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Biomedical subjects

M Sernetz

Publications and source records attributed to M Sernetz.

At least 19 recordsLinked to original sources
PubMed1990

Microbial growth patterns described by fractal geometry.

Fractal geometry has made important contributions to understanding the growth of inorganic systems in such processes as aggregation, cluster formation, and dendritic growth. In biology, fractal geometry was previously applied to describe, for instance, the branching system in the lung airways and the backbone structure of proteins as well as their surface irregularity. This investigation applies the fractal concept to the growth patterns of two microbial species, Streptomyces griseus and Ashbya gossypii. It is a first example showing fractal aggregates in biological systems, with a cell as the smallest aggregating unit and the colony as an aggregate. We find that the global structure of sufficiently branched mycelia can be described by a fractal dimension, D, which increases during growth up to 1.5. D is therefore a new growth parameter. Two different box-counting methods (one applied to the whole mass of the mycelium and the other applied to the surface of the system) enable us to evaluate fractal dimensions for the aggregates in this analysis in the region of D = 1.3 to 2. Comparison of both box-counting methods shows that the mycelial structure changes during growth from a mass fractal to a surface fractal.

Fungi↗
PubMed1986

Detection of acid-beta-galactosidase activity in viable human fibroblasts by flow cytometry.

The fluorogenic substrate fluorescein-di-beta-D-galactopyranoside was used to detect acid beta-galactosidase in intact cultured human fibroblasts. The accumulation of intracellular fluorescein, as measured by flow cytophotometry was linear with the incubation time in three control strains. The two fibroblast strains from patients with acid beta-galactosidase deficiency did not show an accumulation of intracellular fluorescence. Within one control cell population there was a positive correlation between the amount of accumulated intracellular fluorescein fluorescence and the specific acid beta-galactosidase activity as measured biochemically on sorted cells from different zones of the fluorescence distribution. No correlation was found between the specific acid beta-galactosidase activity and the fluorescein fluorescence of three different control cell strains.

Cells, Cultured↗
PubMed1985

The organism as bioreactor. Interpretation of the reduction law of metabolism in terms of heterogeneous catalysis and fractal structure.

Organisms and bioreactors are open, dissipative systems in steady state. They are functionally equivalent with respect to turnover and kinetics, and structurally analogous with respect to fractal organization and self-similar scaling. As heterogeneous catalytic systems both are governed by interaction of mass transport and reaction. The structural equivalent to turbulence in the reactor, yielding high efficiency, is the fractal folding and branching of the transport systems of the organism. Dimensionally and in terms of fractals, organisms and reactors are therefore area-volume hybrids. The physiological consequence of this is the reduction law of metabolism. Introducing limits into allometric functions describing scale-up of similar organisms yields probability density distributions of their realization.

Animals↗
PubMed1983

A kinetic study on the enzymatic hydrolysis of fluorescein diacetate and fluorescein-di-beta-D-galactopyranoside.

The kinetics of the hydrolysis of fluoresceindiacetate and fluorescein-di-beta-D-galactopyranoside were investigated by thin-layer chromatography. The time course of the concentrations of substrate, monosubstituted intermediate, and product was simulated numerically. The mathematical model takes into account the competition of substrate and intermediate and the accumulation of the intermediate at the enzyme.

Chromatography, Thin Layer↗
PubMed1980

Immobilization of beta-galactosidase, albumin, and gamma-globulin on epoxy-activated acrylic beads.

A comparative study was conducted into the immobilization of beta-galactosidase, albumin, and gamma-globulin on an epoxy-activated polyacrylic matrix (oxirane C, Röhm-Pharma GmbH, Darmstadt). The kinetic parameters of the immobilized beta-galactosidase were investigated with three kinds of miniaturized analytical reactors; namely, stirred batch, continuous stirred-tank, and packed-bed reactors. The optimum binding conditions, saturation activity and Michaelis constant of immobilized beta-galactosidase are given, together with determinations of the binding capacity of the oxirane C matrix for the three proteins investigated. For beta-galactosidase a saturation activity of 1300 U/g oxirane C was reached. The maximum binding, achieved by experiment, was 140 mg/g with 0.69 yield for albumin, 120 mg/g with 0.61 yield for gamma-globulin, and 40 mg/g with 0.42 yield for beta-galactosidase. From these data the inner surface of the matrix as a function of the size of the bound proteins was estimated.

Acrylates↗
PubMed1976

[Effect of cromoglicinic acid on the degranulation of mast cells (author's transl)].

An interference microscopic method is described which allows quantitative measurements of the inhibiting effect of the di-sodium salt of 1,3-bis(3-carboxy-chroman-5-yl-oxy)-2-hydroxypropand (cromoglicinic acid; Intal; DSCG) on the degranulation of mast cells in vitro induced by polymixin B and Compound 48/80. The specific degranulation inhibiting effect of DSCG is increased in the presence of Ca++ and Mg++ ions.

Animals↗