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Results for “Cell Physiological Phenomena”

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At least 19 recordsLinked to original sources
PubMed1976

[Place of neuroleptics in geriatric anesthesia].

The elderly show changes in various parenchymas linked to the process of ageing. Pathological abnormalities may be added to this picture leading to physiopathology peculiar to the aged. In relation to special problems raised by this background, the advantages and disadvantages of N.L.A. are discussed. The authors refer to an experiment in the Department of Anesthetics and Intensive Care in Créteil.

Aged↗
PubMed1978

How cells make ATP.

Explore the source record for details and available documents.

Adenosine Triphosphate↗
PubMed1992

Formation of cell protrusions by an electric field: a thermodynamic analysis.

This work gives a thermodynamic analysis of outgrowth extraction from the cell body by a pulling force. The results are applied for a case when the pulling force is generated by an external high-frequency electric field. Two equilibrium conditions are analyzed: internal equilibrium of an outgrowth and equilibrium between the outgrowth and the cell body. In both cases the stability of feasible equilibrium states was studied. The work shows that the curvature of an outgrowth equilibrated with a pulling electric force depends on the squared amplitude of the electric field E0(2), on the outgrowth length l and on the transmembrane pressure differential delta P, and that at a sufficiently large transmembrane pressure differential the cylindrical form of the outgrowth loses its stability. Long outgrowths are more stable than short ones. The minimal value of critical pressure differential was estimated. The work also shows that outgrowth extraction from the cell body requires that the applied force exceeds a critical value below which no outgrowth is formed. The value of the electric field at which outgrowth formation is feasible was estimated.

Biomechanical Phenomena↗
PubMed1976

Computer assistance in multiparameter flow microphotometry of mammalian cells.

Flow system technology enables the biological and medical experimenter to investigate the distribution spectra of various cellular characteristics separately or in parameter combination on the basis of ultrarapid single cell measurements. A typical rate of recognition is about 1000 to 5000 cells per second and the precision of measurements and their statistical relevance has been previously unobtainable. According to the approach of the multiparameter analysis and high data rate, computer assistance in flow system technology is given primary consideration. In this study three different kinds of software controlled modes in data acquisition are demonstrated: normal acquisition and linear accumulation of single parameters, spectra accumulation of two correlated parameters of each single cell and documentation as linear, two- or three-dimensional distribution pattern, and linear accumulation of two correlated parameters simultaneously with their actual signal-to-signal ratio. A first attempt to analyze distribution spectra was the application of the entropy of the structure routinely used in cybernetics. This function seems to be a measure for determining the degree of synchrony in an appropriate pretreated cell population. A special mathematical strategy has been applied to the linear spectra cellular DNA content, whose advantage is the quantitative extraction of the fractions concerning the various phases of the life cycle cells. The validity of this special curve fitting procedure has been proven on various experimental cell populations.

Animals↗
PubMed1992

Relationship between thermal tolerance and protein degradation in temperature-sensitive mouse cells.

The induction of thermotolerance was studied in a temperature sensitive mouse cell line, ts85, and results were compared with those for the wild-type FM3A cells. At the nonpermissive temperature of 39 degrees C, ts85 cells are defective in the degradation of short-lived abnormal proteins, apparently because of loss of activity of a ubiquitin-activating enzyme. The failure of the ts85 cells to develop thermotolerance to 41-43 degrees C after incubation at the nonpermissive temperature of 39 degrees C correlated with the failure of the cells to degrade short-lived abnormal proteins at 39 degrees C. However, the failure of the ts85 cells to develop thermotolerance to 43 degrees C during incubation at 33 degrees C after either arsenite treatment or heating at 45.5 degrees C for 6 or 10 min did not correlate with protein degradation rates. Although the rate of degrading abnormal protein was reduced after heating at 45.5 degrees C for 10 min, the rates were normal after arsenite treatment or heating at 45.5 degrees C for 6 min. In addition, when protein synthesis was inhibited with cycloheximide both during incubation at 33 degrees C or 39 degrees C and during heating at 41-43 degrees C, resistance to heating was observed, but protein degradation rates at 39 degrees C or 43 degrees C were not altered by the cycloheximide treatment. Therefore, there is apparently no consistent relationship between rates of degrading abnormal proteins and the ability of cells to develop thermotolerance and resistance to heating in the presence of cycloheximide.

Acclimatization↗
PubMed1975

Chloride cells of larval Notonecta glauca and Naucoris cimicoides (Hemiptera, Hydrocorisae). Fine structure and cell counts at different salinities.

The chloride cells of the larval waterbugs, Notonecta glauca L. and Naucoris cimicoides L., ultrastructurally resemble the caviform chloride cells of other aquatic insects as well as those of teleost fish. The predominant features are abundant mitochondria, basolateral plasma membrane infoldings and an apical cavity possessing numerous microvilli. After histochemical precipitation of chloride, dense deposits of silver chloride are present in the apical region. The cuticular area overlying the chloride cells is extremely reduced in thickness and differentiated into a plug-like structure. The 1st instars of Notonecta glauca raised from the eggs at various hypo-osmotic salt concentrations have identical numbers of thoracal chloride cells regardless of the external salinity. The number of cells progressively increases with each moult. However, in corresponding larval stages, there is a significant decrease in the number of thoracal chloride cells relative to increases in the external salinity. These results are consistent with the presumptive involvement of the chloride cells in osmotic hyperregulation.

Animals↗
PubMed1977

A random walk model of cellular kinetics.

The sorting out of biological cell mixtures into clusters of one cell type is modelled as a consequence of random cell and cluster motion, during which cells of like type cohere upon collision. After a description of the model and its motility rules, the results of several computer simulation studies are analysed and compared with both laboratory data and certain theoretical predictions. The model is found to be more biologically realistic than previous models with similar results. Suggestions for further reserach are discussed. An Appendix contains details about the data structures and algorithms employed in the simulation.

Cell Adhesion↗
PubMed1979

Simulation of disturbed cell renewal systems by means of a microprocessor system.

In this contribution a computer model is presented which enables a simulation of disturbed cell growth and cell renewal systems by means of a microprocessor system. The results consist of a time course study of the number of cells and of the local configuration of cells in a cell matrix at any arbitrary discrete moment. A similarity to morphological cuts and cell kinetic curves obtained by experiments is obvious.

Cell Division↗