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Biomedical subjects

M Kellermayer

Publications and source records attributed to M Kellermayer.

At least 37 records · Page 2Linked to original sources
PubMed1990

The state of potassium in skeletal muscle and in non-muscle cells.

The relationship between ions, water, and the electrical properties are fundamental to our understanding of cellular function. This paper is primarily directed at reviewing the theoretical explanations for the changes in cellular potential and ionic composition which are associated with early postnatal development of skeletal muscle. The findings are: (a) a two-fold reduction in tissue hydration and a significant reduction of the diffusive motion of cellular water; (b) ten-fold decrease in cellular sodium; (c) six-fold decrease in tissue chloride; (d) the concentrations of intracellular potassium, and of extracellular sodium, potassium and chloride were constant; and (e) the cellular potential changed by 55 mV. A review of the literature concerning the physical state of potassium and water is made. The theoretical explanations of these findings are evaluated in terms of the classical membrane theory and the association induction hypothesis.

Animals↗
PubMed1989

Urinary Escherichia coli infection presenting with jaundice.

A 53-year-old man with lupus erythematosus (LE) developed an acute hemolytic crisis. Alpha-hemolytic Escherichia coli were isolated from the patient's urine and feces, and high titer anti-alpha-hemolytic antibodies appeared in his serum. The hemolytic crisis could be controlled by specific antibiotic treatment of the urinary tract infection. It is assumed that the patient's basic disease -- and the steroid therapy applied -- facilitated the progression of the urinary tract infection, and before starting with adequate antibiotic treatment his erythrocytes must have been subjected to the effect of massive amounts of alpha-hemolysin. The idea that alpha-hemolysin might contribute to the development of severe hemolysis in man is discussed. It is also assumed that harbouring alpha-hemolytic E. coli in the gut may represent a special risk for the immunocompromised host.

Antibodies, Bacterial↗
PubMed1989

Paraproteins associated with low plasma sodium levels.

The mechanism of the maintenance of low plasma sodium levels seen in certain multiple myeloma cases has been attributed to the cationic nature of pathological immunoglobulins (paraproteins). This hypothesis was tested with equilibrium dialysis and polyacrylamide gel electrophoresis techniques. Citrated plasma samples and affinity chromatography purified paraproteins of three multiple myeloma patients with abnormally low plasma sodium levels were dialysed against 140 mmol/L NaCl solution at pH 7.4 for 24 hours. The electrophoresis of paraproteins was conducted under non-denaturing conditions. Low plasma sodium concentrations observed under the dialysis of the patients' plasma samples were in good agreement with earlier reports. However, the isolated paraproteins did not show any sodium exclusion during the dialysis experiment. The electrophoretic mobility of the paraproteins at pH 7.4 indicated that the isoelectric point of these molecules was below 7.4, so they cannot behave as cations at the pH of the blood. From these data it appears that the maintenance of low plasma sodium levels in certain IgG type myeloma cases cannot be explained by the previously postulated cationic nature of the paraproteins.

Amino Acids↗
PubMed1989

Release of hemoglobin and potassium from human red blood cells treated with Triton X-100 under the critical micellar concentration.

The action of detergents is thought to be connected primarily with micelle formation. However, detergent monomers can also effect biological systems. It was found in this study that human red blood cells can be disintegrated with Triton X-100 non-ionic detergent at a concentration of 0.007%, lower than the critical micellar concentration (CMC). The time dependent release of hemoglobin and potassium was detected at 37 degrees C and both were sigmoid in character. Although potassium was released faster than hemoglobin, a cooperative relationship between potassium and hemoglobin within the intact red blood cell is suggested by this observation.

Erythrocytes↗
PubMed1988

Extent and properties of nonbulk "bound" water in crystalline lens cells.

Crystalline lenses provided good material to study and measure the properties of cellular water. Different methods were used to establish the extent and properties of nonbulk water in mammalian lenses. These methods include: NMR titration analysis, a test of the osmotic properties, a test of dye exclusion In lenses with intact cell membranes and in lenses with disrupted cell membranes, and the water-holding capacity of lenses subjected to 40,000 x g for 1 hour with intact cell membranes and in lenses with disrupted cell membranes. The data from these methods, as well as other data from the literature, lead to the conclusion that most, if not all, of the water in lens cells (up to 2.2 g water/g dry mass) has motional and osmotic properties that distinguish it from bulk water. These findings call into question the common and convenient assumption that all but a small proportion of cellular water is like that in dilute solution.

