Comparative aspects of pigmented nevi in children, youths and adults.

Clinicomorphological correlations in children of different ages, youths, and adults with various pigmented nevi are analyzed to determine the diagnostic significance of certain structures. The study included 129 pigmented nevi surgically removed from 122 children, 27 from youths, and 133 from adult subjects. A comparative analysis of the reasons that caused the removal of the pigmented nevi made it possible to clarify a number of peculiarities of pigmented nevi in children that play an important role in the clinical and diagnostic aspects, as well as the decision of management policy. For diagnostic purposes, in the evaluation of pigmented nevi in children, particular attention should not be paid to the marked cellular proliferation of junctional melanoblasts, invasion of the epidermis by nevus cells, and pigmentation of the epidermis by melanin.

[Modifying effects of changes connected with pregnancy on 1,2-dimethylhydrazine-induced carcinogenesis in rats]. / Modifitsiruiushchee vliianie izmenenii, sviazannykh s beremennost'iu, na kantserogenez, indutsirovannyi 1,2-dimetilgidrazinom, u krys.

The modifying effect of pregnancy and lactation on carcinogenesis induced by single injection of 1,2-dimethylhydrazine to female rats 30 days before mating has been studied. The total incidence of malignant tumours in rats with pseudopregnancy, single pregnancy, pregnancy and lactation, repeated pregnancies was lower in comparison with virgin animals (75, 44, 68, 59 and 93%, respectively). Colon adenocarcinoma incidence in rats with single pregnancy or repeated pregnancies was lower than that in virgin rats (42, 49 and 76%, respectively). Protective effect was observed mainly in descending colon. The mesenchymal kidney tumours were not developed at all in rats with single pregnancy. In virgin animals it was 31%. The inhibition of tumour incidence in the liver (cholangioma, cholangiocellular carcinoma) was observed in rats with single pregnancy or pregnancy and lactation in comparison with virgin control (3, 5 and 24%, respectively).

[Effect of disordered thyroid function on the realization of the transplacental carcinogenic action of N-nitrosomethylurea in 1st- and 2d-generation rats]. / Vliianie narusheniia funktsii shchitovidnoi zhelezy na realizatsiiu transplatsentarnogo kantserogennogo deistviia N-nitrozometilmocheviny u krys pervogo i vtorogo pokolenii.

The F1 rats subjected to the influence of N-nitrosomethylurea (NMU) in dose of 20 mg/kg on the 21 day gestation as a result of postnatal disturbances of the thyroid function induced by long administration of thyroxin (3 mg/100 g, daily), methylthiouracil (MTU; 0.1% solution in tap water) or thyroidectomy have shown a decreased incidence of the nervous system tumours, but not of the kidney tumours, i. e. sites typical of NMU transplacental carcinogenesis. At the same time the NMU transplacental effect increased thyroid carcinogenesis, induced by the MTU postnatal application, which manifested in the increased incidence of malignant tumours of this site. The carcinogenic effect was observed in F2 rats, while some of them developed tumours of the nervous system (14.9%) and kidney (8.5%) but with lower incidence than in F1 (35.4; 14.1%, respectively). The same modifying factors (thyroxin, thyroidectomy, MTU) employed under the same conditions produca similar effect on carcinogenesis in F2 animals.

[Modifying effect of thyroid gland functional disorders on realization of transplacental carcinogenesis induced by N-nitrosomethylurea in rats]. / Modifitsiruiushchee vliianie narusheniia funktsii shchitovidnoi zhelezy na realizatsiiu transplatsentarnogo kantserogeneza, indutsirovannogo N-nitrozometilmochevinoi u krys.

The paper discusses the influence of deranged function of the thyroid (in postnatal period) on the transplacental carcinogenic effect of N-nitrosomethylurea (NMU) in albino noninbred rats. It was found that exogenous thyroxin-induced hyperthyroidism and thyroid function suppression either by long-term treatment with a thyreostatic agent--methylthiouracil (MTU) or thyroidectomy are followed by a lower frequency of, chiefly, nervous system tumors which are typical of NMU-induced transplacental carcinogenesis in rats. Moreover, transplacental treatment with NMU potentiated the carcinogenic effect of MTU on the thyroid. The latter manifested itself in a higher frequency of malignancies of the thyroid in animals exposed to a combined treatment with NMU (transplacentally) and MTU (postnatally) as compared with those given MTU only (postnatally).