Inge Brand

Malignant transformation and maturation in non-dividing cells during polymer tumorigenesis.

Summary It was confirmed that, during polymer solid surface carcinogenesis, pre-malignant cells reside on the plastic insert as early as eight months before tumor maturation. No premalignant cells were demonstrated in the surrounding tissue except for the very late stage of less than four weeks. During the premalignant period no mitotic activity or cellular turnover was observed among the cell population that presumably included the premalignant clone. Clearance of carbon particles was minimal. It was concluded that at least in this instance the entire process of premalignant development and maturation seems to take place in non-dividing cells.

Cytotoxicity and Cell Cycle Studied with a Combined Tetrazolium-Feulgen Reaction.

Summary On asynchronous and synchronized cultures of Changs conjunctiva cells it was shown that cytotoxic antibodies (in the presence of complement) were most effective during the stage of cytoplasmic cell division, i.e., between mitosis and G1-phase. All other stages of the cellular life cycle were relatively resistant in that longer incubation periods were required for cell destruction. A newly developed combined tetrazolium-Feulgen reaction was used in these studies with advantage.