The uptake of 3H-thymidine in post-confluent cultures of methylcholanthrene-transformed C3H/10T1/I mouse embryo cells was markedly higher than in their non-transformed counterparts. In a reconstruction experiment as few as 2% transformed cells could be detected by increased thymidine uptake. Measurements made at various times up to 110 days in multi-chambered plates revealed that after 25 days methylcholanthrene-treated cultures incorporated significantly more thymidine than the acetone-treated controls. This increased uptake correlated with the appearance of Type III transformed foci.

A procedure for purifying 2,2',4,4',5,5'-hexabromobiphenyl (HBB) from FireMaster FF-1 in gram amounts by crystallization is presented. Following purification, the structural assignment of HBB was made by using proton and carbon-13 nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, and mass spectroscopy (MS). The growth of C3H/1OT 1/2 cells treated with 5, 37, 75, and 150 Ag of HBB and FF-1 per milliliter of medium was measured at 4, 8, and 13 days following treatment. FF-1 was more toxic at 37 and 75 ug/ml at both 4 and 8 days, but the same at 13 days. At 150 ,g/ml cell growth was completely inhibited by both compounds. Growth of cells was stimulated at 5 ,ug/ml, by HBB at 4 and 8 days, and FF-1 at 8 and 12 days. HCB was compared with HBB and FF-1 for cell growth toxicity at 37 and 75 ,ug/ml. At 75 ,g/ml, HCB was more toxic than HBB and FF-1 during the entire time period. At 37 ,mg/ml, HCB was more toxic than HBB and FF-1 at 4 and 8 days. Cells seeded at high densities and treated with HBB for three days lost the high degree of postconfluence inhibition of cell division observed in control cultures. Cells treated with FF-1 for three days did not adhere well to the plastic growth surface. Ultrastructural features of the HBB-and FF-1-treated cells included decreased surface villi and increased lysosomes relative to the control cells.

A procedure for purifying 2,2', 4,4',5,5'-hexabromobiphenyl (HBB) from FireMaster FF-1 in gram amounts by crystallization is presented. Following purification, the structural assignment of HBB was made by using proton and carbon-13 nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, and mass spectroscopy (MS). The growth of C3H/10T 1/2 cells treated with 5, 37, 75, and 150 microgram of HBB and FF-1 per milliliter of medium was measured at 4, 8, and 13 days following treatment. FF-1 was more toxic at 37 and 75 microgram/ml at both 4 and 8 days, but the same at 13 days. At 150 microgram/ml cell growth was completely inhibited by both compounds. Growth of cells was stimulated at 5 microgram/ml, by HBB at 4 and 8 days, and FF-1 at 8 and 12 days. HCB was compared with HBB and FF-1 for cell growth toxicity at 37 and 75 microgram/ml. At 75 microgram/ml, HCB was more toxic than HBB and FF-1 during the entire time period. At 37 microgram/ml, HCB was more toxic than HBB and FF-1 at 4 and 8 days. Cells seeded at high densities and treated with HBB for three days lost the high degree of postconfluence inhibition of cell division observed in control cultures. Cells treated with FF-1 for three days did not adhere well to the plastic growth surface. Ultrastructural features of the HBB- and FF-1-treated cells included decreased surface villi and increased lysosomes relative to the control cells.