On the variational limits of lattice energies on prestrained elastic bodies

We study the asymptotic behaviour of the discrete elastic energies in presence of the prestrain metric $G$, assigned on the continuum reference configuration $\Omega$. When the mesh size of the discrete lattice in $\Omega$ goes to zero, we obtain the variational bounds on the limiting (in the sense of $\Gamma$-limit) energy. In case of the nearest-neighbour and next-to-nearest-neibghour interactions, we derive a precise asymptotic formula, and compare it with the non-Euclidean model energy relative to $G$

Dysregulations of sonic hedgehog signaling in MED12-related X-linked intellectual disability disorders

BACKGROUND:Mutations in mediator of RNA polymerase II transcription subunit 12 homolog (MED12, OMIM 300188) cause X-linked intellectual disability (XLID) disorders including FG, Lujan, and Ohdo syndromes. The Gli3-dependent Sonic Hedgehog (SHH) signaling pathway has been implicated in the original FG syndrome and Lujan syndrome. How are SHH-signaling defects related to the complex clinical phenotype of MED12-associated XLID syndromes are not fully understood. METHODS:Quantitative RT-PCR was used to study expression levels of three SHH-signaling genes in lymophoblast cell lines carrying four MED12 mutations from four unrelated XLID families. Genotype and phenotype correlation studies were performed on these mutations. RESULTS:Three newly identified and one novel MED12 mutations in six affected males from four unrelated XLID families were studied. Three mutations (c.2692A>G; p.N898D, c.3640C>T; p.R1214C, and c.3884G>A; p.R1295H) are located in the LS domain and one (c.617G>A; p.R206Q) is in the L domain of MED12. These mutations involve highly conserved amino acid residues and segregate with ID and related congenital malformations in respective probands families. Patients with the LS-domain mutations share many features of FG syndrome and some features of Lujan syndrome. The patient with the L-domain mutation presented with ID and predominant neuropsychiatric features but little dysmorphic features of either FG or Lujan syndrome. Transcript levels of three Gli3-dependent SHH-signaling genes, CREB5, BMP4, and NEUROG2, were determined by quantitative RT-PCR and found to be significantly elevated in lymphoblasts from patients with three mutations in the MED12-LS domain. CONCLUSIONS:These results support a critical role of MED12 in regulating Gli3-dependent SHH signaling and in developing ID and related congenital malformations in XLID syndromes. Differences in the expression profile of SHH-signaling genes potentially contribute to variability in clinical phenotypes in patients with MED12-related XLID disorders.Siddharth Srivastava, Tejasvi Niranjan, Melanie M. May, Patrick Tarpey, William Allen ... Jozef Gecz ... et al

Validation of diffusion tensor MRI measurements of cardiac microstructure with structure tensor synchrotron radiation imaging.

Background Diffusion tensor imaging (DTI) is widely used to assess tissue microstructure non-invasively. Cardiac DTI enables inference of cell and sheetlet orientations, which are altered under pathological conditions. However, DTI is affected by many factors, therefore robust validation is critical. Existing histological validation is intrinsically flawed, since it requires further tissue processing leading to sample distortion, is routinely limited in field-of-view and requires reconstruction of three-dimensional volumes from two-dimensional images. In contrast, synchrotron radiation imaging (SRI) data enables imaging of the heart in 3D without further preparation following DTI. The objective of the study was to validate DTI measurements based on structure tensor analysis of SRI data. Methods One isolated, fixed rat heart was imaged ex vivo with DTI and X-ray phase contrast SRI, and reconstructed at 100 μm and 3.6 μm isotropic resolution respectively. Structure tensors were determined from the SRI data and registered to the DTI data. Results Excellent agreement in helix angles (HA) and transverse angles (TA) was observed between the DTI and structure tensor synchrotron radiation imaging (STSRI) data, where HADTI-STSRI = −1.4° ± 23.2° and TADTI-STSRI = −1.4° ± 35.0° (mean ± 1.96 standard deviation across all voxels in the left ventricle). STSRI confirmed that the primary eigenvector of the diffusion tensor corresponds with the cardiomyocyte long-axis across the whole myocardium. Conclusions We have used STSRI as a novel and high-resolution gold standard for the validation of DTI, allowing like-with-like comparison of three-dimensional tissue structures in the same intact heart free of distortion. This represents a critical step forward in independently verifying the structural basis and informing the interpretation of cardiac DTI data, thereby supporting the further development and adoption of DTI in structure-based electro-mechanical modelling and routine clinical applications

Species composition and diversity of free-living Plathelminthes (Turbellaria) from sandy beaches at the Belgian coast

Ten sandy beaches at the Belgian coast were sampled monthly on a qualitative basis. Six of them were also sampled quantitatively every two months. In total, 130 species were encountered, 38% of them occur only in 1 or 2 localities, 32% have a more general distribution (in 3 to 7 localities) and 30% are found in at least 8 localities, Schizorhynchia generally from the dominat taxon in number of species, followed by the Proseriata. In Knokke and Het Zwin, equal numbers of species were found for both taxa. Mariakerke, Bredene, Knokke and Het Zwin have the most diverse turbellarian fauna's, with the lowest dominance ratio's. In the semi-exposed beach of Oostende the fauna is slightly less diverse, dominated by a few species, while the sheltered beach in Heist clearly has the least diverse fauna, strongly dominated by one species, Archilopsis arenaria

Kalyptorhynchia (Plathelminthes Rhabdocoela) from the Kenyan Coast, with descriptions of four new species

Sandy sediments and algae from the littoral and sublittoral zone of the coast near Mombasa were sampled. Eighteen species of Kalyptorhynchia were collected, of which four new species of Schizorhynchia are described here, two Cheliplana species, one Baltoplana sp. and one Carcharodorhynchus sp. Cheliplana asica terminalis Brunet 1968 described from the Mediterranean and also recorded from Somalia was found as well. Five out of 13 species of Eukalyptorhynchia were already recorded from Somalia. Polycystis ali Schockaert 1982, P. subcontorta Schockaert 1982 and Cinturorhynchus karlingi Schockaert 1982 were newly described from the Somalian coast. P. contorta Schockaert & Karling 1975 also known from Norway and the Mediterranean and Gyratrix hermaphroditus Ehrenberg 1831 is an ubiquist. Six new species of Eukalyptorhynchia collected from algae will be described in a later publication. Additional information is given on Alcha evelinae Marcus 1949 and Toia ycia Marcus 1952