[Cyclosporine A fails to prevent thymocyte death induced by ionizing radiation and hydrocortisone].

In experiments with albino mongrel mice the influence of cyclosporine A on thymocyte death in vivo under the effect of ionizing radiation and hydrocortisone has been investigated. The effect was assessed by the amount of soluble polydeoxynucleotides (PDN) that are formed in the cells. Dose dependence of the PDN yield and kinetics of their formation in thymocytes as well as electrophoretic mobility of PDN were studied after irradiation and the cyclosporine A treatment.

The use of flow cytometry for the investigation of cell death.

Flow cytometry is more and more widely used for investigations of cell death, predominantly in the study of DNA degradation in cells dying by apoptosis. There are different interpretations of changes observed in DNA histograms of these cells. We describe an approach based on extraction of chromatin degradation products from fixed cells and subsequent staining with DNA specific dyes.

[D2O inhibition of interphase thymocyte death].

Using the method of flow cytometry and biochemical analysis it was shown that D2O, an agent that stabilizes microtubules, prevented the internucleosome fragmentation of DNA in thymocytes exposed to gamma radiation and dexamethasone in vitro. It was also found that D2O is ineffective with respect to Ca2+/Mg2(+)-dependent nuclease. The transfer of irradiated cells from a medium containing 90% of D2O to a normal one caused rapid DNA degradation; the fragmentation process ceased with the irradiated cells being transferred from H2O to heavy water.

[General similarities and differences in the postradiation death of various animal species and of man].

It was found in various animal species and man that an ordered internucleosome fragmentation of DNA is characteristic of lymphoid cells dying in the interphase. Both in vivo and in vitro, the postirradiation DNA degradation in thymocytes of rodents and piglets preceded the increase in the permeability of their plasma membrane. The in vivo kinetics of death of lymphoid cells from the thymus and spleen is similar in rodents and piglets.

[The patterns of colchicine-induced death of lymphoid cells].

It is shown that colchicine injection at doses higher than 1 mg/kg of animal weight induces cell death in thymus, spleen, bone marrow and intestine mucosa. The cell death is accompanied by a regular internucleosomal cleavage of nuclear DNA and by the elimination of the formed fragments from cells. Both the processes begin after a 1.