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Biomedical subjects

A Iu Iakovlev

Publications and source records attributed to A Iu Iakovlev.

At least 19 recordsLinked to original sources
PubMed2001

[Use of cytochrome C in the prevention of myocardial reperfusion injury during heart valve prosthesis implantation under conditions of extracorporeal circulation].

Cytochrome C used at the postischemic period causes a rapid reestablishment of coronary circulation, hemodynamic parameters, prevents activation of lipid peroxidation in reoxygenation of the heart after prolonged total myocardial ischemia in patients with acute bacterial endocarditis in whom the prostheses of heart valves had been fulfilled. Parallel with the positive inotropic effect, Cytochrome C reduces the postloading and, as a result, transfers the cardiac muscle to a more profitable regimen. At the end of the myocardial ischemia period Cytochrome C provides rapid and effective recovery of the bioelectrical function of the heart, improves its pumping function, thus allowing the dose and duration of inotropic stimulation of the myocardium at the postischemic period to be reduced, lowers pulmonary resistance and finally leads to less postoperative intrahospital lethality from acute heart failure.

Animals↗
PubMed2001

[Parametric survival analysis in patients with cervical cancer following fractionated radiotherapy: a new procedures and results].

A recent theoretical result of Kendal (1998) enabled us to develop a survival model which allows for proliferation of tumor clonogenic cells in the course of fractionated radiotherapy. We explored this model during an analysis of clinical data on survival of 982 patients with cancer of the cervix uteri. The model provided a good description of survival patterns in different groups of patients. The estimated cure probability did not correlate with the rates of cell proliferation between exposures to radiation. Also, our results showed that this parameter cannot be estimated from survival data. Some light has been thrown on the relationship of cell proliferations taking place between exposures, on the one hand, and end-results of treatment for cancer of the cervix uteri, on the other.

Dose Fractionation, Radiation↗
PubMed1991

[A possible approach to the task of the individual choice of treatment for cancer patients].

A procedure for choosing treatment for a cancer patient is suggested. The method was developed on the basis of data of a retrospective analysis of patient characteristics, type and results of treatment. It suggests the use of a computer and is aimed at assessment of a conventional function of survival for each treatment modality, comparison of these functions and choosing optimal therapeutic regimen with regard to patient characteristics. A method for experimental testing of the above procedure that does not require clinical trials is described.

Decision Making, Computer-Assisted↗
PubMed1988

[Biomathematical approaches to the problems of radiation biology and medicine].

A vast experience in the introduction of modern mathematical methods into research activities of the Central Research Roentgenoradiology Institute was accumulated in the Department of Biomathematics. The Information-retrieval System for Storage and Analysis of Data on the Activities of X-ray Service in the USSR, a package of applied programs for statistical analysis of radiation therapy effectiveness, a controlled data base on 6 cancer sites, 2 systems for simulation of radiation effects on heterogeneous cell systems were worked out. Some priority results in the fields of mathematical biology and statistical analysis of incomplete selective data were obtained. The Department is heading the work on the problem "Mathematics and computer technology in radiobiology and radiation biophysics".

Humans↗
PubMed1988

[Comparison of survival curves based on a model of proportional risks].

Regression analysis of proportional risks was adapted to a two-tailed test for comparing survival of cancer patients. The method allowed both testing the hypothesis on the difference between two survival functions and evaluation of the degree of the difference. The method was applied to data on survival of patients with cancer of the cervix uteri following radiation treatment.

Algorithms↗
PubMed1988

[Theoretical limits to the efficacy of radiotherapy].

The upper bound for expected cancer treatment efficacy expressed as the difference between weighted survival probabilities for normal and neoplastic cells has been obtained. The maximum value of this difference has been recorded in a fixed deviation of distributions of normal and neoplastic cell radiosensitivity.

Humans↗
PubMed1988

[Assessment of the parameters of the growth kinetics of an experimental tumor].

A model of the Markov stochastic reproduction and death process is studied as applied to the analysis of time intervals necessary for the experimental tumours to achieve the fixed size. The analysis results have shown nonstationarity of the tumour growth processes during early stages of the tumour development. The presence of such a nonstationarity makes the experimental data interpretation difficult when applying the traditional approach to the tumour cell population kinetics.

Animals↗
PubMed1987

[Parametric analysis of the survival of cancer patients based on the results of radiation therapy of cervical cancer patients].

An approach based on the parametric distribution of the life span of tumor-bearing individuals was suggested for the analysis of cancer patients survival. Two groups of patients with cancer of the cervix uteri were identified on the basis of the pre-treatment data (before radiation therapy) on rates of tumor growth. Kinetic curves for tumor growth were constructed using the said distribution procedure as well as the data on survival in each study group. Mean values of the coefficient of critical increase of tumor cells were obtained. The interpretation of clinical data in terms of kinetic characteristics of tumor process provides a better understanding of the causes underlying differences in survival of various groups of cancer patients.

Carcinoma, Squamous Cell↗
PubMed1984

[Simulation modeling of the initiation of tumor growth in continually renewed cell systems].

A discrete stochastic model of simulation of a cell renewal system is discussed. The model is based on a functional approach to the present-day concepts on the nature of processes of cell proliferation and differentiation as well as mechanisms responsible for integration of these processes. Due to application of specialized programming means of simulation (language GPSS /360) a complete functional pattern of maintenance of cell-population homeostasis in tissue was reproduced. Disturbances in certain mechanisms of intra-tissue regulatory system accompanied by formation of tumor growth foci were simulated experimentally.

Animals↗
PubMed1982

[Modeling of the reliability of regenerating cell systems].

The paper deals with the mathematical model of reliability of simple renewal cell system consisting of two independently functioning populations of actively proliferating and differentiating (maturing) cells. The investigation of some properties of this model makes it possible to suppose that the mechanisms of tissue homeostasis may also participate in the maintenance of reliability of the relationship between cell proliferation and cell differentiation processes.

Cell Differentiation↗