Morphometry and localization of the temporal transverse Heschl’s gyrus in magnetic resonance imaging: a guide for cortical stimulation of chronic tinnitus

Purpose

Subjective tinnitus is considered a phantom auditory phenomenon. Recent studies show that electrical or magnetic stimulation of the cortex can alleviate some tinnitus. The usual target of the stimulation is the primary auditory cortex (PAC) on Heschl’s gyrus (HG). The objective of this study was to specify the anatomy of HG by magnetic resonance imaging (MRI).

Methods

Cerebral MRI of 60 patients with chronic tinnitus, carried out before neuronavigated repetitive transcranial magnetic stimulation targeting the auditory cortex, were included. 3D-T1 MRI was reformatted in Talairach–Tournoux’s stereotactic space, then the following steps were performed: morphometry of HG, localization of the probabilistic center of the PAC (pcPAC) chosen at the junction between the medial third and the lateral two-thirds of HG, relative to external and cortical landmarks, and identification of its coordinates relative to the bicommissural line (AC-PC).

Results

In relation to external landmarks, the pcPAC was identified around 5 cm above the root of the helix of the ear in the direction of a point on the vertex located 4 cm behind the coronal suture, for both sides. In Talairach–Tournoux’s stereotactic space with the anterior commissure as the origin, the pcPAC coordinates were x = 43, y = ?20, z = 6.8 on the right side, and x = ?42.5, y = ?21.5, and z = 6.5 on the left. Probabilistic maps of the presence of HG pointed to a relative contraction of data in space, despite inter- and intraindividual differences.

Conclusion

The choice of our stimulation target was established in the middle of the theoretical position of the PAC. MRI allows a reliable identification of the target structure.     

Solid Polymer Electrolytes from Copolymers Based on Vinyl Dimethyl Phosphonate and Vinylidene Fluoride

Solid polymer electrolytes are prepared by mixing various amounts of lithium bis(trifluoromethanesulfonyl)imide with poly(vinylidene fluoride‐co‐vinyl dimethyl phosphonate) statistical copolymers with different compositions. Such copolymers are obtained by conventional radical copolymerization of vinylidene fluoride (VDF) with vinyl dimethyl phosphonate (VDMP) initiated by peroxides. A morphological study of the obtained solid polymer electrolytes (SPEs) shows that only samples prepared from the copolymer with the lower amount of VDMP (16 mol%) result in the formation of homogeneous electrolytes while aggregates of lithium salts are observed for the other copolymers. The best ionic conductivity values are accordingly observed for the copolymers with the lower VDMP amount and are reaching 5 × 10^?3 mS cm^?1 at 100 °C. The dependence of the ionic conductivity versus temperature suggests that the ionic conductivity is controlled by the motion of polymer segments. Indeed, the ionic conductivity can be increased by adding a small amount of trimethylphosphate plasticizer and can reach 1.9 × 10^?2 mS cm^?1 at 20 °C. Finally, the prepared SPEs exhibit a high electrochemical stability and a good resistance to flame because of the presence of fire‐retardant phosphate groups in their structure.     

Variation of the impact duration during the in vitro insertion of acetabular cup implants

The acetabular cup (AC) is an implant impacted into a bone cavity and used for hip prosthesis surgery. Initial stability of the AC is an important factor for long term surgical success. The aim of this study is to determine the variations of the impact duration during AC implant insertion.Twenty-two bone samples taken from bovine femurs were prepared ex vivo for the insertion of an acetabular cup implant, following the surgical procedure used in the clinic. For each bone sample, ten impacts were applied using reproducible mass falls (3.5 kg) in order to insert the AC implant. Each impact duration was recorded using a wide bandwidth force sensor.For all bone samples, the impact duration was shown to first decrease as a function of the impact number, then reaching a stationary value equal in average to 4.2 ± 0.7 ms after an average number of 4.1 ± 1.7 impacts. The impact duration may be related to variations of the bone–implant interface contact rigidity because of an increase the amount of bone tissue in contact with the AC implant.Measurements of impact duration have a good potentiality for clinical application to assist the surgeon during the insertion of the AC implant, providing valuable information on the bone–implant interface contact properties.     

