"All-or-none" cytochrome c oxidase positivity in mitochondria in chronic progressive external ophthalmoplegia: an ultrastructural--cytochemical study.
Teased single muscle fibers from 6 patients with chronic progressive external ophthalmoplegia (CPEO) showed a segmental defect in cytochrome c oxidase (COX) activity. On ultrastructural--cytochemical examination, the majority of mitochondria in COX-positive segments were COX-positive, whereas all mitochondria in COX-negative segments were COX-negative. This "all-or-none" COX positivity in mitochondria in CPEO with deleted mitochondrial DNA can be explained by the "threshold effect," which induces the tissue-specific involvement and clinical heterogeneity.
Division of Ultrastructural Research, National Center of Neurology and Psychiatry, Tokyo, Japan.
T
T
Matsuoka
Y
Y
Goto
I
I
Nonaka
D003576:Electron Transport Complex IV / Q000032:analysis*; D006801:Humans; D008931:Mitochondria, Muscle / Q000201:enzymology* / Q000648:ultrastructure; D017246:Ophthalmoplegia, Chronic Progressive External / Q000378:metabolism / Q000473:pathology*
D003576:Electron Transport Complex IV