Search

Background Rib cage mobility decreases in various health conditions, for example neuromuscular diseases. A decrease in rib cage mobility reduces respiratory function and therefore increases the risk of respiratory complications. To evaluate the effects of interventions aiming at increasing rib cage mobility, changes should be calculated from measurements before and after such interventions. Therefore, an accurate and easy to perform method is needed. Objective To assess rib cage mobility using computed tomography ( CT). Methods We analysed single-image CT scans of the chest to assess its reproducibility at maximal inspiration and expiration in ten able-bodied individuals and ten subjects with tetraplegia. CT scans were taken twice in the supine position, with a repositioning of subjects in-between. At maximal inspiration and expiration, two images at the fourth and ninth vertebral body were recorded. Intra-costal areas, anterior-posterior distances from the sternum to the vertebral body as well as transversal distances of the chest were measured manually by three independent testers, each of them analysing all data twice. Intra-class correlation coefficients ( ICCs) and Bland and Altman plots were calculated for intra-subject reproducibility at maximal inspiration and expiration as well as for intra- and inter-tester reproducibility. Results Mean differences between the two intra-subject measurements expressed as percentage of their mean were 2·3 ± 1·3% in able-bodied individuals and 2·1 ± 1·3% in subjects with tetraplegia. All ICCs were above 0·95 and thus showed very high reproducibility. Conclusion Assessing rib cage mobility by analysing CT scans of the chest is a simple and highly reproducible method. [ABSTRACT FROM AUTHOR]

Hereditary inclusion body myopathy (HIBM), a neuromuscular disorder, is caused by mutations in UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE), the key enzyme of sialic acid biosynthesis. To date, more than 40 different mutations in the GNE gene have been reported to cause the disease. Ten of them, representing mutations in both functional domains of GNE, were recombinantly expressed in insect cells (Sf9). Each of the mutants that was analyzed displayed a reduction in the two known GNE activities, thus revealing that mutations may also influence the function of the domain not harboring them. The extent of reduction strongly differs among the point mutants, ranging from only 20% reduction found for A631T and A631V to almost 80% reduction of at least one activity in D378Y and N519S mutants and more than 80% reduction of both activities of G576E, underlined by structural changes of N519S and G576E, as observed in CD spectroscopy and gel filtration analysis, respectively. We therefore generated models of the three-dimensional structures of the epimerase and the kinase domains of GNE, based on Escherichia coli UDP-N-acetylglucosamine 2-epimerase and glucokinase, respectively, and determined the localization of the HIBM mutations within these proteins. Whereas in the kinase domain most of the mutations are localized inside the enzyme, mutations in the epimerase domain are mostly located at the protein surface. Otherwise, the different mutations result in different enzymatic activities but not in different disease phenotypes and, therefore, do not suggest a direct role of the enzymatic function of GNE in the disease mechanism. [ABSTRACT FROM AUTHOR]