PubMed Health⌕ Search

Biomedical subjects

L B Townsend

Publications and source records attributed to L B Townsend.

At least 109 records · Page 6Linked to original sources
PubMed1976

Comparative study by circular dichroism of the conformation of deazapurine nucleosides and that of common purine nucleosides.

Purine nucleoside analogs modified by replacement of the nitrogen atom at the 3 position by a CH group give a characteristic circular dichroism curve that is not substantially modified by chemical substitution at the 8 position. Since it is rather well established that 8-substituted purine nucleosides are predominantly in the syn conformation in aqueous solution, it follows that the 3-deazapurine nucleosides, whether substituted at position 8 or not, also favor the syn conformation. These data are in sharp contrast to the circular dichroism data obtained on 8-halogenated and 8-alkylated derivatives of adenosine and guanosine, which give circular dichroism profiles substantially different from those obtained on the parent compounds. Certain purine-nucleoside-utilizing enzymes fail to interact effectively with either the unsubstituted 3-deaza analogs or the 8-substituted derivatives of adenosine and guanosine. The hypothesis recently given that the inactivity of the 8-substituted derivatives springs from their syn-conformational preference is tentatively accepted to explain the inactivity of the 3-deaza analogs.

Adenosine↗
PubMed1975

Phase I study of ftorafur, an analog of 5-fluorouracil.

Ftorafur, a furanyl analog of 5-fluorouracil (5-FU), is reported to be five to six times less toxic and possibly more effective in cancer of the breast and colon than 5-FU. The drug was synthesized, formulated, and utilized in toxicologic studies, and then in 24 patients with advanced incurable malignancies. When Ftorafur is given by intravenous push, it results in immediate flushing, dizziness, nausea, retching, and in some cases transient hypotension. These immediate side effects are largely eliminated by administering the drug slowly by infusion. In patients, 60 mg/kg of Ftorafur given i.v. daily for up to 10 days resulted in mild toxicity. However, 80 mg/kg given i.v. daily for 7 days resulted in severe toxicity, with nausea, vomiting, stomatitis, leukopenia, and thrombocytopenia. These studies confirm those of the Russian investigators as to toxicity and dosage, even with a different method of administration more convenient for therapy. Phase II studies are presently being carried out to compare the effectiveness of Ftorafur and 5-FU.

Adult↗