In urine, levels of 15-F2t-isoprostane (IsoP), a lipid peroxidation product, reflect oxidative stress. We used a validated, commercially available assay that members of our team showed were increased in a prior ALS study (8-isoPGF2a ELISA Kit, Detroit R&D).34
Frontotemporal lobar degeneration and ALS are both marked by nuclear exclusion and cytoplasmic deposition of TDP43, which is considered a pathological hallmark of both disorders.35,36
As an exploratory biomarker, platelet TDP-43 was measured from ALS patient samples. Platelet cytosolic samples were analyzed by a high throughput capillary electrophoresis based SimpleWestern system (Proteinsimple, CA, USA). The samples were analyzed with anti TDP-43 (total) and phosphorylated TDP-43 (p(S409/410) antibodies (ProteinTech, USA) that cross-linked to the capillaries. Fluorescent labeled proteins were eluted and intensities were measured. Predictive phosphorylation value (PPV) was calculated by p(S409/410) TDP43 arbitrary units [a.u.] / Total TDP-43 a.u