Genes at the junction - Candidates for congenital myasthenic syndromes
TRENDS IN NEUROSCIENCES
Authors: Vincent, A; Newland, C; Croxen, R; Beeson, D
Abstract
The neuromuscular junction is the site of several myasthenic (mys, muscle; aesthenia, weakness) disorders of autoimmune and genetic origin. The acquired autoimmune conditions are mainly adult-onset and caused by antibodies to specific neuronal and muscle ion channels, but can occur neonatally due to placental transfer of maternal antibodies. This review focuses on the rarer genetic conditions, called congenital myasthenic syndromes (CMS), that often present at birth. Mutations have yet to be characterized for familial infantile myasthenia, acetylcholinesterase deficiency and ACh-receptor deficiency; but genes encoding both structural and functional NMJ proteins should be considered, Other syndromes have recently been shown to involve defects in the functioning of the ACh receptor itself, In particular, eight different mutations have been reported in cases of the slow channel syndrome, a dominant condition associated with point mutations that generate single amino acid changes within the ACh receptor and result in prolonged channel activations. These investigations are providing new insights into the structure and function of the ACh receptor. Further studies of CMS should pave the way for analysis and treatment of disorders involving other synapses in the peripheral and central nervous system.
The structure of Mars lower atmosphere from Mars Express Radio Science (MaRS) occultation measurements
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
Authors: Tellmann, Silvia; Paetzold, Martin; Haeusler, Bernd; Hinson, D. P.; Tyler, G. Leonard
Abstract
The Mars Express Radio Science Experiment (MaRS) investigates the lower and middle atmosphere of Mars between the surface and about 40 km with a very high vertical resolution. More than 600 profiles of temperature, pressure, and neutral number density were retrieved between 2004 and 2011 covering four Martian years (MYs 27-30). Radio occultation experiments provide the unique possibility to retrieve geopotential height information to supplement temperature values. The temperature field in the northern winter hemisphere displays strong temperature inversions indicating a pronounced polar warming in the northern polar night (MY 27). The temperature and geopotential fields imply the presence of a strong zonal jet, with peak wind speeds of more than 170 m/s at an altitude of about 30 km ( 15 Pa) and a latitude of 60-65 degrees N. The longitudinal temperature and geopotential fields in the southern winter of Martian year 30 at latitudes between 49 degrees and 69 degrees S are dominated by a stationary zonal wave s = 1 structure in the lower atmosphere. Associated meridional wind fields retrieved by assuming geostrophic balance have amplitudes up to 12 m/s at the 200 Pa level. An investigation of small-scale atmospheric waves reveals enhanced gravity wave activity in the daytime atmosphere above elevated terrain and in the winter extratropics. Radio occultation experiments also provide unique insight into the structure of the planetary boundary layer. The deepest convective boundary layers, up to 10 km, are found over elevated terrain. Citation: Tellmann, S., M. Patzold, B. Hausler, D. P. Hinson, and G. L. Tyler (2013), The structure of Mars lower atmosphere from Mars Express Radio Science (MaRS) occultation measurements, J. Geophys. Res. Planets, 118, 306-320, doi:10.1002/jgre.20058.