University of Antwerp

About: University of Antwerp is a education organization based out in Antwerp, Belgium. It is known for research contribution in the topics: Population & Context (language use). The organization has 16682 authors who have published 48837 publications receiving 1689748 citations. The organization is also known as: Universiteit Antwerpen & UAntwerp.

From VO 2 (B) to VO 2 (R): Theoretical structures of VO 2 polymorphs and in situ electron microscopy

Abstract: The intermediate steps of the phase transition between the metastable monoclinic ${\mathrm{VO}}_{2}(B)$ phase and the stable tetragonal rutile ${\mathrm{VO}}_{2}(R)$ phase have been studied by in situ electron microscopy A crystallographic interpretation based on the static concentration waves theory is proposed: as temperature increases, the long-range order in the complex monoclinic ${\mathrm{VO}}_{2}(B)$ phase is lost and gradually a first intermediate ill crystallized phase with a drastically reduced symmetry is formed as evidenced from the diffraction patterns Next, a new tetragonal phase is generated that corresponds to a state where some of the vanadium atoms are now in a disordered state When annealing inside the microscope, this phase grows out into a superstructure, with coexistence of two possible orientation variants In all these phases the ${\mathrm{VO}}_{6}$ octahedra remain virtually parallel, but for the final transition around 450\ifmmode^\circ\else\textdegree\fi{}C into the rutile stable phase, half of the octahedra have to reorient; the transition therefore has the aspects of a reconstructive one as is evident from the in situ experiment

Further delineation of the 15q13 microdeletion and duplication syndromes: a clinical spectrum varying from non-pathogenic to a severe outcome

Abstract: Recurrent 15q13.3 microdeletions were recently identified with identical proximal (BP4) and distal (BP5) breakpoints and associated with mild to moderate mental retardation and epilepsy. To further assess the clinical implications of this novel 15q13.3 microdeletion syndrome, eighteen new probands with a deletion were molecularly and clinically characterised. In addition, we evaluated the characteristics of a family with a more proximal deletion between BP3 and BP4. Finally, four patients with a duplication in the BP3-BP4-BP5 region were included in this study to ascertain the clinical significance of duplications in this region. The 15q13.3 microdeletion in our series was associated with a highly variable intra- and inter-familial phenotype. At least eleven of the eighteen deletions identified were inherited. Moreover, seven of ten siblings from four different families also had this deletion: one had a mild developmental delay, four had only learning problems during childhood, but functioned well in daily life as adults, whereas the other two had no learning problems at all. In contrast to previous findings, seizures were not a common feature in our series (only two of seventeen living probands). Three patients with deletions had cardiac defects and deletion of the KLF13 gene, located in the critical region, may contribute to these abnormalities. The limited data from the single family with the more proximal BP3-BP4 deletion suggest this deletion may have little clinical significance. Patients with duplications of the BP3-BP4-BP5 region did not share a recognizable phenotype, but psychiatric disease was noted in two of four patients. Overall, our findings broaden the phenotypic spectrum associated with 15q13.3 deletions and suggest that, in some individuals, deletion of 15q13.3 is not sufficient to cause disease. The existence of microdeletion syndromes, associated with an unpredictable and variable phenotypic outcome, will pose the clinician with diagnostic difficulties and challenge the commonly used paradigm in the diagnostic setting that aberrations inherited from a phenotypically normal parent are usually without clinical consequences.

Mutations in the CCN gene family member WISP3 cause progressive pseudorheumatoid dysplasia.

Abstract: Members of the CCN (for CTGF, cyr61/cef10, nov) gene family encode cysteine-rich secreted proteins with roles in cell growth and differentiation1. Cell-specific and tissue-specific differences in the expression and function of different CCN family members suggest they have non-redundant roles. Using a positional-candidate approach, we found that mutations in the CCN family member WISP3 are associated with the autosomal recessive skeletal disorder progressive pseudorheumatoid dysplasia (PPD; MIM 208230). PPD is an autosomal recessive disorder that may be initially misdiagnosed as juvenile rheumatoid arthritis2,3,4,5. Its population incidence has been estimated at 1 per million in the United Kingdom4, but it is likely to be higher in the Middle East and Gulf States6. Affected individuals are asymptomatic in early childhood2,3. Signs and symptoms of disease typically develop between three and eight years of age. Clinically and radiographically, patients experience continued cartilage loss and destructive bone changes as they age2,3,4,5,6,7, in several instances necessitating joint replacement surgery by the third decade of life. Extraskeletal manifestations have not been reported in PPD. Cartilage appears to be the primary affected tissue, and in one patient, a biopsy of the iliac crest revealed abnormal nests of chondrocytes and loss of normal cell columnar organization in growth zones5. We have identified nine different WISP3 mutations in unrelated, affected individuals, indicating that the gene is essential for normal post-natal skeletal growth and cartilage homeostasis.