Enhanced Neoplastic Transformation Due to Protracted Exposures of Fission-spectrum Neutrons: Biophysical Model

Ambiguity of the Brenner-Hall Model

“…This numerical estimate led Brenner and Hall (1990) to hypothesize that mitotic C3H/10TH-cells are more sensitive to sustaining transformation damage than the cells in other phases of the cell cycle . Based on different considerations, a similar hypothesis was presented by Elkind (1991) . Although Hall (1991) has stated that extrapolated predictions of the model, such as shown in Figure 10 in Brenner and Hall (1990), `should not be taken too seriously', these results have been subsequently cited (Hall 1991 ;Hall et al 1991), and the authors have suggested that the results might be incorporated in the design of dose-equivalent meters .…”

‘Inter Silvas Academi Quaerere Verum’: Reply to Letter to the Editor by M. M. Elkind.

“…The present explanations ignored the cell cycle dependency of cell survival on total dose ; that is, the lower the dose, the less cell-cycle variation in sensitivity . The X-ray data from Sinclair and Morton (1966), cited by Elkind (1991), show only small cell cycle variations in radiosensitivity at 3 Gy, and no effect at 1 . 5 Gy .…”

“…The letter of Elkind (1991) focused on possible discrepancies of the experiments showing no inverse dose-rate effect, but within the framework of the proposed model fails to consider the major quantitative discrepancy of quoted experiments showing positive results . Specifically, the first reported enhancement of transformation in C3H/l0T} cells had a maximal value of about 20 at 0 .…”

“…1987, Sykes and Watts 1989, Brenner and Hall 1990), but to the extent that these have received little subsequent attention and new explanations continue to appear, one must conclude that the older explanations are considered to be inadequate . With an ever-increasing data base available for analysis, Elkind (1991) has developed a new explanation which attempts to encompass numerous features of the available data in a comprehensive, detailed manner . However, the points enumerated below demonstrate that a similar volume of evidence arguing against this latest explanation has been omitted from the analysis, so that the conclusions are not supportable .…”

Comment on Mechanism of Radiation Effects with Special Reference to Transformation

“…Hypotheses and proposed models for the effect have not yet led to a consensus (Hill et al . 1984, Barendsen 1984, Rossie and Kellerer 1986, Burch and Chesters 1986, Booz and Feinendegen 1988, Sykes and Watt 1989, Elkind 1991, Brenner and Hall 1991, Harrison and Balcer-Kubiczek 1991 . The proposals made seek answers to the mechanisms involved, and to fundamental questions such as : is damage to the DNA a prerequisite for subsequent transformation?…”