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Biomedical subjects

D Schubert

Publications and source records attributed to D Schubert.

At least 19 recordsLinked to original sources
PubMed1979

Modulation of protein synthesis by nerve growth factor.

The effects of nerve growth factor (NGF) and two analogs of cAMP have been studied in the PC12 line of rat pheochromocytoma cells. We have used two-dimensional gel electrophoresis to detect more than 800 proteins from control and NGF-treated cells. Of these proteins, none were qualitatively repressed in response to NGF, and no new proteins appeared after NGF treatment. Visual inspection of the gels showed that approximately 5% of the proteins were detectably increased or decreased in rate of synthesis by NGF, and each of these changes was mimicked by both cAMP analogs. The two-dimensional gel data were further analyzed by a computerized scanning system. This analysis has revealed many significant changes that are smaller than those detected by eye. Approximately 25 to 30% of the proteins analyzed were found to be altered in rate of synthesis by 30% or more. Statistical analysis has shown that the response to NGF and the response to dibutyryl cAMP are highly correlated, even down to changes as small as 30%. No proteins were found to be significantly altered by both dibutyryl cAMP and 8-bromo cAMP, but not by NGF. These results show that NGF causes only quantitative modulations of protein synthesis in PC12 cells, and these data strongly suggest that the response of PC12 cells to NGF is mediated by cAMP.

Animals↗
PubMed1979

Interactions of band 3-protein from human erythrocyte membranes with cholesterol and cholesterol analogues.

The interaction between cholesterol and band 3-protein from human erythrocyte membranes was studied by incorporating the solubilized protein into monolayers of cholesterol and related sterols at the air-water interface and measuring the changes in surface pressure which accompanied protein incorporation. The following results were obtained: 1) Band 3-protein shows a very strong interaction with cholesterol monolayers. Both apolar and polar bonds contribute to this interaction. 2) Steroids with a structure slightly different from that of cholesterol (especially with respect to the polar group and the side chain) in most cases show a reduced affinity for band 3-protein. Thus, the protein-sterol interaction is highly specific. It is assumed that the protein-cholesterol interaction can be subidivided into two parts: an unspecific one which results from contributions from several sterol molecules, and a specific one which is due to the high affinity binding of the protein and cholesterol. The structural element responsible for the high affinity interaction is assumed to be a sterol-binding niche on the surface of band 3-protein. The sterol is thought to be held in the niche by a hydrogen bond at its polar head and a variety of hydrophobic bonds along its ring system and side chain.

Cholesterol↗
PubMed1979

Self-association of band-protein from human erythrocyte membranes in aqueous solutions.

Band 3, the main integral protein of the human erythrocyte membrane, was solubilized and purified in high concentrations of acetic acid. After removal of the organic solvent by dialysis, the self-association of the protein in aqueous solutions was studied by analytical ultracentrifugation. Sedimentation velocity and sedimentation equilibrium experiments clearly demonstrate that, under appropriate conditions of protein preparation, at protein concentrations c less than 200 micrograms/ml, ionic strengths 2 less than 10mM and pH values remote from the isoelectric pH of the protein, band 3 shows a monomer/dimer/tetramer-association equilibrium. With some preparations, as well as at higher values of c or I, hexamers and octamers contribute to the association equilibrium. The time needed for relaxation towards association equilibrium depends on the blood donor from whom the membranes were derived and varies between less than one minute and more than several hours. The results of analytical ultracentriguation, together with previously published data on the incorporation of band 3 into planar lipid bilayers, from chemical crosslinking and from electronmicroscopy suggest that band 3 will also show a monomer/dimer/tetramer-association equilibrium in the human erythrocyte membrane. This hypothesis contrasts the widely-held assumption that, in the membrane, band 3 is a stable dimer; however, it is consistent with nearly all known data on band 3-self-association.

Erythrocyte Membrane↗
PubMed1978

[Automated information processing of systolic time intervals].

The revalorization of the systolic time intervals in clincial and experimental cardiology is described on the basis of informations from literature and own experiences. Concerning the method of work the systolic time intervals have reached a limit which can be overcome only be automatized information processing. It is reported on principles and problems of the automatized information processing of systolic time intervals and an own development is described (HTME 101).

