Features of the popliteal lymph nodes seen on musculoskeletal MRI in a Western population

To asses the features and explore the clinical relevance of popliteal lymph nodes (PLNs) detected on MRI examination for different pathologies of the knee. A total of 150 knee MRIs, which were conducted for various indications, were retrospectively collected from the Picture Archiving and Communication System. Imaging planes in at least two orthogonal planes were mandatory, with a field of view extending 15 cm cranial from the joint space. The localization of the PLN was determined by measuring the distance of the lowest border of the PLN to the lowest border of the lateral femoral condyle. Clinical diagnosis was obtained from radiology reports and a statistician performed the statistical analysis. The patients were 70 males [mean age 36.6 years (range: 5-72 years)] and 80 females [mean age 41.1 years (range: 9-76 years)]. In 36.7% of the patients, a PLN was visible. The number of PLNs was negatively associated with age (p < 0.001). The mean number of PLNs was 0.5 PLN per patient. The mean length, height, and width were respectively: 0.57 cm (SD = 0.15), 0.84 cm (SD = 0.26), and 0.71 cm (SD = 0.23). The mean location was 5.8 cm (SD = 1.61). No association was found between the presence of PLNs and internal derangement, inflammation, or cancer (p = 0.368). PLNs appearance is age related, with a higher frequency at a young age. The presence of the PLNs showed no relation to a specific clinical situatio

Profilin2 is controlled by the Iron Regulatory Proteins and modulates iron homeostasis

Paper presented at the European Iron Club, which was held in Verona (Italy) on 12-14th September 2014.[Objetive] The IRPs/IRE regulatory network plays a central role in the control of cellular iron homeostasis. Using a high throughput approach, we have previously identified novel IRP1 and IRP2 interacting mRNAs. Among the identified mRNAs, we studied more in depth Profilin2 (Pfn2), a protein involved in endocytosis and neurotransmitters release. The aim of this work is to characterize Pfn2 as a novel IRPs target mRNA and study its role in iron homeostasis.[Materials and Methods] Mouse and human Pfn2 mRNAs were tested by non-radioactive competitive electrophoretic mobility shift assays (EMSA) for the binding to IRP1 and IRP2. To test the responsiveness of Pfn2 to IRP activity, Pfn2 mRNA levels were analyzed in mice with intestinal IRP1 and IRP2 deficiency. The labile iron pool (LIP) was measured in HeLa and Hepa1-6 cell lines with transient or stable overexpression of Pfn2. Tissues derived from Pfn2 knock-out mice were analyzed for iron content, measured by atomic absorption or colorimetric assay, and for mRNA and protein levels of iron-related genes.[Results] Combination of EMSA experiments and bioinformatic analyses allowed the identification of a novel and conserved 3’UTR iron responsive element in Pfn2 mRNA with an atypical hexanucleotide apical loop (AAGUGG). Pfn2 mRNA levels were significantly reduced (~20-25%) in duodenal samples from mice with IRP1 and IRP2 intestinal specific ablation, suggesting that IRPs exert a positive effect on Pfn2 mRNA expression in vivo. Overexpression of Pfn2 cDNA in HeLa and Hepa1-6 cells reduces LIP levels compared to control cells. Finally, analysis of Pfn2 KO mice showed iron accumulation in discrete areas of the brain (olfactory bulb, hippocampus and midbrain) together with an hepatic iron deficiency with ferritin reduction.[Conclusions] Our results indicate that Pfn2 is controlled by the IRP regulatory system in vivo and that Pfn2 modulates iron homeostasis in cell lines and mice.Work supported by grant SAF2012-40106 from Spanish Secretary of Research, Development and Innovation (MINECO) and grant CIVP16A1857 “Ayudas a proyectos de Investigación en Ciéncias de la Vida - Fundación Ramón Areces” to M.S. M.S. held a research contract under the Ramón y Cajal program from the Spanish Ministry of Science and Innovation (RYC-2008-02352)

Thymic Lymphapoiesis: Protected from, or Influenced by, External Stimulation?

The mechanisms regulating thymic lymphopoiesis are still a matter of debate. Intracortical proliferation and differentiation of thymocytes are thought to be controlled by locally produced humoral factors and close contact with epithelial, possibly also phagocytic, cells, and restricted by products of the major histocompatibility complex. The observation of a translocation of intraabdominally introduced PVP-coated silica particles (Percoll) via parathymic lymph vessels and through the thymic capsule into the cortical parenchyma demonstrates that the thymic cortex is accessible to materials carried with the transcapsular flux of interstitial fluid, and that this barrier is less effective than the blood-thymus barrier. The proliferative activity of cortical thymocytes following an intraabdominal injection of particulate tetanus toxoid was compared in sites adjacent to, and distant from, parathymic lymph nodes. Absolute numbers of DNA-synthesizing thymocytes were found to be much higher in cortical areas close to the lymph nodes, where lymphatic vessels are most numerous, than on the opposite sides of the thymic lobes. Taken together, these findings indicate that--in addition to intrinsic control mechanisms--cortical thymocyte production may be influenced by peripheral stimulation to some extent, and that materials from sites which are drained by parathymic lymph nodes may be important in this respect