[Immune system senescence and mortality dynamics. Role of antigenic load]. / Starenie sistemy immuniteta i dinamika smertnosti. Analiz roli antigennoi nagruzki.

This paper is dedicated to investigation of the impact of total antigenic load on immunosenescence. Data on pneumonia mortality have been simulated. The results of modelling revealed that antigenic load as well as probability of infecting could account for the shifting in mortality that takes place for different countries. Dynamics of immunosenescence is described by mathematical model for age related changes in T-cell populations. Numerical simulation of the model yields estimates for pneumonia severity at different ages. Probability function is used to describe relationship between pneumonia mortality and age related changes in disease severity.

Immunology and disease control: a systems approach.

The application of system theory (or more precisely, differential equations) to immunology and disease, in general, is presented here. Particular results from U.S.-Russian research collaboration depict the potential role of such systematic analysis for more effective health care and disease control. In particular, some emphasis is given to control of influenza. After a brief systematic overview of immunology, a simple infectious disease model is developed to explain four basic forms of disease: subclinical, acute, lethal and chronic. Then, disease treatment is studied.

Mathematical model of antiviral immune response. I. Data analysis, generalized picture construction and parameters evaluation for hepatitis B.

The present approach to the mathematical modelling of infectious diseases is based upon the idea that specific immune mechanisms play a leading role in development, course, and outcome of infectious disease. The model describing the reaction of the immune system to infectious agent invasion is constructed on the bases of Burnet's clonal selection theory and the co-recognition principle. The mathematical model of antiviral immune response is formulated by a system of ten non-linear delay-differential equations. The delayed argument terms in the right-hand part are used for the description of lymphocyte division, multiplication and differentiation processes into effector cells. The analysis of clinical and experimental data allows one to construct the generalized picture of the acute form of viral hepatitis B. The concept of the generalized picture includes a quantitative description of dynamics of the principal immunological, virological and clinical characteristics of the disease. Data of immunological experiments in vitro and experiments on animals are used to obtain estimates of permissible values of model parameters. This analysis forms the bases for the solution of the parameter identification problem for the mathematical model of antiviral immune response which will be the topic of the following paper (Marchuk et al., 1991, J. theor. Biol. 15).

Mathematical model of antiviral immune response. II. Parameters identification for acute viral hepatitis B.

Considering the mathematical model of antiviral immune response, we describe a method of fitting the model to the data characterizing acute viral hepatitis B. The corresponding procedure employs an idea of sequential parameter estimation to make the problem of fitting manageable. The underlying mechanisms responsible for the quantitative manifestations of the four basic phases of acute hepatitis B are used to select the model parameters. The identified model of acute hepatitis B is then tested with regard to the following situations: the effect of HBsAg-specific antibodies on HBV challenge; the vaccination and the resistance to challenge using live hepatitis B virus; the dose of viruses--the incubation time relationships. The sensitivity of the model with respect to parameters variations is then analysed. The developed model allows us to quantitatively simulate the basic features of the antiviral immune response during acute hepatitis B and some closely related phenomena.

[Results using a quantitative method for evaluating the severity and dynamics of acute pneumonia, chronic bronchitis and bronchial asthma]. / Rezul'taty primeneniia kolichestvennogo metoda dlia otsenki tiazhesti i dinamiki ostroi pnevmonii, khronicheskogo bronkhita, bronkhial'noi astmy.

The authors describe the results of application during 6 months of a quantitative method involving the use of the clinical and laboratory indicators of the disease gravity in routine medical work, which included correction of the therapeutic tactics as regards the immunological characteristics in 668 patients with acute pneumonia, 1100 with chronic bronchitis, and 120 with bronchial asthma. The use of the indicators of the disease gravity made it possible to objectively evaluate the gravity and the time-course of the diseases under consideration, to decide on the etiological treatment, to control the treatment efficacy and make necessary corrections, to specify the time of administration and withdrawal of biological stimulation, as well as to define the time of convalescence or remission. The authors have developed indications and specified contraindications as to the use of passive immunization and biological (immunocorrective) stimulation in the management of acute pneumonia.

The programme 'sections' and monitoring of World Ocean.

The main scientific problems of the programme on investigating the World Ocean's role in short-range climatic variations are discussed. It has been shown that data obtained within the framework of the SECTIONS, TOGA and other programmes should serve as a baseline for ocean physical characteristics monitoring. Some preliminary numerical experiments have been carried out.