CDI analysis of brain regions from a VPSPr case 1 after treatment of the homogenates with various concentrations of PK. The brain regions analysed were cerebral cortex (frontal cortex, FC, temporal cortex, TC, parietal cortex, PC, occipital cortex, OC), cerebellum, (Cb), hippocampus (Hip), thalamus (Thal), midbrain, pons major (PM), and medulla (Me). Homogenates were prepared in 2% N-lauroylsarcosine/PBS and treated with 0, 1, 2.5, 10 or 50 μg/ml PK for 1 h at 37°C. In addition, samples of frontal cortex were analysed from the GSS (~8 kDa PrPres) case, and samples of frontal cortex and cerebellum were analysed from the GSS (type 1 PrPres) case and a case of sCJD VV2 subtype. The results are the mean D-N values (+/- S.D.) for triplicate analyses of single samples.