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PubMed1978

[Adipocyte size in primary hypertriglyceridemia with and without obesity (author's transl)].

Adipose tissue cellularity of patients with endogenous hypertriglyceridemia whether associated with obesity or not has been studied by means of a semiautomatic method of counting and sizing osmium tetroxide fixed adipocytes. Cell population distributions were analyzed by mathematical computation. The Coulter Counter system was able to determine mean diameter (or volume) and cell size dispersion which defined adipocyte population. An overall shift of cell population size has been found to characterize adipose tissue cellularity of the different groups examined. Adipocyte population in the obese was defined by increased fat cell size with overlapping distributions between both groups of same weight. Nevertheless normolipemic obese patients were characterized by larger cell size than hypertriglyceridemic subjects matched for adiposity index. The results are discussed in relation to the removal defect found in endogenous hypertriglyceridemia.

Adipose Tissue↗
PubMed1991

A mathematical model and computer simulation study of insulin receptor regulation.

A homeomorphic mathematical model of cell surface insulin receptor regulation is developed. The overall structure of the model is based on molecular mechanisms suggested by in vivo and in vitro experimental evidence from many different cell types. Model parameters correspond to cellular processes which are constrained by known boundry value conditions. As an example, computer simulation results are compared with published data from BC3H-1 myocytes in culture. With appropriate parameter choice, this model is able to simulate data from other cell types. Cellular processes which are explicitly represented in the model include: bound and unbound receptor endocytosis, receptor recycling, intracellular receptor degradation, and state-dependent receptor synthesis. Most of these processes are represented as first-order events. Using more complex representations of the model structure with higher order rate constants or saturable pathways does not qualitatively improve simulation results. Simulations are able to reproduce ligand-induced down and up regulation of receptors as well as the initial spontaneous display of surface insulin receptors. To demonstrate the behavior of our model and illustrate its utility for explaining insulin receptor regulation for a variety of conditions, simulations for which experimental data is unavailable for direct comparison are also shown. We believe the structure of our model is sufficient to explain insulin receptor regulation in a wide variety of cell types. In addition our model may aid in understanding the receptor component of insulin resistance (decreased sensitivity or responsiveness to insulin) seen in pathological states such as obesity and diabetes mellitus. Finally, this model may be applicable to the study of the regulation of other polypeptide hormone receptors.

Cell Membrane↗
PubMed1991

A mathematical model and computer simulation study of insulin sensitive glucose transporter regulation.

A mathematical model of insulin sensitive glucose transporter regulation is developed. Model structure is based on experimental evidence from adipocytes and myocytes. Model parameters correspond with known cellular processes. As an example, computer simulation results are compared with data from rat adipocytes. Cellular processes explicitly represented in the model include state-dependent glucose transporter synthesis and degradation rates, insulin sensitive glucose transporter translocation rates, and a glucose transporter endocytosis rate. Most of these processes are represented as first-order events. Using more complex representations of the model structure (e.g. higher order rate constants or saturable pathways) or alternative structures did not result in qualitatively better results. The model is able to accurately simulate the insulin sensitive, insulin concentration dependent, reversible translocation of glucose transporters observed in normal adipocytes. The model is also able to accurately simulate the changes in regulation of glucose transporter translocation observed with increases in cell surface area. Finally, the model can simulate pathogenic states which induce impairment of glucose transporter regulation (e.g. altered glucose transporter regulation in adipocytes from rats on high fat diets, rats with streptozotocin induced diabetes, and fasted rats). Since the structure of our model is sufficient to explain glucose transporter regulation in both normal and pathological states, it may aid in understanding the post-receptor components of insulin resistance (decreased sensitivity or responsiveness to insulin) seen in pathological states such as obesity and diabetes mellitus.

Adipose Tissue↗
PubMed1985

Validation of a mathematical procedure for computer analysis of flow cytometric DNA data in human tumors.

