Induction of micronuclei by alkaloids extracted from Senecio brasiliensis and stored for 23 years.

In the present study, we report the results of an investigation on pyrrolizidine alkaloids extracted from Senecio brasiliensis (Sprengel) Less., which were stored for more than 23 years under variable conditions of temperature and humidity and exposed to light. Both the crude alkaloid (integerrimine+retrorsine+impurities) and pure integerrimine conserved the ability to induce acute toxicity in mice, leading to the death of the animals in less than 24h. The alkaloids also conserved the potential to induce significant increases in micronucleus frequencies in polychromatic erythrocytes of mouse bone marrow compared to the negative control. The administration of alkaloids to lymphocyte cultures blocked with cytochalasin-B showed no significant increase in micronucleus frequency in binucleated cells, probably due to the lack of a metabolic activation mechanism. However, an antimitotic effect was observed.

Induction of micronuclei in mouse polychromatic erythrocytes by the administration of non-radioactive CsCl by the oral and intraperitoneal route.

In the present study, we describe the effects of the concentration and route of administration of non-radioactive cesium chloride (CsCl) in inducing micronuclei in mouse bone marrow polychromatic erythrocytes (PCEs). When the dose of 500mg/kg body weight was administered perorally (p.o.), no significant incidence of micronuclei was detected. However, when the same dose was administered intraperitoneally (i.p.), a significant induction of micronuclei in PCEs was observed compared to control. At the dose of 1000mg/kg, both routes were efficient, with no significant difference in micronucleus frequencies. We conclude that both the p.o. and i.p. routes are efficient in inducing micronuclei, with the i.p. route being more efficient when lower CsCl doses are used.

Induction of micronuclei by CsCl in vivo and in vitro.

In the present study, we report the results of an investigation of the potential of nonradioactive CsCl for the induction of micronuclei in polychromatic erythrocytes of mouse bone marrow and in human lymphocytes cultured and blocked with cytochalasin-B. No significant increase in micronucleus frequency was observed in the polychromatic erythrocytes of mice which received 500 mg/kg of CsCl. In vitro experiments with human lymphocytes cultured in medium containing 250 and 500 micrograms/ml CsCl also showed no increase in micronucleus frequency compared to untreated controls. These same experiments, however, demonstrated a reduction in mitotic activity with increasing CsCl concentration in the culture medium. This report is the first to describe studies on the possible induction of micronuclei in vitro and in vivo by nonradioactive CsCl.

Chromosomal aberrations in lymphocytes from car painters.

In the present paper we report the results of biological monitoring of a group of 25 car painters working in different automobile shops in Brasília. There was a significantly higher frequency of aneuplodies and chromosome deletions in the peripheral lymphocytes of car painters than in control subjects. We also detected a significant correlation between the time worked as a car painter and the frequency of aneuploidy. Smoking habits do not represent a significant factor in terms of production of the various types of chromosome aberrations among car painters. These results permitted us to conclude that the individuals studied represent a risk group and should be medically followed up with judicious periodic examinations.

Cytogenetics study on coke oven workers with abnormal blood counts.

Thirty steelworkers with abnormal blood counts and 22 controls were studied cytogenetically. Fifty percent of the workers had a combination of leukopenia, neutropenia and lymphocytosis, and the remaining 50% showed different combinations or even a single type of alteration. The frequency of chromosome and chromatid gaps and chromosome deletions was significantly higher among workers than among controls, and the same was true for the number of individuals with some type of chromosome alteration. We also noted that the major factor related to the production of chromosome breaks is not the total time of work in the steel mill, but specifically the time of work at the coke oven.

Cytogenetic studies on gas station attendants.

Forty-nine gas station attendants employed to pump fuel and 24 controls were studied cytogenetically. This type of worker is occupationally exposed to fuel fumes and to automotive vehicle emissions. Chromosome analysis showed a significantly higher frequency of chromosome deletions among the gas station attendants than a control group. Taking into account the relationship between clastogenicity and increased cancer risk, we may consider these workers to form a risk group.

Postirradiation protection of chromosomes by linoleate.

Physiological concentrations of linoleate reduce the frequency of micronuclei and chromosome aberrations in mouse bone marrow cells in vivo and of micronuclei in human lymphocytes in vitro when administered one hour after exposure of the cells to gamma rays.

Radiation dose enhancement in tumors with iodine.

The loading of tissue with iodine can result in the enhancement of the radiation dose absorbed from low-energy x-ray or gamma ray sources. We have explored the potential of this phenomenon for radiation therapy. We have demonstrated the effect of iodine concentration and radiation quality on this dose enhancement in lymphocytes, we have calculated the effect of such enhancement on depth dose distributions in the brain, we have estimated the iodine content in two human brain tumors during computerized tomography (CT) scans, we have studied the dispersion of the iodine contrast media after direct injection into rabbit tumors, and we have demonstrated that the combination of x-ray and contrast media injection is far more effective than either agent alone in causing the regression of mouse tumors. These results suggest that there may be a therapeutic advantage from loading tumors with iodine and treating them with low-energy photons.