CS and astrocytoma (excluding glioblastoma): However, unlike changes in CS activity [20], CoQ10 level detected in this study was decreased in low-grade astrocytomas and it had a strong inverse correlation with malignancy when the data of Grade IV astrocytomas were not included, suggesting that impaired maintenance of CoQ10 level, but not CS or COX II levels, could be associated with the early phase of tumorigenesis.