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W U Müller

Publications and source records attributed to W U Müller.

64 records · Page 4Linked to original sources
PubMed1985

Supraadditive formation of micronuclei in preimplantation mouse embryos in vitro after combined treatment with X-rays and caffeine.

The influence of caffeine (0.1 or 2 mM), X-rays (0.24 Gy [= 25 R] or 0.94 Gy [= 100 R]), or of a combination of both on the formation of micronuclei in early stages of preimplantation mouse embryos in vitro was studied. X-rays as well as caffeine induced micronuclei. The dose-effect curve after irradiation was linear for the dose range measured (0-3.76 Gy; = 0-400 R). Caffeine did not induce micronuclei if the concentration was 1 mM or less; between 1 mM and 7 mM, however, there was a linear increase in the number of micronuclei. A considerable enhancement of the number of radiation-induced micronuclei was observed when irradiation of the embryos was followed by a treatment with caffeine. Not only was the sum of the single effects exceeded by the combination effects, but the combination results even lay in the range of supraadditivity of the envelope of additivity.

Animals↗
PubMed1985

Enhancement of radiation effects by mercury in preimplantation mouse embryos in vitro.

Mercuric chloride (3 microM or 10 microM) increased several effects of ionizing radiation (1 Gy) on preimplantation mouse embryos in vitro. Blastocyst formation, hatching of blastocysts, and the number of cells per embryo were affected by this increase in radiation risk. The formation of micronuclei, however, was not influenced either in experiments using mercury alone or in combination experiments with X-rays. Not only was the sum of the single effects exceeded in some of the combination experiments, but the dose-pairs, which were necessary for obtaining a certain effect, clearly fell to the left of the envelope of additivity. That is, the enhancement of effects cannot be explained merely by the shape of the dose-response curves, but there is an interaction between mercury and ionizing radiation.

Animals↗
PubMed1984

Distribution of micronuclei among single cells of pre-implantation mouse embryos after X-irradiation in vitro.

The frequency of micronuclei within single cells of pre-implantation mouse embryos in vitro was determined after X-irradiation. The embryos were irradiated in the late G2 phase of the two-cell stage (32 h p.c.) with doses between 0.5 and 14 Gy. The micronuclei were counted 48 h p.c. (with most of the control embryos in the four-cell stage) and 55 h p.c. (with most of the control embryos in the eight-cell stage). The distribution of micronuclei among the single cells of the embryos does not follow a Poisson distribution, but shows a clear tendency to over-dispersion.

Animals↗
PubMed1983

Effects of a combination of X-rays and caffeine on preimplantation mouse embryos in vitro.

The influence of a combination of caffeine (0.1 mM, 1 mM, or 2 mM) and X-rays (0.24 Gy, 0.94 Gy, or 1.88 Gy) on preimplantation mouse embryos in vitro was studied under different conditions. The agents were applied either singly or in combination. The embryos were irradiated in the G2-phase of the two-cell stage (28 h p. c. or 32 h p. c.) either 1 h after or immediately before application of caffeine. Caffeine was present during the whole incubation period (until 144 h p. c.). The effects on the microscopic visible development (formation of blastocysts 96 h p. c., hatching of blastocysts 144 h p. c.) and on the cell numbers of embryos at different times (48 h p. c., 56 h p. c., 96 h p. c., 144 h p. c.) were determined. We found conditions under which caffeine markedly enhanced radiation risk, i.e., under which the combination effect exceeded the sum of the single effects. This is true, in particular, for the embryonal development, for which the risk may almost be doubled, whereas the enhancement of risk is not so great for the proliferation of cells. In some cases the combination results lie even outside the envelope of additivity in the range of supra-additivity. The amount of caffeine necessary for such marked effects, however, is so high (at least 1 mM caffeine for rather long times), that it is almost impossible to reach them in vivo by consumption of caffeine-containing beverages.

Animals↗
PubMed1982

Combined treatment of preimplantation mouse embryos in vitro with sodium nitrite and x-rays.

Man takes up nitrite in a considerable amount. Effects of nitrite on DNA have been reported; therefore, interaction between nitrite and radiation might be possible. Preimplantation mouse embryos in vitro were treated with a combination of sodium nitrite (1 mM or 2.5 mM) and X-rays (0.94 Gy) in order to obtain some information whether radiation risk is influenced by the presence of nitrite. The microscopic visible development up to 144 h post conceptionem (h p.c.), the number of cell nuclei, and the number of micronuclei were determined. None of the experimental results gives any indication that radiation risk is influenced by nitrite. All effects after combined treatment correspond to the sum of the single effects.

Animals↗
PubMed1982

[Influence of actinomycin D or ethidium bromide on the radiation risk in embryos of mice in the preimplantation stage in vitro].

The authors examined if the radiation risk (after X = irradiation with 0.94 Gy or 3H-thymidine treatment with 0.5 kBq/ml) in embryos of mice of the preimplantation stage in vitro is increased by the presence of actinomycin D (0.3 nM for 112 hours or 100 nM for 90 minutes) or ethidium bromide (0.5 microM for 112 hours). The influence of these substances on the radiation effect was determined by microscopic observation of the development of embryos and by investigation of the cell proliferation. The radiation risk was regarded to be increased if the combined effect was significantly higher than the total amount of the individual effects. The radiation risk for the morphologic development of the embryos was significantly increased by actinomycin D; the combined effects were about 1.3 times higher than the total amount of the individual effects. There was no increased risk for the cell proliferation. Ethidium bromide did not modify the radiation risk neither with respect to the morphologic development nor regarding the cell proliferation.

Animals↗
PubMed1981

Effects of a combined treatment with X-rays and phenols on preimplantation mouse embryos in vitro.

Phenols are found everywhere in the environment. Therefore, the investigation of possible interaction between phenols and radiation is of some interest. The effects of a combination of X-rays and phenols (phenol itself and p-nitrophenol) were measured by the preimplantation mouse embryo-system in vitro. The microscopic visible development up to 144 h post conceptionem (h.p.c.), the number of cell nuclei, the DNA-content of each nucleus, the mitotic index, the labelling index, and the number of micronuclei were determined. There was not any indication that the effect of the irradiation was enhanced in a synergistic manner by the presence of phenols. All parameters measured lead to the conclusion that the effects of phenols plus X-rays are, at most, additive.

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