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Biomedical subjects

L M Shabad

Publications and source records attributed to L M Shabad.

At least 19 recordsLinked to original sources
PubMed1980

[Significance of polycyclic aromatic hydrocarbons as carcinogenic risk factors for man (author's transl)].

Polycyclic aromatic hydrocarbons (PAK) are tightly connected with the history of chemical carcinogenesis since they are carcinogenic components of carbon blacks, tars, paraffines, and mineral oils. In selected examples it is shown for some cases of professional cancer that they can induce cancer in man. The carcinogenic effect obtained with PAK containing extracts of very different products, correlates also in animal tests with the detected contents of PAK and particularly of benzo[a]-pyrene (BaP). This concerns, among others, tars, carbon blacks, exhaust gases of combustion engines, and environmental pollutions. BaP may be regarded as representative for the PAKs. PAKs and BaP are ubiquitous. The sources of contamination are briefly summarized. Epidemiologic studies show also a connection between human cancer and influence of PAK. In the opinion of the authors and for the given reasons the PAKs are carcinogenic for many to a very high degree of security.

Animals↗
PubMed1980

[Stimulating effect of certain chemical carcinogens on gastric organ cultures].

Results of measuring the relative growth of the area surrounding the explants of nonibred rat embryonal stomach were studied after transplacental exposure to benz(a)pyrene (BP) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The embryonal tissue of the rat stomach is marked by high sensitivity to the carcinogens. This was manifested in better survival of the test cultures. The magniture of the relative growth of the explants exposed to transplacental MNNG exceeded, over the same period of culture, the control measurements by 2.5--3.5 times on the average, while on transplacental administration of BP the largest growth was recorded on the 6th day.

Animals↗
PubMed1980

[Effect of nitrosoethylurea on sarcomagenesis induced by a foreign body].

Subcutaneous administration to rats of an intact cellophane plate gave rise to sarcomas in 60% of cases, the latent period being 16.5 month. Meanwhile administration of minced cellophane did not produce tumors. Combination of the plate subcutaneously and nitrosoethylurea (NEU) intraperitoneally increased the frequency of sarcomas to 73.3%, the latent period being 13.7 month. Sarcomas emerged in 33.3% of cases at the site of administering minced cellophane coupled with intraperitoneal injection of NEU, the latent period amounting to 13.2 month. The morphological appearance of sarcomas that occurred with the use of NEU differed from tht resultant from administering the cellophane plate alone. Adsorption of NEU on the cellophane is suggested.

Animals↗
PubMed1979

The retrospective study of the carcinogenic hydrocarbon benz[a]pyrene in the biosphere.

The major aim of this study was to determine taking, as an example, the carcinogenic polycyclic aromatic hydrocarbon benz[a]pyrene (BaP), the present biologically active compounds in the early historical and geological epochs with the following assessment of the degree of danger of such compounds in the modern times. In the first section of work, study results of soil samples in the areas of eternal frost confirmed the presence of BaP in the frozen layers of soil aged 10 years, 100 years, 3000--4000 and 10,000 years of age. In the second part of the work, results are furnished on the BaP content in the ice of modern glaciers and their moraines, located in Kamchatka. BaP was found in 11 samples in the concentration of 0.001--0.003 microgram/l. These data represent the first results in the retrospective study of carcinogenic substances in the biosphere.

Benzopyrenes↗
PubMed1979

[Chloramphenicol and dextramycin, inhibitors of mammary carcinogenesis induced by 7,12-dimethylbenz(a)anthracene].

In noninbred rats chloramphenicol and its optical isomer dextramycin diminished the blastomogenic effect of 7,12-dimethylbenz(a)anthracene on mammary glands. The protective effect was shown by a decreased tumor incidence at all periods of observation and an increase in the life span of rats and in the case of dextramycin this action consisted in a prolongation of the latent period of tumor emergence.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1979

[Prospects of the development of research into regulating chemical carcinogens in the environment].

The possibility of regulating the permissible quantities of chemical carcinogens in the environment is being substantiated. The ways of determining the threshold amounts of blastomogenic agents are discussed. Some approaches to the regulation of blastomogens are suggested depending on the degree of risk, effective quantities and action time. The main trends of development of researches in the field of regulation of chemical blastomogens are delineated.

Animals↗
PubMed1979

[Growth-stimulating action of nitroso compounds on organ cultures of mouse and rat embryonic liver].

Transplacental and direct effects of nitroso-methylurea (NMU) on the organ cultures of the liver of 18-20-day embryos of CBA and C57BL mice and the action of diethylnitroso-amine on the embryo liver cultures of noninbred rats were studied. Nitroso-compounds acclerated explant adaptation, enhanced the culture survival as compared with the normal and induced hyperplastic proliferation of small basophilic cells, whose survival in the experiment and under normal conditions was higher than that in the normal embryonal hepatocytes. The growth-stimulating effect depended on the animal species and strain and on the carcinogen, as weel as on the route of administration.

Animals↗
PubMed1979

Organ cultures of embryonic target-tissues exposed transplacentally to chemical substances as a test-system for rapid evaluation of carcinogenicity.

Organ cultures of embryonic target-tissues transplacentally treated by chemical substances are proposed as a test-system for a rapid evaluation of carcinogenicity of environmental pollutions. The results of transplacental effect of some different substances (urethane, polycyclic hydrocarbons, N-nitrosocarcinogens, aminoazo compounds, cyclic amines, aflatoxin B1, pesticide DDT and some noncarcinogenic analogs) on organ cultures of embryonic lung, kidney, liver and brain (hyppocamp) are presented. Transplacental effect in organ cultures depended on the used carcinogen, its dosage, duration of cultivation and on the susceptibility of animals and explanted tissue. The tested carcinogens induced in organ cultures of embryonic target-tissues: 1. specific morphological alterations (diffuse and focal hyperplastic pretumoral alterations of epithelium and tumors); 2. alteration of cell proliferation and 3. an increase of viability and survival of explanted embryonic tissues. This criteria and proposed test-system are critically evaluated with respect to its practical use.

Animals↗
PubMed1978

Methodology of the study of carcinogens in human populations.

Epidemiology, including occupational tumors and other groups at risk; experimental studies; and physiochemical methods of evaluation of environmental carcinogens form the basis of cancer prevention. Hygienic measures of limitation (maximum allowable concentrations) are also discussed.

Air Pollutants↗
PubMed1978

[Liver tumors induced in mice by prenatal and postnatal administration of ortho-aminoazotoluene].

The authors studied the prenatal and postnatal blastomogenic action of orthoaminoazotoluol (OAAT) on the liver of CBA mice. OAAT was administered to mice intragastrically in oil solution, thrice, 4 mg each time (a total of 12 mg). Twelve months after the OAAT administration tumours of the liver during the postnatal period were revealed in 89.3% of female mice (11.5% in control), and in 78.7% of male mice (68.5% in control). In the experimental progeny subjected to OAA action during last 4--5 days of the prenatal period the liver tumours appeared in females at the age of 12 months in 54.8% of cases (5.3% in control), and in males--in 81.1% (35.2% in control). In this progeny, particularly in the male animals malignant neoplasms occurred more frequently than in the intact animals and those subjected to the action of OAAT during the postnatal period.

Animals↗