A simple model of blood flow rate reduction in haemodynamic disorders of the spleen.

The structural rearrangement of human sheathed capillaries in congestive splenomegaly has been considered. In abnormal spleens the external diameter and wall thickness were decreased, while the internal diameter was increased. Moreover, the total length and the absolute number of sheathed capillaries were increased, though not as much as the whole red pulp volume. Thus, in congestive splenomegaly, in addition to the well-known changes of the sinuses, the terminal arterial passages also appear to participate in the morphological rearrangement of the red pulp. The purpose of this paper is to formulate a simple dynamic model explaining the reduction of blood flow rate in the pathologically modified spleen. The main advantage of the present approach is that the coefficients inserted in equations describing the physical phenomena have been eliminated from the final formulae. Consequently, the model does not require the determination of parameters by means of difficult experimental measurements.

A stochastic process approach to the development of atheroma.

This study aims at formulating a dynamic model of particle sedimentation as applied to lipoprotein deposition during atheroma progression. The basic assumption is that all particles are identical and that the number of sedimented particles is relatively great. It is hypothised that sedimentation of a given particle is random; according to the theory of stochastic processes, the probability of a certain number of particles to sediment or deposit changes with time. The stochastic approach may explain some aspects of atherosclerosis development, i.e. its progression or regression.