The determination of tritiated thymidine labeling index and the percentage of cells with S phase DNA content was performed on cell suspensions obtained from 69 patients with non-Hodgkin's lymphoma. The distributions of cells in the cell cycle by computer analysis of flow cytometric data were obtained by two mathematical procedures: the widely adopted Fried model and a new one proposed by Bruni et al. A significant agreement was observed by checking the Spearman index (rs) between the percentages of cells in the different cell cycle phases (G0/1, rs = 0.76; S, rs = 0.60; and G2 + M, rs = 0.43; p less than 0.001) determined by the two procedures. Similarly, a good correlation was observed between the labeling index (LI) and the S phase values obtained by the Fried (rs = 0.45, p less than 0.001) and Bruni (rs = 0.69, p less than 0.001) models, but with a higher agreement for the latter one. The S phase by the Bruni model was also superior in predicting LI: in fact, by employing the S cutoff value of 12%, a better agreement between low LI and low S phase or high LI and high S phase was observed with the Bruni procedure (90%) than with the Fried model (72%). Finally, the analysis of the prognostic significance of the different kinetic variables confirmed the prognostic relevance of LI at any time; the S phase percentage as determined by Bruni et al. was discriminant of survival only at shorter times, and no prognostic significance could be ascribed to S phase according to the Fried procedure.

Adult↗
PubMed1991

Theory of ocular dominance column formation. Mathematical basis and computer simulation.

A general theory previously proposed by the author which describes synaptic stabilization on the basis of three basic assumptions is employed for the understanding of ocular dominance column formation. A reduced mathematical model is constructed based on the thermodynamics in the Ising spin variables representing the afferent synaptic connection distribution. The results of Monte Carlo simulations on the segregation of ipsilateral and contralateral synaptic terminals in the input layer of the primary visual cortex suggest the existence of phase transition phenomena. Three types of ocular dominance column patterns--stripe, blob, and uniform--are visualized according to the values of the correlation strength and the degree of imbalance in activity between the left and right retinas. The theory presented here successfully explains how ocular dominance columns are developed.

Animals↗
PubMed1978

[Role of computer technology and mathematical modelling in the treatment of patients after operations on the heart].

On the basis of ten-year experience in theoretical studies and experimental tests mathematical models of hemodynamics were built for the follow-up of parameters of the cardiovascular system which cannot be determined by means of any other modern methods. Three years of clinical studies of the Hewlett-Pachard monitoring computer system and its modification helped to elaborate the mathematical backing, a bank of mathematical models, original automatic programs for measuring the cardiac index, the index of myocardial viability, etc. The automatic system provides for an individual approach in assessing the patient's condition in actual time and for control of the treatment.

Cardiac Surgical Procedures↗
PubMedDate not supplied

[The use of personal computers for the mathematical processing of the results of chemical-toxicological studies].

Three programs in BASIC and SUPER BASIC language for personal computer are suggested. The first program makes it possible to calculate the degree of substance extraction and factor of its distribution between two liquid immiscible phases. The second program is designed to make calculations on distribution of substance in the organs of experimental animals. The third program is designed to determine specific and molar factors of light absorption. Results of calculations are presented as tables. Programs can be also used in mathematical processing of results obtained in the course of scientific research.

Electronic Data Processing↗
PubMed1988

Mathematical analysis of computed carpal models.

The computed carpal models from digital computed tomography (CT) data obtained in this study compare favorably to natural anatomy. A new application of algebraic analysis of this data provides mathematical markers from which to calculate the position and orientation of each carpal bone. When the origin of the spatial coordinates of a carpal bone is transferred to the centroid of the bone, the data can be treated as three-dimensional pattern vectors describing its surface. It is then possible to calculate vectors that are the principal axes of the geometry. These axes provided references that were used to calculate position and orientation of the carpal bones in three wrist specimens. Comparisons of volumes, surface areas, and sizes and proportions of five computed images of each carpal bone from two of these wrists demonstrate the reliability of the technique. The analysis of CT scans of ceramics with known boundaries allows an estimation of its accuracy. The technique is well suited to the future study of normal wrist kinematics and pathological conditions.

Carpal Bones↗
PubMed1989

Computer-assisted predictive mathematical relationship among electroshock voltage and duration and occurrence of convulsion in mice.

A microcomputer program in BASIC for predicting percentage of occurrence of electroshock-induced convulsion in mice was designed. A formula published by the author to express the mathematical relationship among the drug dose, the time, and the biological response was used in this program. Analysis of the actual, and the computer-assisted predicted percentages of occurrence of convulsion has shown that the program is fairly accurate in expressing convulsion response of mice as a function of the voltage and the duration.

Animals↗
PubMed1991

Fractals and medicine.

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Image Interpretation, Computer-Assisted↗