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Figure 1 An example of "stringent" TUNEL without the use of proteinase K in positive control (tonsil panel A, x1000) and in a patient with dilated cardiomyopathy (panel B, x200). Arrows indicate the presence of TUNEL-positive nuclei in tonsils. Note that when utilizing the "stringent" approach, no TUNEL-positive labeling has been observed in dilated cardiomyopathy patients.