TY - JOUR TI - Activity of 5-formyl tetrahydrofolate cyclodehydrase and 5,10-methenyl tetrahydrofolate cyclohydrolase in primary brain tumors in children AU - TzortzatouStathopoulou, F AU - Mikraki, V AU - Xaidara, A AU - Moschovi, M AU - and Evangelinos, V AU - Panagopoulos, K JO - Pediatric Hematology and Oncology PY - 1996 VL - 13 TODO - 6 SP - 511-519 PB - HEMISPHERE PUBL CORP SN - 0888-0018, 1521-0669 TODO - 10.3109/08880019609030866 TODO - brain tumors; children; cytochemical activity; 5-formyl tetrahydrofolate cyclodehydrase; 5,10-methenyl tetrahydrofolate cyclohydrolase TODO - The activity of the enzymes 5-formyl tetrahydrofolate cyclodehydrase and 5,10-methenyl tetrahydrofolate cyclohydrolase has been studied cytochemically in children’s primary brain tumors. These enzymes play a significant role in purine biosynthesis. Thirty children, aged 1-12 years, were studied, 12 with medulloblastoma, 14 with glioma grade I-IV, and 4 with ependymoma. The activity of the enzymes was apparent as cytoplasmic granules that sometimes overlie the nucleus of the tumor cells. This coincidence showed that different types of brain tumors exhibit different degrees of enzymic activity, which in some cases correlated positively with the malignant potential of the tumor. Approximately one third of the cases were negative for any activity of these enzymes. The intensity of the staining of 5,10-methenyl tetrahydrofolate cyclohydrolase activity was actually higher than that of 5-formyl tetrahydrofolate cyclodehydrase. The clinical or prognostic significance of these findings remains to be clarified, but we believe that cytochemistry provides a sensitive technique for the detection, localization, and description of these enzymes in brain tumor cells. A clear understanding of the mode of action of these enzymes may contribute to devising novel therapeutic strategies. ER -