Cytotoxic synergism of methioninase in combination with 5-fluorouracil and folinic acid

Potentiation of the cytotoxic activity of 5-fluorouracil (FUra) by folinic acid (5-HCO-H4folate) is due to elevation of the methylene tetrahydrofolate (CH2-H4folate) level, which increases the stability of the ternary complex of thymidylate synthase (TS), fluorodeoxyuridine monophosphate, and CH2-H4folate that inactivates the TS. Methionine deprivation results in the production of tetrahydrofolate (H4folate) and, subsequently, CH2-H4folate from methyl tetrahydrofolate, as a consequence of the induction of methionine synthesis. We hypothesized that the efficacy of FUra could be augmented by the combination of high-concentration 5-HCO-H4folate and recombinant methioninase (rMETase), a methionine-cleaving enzyme. Studies in vitro were performed with the cell line CCRF-CEM. Cytotoxic synergism of FUra + rMETase and FUra + 5-HCO-H4folate + rMETase was demonstrated with the combination index throughout a broad concentration range of FUra and rMETase. A subcytotoxic concentration of rMETase reduced the IC50 of FUra by a factor of 3.6, and by a factor of 7.5, in the absence and in the presence of 5-HCO-H4folate, respectively. 5-HCO-H4folate increased the intracellular concentrations of CH2-H4folate and H4folate from their baseline levels. Concentrations of folates were not changed by exposure to rMETase. Levels of free TS in cells treated with FUra + 5-HCO-H4folate and with FUra + rMETase were lower than those in cells exposed to FUra alone. The decrease of TS was still more pronounced in cells treated with FUra + 5-HCO-H4folate + rMETase. The synergism described in this study will be a basis for further exploration of combinations of fluoropyrimidines, folates, and rMETase.     

Population-based validation of a German-language self-administered headache questionnaire

We validated a German-language self-administered headache questionnaire for migraine (M), tension-type headache (TTH) and trigeminal autonomic cephalalgia (TAC) in a general population sample of people with headache. Randomly selected subjects ( n  = 240) diagnosed by the questionnaire as M ( n  = 60), TTH ( n  = 60), a combination of M and TTH (M+TTH, n  = 60) and TAC ( n  = 60) were invited for examination by headache specialists. One hundred and ninety-three subjects (80%) were studied. Sensitivity and specificity for M were 0.85 and 0.85, for TTH 0.6 and 0.88, for M+TTH 0.82 and 0.87, respectively. Cohen's κ was 0.6 (95% confidence interval 0.50, 0.71). Of 45 patients with TAC according to the questionnaire, physicians diagnosed cluster headache in two patients only. We conclude: (i) the questionnaire can be used to diagnose M, TTH and M+TTH, but not TAC; (ii) screening questionnaires for epidemiological research should be validated in a general population sample but not in a tertiary headache clinic.