Plasma membrane alterations due to promoters and antipromoters

Chemical and toxicological characterization of residential oil burner emissions: II. Mutagenic, tumorigenic, and potential teratogenic activity

Extracts of effluents from a modern residential oil burner have been evaluated in several toxicological assay systems. Bacterial mutagens were detected in extracts from both the particulate and vapor phase emissions. Effluents from continuous operation were an order of magnitude less mutagenic than those from cyclic (5 min on, 10 min off) operations. No difference in the yield of bacterial mutagens per gram of fuel burned was found between cyclic operation under low and moderate sooting conditions. On the basis of elution behavior from alumina it appeared that the bacterial mutagens collected from high sooting effluents were more polar than those from low sooting effluent. An extract that was mutagenic in bacteria did not induce a significant increase in mutation frequency to human lymphoblasts. No evidence of tumorigenicity was observed in a limited number of newborn mice after IP injection of effluent extract when compared to historical control data. Putative nonmutagenic teratogens were detected in effluent using an attachment inhibition assay. The level of these agents was reduced in effluents from continuous oil burner operation.

Inhibition of metabolic cooperation between Chinese hamster V79 cells by structurally diverse teratogens

Cell-cell communication through chemical messengers is a fundamental event required for the differentiation of embryonal cells. Interference with this process by xenobiotics may disrupt embryogenesis. Chinese hamster cells (V79) which display a specific form of cell-cell communication called metabolic cooperation were cultured in the presence of structurally diverse chemical teratogens. Among them were 12-O-tetradecanoyl-phorbol-13-acetate (TPA), diphenylhydantoin (DPH), warfarin, and a series of monoalkyl ethers of ethylene glycol with alcohol chain lengths from methyl to butyl. Sodium saccharin and ascorbic acid were examined to represent two chemicals which have been thoroughly tested for teratogenic effects in laboratory animals and cause no birth defects. Recovery of 100 6-thioguanine-resistant V79 (6-TGr) cells in coculture with 400,000 6-thio-guanine-sensitive V79 (6-TGs) cells in the presence of 6-thioguanine (6-TG) and the chemical agent was measured. In amounts that neither interfered with colony forming ability nor caused cytostasis when 100 6-TGr cells were plated alone, all of the substances except for saccharin and vitamin C increased the number of surviving 6-TGr cells in a concentration-related manner. The recovery was increased by the presence of TPA (to 100% by 4 ng/ml), DPH (from 26% at 91 microM to 43% at 274 microM), warfarin (from 15.5% at 162 microM to 44.5% at 487 microM) and to variable extents by all five glycol ethers. The most efficacious in the latter group of compounds was the isopropyl ether which raised 6-TGr recovery from 8% at 0.017 M to 66% at 0.087 M. Based on the evidence accumulated by previous studies involving TPA, we postulate that the teratogens employed inhibited metabolic cooperation. These observations suggest that V79 cells may be suitable to study inhibition of cell-cell communication as a mechanism of teratogenesis.