Spectral analysis of HS-68-positive inclusions in multiple system atrophy (MSA) and Parkinson’s disease (PD). a Plot of the ratio of emission intensities at wavelengths of 486 and 573 nm for HS-68 following binding to inclusions in MSA (coral circles) and PD (cyan squares). Cerebellum was used for MSA; substantia nigra (filled squares) and cingulate gyrus (open squares) for PD. Each dot corresponds to a region of interest. The 8 cases of MSA (1–8) and 9 cases of PD (9–17) are listed in Table 1. Asterisk indicates cases for which both substantia nigra and cingulate gyrus were used. Insert: Mean HS-68 emission spectra when binding to inclusions in brain tissues from MSA (coral) and PD (cyan). Each spectrum represents one MSA (cerebellum) or one PD (substantia nigra and/or cingulate gyrus) case. Dashed lines indicate the wavelengths that were used for calculating the ratio of emission intensity depicted in the plots. b Merging of the ratio values for all MSA (coral circles) and PD (cyan squares) cases shown in a. The results are expressed as means ± S.D.; ns, not significant.