Fig. 4

Comparative analyses of αSyn^D seeding activity in multiple biospecimens of PD by end-point dilution RT-QuIC assay. a RT-QuIC spectra of a neuropathologically confirmed case of PD and a NS control affected by AD (Con) using serially diluted homogenates of the brain and scalp skin, as well as CSF. b RT-QuIC spectra of a neuropathologically confirmed case of PD and a NS control without any neurological disease (Con) using serially diluted homogenates of scalp skin, SMG, and sigmoid colon, as well as CSF. The tenfold serially dilutions were indicated on the top of a and b, and 2 µl from the designated dilutions was used to titrate RT-QuIC reactivity to background levels within 50–60 h. Shown were ThT fluorescence traces from 4 replicate reactions at the designated dilutions. The fractions in the upper left corner of each graph indicated the ThT-positive/total replicate reactions. A threshold of 11% was used to define the positive and negative reactivity. SD₅₀ values (per mg or µl) derived from Spearman-Kärber analyses of end-point dilution results for the PD cases were shown for each type of biospecimens on the right