E.D. Léonard

Chromosome aberrations in employees from fossil-fueled and nuclear-power plants.

Chromosome aberrations were scored in 59 persons from fossil-fueled plants, in 89 persons from nuclear-power plants and in 23 controls. A significant increase in acentric chromosome fragments and dicentric chromosomes compared to the control group was observed in both types of workers. Moreover, the number of abnormal cells was significantly greater in workers of conventional plants than in those of nuclear-power plants. When adjusted for loss of lymphocytes according to a half-life of 3 years, this difference was also significant for the number of dicentric chromosomes observed. A significant effect of length of exposure or of frequency of radiological examinations could be discerned only in the group of workers from conventional plants.

Cytogenetic effects of myleran in vivo on bone-marrow cells from male mice.

The cytogenetic effects of Myleran were examined in bone-marrow cells from male mice. To study the dose--response relationship the male mice were injected with 5, 10, 20 or 40 mg of Myleran/kg. Bone-marrow samples were prepared 24 h later. The time response was investigated by examining bone-marrow samples 1, 2, 4 or 10 days after i.p. injection of 40 mg of Myleran. Most of the structural aberrations were of the chromatid type and the dose--response relationship was linear. The chromatid and chromosomal aberrations were maximal at 2 days and decreased sharply after longer intervals of time.

The radiosensitivities of lymphocytes from pig, sheep, goat and cow

Dose-effect curves for X-irradiation in vitro were determined on cultured blood lymphocytes of four mammalian species-cow, goat, sheep and pig-having approximately the same number of chromosome arms, the same nuclear volume and the same DNA content. The data from cow, but not those from the other species, exhibited significant inhomogeneity between the experiments. On inspection the numerical yields appear not to differ greatly in the lower dose range. Evaluation of the parameters according to the quadratic law and the power law, however, demonstrate significant differences. Pig differs from the other species regardless of which presentation is chosen. For the power law a significant difference is also found between goat and sheep.

Cytogenetic investigations on leucocytes of cattle intoxicated with fluoride

Cattle which grazed in the vicinity of a plant manufacturing enamel and which displayed signs of chronic fluoride poisoning such as osteosclerosis and mottled enamel or dental fluorosis were investigated for the presence of structural chromatid and chromosome aberrations. Venous blood was incubated for 48 h, and 100 cells were analyzed for each animal. No statistical difference in the incidence of such anomalies was observed between the controls and the intoxicated animals.

The radiosensitivity of chromosomes of rabbit lymphocytes

Dicentrics were induced in human and rabbit lymphocytes in vitro by exposure to X-irradiation. The yields were compared with data reported in the literature. To elucidate the reasons for the different findings we have evaluated the parameters for the different models by maximum likelihood methods. From this analysis it can be concluded that the earlier claim of Bajerska and Liniecki [1] that both species have the same radiosensitivity must be discounted, and that their similarity was due to the abnormally low values these investigators observed in irradiated human lymphocytes.

Effect of an enhanced natural radioactivity on mammal fertility

Male and female mice of the BALB/c strain were placed on the floor of a hut built at a site of the Permian Basin of Lodève (Southwest France) where the dose rate of gamma radiation amounts to about 10 mrad/h. In previous experiments such high natural radioactivity was shown to induce point mutations in plant material as well as chromosome aberrations in somatic cells of experimental mammals. Controls were kept near the radioactive site under comparable conditions. After the exposure period, the animals were mated in our laboratory, with control mice of the same strain. Due to the high radiosensitivity of mouse oocytes, the fertility of the exposed females was drastically reduced in spite of the fact that the dose received did not exceed 13.8 rad. The fertility of the males exposed to 13 rad, 15 rad or to 45 rad was increased above the control values but was reduced for the animals receiving 63 rad. Analysis of the results show that the differences in fertility are mainly due to a decrease in the number of sterile pairs when males have been exposed to doses upto 45 rad and to an inverse effect when animals received 63 rad. Since histology and weight of the testes suggest that the germ cell population was normal, one has to conclude that the variations in fertility result from physiological effects.

No evidence for radiation-induced clastogenic factors after in vitro or in vivo exposure of human blood.

Experiments were performed with human plasma irradiated in vitro or in vivo in order to evaluate the extent to which clastogenic factors might disturb the adaptive response to DNA-damaging factors currently studied in our laboratory. The studies were carried out with plasma isolated from whole blood given 4 Gy of X-rays in vitro and with plasma from people receiving local radiotherapy at a total dose of about 60 Gy gamma rays. Addition of irradiated plasma to culture medium did not result in a statistically significant increase in structural aberrations in chromosomes of non-irradiated normal blood.

Evaluation of the ability of paracetamol to produce chromosome aberrations in man

The ability of paracetamol to induce structural chromosome aberrations in human peripheral blood lymphocytes in vivo was evaluated in volunteers who had been administered a single oral dose of 3 g paracetamol, in patients who had received 2 g of propacetamol by intravenous infusion every 6 h for at least 7 days, and in self-poisoned patients who, for suicidal reasons, had ingested more than 15 g paracetamol. In addition to the in vivo observations, the effectiveness of paracetamol to interfere with fusorial microtubule polymerisation was assayed in vitro in order to detect a possible effect of paracetamol on the distribution of chromosomes during cell division. The negative results obtained in all those assays strongly suggest that paracetamol has no mutagenic properties in human. There was, indeed, no significant difference in the percentage of abnormal cells before and after application of paracetamol in volunteers (0.2% before ingestion of 3 g paracetamol, 0.12% after 24 h, 0.04% after 72 h and 0.04% after 168 h) and in patients (0.5% of abnormal cells before treatment versus 0.44% after intravenous infusion of a total of 28 g paracetamol). Moreover, the yield of abnormal cells was not modified in self-poisoned persons (0.24%), in spite of an important decrease in the mitotic index of the PHA stimulated lymphocytes. In the in vitro assay, no inhibition of microtubule polymerisation was detected with concentrations of 2.5, 5 and 10 mM paracetamol.