Animals↗
PubMed1988

Role of plasma membrane and of cytomatrix in maintenance of intracellular to extracellular ion gradients in chicken erythrocytes.

Ultrastructural observations in combination with electron probe X-ray microanalysis on detergent (Brij 58) permeabilized (disruption of the plasma membrane) nucleated chicken erythrocytes support the view that a large fraction of cytoplasmic and nuclear K+ is not freely diffusible and that adsorption of K+ on detergent released mobilizable proteins exists within the cell. The data also suggest that the detergent proteins are normally immobilized by a detergent-resistant cytoskeleton so that they are not immediately free to diffuse from the cell for several minutes after detergent disruption of the plasma membrane.

Animals↗
PubMed1988

Protein synthesis in human platelets.

The platelets and leukocytes of human peripheral blood were separated and cultured for 24 h in the same medium. The culture medium was completed with S-methionine. The overall protein synthetic activity of the platelets, compared with leukocytes, was studied with a two-dimensional gel electrophoresis technique combined with fluorographic detection of labelled proteins. Our findings confirm the platelet-origin of a few newly synthesized proteins. The most pronounced newly synthesized platelet protein with a molecular weight of approximately 35 Kda and with a more acidic isoelectric point than that of actin was identified as a cytoskeleton-associated protein.

Blood Platelets↗
PubMed1988

Bioluminescent monitoring of ATP release from human red blood cells treated with nonionic detergent.

The adaptation of the firefly luciferin-luciferase system for the detection of ATP in the presence of Triton X 100 or Brij 58 nonionic detergents is described. The method is sensitive, easy to perform and is suitable for the continuous monitoring of the mobilization rate of ATP from Triton X 100- or Brij 58-treated human erythrocytes. A very rapid ATP release was observed after Triton X 100 treatment of the red blood cells while the presence of Brij 58 caused a retarded mobilization of the intracellular ATP. The technique described seems to be applicable to all kinds of cells.

Adenosine Triphosphate↗
PubMed1988

Analysis of Triton X-100 insoluble proteins of human chorionic and amniotic tissues with special emphasis on intermediate filaments.

The intermediate filament composition of the chorionic villi of the human full-term placenta and that of the amniotic sac was analysed. The analysis of the protein pattern of the Triton X-100 resistant tissue residues on SDS-polyacrylamide gel did not help us in intermediate filament identification because of the protein heterogeneity of the samples. The in vitro polymerization-depolymerization of the detergent resistant tissue proteins did not result in considerable enrichment of the intermediate filament proteins either. The direct immunological identification done by immunoblotting electrophoresis on the detergent resistant tissue residues, revealed that vimentin and cytokeratins were synthetized in detectable quantities in the human extraembryonal tissues.

Amnion↗
PubMed1988

Ion and water retention by permeabilized cells.

Nonionic detergents, Triton X-100 and Brij 58, removed, within 2-5 minutes, lipid membrane of suspended thymus lymphocytes and monolayer H-50 cells grown in culture. Studies of hydration, ionic asymmetry, and ionic and protein release kinetics were conducted on these membraneless cellular preparations. The hydration of nuclei isolated by Triton X-100 procedures appears to be influenced strongly by the monovalent ionic concentration of the buffer bathing the organelles. The putative monovalent ionic concentration of the cellular aqueous phase (i.e., 150 meq/L) caused nuclei to swell and coalesce. Monovalent ionic concentrations of 30 meq/L or less caused minimal changes in volume and in morphology. Triton X-100 treatment led to rapid mobilization and solubilization of membrane and cytoplasmic lipids and proteins, and the cellular potassium was reduced to very low levels. Brij 58 treatment of the lymphocytes for 5 minutes led to loss of membrane structure. Potassium, however, was retained at significant levels for over 10 minutes. Potassium and protein release kinetic studies in the H-50 monolayer cells following Brij treatment revealed that potassium and the detergent mobilized proteins may be co-compartmentalized and that 10 minutes or more are required before their release is completed. These results support the view that most of the potassium and "diffusible" proteins are not fully dissolved in the cellular water. Furthermore, the integrity of the membranes does not appear to be essential for the retention of the ions and the proteins.

Animals↗
PubMed1987

The bulk of ATP is associated to proteins in the living cell: a release kinetics study.

