In the Original Contribution by Praticò et al titled "Increase of Brain Oxidative Stress in Mild Cognitive Impairment: A Possible Predictor of Alzheimer Disease," published in the June issue of the ARCHIVES (2002;59:972-976), an author was inadvertently omitted from the byline, author affiliations, and author contributions. The byline on page 972 should have read as follows: "Domenico Praticò, MD; Christopher M. Clark, MD; Feyan Liun, MD; Joshua Rokach, PhD; Virginia Y.-M. Lee, PhD; John Q. Trojanowski, MD, PhD." The author affiliations on page 972 should have appeared as follows: "From the Center for Experimental Therapeutics and Department of Pharmacology (Drs Praticò and Liun), Department of Neurology (Dr Clark), Center for Neurodegenerative Disease Research (Drs Lee and Trojanowski), and Alzheimer's Disease Center (Drs Clark, Lee, and Trojanowski), University of Pennsylvania School of Medicine, Philadelphia; and the Claude Pepper Institute for Aging and Therapeutic Research, Florida Institute of Technology, Melbourne (Dr Rokach)." The author contributions on page 975 should have read as follows: "Study concept and design (Drs Praticò and Clark); acquisition of data (Drs Praticò, Clark, and Liun); analysis and interpretation of data (Drs Praticò, Clark, Rokach, Lee, and Trojanowski); drafting of the manuscript (Drs Praticò and Liun); critical revision of the manuscript for important intellectual content (Drs Praticò, Clark, Rokach, Lee, and Trojanowski); statistical expertise (Drs Praticò, Clark, Liun, and Trojanowski); administrative, technical, and material support (Dr Rokach); and study supervision (Drs Praticò and Clark)."