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People had looked for prions in urine before and couldn't find them there. But author and coworkers treated urine samples differently, subjecting them first to dialysis (separation by diffusion through a semipermeable membrane) and then to analysis, and the dialysis step seemed to be essential to the success of the technique. Author now reported, surprisingly, that she and her coworkers can now detect PrPSc in urine without the need to dialyze it first. She didn't explain why this is now possible or why dialysis seemed essential before but isn't now. But she did disclose that her group recently used the test to discover scrapie in Israeli sheep for the first time. The team's ability to find prions in urine has led to suspicions that prion diseases could be spread when animals eat grass contaminated with urine from infected animals. ONE PUZZLING observation in the Israeli group's experiments is that the PrPSc they detect in urine turns out to be noninfectious when isolated and purified. That is, it is misfolded (or else it wouldn't be PrPSc), but it doesn't cause disease. However, a lack of infectivity in some purified forms of PrPSc has in fact been observed before by other investigators.
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