Fig. 4.
Most PrPSc in the frontal cortex and white matter of sCJD brains is protease-sensitive [gray bars, calculated from measurements of total PrPSc (white bars) and rPrPSc (black bars)]. Before measurement by the CDI, undigested samples were PTA-precipitated to measure total PrPSc or digested with 50 μg/ml PK at 37°C for 1 h, followed by PTA precipitation to determine rPrPSc (8, 9). The graph shows the means ± SEM obtained from duplicate measurements of samples from the frontal cortex (n = 19) and white matter (n = 12) of sCJD-infected brains.