Silica Coated Iron/Iron Oxide Nanoparticles as a Nano-Platform for T2 Weighted Magnetic Resonance Imaging.

The growing concern over the toxicity of Gd-based contrast agents used in magnetic resonance imaging (MRI) motivates the search for less toxic and more effective alternatives. Among these alternatives, iron-iron oxide (Fe@FeOx) core-shell architectures have been long recognized as promising MRI contrast agents while limited information on their engineering is available. Here we report the synthesis of 10 nm large Fe@FeOx nanoparticles, their coating with a 11 nm thick layer of dense silica and functionalization by 5 kDa PEG chains to improve their biocompatibility. The nanomaterials obtained have been characterized by a set of complementary techniques such as infra-red and nuclear magnetic resonance spectroscopies, transmission electron microscopy, dynamic light scattering and zetametry, and magnetometry. They display hydrodynamic diameters in the 100 nm range, zetapotential values around -30 mV, and magnetization values higher than the reference contrast agent RESOVIST®. They display no cytotoxicity against 1BR3G and HCT116 cell lines and no hemolytic activity against human red blood cells. Their nuclear magnetic relaxation dispersion (NMRD) profiles are typical for nanomaterials of this size and magnetization. They display high r2 relaxivity values and low r1 leading to enhanced r2/r1 ratios in comparison with RESOVIST®. All these data make them promising contrast agents to detect early stage tumors.

Dose Effect of Intratympanic Dexamethasone for Idiopathic Sudden Sensorineural Hearing Loss: 24 mg/mL Is Superior to 10 mg/mL.

OBJECTIVE: To compare outcomes in patients with idiopathic sudden sensorineural hearing loss (ISSNHL) treated with intratympanic (IT) dexamethasone (DEX) at either 10 mg/mL or 24 mg/mL. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. PATIENTS: Thirty-seven adults with ISSNHL. INTERVENTIONS: In addition to concurrent prednisone taper, patients received a series of IT DEX injections for 2 weeks with either 10 mg/mL or 24 mg/mL. MAIN OUTCOME MEASURE: Greater than 30-dB improvement in pure-tone average (PTA). RESULTS: Baseline characteristics were similar between groups. Mean follow-up was 10 weeks. Ten (53%) of 19 patients treated with 24 mg/mL had greater than 30-dB improvement in PTA compared with 3 (17%) of 18 treated with 10 mg/mL (p = 0.0382, Fisher's exact test). There was a trend toward improved word recognition score outcome with 24 mg/mL. The interval between onset and initiation of IT DEX significantly affected outcome, with earlier treatment resulting in greater improvement in PTA and word recognition score. Multivariate logistic regression confirmed that IT DEX dose and interval to starting treatment were both independent predictors of PTA outcome. Change in PTA was not significantly affected by age, sex, pretreatment hearing levels, or concurrent treatment with hyperbaric oxygen. CONCLUSION: To our knowledge, this is the first demonstration of superiority of IT DEX at 24 mg/mL for the treatment of ISSNHL, with significantly better recovery of PTA. Our data suggest that treatment should be initiated as soon as possible. A prospective randomized trial to confirm the optimal dose is warranted.