- Three approaches to flow cytometric histogram analysis were developed: (1) differential histogram analysis, (2) DNA histogram analysis, and (3) multiparameter data analysis. (1) A large percentage of flow cytometric data are collected and stored as one-parameter histograms, and it is desirable to analyze and compare data sets in pairs. The differential analysis of flow cytometric histogram data is a simple and valid way to evaluate differences between cell populations to show, for example, the existence of subpopulations with abnormal DNA contents. A shifting algorithm was developed to make it possible to compare histograms which are slightly skewed because they were collected under slightly different conditions. (2) Three simplified techniques of DNA histogram analysis, which calculate from one-parameter histogram data the cell cycle phase fractions, were developed, and it was shown that with a very small loss of accuracy, substantial reductions in the computational complexity of DNA histogram analysis can be achieved. (3) A simple, microprocessor-based two-parameter analysis system was designed and constructed for use with a mixture of analog and digital flow cytometric signals. These techniques were applied to an important unresolved problem in radiation biology.
The initial responses to irradiation of a mammalian cell which occur during the first two cell cycles following the irradiation are of considerable interest to the radiation biologist. During the first two post-irradiation cell cycles, cells which ultimately will survive repair radiation-induced damage, while some cells begin to express some of the radiation-induced nuclear and chromatin damage; e.g., abnormal cytokinesis, arrest at mitosis, reproductive and metabolic death, etc. Caffeine- and thymidine-treated, and untreated gamma-irradiated cell populations were studied with respect to the radiation-induced G2 delay, deficient DNA synthesis, and the appearance of cells with abnormal DNA contents. Both caffeine and thymidine were found to ameliorate the G2 delay and to accentuate the degree but not increase the frequency over that found for untreated cells of radiation-induced daughter cells with abnormal DNA content. Hypodiploid daughter cells in treated cultures have significantly less DNA than hypodiploid daughter cells in untreated cultures. It is hypothesized that the measured deficiency in DNA synthesis observed in the first post-irradiation cell cycle may be a result of daughter cells from abnormal first post-irradiation mitoses.
- Dissertation Note:
- Ph.D. The Pennsylvania State University 1982.
- Source: Dissertation Abstracts International, Volume: 43-10, Section: B, page: 3112.
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