Search PubMed⌕ Search

Biomedical subjects

O Varela

Publications and source records attributed to O Varela.

24 records · Page 2Linked to original sources
PubMed1984

Crystalline 2,3:4,5-di-O-isopropylidene-DL-arabinose diethyl dithioacetal: some reactions of acetal derivatives of arabinose.

Acetonation of the diethyl dithioacetals of D- and L-arabinose gives the corresponding 2,3:4,5-diisopropylidene acetals (2a and 2b) as oils having [alpha]D +82 and -81 degrees, respectively; in admixture, the enantiomers form a well crystallized racemate, m.p. 43-45 degrees. The initial product of acetonation is the 4,5-monoisopropylidene acetal. Demercaptalation of 2a with mercury(II) chloride-cadmium carbonate gives 2,3:4,5-di-O-isopropylidene-aldehydo-D-arabinose (5) in high yield, but the literature procedure employing mercury(II) chloride-mercury(II) oxide affords a mixture of 5 and 1,2:3,4-di-O-isopropylidene-beta-D-arabinopyranose (6). A trace of acid readily and completely converts the aldehydo derivative 5 into the cyclic diacetal 6.

Acetals↗
PubMed1984

3'-Deamino-4'-epi-3'-hydroxy-daunorubicin and -doxorubicin. Synthesis and antitumor activity.

3'-Deamino-4'-epi-3'-hydroxy-daunorubicin (11) and -doxorubicin (14) have been synthesized. In the in vivo murine P-388 lymphocytic leukemia assay, these two compounds were more active than daunorubicin (1) and doxorubicin (2), respectively. Comparative studies in the P-388 assay indicated 3'-deamino-3'-hydroxydoxorubicin (3) to be more active than its 4'-epimer 14.

Animals↗
PubMed1984

Synthesis and antitumor activity of 3'-deamino-3'-hydroxydoxorubicin. A facile procedure for the preparation of doxorubicin analogs.

Two successful routes have been developed for preparation of 3'-deamino-3'-hydroxydoxorubicin (11), based on protection of the 14-hydroxyl group of the aglycon by using tert-butylchlorodimethylsilane. The key intermediate, 14-O-tert-butyldimethylsilyl-7-O-(3,4-di-O-acetyl-2,6-dideoxy-alpha-L-ly xo -hexopyranosyl)adriamycinone (9), was successively deacetylated and desilylated in high yield to give the desired product 11. This route constitutes a general method of access to glycon-modified doxorubicin analogs. Compound 11 showed high antitumor activity in vivo in the murine P388 lymphocytic leukemia assay.

Animals↗
PubMed1980

[Transparieto-hepatic cholangiography with Chiba needle].

253 percutaneous transhepatic cholangiographies with Chiba needle were performed. In 83% of the cases the biliary tract could be visualized. In the patients with extrahepatic cholestasis 92% success was achieved, while only 48% success in the cases with intra-hepatic cholestasis. Complications were developed in 3,87% of cases (choleperitoneum 4, cholangitis 2, hemorrhage 2, paralytic ileum 1, hemobilia 2). There was no mortality. Patients with dilated biliary tract should be operated upon in no more than 24 hours following the procedure.

Adolescent↗