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Biomedical subjects

A Iu Iakovlev

Publications and source records attributed to A Iu Iakovlev.

At least 37 records · Page 2Linked to original sources
PubMed1980

[Dynamics of systems with induced cell proliferation within the framework of a branching stochastic process model. I. The number of cell generations induced to proliferate].

The probabilistic description of cell generation numbers in the populations induced to proliferate is considered on the basis of the model of branching age-dependent stochastic process. The recurrent formulas for generating functions (and moments) are derived for the following process which are of interest for the analysis of induced proliferation in closed cell populations: the number of cells in n-th generation horn up to the moment of observation, and the number of cell in n-th generation existing at a given moment.

Cell Division↗
PubMed1979

[Hepatocyte dynamic reserve: the mechanism for the assurance of specialized functions in the regenerating liver].

A short review is presented of the experimental data on the interrelation between specialized functions and proliferative activity of cells in regenerating mammalian liver. Using the results of the kinetic analysis of induced cell proliferation makes it possible to elicit an existence of the dynamic redistribution of hepatocytes between "the reserve" of quiscent cells (in respect to the mitotic cycle) and the population of actively proliferating cells. This fenomen referred to as "the dynamic reserving of cells" is considered in this work as a possible mechanism of maintenance of the specialized functions of the liver during its regeneration after a partial hepatectomy.

Adaptation, Physiological↗
PubMed1978

[Labeled mitosis curve in the presence of different states of cell proliferation kinetics. IV. Additional remarks on the method of a posteriori modeling].

Using the conditional probability density function of phase duration--h (a, t), defined for a cell just completing a given phase of the mitotic cycle at the moment t it is possible to construct a mathematical description of the fraction labeled mitoses curve. The function h (a, t) defined for any separate phase can be described by means of a certain mathematical expression which is applicable even in the presence of transient processes in cell kinetics and serves as an appropriate generalization of the same result from the theory of exponentially growing cell populations (the model of age-dependent branching process). When the sum of r successive phases with stochastically dependent durations is under consideration and the age of a cell is measured from the start of phase r, it is necessary to find out the expression for the function hr (ar, t). The derivation of such an expression is given.

Cytological Techniques↗
PubMed1978

[Curve of labeled mitoses with different states of cell proliferation kinetics. V. Effect of the circadian rhythm of cell proliferation on the shape of the labeled mitosis curve].

The influence of the diurnal rhythm in cell proliferation processes on the behavior of labeled mitoses curve (LMC) is under investigation. The mathematical model predicts that LMC observed following 3H-thymidine administration to experimental animals at different day-times can differ greatly even when temporal parameters of the mitotic cycle remain unchanged. The analysis of the experimental data on the hamster's cheek pouch epithelium suggests that diurnal differences in LMCs cannot be explained in certain cases by the influences of transient processes in cell kinetics only, and therefore the existence of a slight trend in prolongation of periods of the mitotic cycle cannot be completely excluded.

Animals↗
PubMed1976

[Curve of labeled mitoses in different kinetic states of cell proliferation. III. Experiments with a mathematical model].

By means of computer simulation, the dynamic structure of labeled mitoses curve (LMC) has been investigated. Experiments using computer demonstrated the dependence of LMC form not only on the values of temporal parameters of the mitotic cycle, but also on the state of cell proliferation kinetics before and after pulse labeling. Of particular interest was a case of a temporal block of cell entry into the S period which has been studied in a greater detail. The results of modelling experiments have shown that the universally accepted graphic procedures for the evaluation of mean durations of S- and G2-periods (using 50%-level of LMC) yield the satisfactory estimates only for systems with stationary age distribution for cells in the mitotic cycle (steady, in the strict sense, and exponential states of cell proliferation kinetics). The paper presents also the kinetic interpretation of certain abnormalities in LMC form arising from some peculiarities of cell population kinetics in the real biological experiment.

Computers↗
PubMed1976

[Labeled mitoses curve in different states of cell proliferation kinetics. 2. Mathematical model with the calculation of transient processes].

The available information about the temporal patterns of labelling and mitotic indices in the same system has been used to develop a general approach to the mathematical simulation of labelled mitoses curve. Such states of cell proliferation kinetics as induced DNA synthesis, steady (in narrow sense) state and diurnal rhythm of proliferative processes are investigated in a greater detail. The principle of a mathematical description of an additional DNA synthesis stimulation coming from the states under consideration is also discussed in this work.

Cell Division↗
PubMed1975

[Analysis of the kinetics of the transition of cells to DNA synthesis in systems with stimulated proliferation. III. Regenerating liver].

The application of the previously reported methods of kinetic analysis to cell proliferation studies in the regenerating rat liver is under consideration. A fraction of hepatocytes (nearly 60% of the initial hepatocyte number) synchronously entering the mitotic cycle in response to partial hepatectomy has been discovered. The investigation of the temporal pattern of the kinetic criterium qS (t) allowed to make a detailed description of the main features of the transition of hepatocytes to DNA synthesis during the first 40 hours of liver regeneration. Using kinetic criteria of the initial and repeated entry of cells into S-period made it possible to reveal that the prereplicative period in the second mitotic cycle was shorter than that in the first one. Thus, the hypothesis about a special period which is necessary for the quiescent cell to acquire the competence to proliferation is additionally supported.

Animals↗
PubMed1975

[Some characteristics of the process of forming autophagocytic vacuoles in the hepatocytes of regenerating rat liver].

This work deals with the previously described process of cellular autophagocytosis in regenerating rat liver. The experimental data obtained indicate that the early appearance of acid phosphatase positive cytoplasmic vacuoles (with diameter more than 2 mu) occur only in a certain portion of the parenchymal cell population (nearly 30% of the total number of hepatocytes) and mainly in the central area of the hepatic lobule. It may be concluded that the observed reaction of the cell vacuolar apparatus concerns hepatocytes that undergo the entry into the mitotic cycle much later than does the main part (ca 60%) of cell population.

Animals↗