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Biomedical subjects

Z Krawczyk

Publications and source records attributed to Z Krawczyk.

At least 55 records · Page 3Linked to original sources
PubMed1982

Inhibition of RNA polymerase B activity in normal and regenerating rat liver after administration of 9-aminoacridine.

Ledakrin, 1-nitro-9-[3'-(N,N'-dimethyl)aminopropyl]aminoacridine administered intraperitoneally at a dose up to 20 mg/kg into sham operated and partially hepatectomized rats inhibited RNA polymerase B activity in the isolated liver nuclei. The average chain length of the in vitro transcript was reduced while the number of elongating RNA polymerase B molecules was not changed after Ledakrin treatment. The drug inhibited RNA polymerase B activity in 18 hour regenerating liver to a much greater extent than in control liver. However, one molecule of tritium-labelled Ledakrin was bound with the same number of base pairs of DNA both in normal and regenerating liver. About 60 to 70% of the label was found to form labile complexes with DNA and could be liberated on thermal, alkaline or acidic denaturation of DNA. The remaining label seems to be covalently bound to DNA. The drug induced "cross-links" between the two strands of rat liver DNA in vivo. DNA from the liver nuclei unable to synthesize RNA due to Ledakrin treatment, retained the template activity against E. coli RNA polymerase. The presented results point to a limited preference of Ledakrin to bind to the transcriptionally active regions of chromatin.

Aminacrine↗
PubMed1980

Activity of chromatin-bound protease in histone fractions from rat liver and Morris hepatoma.

Activity of chromatin-bound protease of rat liver and Morris hepatoma 7777 was studied. Proteolytic enzyme was copurified with histones during extraction of chromatin with 0.25 M HCl. Total histone was fractionated by Oliver's et al. method. Histone fractions were incubated in 0.01 M Tris-HCl buffer (pH 7.6) at 37 degrees C within different periods of time. The behavior of these fractions in polyacrylamide gel electrophoresis as well as the amounts of peptides soluble in 5% TCA released during incubation indicated that enzyme was coextracted with histone H2B only. It was shown that the activity of protease coextracted selectively with histone H2B was higher in tumor tissue than in normal liver.

Animals↗
PubMed1978

Changes in cellular concentration of DNA-dependent RNA polymerases A and B during regeneration of rat liver.

1. DNA-dependent RNA polymerases A and B were solubilized from rat liver nuclei at different intervals after partial hepatectomy, and chromatographed on DEAE-Sephadex A-25. Activity of the solubilized RNA polymerases remained unchanged till 6 h after hepatectomy, then started to increase reaching a maximum (350% and 150% of control for the A and B enzyme, respectively) at the 18th hour of regeneration, and was still high at the 36th hour of regeneration. 2. RNA polymerases A and B were extracted and extensively purified from the nuclei of normal and regenerating rat liver. No marked differences in the specific activities between the analogous purified enzymes from normal and regenerating liver were observed, thus the increase in RNA polymerase activities (especially marked in the case of enzyme A) observed after partial hepatectomy is probably due to a real increase in the quantities of enzymes. 3. Concentration of RNA polymerase A in hepatocyte increases from 1.3 x 10(4) (normal liver) to 7.5 x 10(4) (18 h after hepatectomy) molecules per haploid genome. The concentration of polymerase B increases from 3.4 x 10(4) to 5.5 x 10(4) molecules per haploid genome, respectively.

Ammonium Sulfate↗
PubMed1977

Early postoperative bleedings after prostatectomy in the light of statistical figures.

A statistical analysis of intraoperative and early postoperative bleedings in cases of surgery for prostatic adenoma is presented, consideration being given to the surgical technique and to lethality. It has emerged that all patients having had intraoperative or early postoperative bleedings had been operated on by the Hryntschak method and all were over 60 years of age (average age 68 years). Age-matched patients operated on by the Freyer method had no major bleedings.

Aged↗