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A S Deakin

Publications and source records attributed to A S Deakin.

2 recordsLinked to original sources

Model for initial vascular patterns in melanoma transplants.

In this paper we present a simple mathematical model that adequately accounts for at least the initial vasculature that is established in a melanoma transplant. It is assumed that the tumor produces a substance (tumor angiogenesis factor--TAF) that elicits capillary sprouts from the vascular bed of the host. These sprouts then invade the tumor along the gradient of TAF and cross-connect forming a vascular pathway that is similar to the experimental patterns observed in a hamster cheek pouch. This model is then extended to include the migration of loops. The rupture and formation of sprouts from these loops is assumed to depend on the strength of the stimulus (TAF). Under the assumption that the production of TAF is significantly reduced in a neighborhood of an established vessel, the network formed by the vessels in the tumor corresponds to the observed arboreal patterns.

Capillaries↗

Model for the growth of a solid in vitro tumor.

A model for the growth of a tumor by diffusion is considered for spheroids which are grown in a normal medium in suspension culture. The experimental evidence indicates that, upon the onset of necrosis in the centre of the spheroid, the viable rim thickness decreases relatively slowly. This evidence contradicts the results of the usual model in which the oxygen consumption per unit volume is assumed to be constant. The proposed model assumes that the oxygen concentration is constant above a critical value, and proportional to the concentration below this critical value. The viable rim thickness of the spheroid, as a function of the necrotic radium, varies markedly over the range of the parameters in this model. By suitably choosing these parameters, the results of this model agree with the experimental evidence.

Diffusion↗