[Monitoring chromosome mutations in large-scale breeding operations]

The frequency of chromosomal aberrations and exchanges of sister chromatids (SCEs) in peripheral lymphocytes was studied in 65 pigs from five large breeding herds. Four groups comprised fattened pigs and the fifth group consisted of sows from a large multiplier breeding herd. During the investigation, the dust from the sites was analyzed for the presence of zinc, lead, cadmium, mercury, aflatoxin B1, PCB, DDT, and lindane. The average frequency of aberrant cells (AB.B) in the pigs of group I was 3.85 +/- 1.60%, in group II 2.10 +/- 1.52%, in group III 5.01 +/- 2.1%, in group IV 3.50 +/- 1.58%, and in group V 6.20 +/- 3.21%. The cytogenetic finding corresponded to the differences in the amount of foreign substances found in the dust on the premises where the animals of all groups were kept. The average frequency of the SCEs was 7.00 +/- 1.10 (I), 6.51 +/- 0.89 (II), 6.92 +/- 0.72 (III), 7.10 +/- 0.85 (IV) and 7.06 +/- 1.47 (V) per one cell. Statistically significant differences in the numbers of AB.B. were recorded between groups II and I, II and IV, I and III, IV and V (p less than 0.05) and between groups II and III, II and V (p less than 0.01). There was no statistically significant difference in the frequency of SCEs. The determination of the frequency of chromosomal aberrations can be used for the hygienic control of the degree of exposure of pigs to mutagens.

[The effect of polychlorinated biphenyls (Delor 103, 105, and 106) in animal feed on the health of young pigs]

Five trials involving 71 piglets and young porkers were conducted to test the toxic action of polychlorinated biphenyls (PCB) added to the complete feed mixtures as Delor 103, 105 or 106 (manufactured by Chemko Strázske) administered to the experimental groups. The intake of these biphenyls for 14 or 21 days at rates from 100 to 250 mg per kg of feed had no adverse effect on the health condition, production parameters and concentration of total protein, albumin, globulin, urea, glucose and cholesterol in blood serum. Delor 105 had the highest biological effectiveness: its intake increased the relative weight of liver, reduced the serum level of thyroid hormones and corticosteroids. When the weaned piglets consumed a starter feed with an addition of 1 mg of Delor 105 per kg (corresponding to a high natural PCB contamination) for 26 days, no adverse effect was recorded and, on the contrary, the growth of the animals was stimulated and their feed utilization was better. The results suggest that the young pigs are comparatively resistant to the toxic action of PCB.

Effects of stimulated adrenocortical activity on the concentration of thyroxine and triiodothyronine in blood serum of piglets

The effects of elevated adrenocortical activity, induced by cold exposure, weaning or starvation, or exogenous adrenocorticotrophin (ACTH) on the concentrations of thyroxine (T4) and triiodothyronine (T3) in blood serum were investigated in 99 sucking piglets and weaners, divided into five experiments. No changes in concentrations of circulating iodothyronines were recorded during a 3-hour exposure of 3- to 4-day-old piglets to ambient temperature of 8-12 degrees C. Two days after weaning of 4-week-old piglets the concentration of T4 increased. At the same time a decrease of the concentration of T3 was observed in their starving littermates. Two hours after the administration of ACTH, the concentration of both iodothyronines decreased, that of T4 nonsignificantly. 17 hours after the administration of the second of two doses of ACTH, i.e. at the time when the concentration of corticosteroids approached initial values, the blood concentration of iodothyronines both in sucking piglets and in weaners was elevated, that of T4 nonsignificantly. We suggest that for the changes of T4 and T3 concentrations in blood sera of stressed animals both specific stressor effects and circulating corticosteroids are responsible. The suppressive action of corticosteroids seems to be limited to the period of adrenocortical stimulation only.

[Growth in weaned piglets and levels of iodothyronines in the blood during the administration of thyroactive substances]

In five trials with 100 piglets we studied the effects of thyreoglobulin, potassium nitrite and the thyreostatic preparation Carbimazol, which were added to a complete starter in the period from early weaning to the age of four weeks. Changes in the concentrations of thyroxine (T4) and triiodothyronine (T3) in the blood serum of control unmedicated piglets weaned from the sows can be characterized, after a short rise, by a decrease which stopped usually in the fourth week, accompanied by higher body weight gains. The lowest drop of T4 level was recorded in the group given potassium nitrite, with 21% methemoglobin, having the highest actual and relative weight gains. The T4 and T3 levels were not influenced by thyreoglobulin. They were decreased by Carbimazol by more than two thirds of the values which were usual at weaning if Carbimazol was administered at the highest rate of 60 mg per 1 kg of feed; neither was the growth of body weight nor feed consumption per unit of weight gain negatively influenced. An application of thyreotropic hormone on the 14th day after weaning demonstrated an inhibition of iodothyronine secretion in piglets which had been given Carbimazol, and a good response in control piglets. We drew a conclusion that the decrease in T4 and T3 levels after early weaning did not occur when iodothyronine intake with mother milk was interrupted nor was it caused by iodine deficiency, nor was it a primary cause of the reduced growth rate of piglets.

Short-term effects of tamoxifen, medroxyprogesterone acetate, and their combination on receptor kinetics and 17 beta-hydroxysteroid dehydrogenase in human endometrium

The interactions of an antiestrogen (tamoxifen) and a progestin (medroxyprogesterone acetate) on endometrial 17 beta-hydroxysteroid dehydrogenase activities were studied in short-term experiments (four to 96 hours) in normally menstruating women at the follicular phase and were related to simultaneously measured concentrations of cytosol and nuclear estrogen and progestin receptors. Tamoxifen effected a decrease in the activity of 17 beta-hydroxysteroid dehydrogenase. This was associated with an apparent translocation to and retention of estrogen receptor in the nucleus without any significant changes in cellular progestin receptor. Medroxyprogesterone acetate administration led to a rapid increase in endometrial 17 beta-hydroxysteroid dehydrogenase activity, and depletion of cytosol and total cellular progestin receptor. Combination of the drugs led to effects that could be addressed to the individual drugs separately, and under the experimental conditions the effects of medroxyprogesterone acetate were uninfluenced by simultaneous tamoxifen administration. Put together with the authors' previous findings on the same parameters during long-term (three-week) medroxyprogesterone acetate administration, it seems possible that potentiation of progestin effects on endometrial carcinoma is not to be expected during long-term simultaneous antiestrogen-progestin treatment. It is therefore likely that the favorable effects of combining these two drugs in long-term treatment are due to their different endocrine action mechanisms.