonstrate that Pax7 is an absolute requirement for satellite cell function in adult skeletal muscle.

Isolation and culture of individual myofibers and their satellite cells from adult skeletal muscle.

Muscle regeneration in the adult is performed by resident stem cells called satellite cells. Satellite cells are defined by their position between the basal lamina and the sarcolemma of each myofiber. Current knowledge of their behavior heavily relies on the use of the single myofiber isolation protocol.

Transcriptional dominance of Pax7 in adult myogenesis is due to high-affinity recognition of homeodomain motifs.

Pax3 and Pax7 regulate stem cell function in skeletal myogenesis. However, molecular insight into their distinct roles has remained elusive. Using gene expression data combined with genome-wide binding-site analysis, we show that both Pax3 and Pax7 bind identical DNA motifs and jointly activate a large panel of genes involved in muscle stem cell function.

Transcriptional networks that regulate muscle stem cell function.

Muscle stem cells comprise different populations of stem and progenitor cells found in embryonic and adult tissues. A number of signaling and transcriptional networks are responsible for specification and survival of these cell populations and regulation of their behavior during growth and regeneration. Muscle progenitor cells are mostly derived from the somites of developing embryos, while satellite cells are the progenitor cells responsible for the majority of postnatal growth and adult muscle regeneration.

Wnt7a activates the planar cell polarity pathway to drive the symmetric expansion of satellite stem cells.

Satellite cells in skeletal muscle are a heterogeneous population of stem cells and committed progenitors. We found that quiescent satellite stem cells expressed the Wnt receptor Fzd7 and that its candidate ligand Wnt7a was upregulated during regeneration. Wnt7a markedly stimulated the symmetric expansion of satellite stem cells but did not affect the growth or differentiation of myoblasts.

Successful treatment of pediatric stroke with recombinant tissue plasminogen activator (rt-PA): a case report and review of the literature.

Pediatric stroke is a rare disorder with a paucity of evidence-based treatment options, and can result in significant morbidity and mortality. In contrast to adult acute ischemic stroke, where the use of recombinant tissue plasminogen activator (rt-PA) has been studied in several large, randomized clinical trials, no high-level evidence exists for the use of thrombolytics in children with stroke. We report a case of a 15-year-old girl who suffered an acute ischemic stroke and had a dramatic improvement in symptoms following the administration of intravenous rt-PA.