Neutrophil Extracellular Traps and Thrombolysis in the Acute Stroke

Neutrophil extracellular traps (NETs) were measured in serum at the time of hospitalization, then at 4 hours, 24 hours and 72 hours after stroke. Because of nucleosome instability, a strict preanalytical protocol was followed. Blood samples were centrifuged within 1-2 h after blood drawing. A strict preanalytical protocol was followed including early centrifugation of the samples and storage at - 80°C. NETs were quantified in batches containing all samples from a patient using the detection of MPO (myeloperoxidase) then the Cell-Death-Detection ELISAPLUS (Roche Diagnostics, Germany) as described earlier. Nucleosomes were quantified in relative arbitrary units (AU). Blood samples from each patient were measured within the same run to improve the comparability of the results.

For statistical analysis, various variables of nucleosomes were considered, such as the absolute concentrations determined at admission, at 24 hours and at 72 hours after stroke. Influence of nucleosome concentration on recanalization was tested. Continuous correlations of nucleosomes and infarction volume, nucleosomes and clot size, as well as of infarction volume and NIHSS were calculated by Spearman's rank correlation together with the 95% confidence interval. A p value < 0.05 was considered statistically significant.

The extent of the morphological damage was determined at time of admission to the hospital and 24 hours after thrombolysis by diffusion-weighted magnetic resonance imaging (MRI). The pretreat¬ment and follow-up DWI lesions was segmented using interactive tools based on DWI signal intensity thresholding within a 3-dimensional mask encompassing the apparent area of bright DWI signal intensity and morphometric filtering. The clot location and length were assessed on the susceptibility vessel sign on T2* as describe earlier.