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Biomedical subjects

H Slor

Publications and source records attributed to H Slor.

At least 55 records · Page 3Linked to original sources
PubMed1981

Immunochemical visualization of binding of the chemical carcinogen benzo(a)pyrene diol-epoxide 1 to the genome.

antisera against DNA modified with r-7,t-8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BPDE-1) was elicited in rabbits. Such sera reached with either single- or double-stranded modified DNA but not with unmodified DNA, free benzo(a)pyrene, or proteins modified by BPDE-1. Indirect immunofluorescence studies indicated that the immunoglobulin G in the sera bound specifically to the nuclei of KD cells which were treated with BPDE-1. The intensity of fluorescence was proportional to the dose of BPDE-1 used to treat the cells. About 50% of the BPDE-1-DNA adducts remained bound to DNA 24 hr after the removal of the carcinogen. The location of BPDE-1-modified bases in Col E1 DNA was visualized by immunoelectron microscopy.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1980

Neutral deoxyribonucleases of HeLa S3 cells: electrophoretic separation, characterization, substrate specificity and mode of action.

Extracts of HeLa S3 cells were electrophoresed on polyacrylamide gels; gel slices were eluted and the eluates were assayed for DNase activities against native and denatured DNA substrates in the presence of MgCl2 or Na2EDTA. Aliquots of each eluate were also assayed for their ability to nick the circular supercoiled PM2 phage DNA to distinguish endonucleases from exonucleases. Peaks of endonuclease activities were characterized as forming 3'-phospho-oligonucleotides or 5'-phospho-oligonucleotides by the use of oligonucleotides produced by these enzymes as substrates for the 5'-phosphate-specific snake venom exonuclease. The total activity of DNases in gel eluates was much higher than that in cell extract applied to the gel, indicating the presence of inhibitors in the cell extract.

DNA, Circular↗
PubMed1977

Evidence for inactivation of DNA repair in frozen and thawed mammalian cells.

A variety of cell strains and lines were frozen and thawed by conventional techniques for cell storage. Following thawing, extracts of cells were prepared and incubated with UV-irradiated E. coli DNA. Thymine dimer excision activity present in extracts of unfrozen cells was lost in extracts of recently thawed cells. The ability to exercise dimers was restored after about 40 h post-thawing, but the recovery was inhibited if cells were cultured in the presence of puromycin. Correlating with the loss of dimer excising activity there was a reduced cell viability as measured by trypan blue dye exclusion.

Cell Line↗
PubMed1976

Effects of prednisolone metasulfabenzoate on the induction of DNase II in comparison to alkaline phosphatase and acid phosphatase activities in cultures of HeLa S3 cells.

Cultures of HeLa S3 cells were treated with prednisolone metasulfobenzoate (Na), a derivative of prednisolone which is readily soluble in water. The steroid induced an increase in DNase II, a lysosomal enzyme which was not used previously in enzyme induction by steroids. Alkaline phosphatase, a known inducible enzyme by other steroids and acid phosphatase, a known uninducible enzyme by other steroids, were included for comparative reasons.

Acid Phosphatase↗
PubMed1976

Defective thymine dimer excision by cell-free extracts of xeroderma pigmentosum cells.

Crude extracts of normal human diploid fibroblasts and of human peripheral blood lymphocytes excise thymine dimers from purified ultraviolet-irradiated DNA, or from the DNA presumably present as chromatin in unfractionated cell-free preparations of cells that had been labeled with [3H]thymidine. Extracts of xeroderma pigmentosum cells from complementation groups A, C, and D also excise thymine dimers from purified DNA, but extracts of group A cells do not excise dimers from the DNA of radioactively labeled unfractionated cell-free preparations.

Cell Line↗
PubMed1975

Purification of S1 muclease from Takadiastase by affinity chromatography on single-stranded DNA-acrylamide columns.

When S1 nuclease from Takadiastase was partially purified according to previously reported methods, it showed a 10 to 15 fold increase in specificactivity. Although such preparations were highly active on single-stranded DNA, they had traces of activity on native DNA and were contaminated by T1-RNase. The S1 enzyme was further purified by a single step of affinity chromatography on single-stranded DNA-acrylamide column to a final purification of 275-fold. This preparation was free of T1-RNase and had an absolute specificity for single-stranded DNA.

Acrylamides↗
PubMed1975

A new assay of deoxyriboucleases using as a substrate radioactively labelled DNA bound either directly or through anti-DNA antibodies to plastic depression plates.

A simple and accurate method for the detection of Deoxyribonucleases is described. The DNA substrate (3H-labeled) is bound to DNA-binding sites in the "wells" of plastic depression plates either directly of via anti-DNA antibodies. Following incubation with the appropriate enzyme, the radioactivity released from the wells or left bound to the wells is determined. The method is suitable for enzymes which attack native DNA, single stranded DNA and modified DNA (e.g., u.v.-irradiated) as substrates.

Animals↗
PubMed1975

Differentiation between exonucleases and endonucleases and between haplotomic and diplotomic endonucleases using 3-h-dna-coated wells of plastic depression plates as substrate.

Using our new method for assaying DNases with radioactively labeled DNA bound to wells of plastic depression plates as substrate, we could distinguish between endonucleases and exonucleases and between haplotomic and diplotomic endonucleases. Oligonucleotides smaller than 30 detach from the DNA binding sites of the well into the reaction mixture. Thus, a lag period was evident before endonucleases produced small soluble oligonucleotides, while exonucleases released mononucleotides or short oligonucleotides without any lag period. Haplotomic and diplotomic endonucleases were detected because of the different rates in which they produce small soluble oligonucleotides which were expressed in different lag periods. Under conditions in which the haplotomic DNase 1 changes its mode of action to become a diplotomic enzyme, the shift was clearly detected by a change in the lag period in the well assay.

DNA↗