[A promising search for substances, suppressing the development of the human immunodeficiency virus, among natural and semisynthetic antibiotics]. / Perspektivy poiska preparatov, podavliaiushchikh razvitie virusa immunodefitsita cheloveka, sredi prirodnykh i polusinteticheskikh antibiotikov.

Perspectives of search, among natural and semisynthetic antibiotics, for inhibitors of different stages of the human immunodeficiency virus replication are discussed. The compounds which inhibit the virus absorbtion, reverse transcription, viral mRNA synthesis, viral protein translation or viral glycoprotein processing are presented.

[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.

[Antiherpetic activity of xylure]. / Protivogerpeticheskaia aktivnost' ksilura.

In vivo experiments demonstrated antiherpetic activity of abnormal nucleoside, 5-trimethylsylil-2'-deoxyuridine alpha-anomer. In a model of herpetic encephalitis in cotton rats the preparation, inoculated intraperitoneally and administered orally, reduced the lethality by 25%-30% as compared with the controls, and also was effective in topical treatment of genital herpes in guinea pigs. Low toxicity, clear-cut antiherpetic activity, favourable metabolic properties as compared with known antiherpetic drugs indicate the necessity of further thorough investigation of this preparation.

[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.