Studies on in vitro chrysotile-pleural mesothelial cell interaction: morphological aspects and metabolism of benzo-3,4-pyrene.

Cultures of rat pleural mesothelial cells (PMC) were exposed to nonlethal doses of UICC chrysotile A. The morphology was studied by optical and electron microscopy. The consequences of chrysotile ingestion on the rate of pinocytosis of horseradish peroxidase (HPR) metabolism and benzo-3-4-pyrene (BP) were studied. Nonlethal doses of chrysotile (5 micrograms/mL) induced a time-dependent vacuolation of PMC; a dose-dependent inhibition of the vacuolation was observed when PMC were pretreated with DMSO. The origin of the vacuoles is not clear, but some features of autophagy and lysosomal storage were observed. Chrysotile fibers did not modify the rate of pinocytosis of HRP. Similarly, the metabolism of BP was unchanged when BP and chrysotile were both added to the culture medium or when PMC were preincubated with the fibers 24 hr prior to the addition of BP.

Establishment of normal diploid and malignant heteroploid cell lines from non-treated and benzo(a)pyrene treated hamster embryo cell cultures.

Two normal diploid control cell lines and a heteroploid malignant transformed cell line from B(a)P treated hamster embryo cell cultures were established. The 14-month-old B(a)P transformed cell line grew 8-times faster than the 20-month-old control cell line. The control cell line showed normal diploid chromosome complement in 93% cells and heteroploidy in 7% cells while B(a)P treated line showed 83% heteroploid cells and only 17% diploid cells. This is the first report on the establishment of diploid hamster cell cultures grown for extended period.

[The tobacco-cancer problem]. / Sur quelques aspects du problème tabac-cancer

Statistical, biological and chemical data on the carcinogenic effect of tobacco smoke are given and are discussed. The epidemiological studies have clearly shown the particularly noxious action of inhalation, and the direct ratio between the risk and the number of cigarettes smoked. The laboratory experiments on biological properties of cigarette smoke raise various problems of interpretation, however they reinforce the results given by statistical studies on man. The quantities of carcinogenic compounds which have been isolated from cigarette smoke are too small to account for the whole action. The co-carcinogenic, promoting, necrosing and toxic effects of some smoke condensate fractions could play an important part in the carcinogenic action. To cope with the health problems of the smoking habit, the tobaccoproducers and the public health organisations have taken steps, which led to a better knowledge of the problem and to the production of cigarettes which are less harmful to man.

[Effect of a microsomal system on the toxicity and on the interactions of various polycyclic carconogenic hydrocarbons with cells in culture]. / Effet d'un systme microsomal sur le pouvoir toxique et sur l'interaction de certains hydrocarbures polycycliques cancérogènes avec des cellules en culture

The addition of a liver microsomal system (extracted from phenobarbital pretreated hamster livers) to hamster embryo cell cultures, together with a carcinogenic hydrocarbon, reduces the hydrocarbon toxicity and increases the velocity of hydrocarbon uptake by cells.

[Chemical cancerization of hamster embryo cells in mass culture]. / Sur la cancérisation chimique de cellules d'embryon de hamster en culture de masse

For periods between 24 and 72 hours mass cultures of hamster embryo cells were put in contact with the following carcinogens: 7,10-dimethylbenz (c) acridine (2 mug/ml), benzo (a) pyrene (0,1 mug/ml), 7-methyl benz (a) anthracene (5 and 10 mug/ml), 3-methyl-cholanthrene (0,1 mum/ml), and 7,12-dimethyl benz (a) anthracene (0,05 mug/ml). The cancerisation of cells thus treated was demonstrated by hamster grafting as soon as 4 1/2 months post-treatment. By contrast neither the cells treated by benzo (e) pyrene (non-carcinogenic in animals) nor those of the two control lines resulted in tumours when grafted into hamsters even after culture for 8 and 15 months. These transformed and malignant cultures differ from the controls by their rapid uncontrolled growth and in their morphology. Moreover the morphological characteristics of transformation are evident as soon as 2 months after treatment and for the majority of the compounds studied well before cancerization is demonstrable by hamster grafts. During the course of the first 2 months toxic effects of the compounds are evident in the partial destruction of the cultures and by the appearance of colonies composed in part of cells in disorderly growth. The cells of these colonies when isolated and returned to culture do not survive beyond 4 or 5 passages. Moreover grafts of cultures at 30 days after exposure to carcinogens has never resulted in tumour in the hamster host.