Antagonism between Notch and bone morphogenetic protein receptor signaling regulates neurogenesis in the cerebellar rhombic lip

BACKGROUND: During the embryonic development of the cerebellum, neurons are produced from progenitor cells located along a ventricular zone within dorsal rhombomere 1 that extends caudally to the roof plate of the fourth ventricle. The apposition of the caudal neuroepithelium and roof plate results in a unique inductive region termed the cerebellar rhombic lip, which gives rise to granule cell precursors and other glutamatergic neuronal lineages. Recently, we and others have shown that, at early embryonic stages prior to the emergence of granule cell precursors (E12), waves of neurogenesis in the cerebellar rhombic lip produce specific hindbrain nuclei followed by deep cerebellar neurons. How the induction of rhombic lip-derived neurons from cerebellar progenitors is regulated during this phase of cerebellar development to produce these temporally discrete neuronal populations while maintaining a progenitor pool for subsequent neurogenesis is not known. RESULTS: Employing both gain- and loss-of-function methods, we find that Notch1 signaling in the cerebellar primordium regulates the responsiveness of progenitor cells to bone morphogenetic proteins (BMPs) secreted from the roof plate that stimulate the production of rhombic lip-derived neurons. In the absence of Notch1, cerebellar progenitors are depleted during the early production of hindbrain neurons, resulting in a severe decrease in the deep cerebellar nuclei that are normally born subsequently. Mechanistically, we demonstrate that Notch1 activity prevents the induction of Math1 by antagonizing the BMP receptor-signaling pathway at the level of Msx2 expression. CONCLUSION: Our results provide a mechanism by which a balance between neural induction and maintenance of neural progenitors is achieved in the rhombic lip throughout embryonic development

Single-cell delineation of lineage and genetic identity in the mouse brain

During neurogenesis, mitotic progenitor cells lining the ventricles ofthe embryonic mouse brain undergo their final rounds of cell division, giving rise to a wide spectrum of postmitotic neurons and glia(1,2). The link between developmental lineage and cell-type diversity remains an open question. Here we used massively parallel tagging of progenitors to track clonal relationships and transcriptomic signatures during mouse forebrain development. We quantified clonal divergence and convergence across all major cell classes postnatally, and found diverse types of GABAergic neuron that share a common lineage. Divergence of GABAergic clones occurred during embryogenesis upon cell-cycle exit, suggesting that differentiation into subtypes is initiated as a lineage-dependent process at the progenitor cell level

Leflunomide in the treatment of patients with early rheumatoid arthritis—results of a prospective non-interventional study

Leflunomide is effective and well tolerated in the treatment of rheumatoid arthritis (RA), however, data on its use in early RA are scarce. This study seeks to evaluate effectiveness and safety of leflunomide in the treatment of early RA in daily practice. This prospective, open-label, non-interventional, multi-center study was carried out over 24 weeks including adults with early RA (≤1 year since diagnosis). Leflunomide treatment was according to label instructions. Three hundred thirty-four patients were included. Disease activity score in 28 joints (DAS28) response (reduction in DAS28 of >1.2 or reduction of >0.6 and a DAS28 of ≤5.1) was 71.9% at week 12 and 84.6% at week 24. 25.0% of patients achieved clinical remission (DAS28 ≤ 2.6). Most frequently reported adverse drug reactions (ADR) were diarrhea (3.0%), nausea (2.4%), hypertension (1.8%), and headache (1.5%). Serious ADR were reported in four patients (1.2%). Leflunomide showed the effectiveness which was to be expected from controlled studies without revealing any new or hitherto unknown side effects. Onset of action was quick and significant improvement of disease was seen after 12 weeks of therapy and at even higher rates after 24 weeks irrespective of the use of a loading dose. Interestingly, the DAS28-remission rate achieved was similar to the rate seen with methotrexate or biologic therapy in other studies

Sonic Hedgehog Is a Chemoattractant for Midbrain Dopaminergic Axons

Midbrain dopaminergic axons project from the substantia nigra (SN) and the ventral tegmental area (VTA) to rostral target tissues, including the striatum, pallidum, and hypothalamus. The axons from the medially located VTA project primarily to more medial target tissues in the forebrain, whereas the more lateral SN axons project to lateral targets including the dorsolateral striatum. This structural diversity underlies the distinct functions of these pathways. Although a number of guidance cues have been implicated in the formation of the distinct axonal projections of the SN and VTA, the molecular basis of their diversity remains unclear. Here we investigate the molecular basis of structural diversity in mDN axonal projections. We find that Sonic Hedgehog (Shh) is expressed at a choice point in the course of the rostral dopaminergic projections. Furthermore, in midbrain explants, dopaminergic projections are attracted to a Shh source. Finally, in mice in which Shh signaling is inactivated during late neuronal development, the most medial dopaminergic projections are deficient

Auxetic foam for snowsport safety devices

Skiing and snowboarding are popular snow-sports with inherent risk of injury. There is potential to reduce the prevalence of injuries by improving and implementing snow-sport safety devices with the application of advanced materials. This paper investigates the application of auxetic foam to snow-sport safety devices. Composite pads - consisting of foam covered with a semi-rigid shell - were investigated as a simple model of body armour and a large 70 x 355 x 355 mm auxetic foam sample was fabricated as an example crash barrier. The thermo-mechanical conversion process was applied to convert open-cell polyurethane foam to auxetic foam. The composite pad with auxetic foam absorbed around three times more energy than the conventional equivalent under quasi-static compression with a concentrated load, indicating potential for body armour applications. An adapted thermo-mechanical process - utilising through-thickness rods to control in-plane compression - was applied to fabricate the large sample with relatively consistent properties throughout, indicating further potential for fabrication of a full size auxetic crash barrier. Further work will create full size prototypes of snow-sport safety devices with comparative testing against current products

Aggressive therapy in patients with early arthritis results in similar outcome compared with conventional care: the STREAM randomized trial

Objective. To compare the effects of aggressive tight control therapy and conventional care on radiographic progression and disease activity in patients with early mild inflammatory arthritis