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Biomedical subjects

Z Darzynkiewicz

Publications and source records attributed to Z Darzynkiewicz.

At least 343 records · Page 19Linked to original sources
PubMed1976

Cytofluorometric studies on conformation of nucleic acids in situ. II. Denaturation of deoxyribonucleic acid.

Thermal denaturation of deoxyribonucleic acid (DNA) in situ in individual unbroken cells is studied by a cytofluorometric method. This method allows us to investigate DNA denaturation in the presence of divalent cations at concentrations reported to be necessary to maintain native structure of nuclear chromatin. Under these conditions the pattern of DNA denaturation is very different than when studied in the presence of ethylenediaminetetraacetate or citrate. The results suggest that with divalent cations present, the histone basic charges are more uniformly distributed along whole nuclear DNA. Various cell types exhibit great differences in sensitivity to DNA denaturation when assayed in the presence of 1 mM MgCl2. Human lymphocytes, monocytes and certain kinds of human leukemic cells show differences large enough to be used as a parameter for their recognition in mixed samples. Possible applications of the method in basic research on chromatin conformation and as a tool for cell recognition in diagnostic cytology or in the classification of human leukemia are proposed.

Animals↗
PubMed1976

Urinary cytology automation. Preliminary studies with acridine orange stain and flow-through cytofluorometry.

Preliminary results are reported in an ongoing program to develop automated cytologic examinations for the detection of bladder cancer from exfoliated urinary epithelium. A metachromatic fluorescent dye, acridine orange, was used to stain the cells in suspension in such a way that their nuclei (DNA) fluoresced green in blue light, and their cytoplasm (chiefly RNA) fluoresced red. The intensities of green and red fluorescence per cell were measured for up to 5000 cells per sample by a flow-through cytofluorometer, and differences were found between cell types that served to identify bladder epithelial cells, leukocytes, squamous cells, and other particulates. Benign and malignant bladder epithelial cells differed principally in their cytoplasmic RNA staining intensity, and methods are discussed for amplifying this and other differences that may be of diagnostic value in an automated instrumental system.

Automation↗
PubMed1974

Chick-erythrocyte nucleus reactivation in heterokaryons: suppression by inhibitors of proteolytic enzymes.

Reactivation of chick-erythrocyte nuclei in heterokaryons (obtained by Sendai virus-induced fusion of chick erythrocytes with HeLa cells) is suppressed by specific inhibitors of trypsin and trypsin-like enzymes. N-alpha-tosyl-L-lysyl-chloromethane and N-alpha-tosyl-L-arginine methylester inhibit erythrocyte nuclear enlargement and suppress RNA and DNA synthesis in nuclei of erythrocytes and HeLa cells in heterokaryons at concentrations that only minimally influence individual HeLa cells or HeLa homokaryons. Although other unknown mechanisms of action cannot be formally excluded, the data are interpreted as fitting best with an intracellular site of action of the protease inhibitors studied, and as suggesting a role for cellular proteases in reactivation of chick-erythrocyte nuclei in heterokaryons.

Animals↗