5'-Peptidyl substituents allow a tuning of the affinity of oligodeoxyribonucleotides for RNA.

The affinity of amide-linked 5'-aminoacyl and 5'-dipeptidyl DNA octamers for two RNA undecamers with 3'-overhangs was measured via UV melting analysis. A sequence-dependent increase in melting points was observed. At low ionic strength, two appended lysine residues elevate melting points more than two additional A:U base pairs.

Miotics and retinal detachment: upgrading the community standard.

The majority of ophthalmologists who responded to a questionnaire regarding the relationship between miotics and retinal detachment felt that such a relationship does exist, and that myopia and aphakia/pseudophakia predispose to the formation of new retinal breaks or to retinal detachment from pre-existing breaks with miotics. Horseshoe breaks and dialyses are pre-existing lesions that should be treated prophylactically prior to miotic therapy. Patients with no predisposing pathology or whose eyes have lattice degeneration or operculated breaks should be warned of possible retinal detachment prior to starting miotics. Not performing a peripheral retina examination prior to prescribing a miotic is acceptable, but not optimal, medical practice. Examining the peripheral retina or obtaining a retina consultation prior to prescribing a miotic may be beneficial to the patient and could be invaluable in the defense of litigation.

A comparative trial of mitoxantrone and doxorubicin in patients with minimally pretreated breast cancer.

A randomized trial began in 1980 comparing the efficacy and toxicity of mitoxantrone and doxorubicin. Patients with metastatic breast cancer unresponsive to cyclophosphamide-methotrexate-5-fluorouracil with or without tamoxifen were randomized to either mitoxantrone, 12 mg/m2, or doxorubicin, 60 mg/m2, every 3 weeks. Patients were crossed over to the alternative treatment if they progressed after two courses or fail to respond after four courses. Fifty-nine patients have been randomized at the present time, and most of these have a performance status near to normal. During initial therapy, partial responses were obtained in 10 of 25 patients receiving doxorubicin, and a further 12 showed stable disease; 3 showed progressive disease. Of the 26 patients who received mitoxantrone as initial therapy, 7 achieved a partial response, 14 had stable disease, and 5 progressive disease. Twenty-seven patients received doxorubicin or mitoxantrone as secondary therapy; two patients each responded to these drugs, suggesting a lack of cross-resistance. The median time to response was 48 days for doxorubicin and 57 days for mitoxantrone. The duration of partial responses measured from the onset of response was similar for both drugs, being 84 days for doxorubicin and 96 days for mitoxantrone. Hematologic toxicity, vomiting, alopecia, and fatigue tended to be less frequent and less severe with mitoxantrone than with doxorubicin. Mitoxantrone appears to be an effective and well-tolerated agent for breast cancer. Definitive comparisons will be available at the completion of this study.

Isolation of a DNA polymerase alpha-associated regulatory protein from calf thymus.

A regulatory protein for DNA polymerase alpha, responsive to noncomplementary deoxyribonucleoside triphosphates, has been isolated from calf thymus. The regulatory protein was separated from DNA polymerase alpha using Affi-Gel Blue and gel filtration. The regulatory protein had a molecular weight of approximately 70,000 as determined by gel filtration, and its activity was nondialyzable, heat labile, and abolished by pronase treatment. In the presence of regulatory protein, DNA polymerase alpha activity, measured by using polydeoxyadenylate-oligodeoxythymidylate as template primer, was inhibited by 2'-deoxyguanosine 5'-triphosphate in a parabolic-competitive fashion [Ki = 15 +/- 1 (S.E.) microM] and by 2'-deoxycytidine 5'-triphosphate in a linear-competitive manner (Ki = 162 +/- 23 microM). Neither the four natural ribonucleoside triphosphates nor 2'-deoxyadenosine 5'-triphosphate inhibited the DNA polymerase-regulatory protein system to any significant extent. The regulatory protein by itself had no effect on either DNA polymerase alpha activity or the Km for template primer. These results indicate that deoxyribonucleoside triphosphate pools may be involved in the regulation of cellular DNA synthesis through a direct effect on DNA polymerization.