[Enhanced antitumor action of 5-fluorouracil when used in combination with 4-methylmercaptopyrazolo[3,4-d]pyrimidine 1-nucleoside]. / Povyshenie protivoopukholevogo deistviia 5-ftoruratsila pri kombinirovannom primenenii s 1-nukleozidom 4-metilmerkaptopirazolo[3,4-d]pirimidina.

Mice BDF1 with L 1210 or mice BALB/c with plasmacytoma MOPS-406 after pretreatment with ineffective doses of 1-beta-D-ribofuranosyl-4-methylmercaptopyrazolo(3,4-d)pyramidin e (25 to 100 mg/kg per 5 days) were treated with 5-fluorouracil at the optimal dose 100 mg per day. This combination produced a 1.5-2-fold or 2 to 4 fold enhancement of the antitumour effect of 5-fluorouracil without simultaneous increase of lethal toxicity.

[Therapeutic effect of blastolysin in athymic mice with transplanted strains of human tumors]. / Terapevticheskii éffekt blastolizina u bestimusnykh myshei s perevivnymi shtammami opukholei cheloveka.

9 transplanted strains were used for the evaluation of antitumour effect of blastolysin. The short-term inhibition of the tumour growth was observed on the following models: breast cancer, stomach cancer, kidney cancer and chorionepithelioma.

[Ribamidyl (ribavirin) as a modulator of the biological action of arabinosylcytosine and methotrexate]. / Ribamidil (ribavirin) kak moduliator biologicheskogo deistviia arabinoziltsitozina i metotreksata.

Administration of ribamidyl (Rb) prior to Ara-C to intact mice or mice with implanted tumours enhanced Ara-C toxicity. The growth of tumours (plasmacytoma MOPC-21, adenocarcinoma of the small intestine (strain AKATON), mammary adenocarcinoma 755 (Ca 755) resistant to Ara-C or Rb was inhibited after coadministration of these drugs. The augmentation of toxic and antitumour effects of Ara-C by Rb is similar to the described effect of high doses of thymidine. This is in accordance with the enhancement of the intracellular pool of thymidine phosphates under the action of Rb. The toxicity of methotrexate in vivo was increased by coadministration with Rb. This effect may be connected with a decrease in purine precursors pool under the action of Rb.