[Mathematical modeling of oxygen diffusion and consumption in malignant tumor].

A mathematical model of oxygen diffusion and consumption in a malignant spherical tumor was developed. The model takes into account the dependence of the rate of oxygen consumption by cells on oxygen concentration. The expressions for the description of the dependence of oxygen concentration on the coordinate in the tumor are presented.

[The isolation of the contribution of the parenchyma to the radionephrogram and the assessment of kidney purifying function].

The authors described the principle and algorithms of the separation of a summary radionephrogram into constituents, reflecting the contribution of a radiopharmaceutical, uptaken by neutrons, and RP in the surrounding tissues. The authors proposed a correct method for estimation (using the first constituent) of the efficacy indicator of RP uptake by the kidneys (Q-parameter) and the indicator of the mean time of transit (t) in the kidneys of RP uptaken by their parenchyma. The results of testing of the proposed methods of Q and t calculation were presented.

[Permeability of the hemato-ophthalmic barrier in uveitis].

The results of examining the hematoophthalmic barrier permeability by radiometry and biotests with anterior chamber and vitreous humor are analyzed. Injection of the radiopharmaceutical into the vorticose veins provides the most effective pharmacokinetics, vs. suprachoroidal and subconjunctival injections.

[Mathematical model of the kinetics of radiopharmaceutical preparations in the right compartments of the heart].

The paper is concerned with the description of a mathematical model of the kinetics of radiopharmaceutical drugs (RPD) in the right heart with due regard for its two-compartmental structure. A formula has been obtained to describe a right heart radiogram (RHRG) for any RPD entry into the heart (with any type of entry function). It has been shown that in case of an impulsed entry a RHRG curve is described by the following formula (formula; see text) which is a biexponential one.