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New deep brain stimulation (DBS) electrode designs offer operation in voltage and current mode and capability to steer the electric field (EF). The aim of the study was to compare the EF distributions of four DBS leads at equivalent amplitudes (3 V and 3.4 mA). Finite element method (FEM) simulations (n = 38) around cylindrical contacts (leads 3389, 6148) or equivalent contact configurations (leads 6180, SureStim1) were performed using homogeneous and patient-specific (heterogeneous) brain tissue models. Steering effects of 6180 and SureStim1 were compared with symmetric stimulation fields. To make relative comparisons between simulations, an EF isolevel of 0.2 V/mm was chosen based on neuron model simulations (n = 832) applied before EF visualization and comparisons. The simulations show that the EF distribution is largely influenced by the heterogeneity of the tissue, and the operating mode. Equivalent contact configurations result in similar EF distributions. In steering configurations, larger EF volumes were achieved in current mode using equivalent amplitudes. The methodology was demonstrated in a patient-specific simulation around the zona incerta and a “virtual” ventral intermediate nucleus target. In conclusion, lead design differences are enhanced when using patient-specific tissue models and current stimulation mode.

Thylakoids are membranes isolated from plant chloroplasts which have previously been shown to inhibit pancreatic lipase/colipase catalysed hydrolysis of fat in vitro and induce short-term satiety in vivo. The purpose of the present study was to examine if dietary supplementation of thylakoids could affect food intake and body weight during long-term feeding in mice. Female apolipoprotein E-deficient mice were fed a high-fat diet containing 41% of fat by energy with and without thylakoids for 100 days. Mice fed the thylakoid-enriched diet had suppressed food intake, body weight gain and body fat compared with the high-fat fed control mice. Reduced serum glucose, serum triglyceride and serum free fatty acid levels were found in the thylakoid-treated animals. The satiety hormone cholecystokinin was elevated, suggesting this hormone mediates satiety. Leptin levels were reduced, reflecting a decreased fat mass. There was no sign of desensitization in the animals treated with thylakoids. The results suggest that thylakoids are useful to suppress appetite and body weight gain when supplemented to a high-fat food during long-term feeding.

Introduction: Lead movement after deep brain stimulation may occur and influence the affected volume of stimulation. The aim of the study was to investigate differences in lead position between the day after surgery and approximately 1 month postoperatively and also simulate the electric field (EF) around the active contacts in order to investigate the impact of displacement on affected volume. Methods: Twenty-three patients with movement disorders underwent deep brain stimulation surgery (37 leads). Computed tomography at the 2 time points were co-fused respectively with the stereotactic images in Surgiplan. The coordinates (x, y, and z) of the lead tips were compared between the 2 dates. Eleven of these patients were selected for the EF simulation in Comsol Multiphysics. Postoperative changes of EF spread in the tissue due to conductivity changes in perielectrode space and due to displacement were evaluated by calculating the coverage coefficient and the Sørensen-Dice coefficient. Results: There was a significant displacement (mean ± SD) on the left lead: x (0.44 ± 0.72, p < 0.01), y (0.64 ± 0.54, p < 0.001), and z (0.62 ± 0.71, p < 0.001). On the right lead, corresponding values were: x (−0.11 ± 0.61, ns), y (0.71 ± 0.54, p < 0.001), and z (0.49 ± 0.81, p < 0.05). The anchoring technique was a statistically significant variable associated with displacement. No correlation was found between bilateral (n = 14) versus unilateral deep brain stimulation, gender (n = 17 male), age <60 years (n = 8), and calculated air volume. The simulated stimulation volume was reduced after 1 month because of the perielectrode space. When considering perielectrode space and displacement, the volumes calculated the day after surgery and approximately 1 month later were partly overlapped. Conclusion: The left lead tip displayed a tendency to move lateral, anterior, and inferior and the right a tendency to move anterior and inferior. The anchoring technique was associated to displacement. New brain territory was affected due to the displacement despite considering the reduced stimulated volume after 1 month. Postoperative changes in perielectrode space and small lead movements are reasons for delaying programming to 4 weeks following surgery.