[Mercury ions inhibit human neutrophil apoptosis induced by ultraviolet C irradiation].

The action of ultraviolet C (UVC) and mercury ions (HgCl2) on human neutrophil apoptosis was investigated by flow cytometry. It is shown that HgCl2 (5-10 microM) inhibits UVC-dependent acceleration of neutrophil apoptosis but does not inhibit spontaneous apoptosis.

[Apoptosis dynamics in human neutrophils induced by ultraviolet C irradiation during lipopolysaccharide and zinc exposure].

The action of ultraviolet radiation with lambda = 254 nm (UVC), zinc and lipopolysaccharide on the apoptosis of human neutrophils was investigated by flow cytometry. It was shown that zinc (0.2-1 mM) inhibits the UVC-dependent acceleration of neutrophil apoptosis.

[Effect of urea on conformational changes in the active site of native and reconstituted Ca-ATPase of the sarcoplasmic reticulum].

The effect of urea (1-3 M) on conformational changes in the active center of native and reconstituted Ca-ATPase of sarcoplasmic reticulum modified by fluorescein-5-isothiocyanate (FITC) was studied using the method of fluorescence titration by neodymium (Nd3+) ions. Based on the analysis of curves of fluorescence quenching of FITC-labeled Ca-ATPase by Nd3+ ions, the parameters characterizing the structural changes in the Mg-ATP binding center were determined. It was assumed that FITC and Nd3+ ion bind to different polypeptide fragments moving relative to each other, which provides the conformational lability of the nucleotide binding site at some stages of the catalytic cycle.

Steroid-induced conformational changes of FITC-labelled sarcoplasmic reticulum Ca2+-ATPase.

Interactions between transmembrane and cytoplasmic domains of Ca2+-ATPase from sarcoplasmic reticulum (SR) have been studied. To affect the hydrophobic transmembrane domain, we used four amphiphilic steroids - esters of a dibasic acid and 20-oxypregnene. All four steroids contained cholesterol-like nuclei and differed by the structure of side chains.

[Activation of poly(ADP-ribose)-polymerase inhibits apoptosis of thymocytes, caused by short-wave ultraviolet radiation].

The effect of (i) aphidicolin, a specific inhibitor of delta- and epsilon-polymerases, and nucleotide excision repair; (ii) 3-aminobenzamide, an inhibitor of poly(ADP-ribose) polymerase and base excision repair; and (iii) actinomycin D and cycloheximide, inhibitors of protein and RNA synthesis, respectively, on the induction of suppression of apoptosis of rat thymocytes by different doses of short-wavelength ultraviolet radiation was studied by flow cytometry. 3-Aminobenzamide suppressed the inhibition of apoptosis induced by the doses of short-wavelength ultraviolet radiation higher than 20 J/m2, increasing the cell death to a maximum. Thus, the inhibition of apoptosis by high short-wavelength ultraviolet radiation doses depends on the status of poly(ADP-ribose) polymerase and is prevented by 3-aminobenzamide.

[Modulation of human peripheral blood neutrophil apoptosis by ultraviolet C-range radiation and by gamma-irradiation].

It was found that the irradiation with in vitro UVC (254 nm) in the dose range of 6-600 J/m2 accelerates the apoptosis of human peripheral blood neutrophils in a dose-dependent manner, with saturation occurring at UVC doses of 250-300 J/m2. gamma-Irradiation with a dose of 2 Gy accelerates the apoptosis of neutrophils, whereas the irradiation with doses of 10 and 20 Gy suppresses it (by 9 h of cultivation). Lipopolysaccharide (1 microgram/ml) suppresses the UVC-induced apoptosis of neutrophils.

[Conformational changes at the ATP-catalytic site of the reconstituted sarcoplasmic reticulum Ca-ATPase under th action of pH, Ca2+, and lanthanides].

Conformational changes at the ATP-catalytic site of the sarcoplasmic reticulum Ca-ATPase reconstituted in proteoliposomes have been studied by the fluorescence of the fluorescein 5-isothiocyanate (FITC). It binds to Lys-515 at the adenine binding site of the nucleotide domain. The FITC-Ca-ATPase fluorescence parameters have been examined in the pH range 5,7-8,0 in the presence of EGTA, Ca2+, lantanides.

[Induction and inhibition of rat thymocyte apoptosis by ultraviolet irradiation].

Flow cytometry was used to investigate the effect of 254 nm wavelength UV irradiation on single rat thymocytes suspension in vitro. The induction of apoptosis has been observed in dose range less 20 J/m2. More high UV doses inhibited thymocyte apoptosis induced by dexamethasone, ionizing radiation and by UV itself.

[The role of histidine residues in conformational changes in the sarcoplasmic reticulum Ca-ATPase active site].

Conformational pH-induced changes of Mg-ATP binding site of the sarcoplasmic reticulum Ca-ATPase (SR-ATPase) were investigated by fluorescence energy transfer between covalently bound fluorescent label (fluorescein-5-isothiocyanate, FITC) and lanthanide ion (Nd3+). These changes were approximated by simple Henderson-Hasselbach equation with the apparent pK 7.0 +/- 0.

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.

