Biomedical subjects

K S Skramstad

Publications and source records attributed to K S Skramstad.

5 recordsLinked to original sources

PubMed1982

Artifacts associated with mithramycin fluorescence in the clinical detection and quantitation of aneuploidy by flow cytometry.

Ethanol-fixed cells stored at 4 degrees C exhibit fixation time-dependent hyperchromatism in comparison with freshly fixed cells when stained with mithramycin and examined by flow cytometry. This hyperchromatism has been found to be temperature-dependent, developing fully within 72 hr at room temperature, and within 2 hr at 37 degrees C. Cells from normal donors that are stained with mithramycin exhibit spurious aneuploid peaks. These spurious aneuploid peaks can be eliminated by incubating ethanol-fixed cells at 37 degrees C for 2 hr prior to staining; true aneuploidy is not affected by this procedure. In rare instances, cytoplasmic fluorescence can be observed in mithramycin-stained cells. In addition, unexplained hypochromatism and hyperchromatism can be observed in some clinical samples, particularly in human melanoma. The effects of these unexplained staining artifacts can be minimized or eliminated by adopting strict criteria for the clinical detection of aneuploidy by flow cytometry.

Aneuploidy↗

PubMed1982

Increased relative effectiveness of doxorubicin against slowly proliferating sarcoma 180 cells after prolonged drug exposure.

Doxorubicin (ADR) lethality was studied in Sarcoma 180 cells grown in vitro during log phase and early plateau phase. For both log phase and plateau phase cells, ADR lethality increased progressively with continuous drug exposure, and was dependent on drug concentration at every point in time. For any given level of toxicity to log phase cells, greater killing of plateau phase cells was achieved with prolonged drug exposure. The inhibition of DNA synthesis by ADR was delayed in onset, and increased gradually, both at low and high drug concentrations. The data suggest that the dependence of ADR lethality on proliferation rate and the higher therapeutic ratio in plateau phase cells with prolonged drug exposure are not directly related to the ADR effects on DNA synthesis.

Animals↗

PubMed1980

Dual parameter flow cytometry studies in human lymphomas.

Dual parameter flow cytometry studies using Coulter volume and cell DNA content were carried out in monodisperse cell suspensions of 64 samples of human lymphoma, chronic lymphocytic leukemia, hairy cell leukemia, and benign lymphoid proliferations. Differences in mean Coulter volume among the lymphomas were due both to the intrinsic differences in mean G1 cell Coulter volume and to the presence of increased fractions of larger S and G2 cells, especially among the large B cell lymphomas. However, the relative contribution of large non-G1 cells to the overall population Coulter volume distribution was a relatively minor one; the presence of cells in S did not increase mean Coulter volume by more than 10%, even in samples with high S fractions. There was a good correlation between mean G1 cell Coulter volume and the log of the fraction of cells in S among the B cell lymphomas (r = 0.55). Evidence is presented that within individual samples, large cells proliferate more rapidly than small cells. This was seen in every case, both in the normal samples and in the lymphomas, and in the T cell lymphomas as well as in the B cell lymphomas. Aneuploidy was detected by flow cytometry in 11 cases; in 7 cases the aneuploid cell component could be analyzed separately from the diploid cell component on the basis of cell Coulter volume differences. The aneuploid components of diploid-aneuploid mixtures had higher S fractions than the diploid components in six of seven cases (0.16 +/- 0.04 [SE] vs. 0.08 +/- 0.02). These findings are considered in relation to the histopathological classification of the lymphomas, and in relation to the concept of clonal selection and clonal evolution of tumors.

Aneuploidy↗

PubMed1980

Electrolytic degradation of DNA fluorochromes during flow cytometric measurement of electronic cell volume.

Changes in flow cytometric measurement of DNA content can result from electrolytic chemical degradation of mithramycin, ethidium bromide, and propidium iodide during simultaneous measurement of electronic cell volume. Bench electrolysis also degrades these fluorochromes without changing the quantum yields, even when they are complexed to DNA. In the flow cytometer, electrolytic production of chlorine at the anode is the probable cause of this degradation, since exposure of these fluorochromes to chlorine gas produces the same effect. It is therefore advisable to measure the DNA content distribution alone before simultaneously measuring the DNA content and the electronic cell volume. If unavoidable effects on the DNA distribution are present, narrow forward-angle light scatter should be used as the cell size indicator during dual parameter measurements. Modifying instrument design by reversing electrode polarity might eliminate this problem.

Cytological Techniques↗

PubMed1979

The T-lymphocyte as a diploid reference standard for flow cytometry.

T-lymphocytes prepared from the peripheral blood of normal individuals exhibit uniform postmitotic DNA contents that are constant from individual to individual when fixed in ethanol and stained with mithramycin, or when fixed in formalin and stained with acriflavine-Feulgen and analyzed by flow microfluorometry. T-lymphocytes fixed by either method are stable on storage for several months. These cells are suitable for use as an external diploid reference standard for flow cytometric detection of cells with abnormalities in postmitotic content exceeding 5% of diploid reference. Cells with abnormalities in postmitotic DNA content of less than 5% can be detected in mixtures containing both normal and malignant cells by multiparameter analysis.

DNA↗