HHV-6 cell receptor CD46 expression on various cell subsets of six blood and graft sources: A prospective series

BackgroundCord Blood (CB) are increasingly used as an alternative stem cells source in adults for allogeneic Stem Cell Transplantation (allo-SCT). The risk of human herpesvirus (HHV-6) reactivation is significantly higher after CB transplant vs unrelated peripheral blood stem cells (PBSC) allo-SCT. Higher HHV-6 cell receptor CD46 expression on progenitor cells in CB may explain this difference.ObjectivesTo prospectively compare the HHV-6 cell receptor CD46 expression on various cell subsets of three freshly harvested blood sources on one hand and of three graft sources on the other hand.Study design52 samples were used for the purpose of this study. They were issued from peripheral blood (PB, n = 10), G-CSF mobilised PB (GCSF-PB, n = 10), cord blood (CB, n = 10), unmanipulated bone marrow (uBM, n = 5), leukapheresis product (LP, n = 10) and thawed CB graft (n = 7). CD46 expression was assessed by FACS analysis on total lymphocytes, monocytes, NK cells, T and B cells subsets, plasmacytoid (pDCs) dendritic cells and stem cells.ResultsAs all cell subsets were found CD46 positive, CD46 mean fluorescence intensity (MFI) was then considered for comparison between the three blood sources and the three graft sources. The most impressive result observed was that HHV-6 cell receptor CD46 expression was significantly reduced in almost all cell components of thawed CB graft compared to other graft sources.ConclusionsThis original study shows strong differences in term of quantitative CD46 expression between several blood and grafts samples. Our results suggest that other factors than the qualitative CD46 expression play a role in the higher HHV-6 reactivation observed after CB transplant in adults.     

Combined MEK Inhibition and BMP2 Treatment Promotes Osteoblast Differentiation and Bone Healing in Nf1Osx−/− Mice

Neurofibromatosis type I (NF1) is an autosomal dominant disease with an incidence of 1/3000, caused by mutations in the NF1 gene, which encodes the RAS/GTPase‐activating protein neurofibromin. Non‐bone union after fracture (pseudarthrosis) in children with NF1 remains a challenging orthopedic condition to treat. Recent progress in understanding the biology of neurofibromin suggested that NF1 pseudarthrosis stems primarily from defects in the bone mesenchymal lineage and hypersensitivity of hematopoietic cells to TGFβ. However, clinically relevant pharmacological approaches to augment bone union in these patients remain limited. In this study, we report the generation of a novel conditional mutant mouse line used to model NF1 pseudoarthrosis, in which Nf1 can be ablated in an inducible fashion in osteoprogenitors of postnatal mice, thus circumventing the dwarfism associated with previous mouse models where Nf1 is ablated in embryonic mesenchymal cell lineages. An ex vivo–based cell culture approach based on the use of Nf1^flox/flox bone marrow stromal cells showed that loss of Nf1 impairs osteoprogenitor cell differentiation in a cell‐autonomous manner, independent of developmental growth plate–derived or paracrine/hormonal influences. In addition, in vitro gene expression and differentiation assays indicated that chronic ERK activation in Nf1‐deficient osteoprogenitors blunts the pro‐osteogenic property of BMP2, based on the observation that only combination treatment with BMP2 and MEK inhibition promoted the differentiation of Nf1‐deficient osteoprogenitors. The in vivo preclinical relevance of these findings was confirmed by the improved bone healing and callus strength observed in Nf1_osx^?/? mice receiving Trametinib (a MEK inhibitor) and BMP2 released locally at the fracture site via a novel nanoparticle and polyglycidol‐based delivery method. Collectively, these results provide novel evidence for a cell‐autonomous role of neurofibromin in osteoprogenitor cells and insights about a novel targeted approach for the treatment of NF1 pseudoarthrosis. © 2014 American Society for Bone and Mineral Research.