Effects of pH, Ca2+ and lanthanides on conformation of the sarcoplasmic reticulum Ca(2+)-ATPase catalytic site.

The conformational changes at the ATP-catalytic site of the sarcoplasmic reticulum (SR) Ca(2+)-ATPase have been studied by the fluorescence of the fluorescein 5-isothiocyanate (FITC) bound to the adenine subsite. The FITC-SR fluorescence parameters have been examined in the pH range 5.7-8.

[Effective reconstitution of sarcoplasmic reticulum Ca2+-ATPase using lubrol PX].

Ca2(+)-ATPase of sarcoplasmic reticulum was reconstituted in the proteoliposomes by the salting out procedure. Triton X-100, C12E8 and Lubrol PX were used for the solubilization of the Ca2(+)-ATPase. Using fluorescent probes (diS-C3-(5), chlortetracycline) as well pH-measuring method, the functional of the reconstituted Ca2(+)-ATPase was comparatively studied in three types of proteoliposomes.

[The effect of electromagnetic radiation on the membranes of the sarcoplasmic reticulum].

On the sarcoplasmic reticulum membranes has been shown that at temperature of Ca2(+)-ATPase activity change of dependence in the Arrhenius plot the microwaves (2450 MHz, specific absorption rate 12 w/kg) inhibit the ATP-hydrolase and Ca2(+)-transporting activity of Ca2(+)-ATPase. The effect of radiation exhibits within the narrow temperature range (approximately 1 degree C) and quantitatively corresponds to the decrease of Ca2(+)-ATPase activity caused by the decrease of temperature by 1.6 degrees C from 18 degrees C.

[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.

[Sarcoplasmic reticulum Ca2+-ATPase reconstructed into low-permeable proteoliposomes].

The kinetic characteristics of Ca2+-ATPase reconstructed into proteoliposomes were studied with fluorescent probes. Reconstruction was made using purified resin XAD-2. The data obtained evidence for an electrogenic character of the reconstructed Ca2+-ATPase activity.

Interaction of the voltage-sensing fluorescent probe diS-C3-(5) with dipalmitoylphosphatidylcholine liposomes.

The interaction of the probe diS-C3-(5) with dipalmitoylphosphatidylcholine (DPPC) liposomes has been studied using fluorescence and differential scanning calorimetry (DSC). The partition coefficients (K) of the probe for the lipid and the aqueous phase (in terms of molar part units) were (1.20 +/- 0.

[Quantitative analysis of the effect of cysteamine on interphase cell death by flow cytometry].

The method of flow cytofluorometry was used to study the radioprotective effect of cysteamine on cells dying in the interphase. DMF was 1.67, 1.

[Determination of the radiosensitivity of interphase-dying cells in the thymus, spleen and bone marrow of rats by flow cytometry].

The flow cytofluorometry of cells stained with a DNA-specific probe was used to determine the share of dying cells (containing less than 2C DNA) in thymus, spleen and bone marrow cells of irradiated rats. The cell death curves for spleen and bone marrow had a plateau by the 6th h, and for thymus, by the 10th h following irradiation with different doses. On the basis of the dose-response relationship the share of cells dying in the interphase was determined in each organ under study, and dose-response curves shaped.

[Interaction of the fluorescent probe diS-C3-(5) with lecithin-cholesterol membranes].

Behaviour of fluorescent carbocyanine probe disS-C3(5) in the egg lecithin-cholesterol membrane suspension was studied in relation to the lecithin/cholesterol ratio. The partition coefficient of the probe between aqueous and lipid phases decreases unlinearly with increase of cholesterol molar part in a bilayer. This parameter over molar part units was estimated to be (2.

Flow cytometry analysis of DNA degradation in thymocytes of gamma-irradiated or hydrocortisone treated rats.

The pattern of DNA degradation in thymocytes of irradiated or hydrocortisone-treated rats has been studied by means of flow cytometry of the cells, treated with probes specifically bound to the AT or GC-pairs of DNA. It has been shown that the death of thymocytes is accompanied by a decrease in their DNA content. The main features of the occurrence and accumulation of cells with a DNA content less than the normal diploid level correspond with those of internucleosomal DNA fragmentation: such cells appear after a 1 hour lag-period, their accumulation is prevented by cycloheximide injection and is lower at 300 Gy than at doses of 10 to 30 Gy.

Flow cytometry and biochemical analysis of DNA degradation characteristic of two types of cell death.

By flow cytometry it has been shown that in rat thymocytes dying upon gamma-irradiation the reduction in DNA content per cell occurs well before the increase in outer membrane permeability. In contrast, in irradiated Burkitt's lymphoma cells the disturbance of plasma membrane permeability precedes the decrease of DNA content. Genome degradation in dying thymocytes of irradiated or hydrocortisone-treated rats is accounted for by internucleosomal DNA fragmentation.

[DNA degradation during radiation death of cultured cells].

The method of flow cytofluorometry was used to study postirradiation changes in plasma membrane permeability and DNA content of the Burkitt's lymphoma cells (Raji line). At a dose of 10 Gy, the increase in membrane permeability preceded the appearance of cells with diminished DNA content. The synchronization of cells in phase G2 was associated with a virtually complete radiation arrest of mitoses.