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Göttingen, Germany

Dutta A.,Charite - Medical University of Berlin | Dutta A.,Montpellier University | Jacob A.,Indian Institute of Technology Madras | Chowdhury S.R.,International Institute of Information Technology, Hyderabad | And 2 more authors.
Journal of Medical Systems | Year: 2015

A method for electroencephalography (EEG) - near-infrared spectroscopy (NIRS) based assessment of neurovascular coupling (NVC) during anodal transcranial direct current stimulation (tDCS). Anodal tDCS modulates cortical neural activity leading to a hemodynamic response, which was used to identify impaired NVC functionality. In this study, the hemodynamic response was estimated with NIRS. NIRS recorded changes in oxy-hemoglobin (HbO2) and deoxy-hemoglobin (Hb) concentrations during anodal tDCS-induced activation of the cortical region located under the electrode and in-between the light sources and detectors. Anodal tDCS-induced alterations in the underlying neuronal current generators were also captured with EEG. Then, a method for the assessment of NVC underlying the site of anodal tDCS was proposed that leverages the Hilbert-Huang Transform. The case series including four chronic (>6 months) ischemic stroke survivors (3 males, 1 female from age 31 to 76) showed non-stationary effects of anodal tDCS on EEG that correlated with the HbO2 response. Here, the initial dip in HbO2 at the beginning of anodal tDCS corresponded with an increase in the log-transformed mean-power of EEG within 0.5Hz-11.25Hz frequency band. The cross-correlation coefficient changed signs but was comparable across subjects during and after anodal tDCS. The log-transformed mean-power of EEG lagged HbO2 response during tDCS but then led post-tDCS. This case series demonstrated changes in the degree of neurovascular coupling to a 0.526 A/m2 square-pulse (0–30 s) of anodal tDCS. The initial dip in HbO2 needs to be carefully investigated in a larger cohort, for example in patients with small vessel disease. © 2015, Springer Science+Business Media New York. Source


Ebner N.,University of Medicine Goettingen | Foldes G.,Imperial College London | Schomburg L.,Institute for Experimental Endocrinology | Renko K.,Institute for Experimental Endocrinology | And 7 more authors.
Journal of Molecular and Cellular Cardiology | Year: 2015

Background: The origin of pro-inflammatory activation in chronic heart failure (HF) remains a matter of debate. Lipopolysaccharide (LPS) may enter the blood stream through the morphologically altered and leaky gut barrier. We hypothesized that lower LPS reactivity would be associated with worse survival as compared to normal or higher LPS reactivity. Methods: LPS responsiveness was studied in 122 patients with chronic HF (mean. ±. SD: age 67.3. ±. 10.3. years, 24 female, New York Heart Association class [NYHA] class: 2.5. ±. 0.8, left ventricular ejection fraction [LVEF]: 33.5. ±. 12.5%) and 27 control subjects of similar age (63.7. ±. 7.7. years, p. >. 0.05). Reference LPS was added at increasing doses to ex vivo whole blood samples and necrosis factor-α (TNFα) was measured. Patients were subgrouped into good- and poor-responder status according to their potential to react to increasing doses of LPS (delta TNFα secretion). The optimal cut-off value was calculated by receiver-operator characteristic curve (ROC) analysis. Results: A total of 56 patients with chronic HF died from any cause during follow-up. At 24. months, cumulative mortality was 16.4% (95% confidence interval 16.0-16.7%). The delta TNFα value representing the optimal cut-off for the prediction of mortality was 1522. pg/mL (24. months) with a sensitivity of 49.3% (95% confidence interval 37.2-61.4%) and specificity of 81.5% (95% confidence interval 61.9-93.6%). LPS responder status remained an independent predictor of death after multivariable adjustment (hazard ratio 0.09 for good- vs. poor-responders, 95% confidence interval 0.01-0.67, p. <. 0.05). Conclusions: LPS responsiveness in patients with chronic HF is an independent predictor of death. © 2015 Elsevier Ltd. Source


Kemmling A.,University of Hamburg | Kemmling A.,University of Munster | Kemmling A.,University of Lubeck | Flottmann F.,University of Hamburg | And 9 more authors.
Journal of Cerebral Blood Flow and Metabolism | Year: 2015

Benefit of endovascular recanalization beyond established treatment time windows likely exists in select stroke patients. However, there is currently no imaging model that predicts infarction adjusting for elapsed time between the pathologic snapshot of admission imaging until endovascular recanalization. We trained and cross validated a multivariate generalized linear model (GLM) that uses computer tomography perfusion and clinical data to quantify patient-specific dynamic change of tissue infarction depending on degree and time of recanalization. Multicenter data of 161 patients with proximal anterior circulation occlusion undergoing endovascular therapy were included. Multivariate voxelwise infarct probability was calculated within the GLM. The effect of increasing time to treatment and degree of recanalization on voxelwise infarction was calculated in each patient. Tissue benefit of successful relative to unsuccessful recanalization was shown up to 15 hours after onset in individual patients and decreased nonlinearly with time. On average, the relative reduction of infarct volume at the treatment interval of 5 hours was 53% and this salvage effect decreased by 5% units per hour to <5% after 10 additional hours to treatment. Treatment time-adjusted multivariate prediction of infarction by perfusion and clinical status may identify patients who benefit from extended time to recanalization therapy. © 2015 ISCBFM All rights reserved. Source

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