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K Sailer

Publications and source records attributed to K Sailer.

6 recordsLinked to original sources
PubMed1997

Kinetics of radiation- and cytochrome c-induced modifications in liposomes analysed by FT-Raman spectroscopy.

Fourier transform Raman spectroscopy on artificial lipid membranes was used to study radiation-induced peroxidation processes as a function of time after radiation exposure. The time dependent intensity changes of the Raman lines of various C=C bondings were compared to results obtained by measuring conjugated dienes and by the thiobarbituric acid test for malondialdehydes. The results show that mainly the cis C=C bonds of the lipid chains are involved and, therefore, indicate that gamma-radiation induces conformational changes in the lipid chain while the mobility of the lipid chains is reduced. New Raman bands can be assigned to aldehyde products induced at the end of the peroxidation process. The immediate decrease of the =CH vibration lines was directly correlated with the formation of conjugated C=C double bonds suggesting that these vibration lines are in contrast to the C=C lines solely Raman active, when isolated C=C bonds are present. Cytochrome c (ox.) incorporated into the bilayer of the artificial membranes induced autooxidation processes not influenced by gamma-radiation. It was observed that cytochrome c (ox.)-induced changes of the relative intensity of the C=C bonds differ from those induced by gamma-radiation. These results of cytochrome c together with the inhibitory effects of the antioxidant alpha-tocopherol suggest that the radical species involved in the cytochrome c induced process might be different from the free radicals involved in the gamma-radiation-induced process.

Antioxidants↗
PubMed1996

Radiation-induced structural modifications in dsDNA analysed by FT-Raman spectroscopy.

Structural changes of double stranded DNA in aqueous solution induced by ionizing radiation were studied by Fourier-Transform-Raman spectroscopy. In addition to base damage, strand breaks, structural changes, i.e. unstacking of the bases, premelting effects and disordering of the B-form backbone could be observed. The amount of these different kinds of damage depended on the concentration of the DNA solution. Specifically, the following modifications were found depending on the gamma-ray dose and DNA concentration. (1) Intensity increase of the lines of dT (1240 cm-1) and dA (729, cm-1) indicating unstacking of these bases. (2) Intensity and frequency changes of the marker bands of all four bases indicating structural modifications. (3) Intensity decrease of the sugar marker lines showing change of the bonds in the deoxyribose and of bonds between the sugar moiety and the phosphodiester. (4) Intensity decrease of the lines of the phosphodiester groups (1094 and 790 cm-1) with simultaneous appearance of a difference peak at 1080 cm-1 and a new peak at 980 cm-1 suggesting the presence of strand breaks. (5) Intensity decrease of the B-form marker band (approximately 835 cm-1) and new lines at 876 cm-1), at approximately 660 cm-1 (C3'-endo/anti of dG) and at 1312 cm-1 (C3'endo/syn of dA) indicating decrease of the B-form conformation and the developing of partly new secondary forms of the DNA representing a helix-to-coil transition.

DNA↗
PubMed1995

Induction of kinetochore-containing micronuclei by exogenous O6-methylguanine requires conversion of the methylated base to a nucleotide.

It has been reported that exogenous alkylated purines, such as O6-methylguanine (O6meG), induce aneuploidy in mammalian cells. It is shown here that the aneugenic effect of O6meG, evidenced by its ability to induce micronuclei in rodent cells, is dependent on its conversion to O6-methyl-guanosine-5'-monophosphate (O6me-5'-GMP) by hypoxanthine-guanine phosphoribosyl transferase (HPRT). This conclusion, in contrast with previous in vitro data showing that O6meG does not seem to be a substrate for HPRT, was based on the following observations: 1) O6meG did not induce micronuclei in HPRT-deficient Chinese hamster cells, but did induce micronuclei in HPRT-proficient cells, and in mouse cells partially or totally deficient in adenine phosphoribosyl transferase; 2) O6meG was not metabolized in HPRT-deficient cells, while in wild-type cells a number of metabolites were detected by high performance liquid chromatography (HPLC) analysis of cold acid extracts, one of them coeluting with O6me-5'-GMP used as a marker; 3) when de novo synthesis of purine nucleotides was inhibited by aminopterin, O6meG sustained the growth of HPRT-proficient, but not of HPRT-deficient, cells; and 4) when HPRT-deficient cells were treated with liposomes charged with O6me-5'-GMP, induction of micronuclei was shown. The finding that methylated guanine exerts its aneugenic action through methylated nucleotide(s) provides an important, though indirect, support to the hypothesis that alkylating agents may induce aneuploidy via nucleotide pool alkylation.

Adenine↗
PubMed1981

[Induction and synchronization of pregnancy in cows].

Inductions and synchronizations of parturitions by the analogue PG F2alpha, Cloprostenol, were tested in cows under production conditions. The average time from induction to delivery is 40.5 hours (33-49 hours). No significant relation exists between the length of gravidity and the time of delivery induction (correlation coefficient = -0.325). A scheme was proposed from the system of calving days in cows to organize synchronized parturitions. In production conditions the induction and synchronization of cow parturitions cannot be recommended because amnions are retained frequently (69.7%). No relationship was demonstrated between gravidity length at the time of delivery induction and the order of parturition in the cow (first-calver-cow).

Animals↗