Brain Changes Induced by Electroconvulsive Therapy Are Broadly Distributed

© 2019 Society of Biological Psychiatry Background: Electroconvulsive therapy (ECT) is associated with volumetric enlargements of corticolimbic brain regions. However, the pattern of whole-brain structural alterations following ECT remains unresolved. Here, we examined the longitudinal effects of ECT on global and local variations in gray matter, white matter, and ventricle volumes in patients with major depressive disorder as well as predictors of ECT-related clinical response. Methods: Longitudinal magnetic resonance imaging and clinical data from the Global ECT-MRI Research Collaboration (GEMRIC) were used to investigate changes in white matter, gray matter, and ventricle volumes before and after ECT in 328 patients experiencing a major depressive episode. In addition, 95 nondepressed control subjects were scanned twice. We performed a mega-analysis of single subject data from 14 independent GEMRIC sites. Results: Volumetric increases occurred in 79 of 84 gray matter regions of interest. In total, the cortical volume increased by mean ± SD of 1.04 ± 1.03% (Cohen\u27s d = 1.01, p \u3c .001) and the subcortical gray matter volume increased by 1.47 ± 1.05% (d = 1.40, p \u3c .001) in patients. The subcortical gray matter increase was negatively associated with total ventricle volume (Spearman\u27s rank correlation ρ = −.44, p \u3c .001), while total white matter volume remained unchanged (d = −0.05, p = .41). The changes were modulated by number of ECTs and mode of electrode placements. However, the gray matter volumetric enlargements were not associated with clinical outcome. Conclusions: The findings suggest that ECT induces gray matter volumetric increases that are broadly distributed. However, gross volumetric increases of specific anatomically defined regions may not serve as feasible biomarkers of clinical response

Magnetic hyperthermia experiments with magnetic nanoparticles in clarified butter oil and paraffin: A thermodynamic analysis

In specific power absorption models for magnetic fluid hyperthermia (MFH) experiments, the magnetic relaxation time of nanoparticles (NPs) is known to be a fundamental descriptor of the heating mechanisms. The relaxation time is mainly determined by the interplay between the magnetic properties of NPs and the rheological properties of NPs’ environment. Although the role of magnetism in MFH has been extensively studied, the thermal properties of the NP medium and their changes during MFH experiments have been underrated so far. Herein, we show that ZnxFe3-xO4 NPs dispersed through different media with phase transition in the temperature range of experiment as clarified butter oil (CBO) and paraffin. These systems show nonlinear behavior of the heating rate within the temperature range of MFH experiments. For CBO, a fast increase at ~306 K is associated with changes in the viscosity (¿(T)) and specific heat (cp(T)) of the medium at its melting temperature. This increment in the heating rate takes place around 318 K for paraffin. The magnetic and morphological characterization of NPs together with the observed agglomeration of NPs above 306 and 318 K for CBO and paraffin, respectively, indicate that the fast increase in MFH curves could not be associated with the change in the magnetic relaxation mechanism, with Neél relaxation being dominant. In fact, successive experimental runs performed up to temperatures below and above the CBO and paraffin melting points resulted in different MFH curves due to agglomeration of NPs driven by magnetic field inhomogeneity during the experiments. Our results highlight the relevance of the thermodynamic properties of the system NP-medium for an accurate measurement of the heating efficiency for in vitro and in vivo environments, where the thermal properties are largely variable within the temperature window of MFH experiments

Formation of tetragonal hydrogen tungsten bronze by reactive mechanical alloying

Hydrogen tungsten bronzes have been synthesized by reactive mechanical alloying monoclinic tungsten (VI) oxide under hydrogen atmosphere. Two milling devices with different energy ranges were used. Regardless of the distinct reaction times, a similar phase evolution was observed with both apparatus. The characterization of the materials was performed by XRD, SEM, DSC and total hydrogen content determination. The final product obtained was a mixture of tetragonal H0.33WO3 and H0.23WO3 bronzes

Carbothermal reduction of quartz in methane-hydrogen-argon gas mixture

Synthesis of silicon carbide (SiC) by carbothermal reduction of quartz in a CH4-H2-Ar gas mixture was investigated in a laboratory fixed-bed reactor in the temperature range of 1573 K to 1823 K (1300 °C to 1550 °C). The reduction process was monitored by an infrared gas analyser, and the reduction products were characterized by LECO, XRD, and SEM. A mixture of quartz-graphite powders with C/SiO2 molar ratio of 2 was pressed into pellets and used for reduction experiments. The reduction was completed within 2 hours under the conditions of temperature at or above 1773 K (1500 °C), methane content of 0.5 to 2 vol pct, and hydrogen content ≥70 vol pct. Methane partially substituted carbon as a reductant in the SiC synthesis and enhanced the reduction kinetics significantly. An increase in the methane content above 2 vol pct caused excessive carbon deposition which had a detrimental effect on the reaction rate. Hydrogen content in the gas mixture above 70 vol pct effectively suppressed the cracking of methane

Thermographical method to assess the performance of magnetic nanoparticles in hyperthermia experiments through spatiotemporal temperature profiles

The evaluation of the specific power absorption of magnetic nanoparticles (MNPs) for magnetic hyperthermia (MH) applications has been performed through either local temperature probing or magnetic measurements so far. Each of these methods has advantages and drawbacks, and the concurrent use of both techniques offers the most reliable results. In this work, we propose an alternative strategy based on thermographic images to obtain two-dimensional temperature maps that allow the determination of the power absorption and other relevant thermodynamic parameters in MH experiments in a noninvasive way. This procedure and analysis are convenient to determine the heating performance of MNPs under the viscous conditions of in vitro and in vivo assays and to follow the time evolution of the temperature spatial distribution in the sample simultaneously. For this purpose, iron-oxide MNPs with 25-nm average diameter are coated with glucose and dispersed into different 8% polyacrylamide gels, which serve as phantoms that emulate intracellular viscosity. Power absorption experiments are performed under ac magnetic fields ( H = 32 kA/m; f = 350 kHz) and the temperature evolution of the sample is monitored through a commercial thermographic camera (resolution, 240 × 180 pixels; temperature accuracy, 2 K). To complement this simple setup, we design a program consisting of a detailed procedure for extracting graphical information from the video frames and obtaining spatiotemporal temperature profiles. The analysis of these profiles allows us to gather information on temperature, energy, power, and heat flux during the MH experiments. This method and analysis allows us to identify spatial inhomogeneities in samples, such as different local MNP density, which is extremely useful for the development of the therapy in vitro and the application in vivo where MNP aggregation is often present.This work is part of a research project supported by Agencia Nacional de Promoción Científica y Tecnológica (Argentina) under Projects No. PICT-2016-0288 and No. PICT-2015-0883 and UNCuyo’s Project SIIP No. 06/C564. The authors gratefully acknowledge the EU Commission financial support through Project No. H2020- MSCA-RISE-2020 101007629-NESTOR.Peer reviewe