Evidence for a high free radical state in low-grade astrocytomas.
OBJECTIVE
It is postulated that reactive oxygen species may play an inductive role in neuro-oncogenesis. However, data pertaining to the redox state of astrocytomas are limited, which prompted us to undertake this study.


METHODS
Intraoperative snap-frozen samples were obtained from the surface and core of 8 low-grade and 11 high-grade astrocytomas. Small portions of each specimen were fixed in 10% neutral formalin or cacodylate-buffered glutaraldehyde. Lipid peroxidation was estimated by measuring thiobarbituric acid-reactive substances, and total glutathione levels were determined. Light microscopy was performed to define the relevant histopathology, and electron microscopy was used to quantitate peroxisomal content.


RESULTS
Thiobarbituric acid-reactive substance values for low-grade astrocytomas were significantly elevated compared to those for malignant lesions, as was the case for total glutathione. This discrepancy was especially marked at the tumor surface. Peroxisomes predominated in the low-grade category.


CONCLUSIONS
We speculate regarding malignant transformation as a possible consequence of this decline in antioxidant capacity, as well as regarding the role of seizures and astrocytoma glutamate receptors in the initiation of free radical cascades. The therapeutic and teleological implications are considerable.
Louw
D F
DF
Department of Clinical Neurosciences, University of Calgary, Alberta, Canada.
Bose
R
R
Sima
A A
AA
Sutherland
G R
GR
D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000378:metabolism* / Q000473:pathology / Q000601:surgery / Q000648:ultrastructure; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000601:surgery / Q000648:ultrastructure; D002374:Catalase / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D002648:Child; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D005609:Free Radicals / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000032:analysis; D008830:Microbodies / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D008875:Middle Aged; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis
D005609:Free Radicals; D017392:Thiobarbituric Acid Reactive Substances; D008315:Malondialdehyde; D002374:Catalase; D005978:Glutathione; D019803:Glutathione Disulfide