Multivariate Analysis of Survival for the Cohorts with High and Low CcO Activity.

<p><b>Panel A</b> shows the Kaplan-Meier estimate of the probability of overall survival, according to CcO activity, in all 84 patients combined from the training and validation tissue cohorts (P<0.0001 by the log-rank test; hazard ratio for death in patients with high CcO activity, 24.20; 95% CI, 9.12 to 34.20). Red denotes tumors with low CcO activity and blue denotes tumors with high CcO activity. <b>Panel B, C, D, and E</b> show the probability of survival in patients with high (left) and low (right) CcO activity with respect to age (Panel B; hazard ratio, 0.24; P = 0.14), gender (Panel C; hazard ratio, 0.58; P = 0.42), treatment administered (Panel D; hazard ratio, 0.39; P = 0.05) and MGMT promoter methylation status (Panel E; hazard ratio, 0.9; P = 0.83). Black circles denote censored points, and the numbers between brackets indicate the median survival for each group. CcO denotes cytochrome c oxidase, F denotes female, M denotes male, TMZ denotes temozolomide, and Rad denotes radiotherapy.</p

Kaplan–Meier Estimates of Overall Survival and Progression Free Survival.

<p><b>Panel A</b> shows the probability of overall survival and <b>Panel B</b> shows the probability of progression-free survival for the 58 patients with grade IV primary glioblastoma in the training set. <b>Panel C</b> shows the difference in the probability of overall survival for patients with high and low tumor CcO activity (P<0.0001 by the log-rank test; hazard ratio for death in patients with high tumor CcO activity, 10.75; 95% CI, 3.79 to 30.51). <b>Panel D</b> shows the difference in the probability of progression-free survival for patients with high and low tumor CcO activity (P = 0.0087 by the log-rank test; hazard ratio for death in patients with high tumor CcO activity, 3.57; 95% CI, 1.38 to 9.22). Black circles denote censored points, and the numbers between brackets indicate the median survival for each group. CcO denotes cytochrome c oxidase.</p

Determination of CcO Activity Levels.

<p><b>Panel A</b> shows the representative time course curves of CcO activity (top) and CS activity (bottom). CcO activity was determined by spectrophotometrically measuring the oxidation of cytochrome <i>c</i>, as indicated by the decrease of absorbance at 550 nm. CS activity was determined by measuring spectrophotometric thionitrobenzoic acid (TNB) production, as indicated by the increase of absorbance at 412 nm. For each tissue sample, activities were measured at least twice at protein concentrations that ensured the linearity of the reaction. CcO-specific and CS-specific activities were calculated using the slopes of the curves, and activities were expressed as nanomoles of cytochrome <i>c</i> oxidized per minute per milligram of protein. Red and black lines denote duplicate determinations of a representative tissue. <b>Panel B</b> shows representative CcO/CS ratios from normal brain (epilepsy patients, gray bars) and from primary glioma tissue samples (red bars). Bars represent the average of at least two independent determinations ± SEM.</p