The relationship between DNA topoisomerase II activity and drug resistance was studied in cloned cell lines of Adriamycin (ADR)-sensitive and -resistant P388 leukemia; drug resistant P388/ADR/3 (clone 3) and P388/ADR/7 (clone 7) cells are 5and 10-fold more resistant to ADR than the sensitive cell line P388/4 (Cancer Res., 46: 2978, 1986). Topo isomerase II catalytic activity in crude nuclear ex...

EMT-6 cells treated for 16 h with 1-10 units/ml IFN-y showed a gradual activation ofinducible nitric oxide synthase (¡NOS)in Western and Northern blots, a simultaneous raise in NO output, and an increase in hypoxic cell radiosensitivity almost to the level of aerobic cells. Both the NO signal and radioseasitization were counteracted by the NO scavenger oxyhemoglobin, by the specific ¡NOSinhib...

An efficient two-dimensional magic-angle-spinning (MAS) NMR technique to selectively detect â-sheet residues in proteins is demonstrated. The method exploits the relative orientation between N-H and CR-HR dipolar couplings, that is, the φ torsion angle, in each amino acid residue. The different φ angles between the R-helical and â-sheet conformations give rise to distinctly different dipolar mo...

Uridine enhances the growth inhibition due to 5-fluorouracil (FUra) in a cultured mouse T-cell lymphoma (S-49). Using colony formation assays we found that cytotoxicity produced by 24-h continuous exposure to FUra (0.5 to 3.5 /¿M) was increased more than two-fold by simultaneous exposure to 10 /IM undine. Studies were undertaken to explain the mechanism by which undine enhanced the cytotoxicit...

We show that any locally finite automata network A with global synchronous updates can be emulated by another one Â, whose structure derives from that of A by a simple construction, but whose updates are made asynchronously at its various component automata (e.g., possibly randomly or sequentially, with or without possible simultaneous updates at different nodes). By “emulatation”, we refer to ...

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EMT-6 cells treated for 16 h with 1-10 units/ml IFN-y showed a gradual activation ofinducible nitric oxide synthase (¡NOS)in Western and Northern blots, a simultaneous raise in NO output, and an increase in hypoxic cell radiosensitivity almost to the level of aerobic cells. Both the NO signal and radioseasitization were counteracted by the NO scavenger oxyhemoglobin, by the specific ¡NOSinhib...

The limited angular resolution of γ–ray telescopes prevents the straight identification of the majority of the sources detected so far. This is particularly true for the low latitude, probably galactic ones, only 10 % of which has been identified. Most of the counterparts are Isolated Neutron Stars, both radio–loud and radio–quiet, characterised by an extremely high value of fX /fopt. The best ...