[Carcinogenic activity of the pesticide propoxur].

Wistar rats were fed propoxur in their diet at 0, 500, 3000, and 8000 ppm during throughout their life. The number of tumors was equal in the control and experimental groups. These were hemoblastoses and breast and uterine tumors. All tumors occurred spontaneously in the rats. A few experimental animals were found to have bladder epithelial hyperplasia that might be pretumorous; however, no bladder tumors were detected. It is concluded that the investigations revealed no carcinogenic activity of propoxur.

[Experimental rationale for carcinogenic risk of asbestos cement industry and its products].

During intraperitoneal administration of dispersiveness-comparable chrysotile or asbestos cement fibers to rats (20 mg thrice), mesotheliomas were found in 45.1 and 7.7% of cases respectively. Asbestos cement dust induced tumors in 2.5% of cases, which is of biological importance. Cement or freeze asbestos destruction cement dust failed to cause tumors. The latter were not detected in a control group receiving physiological saline. Asbestos cement fibers and fascicles are covered by a cement matrix. Fiber amorphization gradually occurs. In lung tissue, there may be destruction of the cement coat of fascicles and release of native chrysotile fibers that are carcinogenic.

[Evaluation of the carcinogenic activity of phenol-free coal-tar creolin].

When orally administered to rats and mice, phenol-free coal-tar creolin containing 0.018+/-0.002 g/kg of benz(a)pyrene showed no carcinogenic activity. The discrepancy of the biological activity and content of carcinogen in the combined mixture, the role of their components in carcinogenesis, the value of control experiments, and historic control test, and the implication of these rapid tests in the evaluation of their carcinogenicity is shown.

[Carcinogen activity of the new drug thymodepressin studied in chronic tests on rats and mice]. / Izuchenie kantserogennoi aktivnosti novogo lekarstvennogo sredstva - timodepressina v chronicheskikh opytakh na krysakh i myshakh.

The new drug thymodepressin was subcutaneously injected in doses 0.0145 and 0.145 mg/kg in rats and mice over a period of 104 weeks. No statistically significant difference in the tumor frequencies between the test and control groups was observed during this period of time. It is concluded that thymodepressin is not carcinogenic.

[Carcinogenic danger of zeolite from Kholinsk]. / Kantserogennaia bezopastnost' tseolita kholinskogo mestorozhdeniia.

The carcinogenic activity of the enterosorbent optisorb (pure zeolite) and the biologically active food additive litovite [zeolite and rye brans (1:1)] based on zeolite-clinoptololite from the Kholinsk deposit was studied. The intrapleural three-fold administration of optisorb (20 mg x 3) to rats and the inclusion of optisorb (5% of the feed) and litovite (5 and 0.06%) into the feed showed that these agents had no carcinogenic activity.

Effect of mesna on lethal effect and hematological toxicity of taxol and vepeside in mice.

Mesna, an SH-containing uroprotector, attenuates the lethal effect and hematological toxicity of vepeside and taxol, but did not reduce specific activities of the studied cytostatics in mice with transplanted tumors. This selective antitoxic effect of mesna towards vepeside and taxol allows to intensify the anticancer chemotherapy with these highly effective but extremely toxic cytostatics and to improve the efficiency of anticancer therapy.

[Mouse hepatoblastoma: comparative aspects]. / Gepatoblastoma myshei v sravnitel'nom aspekte.

The structure of 12 spontaneous hepatoblastomas found in old (average age 26.5 months) male mice is described. There were considerable strain differences in their incidence: 0.5% (1/194), 0.5% (1/194) and 5% (10/198) in strain C57B1, CBA and F1 (CBA X C57B1), respectively. This proves the importance of genetic factor the role of which in the development of human hepatoblastoma is not established so far. Mouse hepatoblastoma develops almost invariably within or adjacent to liver cell tumours (adenoma or carcinoma). There was a correlation between the incidence of liver cell tumours within a given strain treated with different doses of carcinogen but such correlation was absent in mice of different strains. Histologically and ultrastructurally, mouse hepatoblastoma corresponds to the anaplastic variant of human hepatoblastoma. As distinct from human tumour, mouse hepatoblastoma does not contain alpha-fetoprotein. One tumour was transplanted to the syngeneic host and passed 30 transplant generations retaining the structure of a primary tumour with areas of osteoid tissue and foci of squamous cell metaplasia. Mouse hepatoblastoma may be induced by carcinogens. Likewise, according to the literature, risk of hepatoblastoma is higher in children whose mothers were exposed to the potential carcinogens before or during the pregnancy.

[Stimulating action of the vaccinia virus on the development of spontaneous and induced neoplasms in mice]. / Stimuliruiushchee deistvie virusa ospovaktsiny na razvitie spontannykh i indutsirovannykh novoobrazovanii u myshei.

Vaccinia virus was shown to exert a stimulating effect on the emergence of spontaneous neoplasia and Rauscher virus-induced hemoblastoses in BALB/cJLacSto mice. The mechanism of the stimulating effect is discussed.

Transplantable mouse hepatoblastoma: histologic, ultrastructural and immunohistochemical study.

