Abnormalities in the EEG power spectrum in bulimia nervosa,binge‐eating disorder,and obesity: A systematic review

To provide a basis for electroencephalography (EEG) neurofeedback protocols for bulimia nervosa (BN), binge‐eating disorder (BED), and obesity, this systematic review investigates alterations in EEG‐measured brain activity, specifically frequency bands. A systematic literature search with predefined search terms yielded N = 7 studies meeting the inclusion criteria. The risk of bias was assessed for all studies. In resting‐state EEG, the beta activity was elevated in fronto‐central regions in individuals with obesity and co‐morbid BED. In food‐cue conditions, both obese individuals with and without BED showed increased beta activity, suggesting increased awareness of food cues and a heightened attentional focus towards food stimuli. The level of beta activity was positively correlated with eating disorder psychopathology in resting and food‐cue conditions. In individuals with BN, there was no evidence for altered EEG spectral power. The results indicate specific alterations in EEG‐based brain activity in individuals with BED and obesity. More high‐quality studies are needed to further confirm these findings and to transfer them into EEG‐based interventions.     

Compressed sensing with signal averaging for improved sensitivity and motion artifact reduction in fluorine‐19 MRI

Fluorine‐19 (¹⁹F) MRI of injected perfluorocarbon emulsions (PFCs) allows for the non‐invasive quantification of inflammation and cell tracking, but suffers from a low signal‐to‐noise ratio and extended scan time. To address this limitation, we tested the hypotheses that a ¹⁹F MRI pulse sequence that combines a specific undersampling regime with signal averaging has both increased sensitivity and robustness against motion artifacts compared with a non‐averaged fully sampled pulse sequence, when both datasets are reconstructed with compressed sensing. As a proof of principle, numerical simulations and phantom experiments were performed on selected variable ranges to characterize the point spread function of undersampling patterns, as well as the vulnerability to noise of undersampling and reconstruction parameters with paired numbers of x signal averages and acceleration factor x (NAx ‐AFx ). The numerical simulations demonstrated that a probability density function that uses 25% of the samples to fully sample the k‐space central area allowed for an optimal balance between limited blurring and artifact incoherence. At all investigated noise levels, the Dice similarity coefficient (DSC) strongly depended on the regularization parameters and acceleration factor. In phantoms, the motion robustness of an NA8‐AF8 undersampling pattern versus NA1‐AF1 was evaluated with simulated and real motion patterns. Differences were assessed with the DSC, which was consistently higher for the NA8‐AF8 compared with the NA1‐AF1 strategy, for both simulated and real cyclic motion patterns (P < 0.001). Both strategies were validated in vivo in mice (n = 2) injected with perfluoropolyether. Here, the images displayed a sharper delineation of the liver with the NA8‐AF8 strategy than with the NA1‐AF1 strategy. In conclusion, we validated the hypotheses that in ¹⁹F MRI the combination of undersampling and averaging improves both the sensitivity and the robustness against motion artifacts.     

Effects of Constant Static Pressure on the Biological Properties of Porcine Aortic Valve Leaflets

An understanding of how mechanical forces impact cells within valve leaflets would greatly benefit the development of a tissue-engineered heart valve. In this study, the effect of constant ambient pressure on the biological properties of heart valve leaflets was evaluated using a custom-designed pressure system. Native porcine aortic valve leaflets were exposed to static pressures of 100, 140, or 170 mmHg for 48 h. Collagen synthesis, DNA synthesis, sulfated glycoaminoglycan (sGAG) synthesis, alpha-SMC actin expression, and extracellular matrix (ECM) structure were examined. Results showed that elevated pressure caused an increase in collagen synthesis. This increase was not statistically significant at 100 mmHg, but at 140 mmHg and 170 mmHg collagen synthesis increased by 37.5 and 90%, respectively. No significant difference in DNA or sGAG synthesis was observed at elevated pressures, with the exception that DNA synthesis at 100 mmHg decreased. A notable decline in alpha-SMC actin was observed over the course of the experiments although no significant difference was observed between the pressure and control groups. It was concluded that elevated pressure caused a proportional increase in collagen synthesis of porcine aortic valve leaflets, but was unable to preserve alpha-SMC actin immunoreactive cells.