Electrocardiography↗
PubMed1978

Biology of cultured nerve and muscle.

Cells from the nervous system can be grown in culture and exhibit many of the biophysical, biochemical, and morphological properties found in vivo. They can be induced to differentiate in culture and perform some of the interactions that occur in the nervous system, including synaptogenesis. A number of important questions relating to nervous system development and function have been approached in culture in ways that cannot be done in vivo. The use of clonal cell lines should lead to rapid progress in the analysis of the nervous system at the chemical level.

Acetylcholine↗
PubMed1978

Social class and psychiatric diagnosis: differential findings in a lower-class sample.

Social class and the American Psychiatric Association Diagnostic and Statistical Manual II Diagnosis were examined for all patients contracting the Department of Psychiatry over a year at a large county hospital. This sample was primarily lower class -50 per cent Class V and 33 per cent in Class IV. All diagnoses showed average class between IV and V. Organic brain syndrome, both psychiatric and non-psychotic, and mental retardation had lower average social class than other diagnoses. A small sample of the diagnosis behaviour disorder of childhood and adolescence was also lower than other diagnoses. Class V patients with mental malfunction may present differently than patients from other social classes. The absence of differences on neurosis and functional psychosis may have been due to the predominance of lower class patients, diagnosticians more familiar with lower class patients, or the allowable choice of diagnoses.

Adolescent↗
PubMed1978

A new method for the preparation of band 3, the main integral protein of the human erythrocyte membrane.

Band-3 protein from human erythrocyte membranes was isolated, without using detergents, by a two-step procedure: (1) The peripheral proteins were removed from the membrane by treatment with 10% acetic acid. (2) The remaining lipoprotein complex was solubilized in approximately 92% (v/v) acetic acid and then separated into its components by preparative zonal electrophoresis in a gradient made up of acetic acid, water and sucrose. Band 3 was recovered from the gradient at a yield of 60 - 70% and purity of about 95%. Approximately 25 mg of band 3 could be prepared in one run. The protein is soluble in aqueous solutions, even in the absence of organic solvents or detergents. In addition to band 3, the proteins stained by periodic acid/Schiff's reagent (the sialoglycoproteins) are also separated from the other proteins.

Acetates↗
PubMed1977

The substrate attached material synthesized by clonal cell lines of nerve, glia, and muscle.

A large number of clonal cell lines were examined for the deposition of proteins (substrate attached material, SAM) on the substratum of culture dishes. Of the many cell types examined, only nerve, muscle, and glia synthesized SAM containing a predominant species of protein with a apparent molecular weight of 55,000. This 55,000 molecular weight protein is distinguishable from actin, tubulin, and collagen.

Actins↗
PubMed1977

Storage and release of acetylcholine by a clonal cell line.

The nerve cell line PC12, in its morphologically undifferentiated state, synthesizes, stores, and secretes catecholamines and acetylcholine. At least 60% of the basal level of neurotransmitter release is due to a calcium-dependent mechanism, and the rate of secretion is enhanced by increasing external potassium. A minimum of 80% of the intracellular acetylcholine and catecholamines are stored in particulate structures. The storage site for acetylcholine is dense core vesicles that can be distinguished from those containing catecholamines on the basis of vesicle density on sucrose gradients, vesicle size, and reserpine sensitivity. These results are discussed in relation to what are thought to be the early stages of synapse formation in cell culture.

Acetylcholine↗
PubMed1977

Cholinergic metabolism and synapse formation by a rat nerve cell line.

The PC12 clone of a rat pheochromocytoma is able to synthesize acetylcholine. The amount of acetylcholine synthesized, and the specific activity of choline O-acetyltransferase (acetyl-CoA:choline O-acetyltransferase, EC 2.3.1.6), varies as a function of the culture growth curve and is dependent on cell density. The specific activity of choline acetyltransferase is increased by nerve growth factor, growth-conditioned medium from a variety of cell types, and adenosine 3':5'-monophosphate. Finally, the PC12 cell line is able to form cholinergic synapses with a clonal cell line of skeletal muscle origin.

Acetylcholine↗