Hepatoblastoma found adjacent to a liver cell adenoma in an aged (CBA x C57Bl/6)F1 male mouse was transplanted to the syngeneic host and passed through 30 generations. Histologically, tumours that grew on transplantation retained principal morphological features of the primary tumour. Transplanted tumours were negative for AFP and for antigen A6. This antigen in the normal mouse liver is found in epithelial cells lining bile ducts and ductules including the terminal Hering canals. Some of the Hering cells were consistently A6 negative under normal conditions, and the suggestion is made that these A6 negative cells might be the cells of hepatoblastoma origin.

[Genetic and oncologic characteristics of CBA/CaLacSto mice]. / Geneticheskaia i onkologicheskaia kharakteristika myshei kinii CBA/CaLacSto.

400 male and female CBA/CaLacSto mice were analyzed from the age of two months to their death. The spontaneous malignancy incidence of frequency in this line amounted to 76.3% with prevailing hepatomas (65%), neoplasms of lung, fat tissue. Homozygosity of CBA/CaLacSto mice was revealed in all the gene under test.

[Spontaneous hepatomas in hybrid mice (CBA x C57Bl/6)F1]. / Issledovanie spontannykh gepatom myshei-gibridov (CBA x C57Bl/6)F1.

The spontaneous hepatomas of male mice (CBA X C57B1/6)F1 were studied using complex cytologic, histologic, immunochemical, and cytochemical methods. The AFP was detected in trace amount in the serum of tumour-bearing mice and in single cells of hepatomas. As a rule the hepatocarcinoma cells have the polymodal DNA distribution (2C-8C) with major peak of 4 C (in 18 out of 26 cases). More rarely the tumours with predominant diploid and octoploid cells were observed.

[Ploidy level and alpha-fetoprotein production in spontaneous murine hematomas in relation to the degree of histological differentiation]. / Uroven' ploidnosti i produktsiia al'fa-fetoproteina v spontannykh gepatomakh myshei v zavisimosti ot stepeni gistologicheskoi differentsirovki.

Comparative morphological, cytospectrophotometric and immunochemical studies were carried out on 26 hepatocarcinomas of various malignancy excised from 21 F1 (CBA X C57B16) mice. It has been shown that in morphologically similar hepatomas the ploidy level and alpha-fetoprotein production intensity may vary markedly. Highly differentiated carcinomas usually of smaller sizes and homogeneous morphology have the modal class nuclei with tetraploid (6 cases) or octaploid (3 cases) DNA content. In moderately- and low-differentiated carcinomas the diploid class of nuclei significantly increased (in 4 out of 6 tumours). Large tumours morphologically heterogeneous according to the differentiation level had polymodal DNA distributions with predominating tetraploid nuclei (II cases).

[Effect of the carcinogenic tyrosine metabolite p-hydroxyphenyllactic acid on the ascorbic acid concentration in the organs and blood of mice]. / Vliianie kantserogennogo metabolita tirozina p-oksifenilmolochnoi kisloty na kontsentratsiiu askorbinovoi kisloty v organakh i krovi myshei.

The effect of cancerogenic tyrosine metabolite, p-hydroxyphenyllactic acid, on the concentration of ascorbic acid in the organs and blood of mice has been studied. p-Hydroxyphenyllactic acid was demonstrated to decrease considerably ascorbic acid concentration in the liver, adrenal glands and blood of mice. The above phenomenon and the previous data on tyrosine aminotransferase induction by p-hydroxyphenyllactic acid suggest the existence of two interdependent mechanisms of cancerogenic tyrosine metabolite (p-hydroxyphenyllactic acid) accumulation.

[Oncological characteristics of C57Bl/6JY mice]. / Onkologicheskaia kharakteristika myshei linii C57Bl/6JY.

The oncological characteristic is presented for C57BL/6JY mice widely used in experiments. The mice over eighteen month had different spontaneous neoplasms among which hemoblastoses prevailed. The influence of sex, age and vaccination on the rate of spontaneous neoplasms in these mice is analyzed.

[Morphological and cytochemical characteristics of spontaneous hemoblastoses in AKR mice]. / Morfologicheskaia i tsitokhimicheskaia kharakteristika spontannykh gemoblastozov myshei linii AKR.

Spontaneous hemoblastoses of AKR mice are widely used in experimental oncology and hematology. To study their morphological characteristics, 500 AKR mice were used. Of these, 400 animals were followed up throughout their lives. Ten animals were sacrificed monthly out of the group of 100 rats. All the animals which died or were sacrificed were autopsied and subjected to cytological and histological studies. Besides, 36 animals with hemoblastoses were examined cytochemically for the activity of acid and alkaline phosphatases, peroxidase and nonspecific esterase and glycogen. Analysis of the data obtained suggests that hemoblastoses of AKR mice are the generalized forms of lymphosarcoma, characterized by a significant degree of cytochemical and cytological heterogeneity.

[Oncological characteristics of AKR/JY mice]. / Onkologicheskaia kharakteristika myshei linii AKR/JY.

The oncological characteristic of AKR/J mice widely used in experimental investigations is presented. The incidence of spontaneous hemoblastoses in this subline is sufficiently high during the last ten years, that allows to use this subline as an experimental model of hemoblastoses. The analysis of the influence of sex factors, age and vaccination on the rate of spontaneous tumours of the lymphoid tissue is given.