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F Otto

Publications and source records attributed to F Otto.

35 records · Page 2Linked to original sources
PubMed1983

Cellular radiation effects and hyperthermia cell cycle kinetics of radiation sensitive mutants of Saccharomyces cerevisiae after X-irradiation and hyperthermia.

Radiosensitive mutants rad2, rad9, and rad51 of Saccharomyces cerevisiae were X-irradiated with 120 Gy or 60 Gy, heated at 50 degrees C for 30 min or treated with a combination of both and incubated in nutrient medium at 30 degrees C. Cell number, percentage of budding cells, and cell cycle progression were determined in 45-min intervals. Cell cycle kinetics were investigated by flow cytofluorometry. Hyperthermia leads mainly to a lengthening of G1, whereas X-rays arrest cells of the rad2 and rad9 mutant in G2 and the rad51--mutant additionaly in a state with DNA contents above G2. Cell division delay is influenced by oxygen in all strains but to a lesser extent in the rad2 mutant. The effect of the combined treatment appears to be merely additive in the rad2 and rad9 mutant while the rad51 mutant is sensitized to X-irradiation by hyperthermia. No selective action of hyperthermia on hypoxic cells was found.

Cell Cycle↗
PubMed1980

Cellular radiation effects and hyperthermia: cytokinetic investigations with stationary phase yeast cells.

Wild type diploid yeast, Saccharomyces cerevisiae strain 211, was subjected to 250 kV X-rays or 50 degrees C heat treatment for 30 min or to a combination of both. X-ray exposure took place either in air or in nitrogen. Cell number, percentage of budding cells and cell cycle progression was followed for up to 12 h post irradiation. The distribution of cell cycle stages was determined by flow cytofluorometry. All treatments cause a retardation of cell division rate. Hyperthermia leads mainly to a lengthening of G1, whereas X-rays arrest the cells reversibly in G2. The effect of the combined treatment appears to be merely additive. No. selective action of hyperthermia on hypoxic cells was found.

Cell Cycle↗
PubMedDate not supplied

Flow cytometry and sizing for routine andrological analysis.

Flow fluorometry and Coulter type sizing analysis of sperm have been applied separately in order to improve human semen analysis. Different methods of sample preparation were evaluated and a protocol involving prestaining pepsin treatment of sperm samples is proposed for fluorometric analysis. The data obtained with fluorometry and sizing analysis result in different kinds of information: Coulter counting allows to automate sperm counting and fluorometry yields more detailed information about normozoospermia and oligozoospermia by determining the proportion of mature spermatozoa and immature germ-cells. These two methods, together with light microscopy, may help to explore the correlation of fertility and pathology of spermatozoa. The aim of these investigations is to yield the preconditions for simultaneous two-parameter analysis of DNA content and cellular size distributions.

DNA↗