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Biomedical subjects

E L Uhlenhopp

Publications and source records attributed to E L Uhlenhopp.

8 recordsLinked to original sources

Reaction of anthramycin with DNA. Biological consequences of DNA damage in normal and xeroderma pigmentosum cell.

Anthramycin, an antitumor antibiotic produced by Streptomyces refuineus, produces a well defined covalent adduct with DNA and lies within the narrow groove of DNA, attached through a thermal-labile covalent animal linkage to the exocyclic amino group of guanine, without detectable distortion of the helix (Petrusek, R. L., Anderson, G. L., Garner, T. F., Fannin, Q. L., Kaplan, D. J. Zimmer, S. G., and Hurley, L. H. (1981) Biochemistry 20, 1111-1119). This paper described results in which the biological consequences of DNA damage and repair by repair-proficient and a repair-deficient xeroderma pigmentosum (XP 12RO) cell line are presented. Anthramycin has been shown to produce excision-dependent single and double strand breaks in DNA, both of which appear to persist many hours after removal of the drug from the media. The lower ability of the xeroderma pigmentosum cell line to remove ability of the xeroderma pigmentosum cell line to remove anthramycin lesions from DNA is correlated with a decreased cell survival. The biological consequences of DNA damage (genetic effects, DNA strand breakage, and cytotoxicity) are discussed with respect to the defined structure and stability of the anthramycin-deoxyguanosine adduct.

Anthramycin↗

Viscoelastic characterization of single-stranded DNA from Escherichia coli.

Single-stranded DNA released from E. coli wild type and mutant cells by alkaline-EDTA-detergent was analyzed using the recently developed biophysical technique of viscoelastometry. Under the lysis conditions used, it was possible to detect single strands of molecular weight approximately 2 times 10-9 daltons. Little difference was detected in the size of single-stranded DNA from log phase vs. stationary phase cultures, or from cells treated with chloramphenicol to allow completion of replicating chromosomes. The largest single strands from ligase overproducing, endonuclease minus, and pol A1 mutants were likewise of approximately the same size as wild type, but were present in smaller yields. The reduction in single-strand molecular weight as a result of heating intact cells was investigated as a function of time and temperature. Heating at 37 degrees C for up to 20 min produced no additional single-strand breaks, but temperatures from 45 to 65 degrees introduced breaks. Solutions maintained at pH 12.5 were not stable indefinitely, and the relative viscosity of such solutions was found to decrease over a period of several hours.

DNA, Bacterial↗

Viscoelastic analysis of high molecular weight, alkali-denatured DNA from mouse 3T3 cells.

Alkaline lysates of mouse 3T3 cells showed viscoelastic properties characteristic of very large molecules of single-stranded DNA. The viscoelastic retardation time and the sensitivity to low doses of nitrogen mustard and of X-irradiation suggest a molecular weight in excess of 10-10 daltons. Contact-inhibited cells yielded larger single strands than actively growing cells.

Animals↗