Toxicological potential of 2-alkylcyclobutanones--specific radiolytic products in irradiated fat-containing food--in bacteria and human cell lines.

Food irradiation has been considered as a safe processing technology to improve food safety and preservation, eliminating efficiently bacterial pathogens, parasites and insects. This study aims to characterize the toxicological potential of 2-alkylcyclobutanones (2-ACBs), radiolytic derivatives of triglycerides, formed uniquely upon irradiation of fat-containing food. In irradiated food they are generated proportionally to fat content and absorbed radiation dose. The cyto- and genotoxic potentials of various highly pure synthetic 2-ACBs were studied in bacteria and human cell lines. While pronounced cytotoxicity was evident in bacteria, no mutagenic activity has been revealed by the Ames test in Salmonella strains TA 97, TA 98 and TA 100. In mammalian cells genotoxicity was demonstrated mainly by the induction of DNA base lesions recognized by the Fpg protein as determined by both the Comet Assay and the Alkaline Unwinding procedure. Formation of DNA strand breaks was observed by the Alkaline Unwinding procedure but not by the Comet Assay. The extent of cytotoxicity and genotoxicity were dependent on chain length and degree of unsaturation of the fatty acid chain. Further studies will have to clarify mechanisms of action and potential relevance for human exposure situation.

Nuclear boundary detection algorithm based on a minimax derivative statistic for atypical bronchial squamous epithelial cells.

The thresholding approach in scene segmentation of digitized cell images was found to be unreliable for use with squamous epithelial cells characterized by chromatin condensation within the nucleus. It was observed that the nuclear boundaries of such cells were visually distinguishable. An algorithm was developed for detecting nuclear boundaries in digitized cell images. This algorithm is based on a minimax derivative statistic that has maximum values at nuclear boundaries and low values elsewhere. The statistical properties of the confusion matrix of cellular scene segmentation are outlined. A measurement and a test statistic for scene segmentation errors based on those properties are presented.