The analysis of the nonionic detergent induced release kinetics of intracellular components is a promising approach to obtain information on the possible molecular interactions inside the living cell. The molecular interactions of ATP were studied by monitoring the nonionic detergent-induced release kinetics of ATP from cultured human cells. The observed rapid mobilization rate in the presence of Triton X 100 and the retarded release in the presence of Brij 58 were in good agreement with the detergent-induced release kinetics of proteins and K+ reported earlier. These data are consistent with the idea that the bulk of ATP is associated to the protein macromolecules of the living cell.

Adenosine Triphosphate↗
PubMed1987

Hydrogen ion dependent reversible fibrillarization and hydration of chromatin in divalent cation-depleted isolated rat liver nuclei.

Rat liver cell nuclei isolated in the presence of Ca++ and Mg++ ions were exposed to citrate buffer at different pH levels. Their morphology was studied with the electron microscope and the water content measured. At a low pH the chromatin remained compact, but at neutral pH an intense fibrillarization of the chromatin was observed; and, seemed to be reversible, because of deoxyribonucleoproteins (DNP) filaments which dispersed at a pH of 7 were repacked to their previous site at a pH of 3. The ribonucleo-proteins (RNP)-containing structures did not show the same reversible fibrillarization. In addition to the morphological changes, a large increase in the water content ("water-holding capacity") of the chromatin structures was observed.

Animals↗
PubMed1986

Cocompartmentation of proteins and K+ within the living cell.

Monolayer H-50 tissue culture cells were treated with Triton X-100 and Brij 58 nonionic detergents, and their electron microscopic morphology along with the release of the intracellular proteins and K+ were studied. Although Triton X-100 was more effective, both detergents removed the lipoid membranes within 5 min. The mobilization and solubilization of the cytoplasmic and nuclear proteins occurred much faster with Triton X-100 than with Brij 58. In Triton X-100-treated cells, the loss of K+ was complete within 2 min. The loss of K+ from the Brij 58-treated cells was complete only after 10 min and the mobilization of K+ showed sigmoid-type release kinetics. These results support the view that most of K+ and "diffusible" proteins not freely dissolved in the cellular water, but they are cocompartmentalized inside the living cell.

Animals↗
PubMed1984

Platelet-derived growth factor (PDGF) induces intranuclear protein accumulation in 3T3 fibroblasts.

Quiescent 3T3 fibroblasts were grown for a short time in the presence of [3H]amino acids then treated with PDGF, and the nucleo-cytoplasmic distribution of the 3H-labelled proteins was analysed by autoradiography. There was no difference in the total amount of 3H-labelled proteins in PDGF-treated and untreated cells but PDGF induced a significant increase in intranuclear protein accumulation.

Animals↗
PubMed1984

Fluorescence polarization analysis of antigen determinant peptides of human fibrinogen.

Fluorescamine-labelled human fibrinogen was degraded with trypsin. Using fluorescence detection, the degradation products were fractionated by Sephadex G 50 gel filtration. Fragments of 3000-10 000 molecular weight were isolated for the fluorescence polarization studies. Specific antifibrinogen antibody increased the polarization of the isolated low molecular weight fragments. These results suggest that even the smallest proteolytic fragments of fibrinogen contain antigen determinant sequences. The fluorescence polarization method offers a sensitive and valuable approach for the analysis of the small antigenic peptides of human fibrinogen.

Epitopes↗
PubMed1984

Potassium retention in membraneless thymus lymphocyte nuclei.

Nonionic detergents, Triton X-100 and Brij 58, removed lipoid membranes of suspended thymus lymphocytes within 5 minutes. The mobilization and solubilization of cytoplasmic and nuclear proteins occurred much faster (less than 5 minutes) with Triton X-100 treatment than with Brij 58 treatment (less than 10 minutes). In Triton X-100 treated cells the loss of K+ was complete within 5 minutes whereas with Brij 58 treatment the K+ loss was not complete after 10 minutes. Thus, the high concentration of K+ and the low concentration of Na+ in the nuclei can remain near normal for minutes in the absence of membrane structures. If the ions were in free solution within the cells, disruption of membrane integrity should lead to equilibration of the ions with external media within seconds. The decrease of K+ in the Brij 58 treated cells with exposure time was correlated with the solubilization of the proteins. These results support the view that K+ and Na+ are not freely dissolved in the cellular water, but are co-compartmentalized with proteins inside the living cell.

Animals↗