Magnetic resonance imaging of disorders with white matter changes in children and adolescents: a pictorial essay.

White matter changes are seen in a spectrum of disorders in children and adolescents. Understanding their distribution and appearance helps to reach diagnoses in daily radiologic practice. This pictorial essay will outline the magnetic resonance imaging (MRI) appearances of diseases with white matter changes including demyelinating diseases, dysmyelinating disorders/leukodystrophies, infections, autoimmune diseases, vascular causes, mitochondrial disorders and neurocutaneous syndromes, along with a brief overview of clinical aspects of the diseases such as typical age of presentation, etiology, symptoms and signs and treatment options. This article highlights important features in common white matter diseases in children and adolescents.

Management of failed inferior vena cava filter retrieval for complex cases: A case series.

The aim of this report is to describe our experience in managing cases of difficult inferior vena cava (IVC) filter retrieval with emphasis on different advanced retrieval techniques. We report three cases of difficult IVC filter retrieval at our institution. We included three patients age ranging from 42 to 72 years. Two of the cases were presenting with the lower limb deep vein thrombosis and one of the cases had pulmonary embolism and they all had Retrievable Celect Platinum IVC filter (Cook Medical, Bloomington, Ind.) inserted preoperatively. One case was managed conservatively after failing IVC filter retrieval using standard retrieval set, meaning the filter was left in place, one was successfully removed with advanced endovascular retrieval techniques, and one failing advanced endovascular retrieval and finally had it removed with open surgery. We reviewed the risk factors contributing to difficult IVC filter retrieval and discussed the different options for managing these cases including conservative management, endovascular treatment, and open surgery for retrievable type of IVC filter which can be placed permanently. Knowledge of these options will help us better understand conditions, leading to difficult IVC retrieval on insertion, hopefully to minimize the occurrence of these cases, and to better manage cases with difficult IVC filter retrieval to decide the best option for each patient after careful consideration and multidisciplinary discussion with surgeons and patients.

CD146+ human umbilical cord perivascular cells maintain stemness under hypoxia and as a cell source for skeletal regeneration.

The human umbilical cord perivascular cells (HUCPVCs) have been considered as an alternative source of mesenchymal progenitors for cell based regenerative medicine. However, the biological properties of these cells remain to be well characterized. In the present study, HUCPVCs were isolated and sorted by CD146(+) pericyte marker. The purified CD146(+) HUCPVCs were induced to differentiate efficiently into osteoblast, chondrocyte and adipocyte lineages in vitro. Six weeks following subcutaneous transplantation of CD146(+) HUCPVCs-Gelfoam-alginate 3D complexes in severe combined immunodeficiency (SCID) mice, newly formed bone matrix with embedded osteocytes of donor origin was observed. The functional engraftment of CD146(+) HUCPVCs in the new bone regenerates was further confirmed in a critical-sized bone defect model in SCID mice. Hypoxic conditions suppressed osteogenic differentiation while increased cell proliferation and colony-forming efficiency of CD146(+) HUCPVCs as compared to that under normoxic conditions. Re-oxygenation restored the multi-differentiation potential of the CD146(+) HUCPVCs. Western blot analysis revealed an upregulation of HIF-1α, HIF-2α, and OCT-4 protein expression in CD146(+) HUCPVCs under hypoxia, while there was no remarkable change in SOX2 and NANOG expression. The gene expression profiles of stem cell transcription factors between cells treated by normoxia and hypoxic conditions were compared by PCR array analysis. Intriguingly, PPAR-γ was dramatically downregulated (20-fold) in mRNA expression under hypoxia, and was revealed to possess a putative binding site in the Hif-2α gene promoter region. Chromatin immunoprecipitation assays confirmed the binding of PPAR-γ protein to the Hif-2α promoter and the binding was suppressed by hypoxia treatment. Luciferase reporter assay showed that the Hif-2α promoter activity was suppressed by PPAR expression. Thus, PPAR-γ may involve in the regulation of HIF-2α for stemness maintenance and promoting the expansion of CD146(+) HUCPVCs in response to hypoxia. CD146(+) HUCPVCs may serve as a potential autologous cell source for bone regeneration.