The interaction between E. coli RNA polymerase and the tetR promoter from pSC101, was studied by protection and premodification experiments, using dimethyl sulfate, methylation of single stranded cytosines, and DNAase I footprinting. Whereas qualitative and quantitative results from the chemical approach conform to patterns already displayed by other promoter systems, hypersensitive sites to DNAase I attack differ from those of other promoters. Distribution and nature of the contacts suggest that regions of the promoter sequence participates differently in complex formation. The involvement of major and minor grooves of the double helix in the complex with the enzyme, differs along the promoter. After a comparison of the results from seven different promoters, a pattern of conserved contacts seem to appear. Comparison of temperature dependence of local unwinding around the transcription start site (detected by the appearance of single stranded cytosines), and DNAase I footprinting, reveals that the process leading to stable complex formation can be achieved without disruption of base-pairing.

Base Sequence↗

PubMed1986

Inclusive phi production in B-meson decay.

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Journal Article↗

PubMed1986

An algorithm for studying cooperative transitions in DNA.

Cooperative transitions in DNA (B to Z, B to A, helix to coil, etc.) are known to depend strongly on nucleotide sequence. In general the change in free energy involved in the transition can be expressed as: delta G(seq) = 2RT log (sigma) where sigma is a factor arising from the free energy associated with boundaries of different conformations along the molecule. This formula allows to infer a general algorithm with which DNA sequences can be partitioned into well defined domains in which, under suitable conditions, base pairs change state cooperatively. The different partitions of the sequence that can be generated by varying the values of the physical parameters involved in the above formula, are shown to be embedded into a binary tree hierarchy. Application to a reliable prediction of Z-DNA antibody binding sites will be illustrated for the 0X174 genome. Possible biological implications are briefly discussed.

Antibodies, Antinuclear↗

PubMed1986

Search for monoenergetic photons from Upsilon (1S)--> gamma +X.

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Journal Article↗

PubMed1986

Long-term follow-up of cardiac rhythm in repaired total anomalous pulmonary venous drainage.

Seven consecutive patients with total anomalous pulmonary venous drainage were operated at the Medical College of Ohio at Toledo and long-term follow-up is reported on their rhythm status. The patients were generally under 3 months of age at operation. All patients are alive at the present time. The median length of follow-up is 4 years. Five of the 7 patients demonstrated ectopic pacemaker activity and 2 exhibited episodes of nodal rhythm as well. In general, these were not apparent on standard screening electrocardiography. There was no correlation between the presence or absence of this arrhythmia and the type of repair. It is concluded that arrhythmias may be present in these patients, but that they are unrelated to the type of surgery performed. The ectopic atrial focus may be of no clinical significance but there is more cause for concern in those patients with nodal rhythm.

Arrhythmias, Cardiac↗

PubMed1986

Marker and function analysis of natural killer and alloreactive T cells during early stages of dimethylbenzanthracene carcinogenesis. The immunity system during the precancer period.

The effect of the chemical carcinogen dimethylbenzanthracene (DMBA) on cellular immunity was studied at a 6-mg dose which induces adenocarcinomas and adenoacanthomas in more than 70% of BalB/c mice within 1 year after administration. DMBA caused a significant reduction of splenic natural killer (NK) activity and responsiveness to alloantigens in mixed lymphocyte reactions (MLR). These activities decreased soon after the carcinogen treatment and remained suppressed during the entire tumor induction period. There was a linear correlation between the reduction in NK activity and a selective decrease in the number of asialo GM1 positive cells in the spleen. However, cell sorting experiments using the flow cytometer have shown that the lytic activity per cell of asialo GM-1 positive cells in untreated mice and in DMBA-treated ones was similar. There was no correlation between the suppressed response of the T cells in MLR and the percentage of T cell subpopulations residing in the spleen of the DMBA-treated mice. The decrease in the number of NK cells and the reduced MLR activity in the spleen occurred simultaneously with a decrease in the potential of bone marrow precursor cells to reconstitute NK and MLR activity in the spleen of lethally irradiated mice. These results indicate that the carcinogen DMBA effects the immune system at various levels and either eliminates or inactivates precursor cells as well as mature lymphoid cells.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1985