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Biomedical subjects

J Roth

Publications and source records attributed to J Roth.

At least 757 records · Page 42Linked to original sources
PubMed1976

[Properties of Masonite as phantom material].

The radiophysical properties of the material "Masonit" are examined by experimental methods. Indications are given as to atomic composition, density, effective atomic number, concentration of electrons, and linear attenuation coefficient. A comparison with water shows that "Masonit" is a suitable phantom material especially for the purposes of radiotherapy.

Health Physics↗
PubMed1975

The NSILA-s receptor in liver plasma membranes. Characterization and comparison with the insulin receptor.

NSILA-s (nonsuppressible insulin-like activity, soluble in acid ethanol) is a serum peptide that has insulin-like and growth-promoting activities. We have demonstrated previously that liver plasma membranes possess separate receptors for NSILA-s and insulin and have characterized the insulin receptor in detail. In the present study we have characterized the properties and specificity of the NSILA-s receptor and compared them to those of the insulin receptor in the same tissue. Both 125I-NSILA-s and 125I-insulin bind rapidly and reversibly to their receptors in liver membranes; maximal NSILA-s binding occurs at 20 degrees while maximal insulin binding is seen at 1-4 degrees. The pH optimum for NSILA-s binding is broad (6.0 to 8.0), in contrast to the very sharp pH optimum (7.5 to 8.0) for insulin binding. Both receptors exhibit a high degree of specificity. With the insulin receptor, NSILA-s and insulin analogues compete for binding in proportion to their insulin-like potency: insulin greater than proinsulin greater than NSILA-s. With the NSILA-s receptor, NSILA-s is most potent and the order is reversed: NSILA-s greater than proinsulin greater than insulin. Furthermore, six preparations of NSILA-s which varied 70-fold in biological activity competed for 125I-NSILA-s binding in order of their potencies. NSILA-s which had been inactivated biologically by reduction and aminoethylation and growth hormone were less than 1/100,000 as potent as the most purified NSILA-s preparation. Purified preparations of fibroblast growth factor, epidermal growth factor, nerve growth factor, and somatomedins B and C were less than 1% as effective as NSILA-s in competing for the 125I-NSILA-s suggesting that these factors act through other receptors. In contrast, somatomedin A was 10% as active as NSILA-s and multiplication-stimulating activity was fully as active as NSILA-s in competing for the NSILA-s receptor. Analysis of the data suggests that there are approximately 50 times more insulin receptors than NSILA-s receptors per liver cell, while the apparent affinity of NSILA-s receptors is somewhat higher than that of the insulin receptor.

Animals↗
PubMed1975

Electron microscopic demonstration of cell surface carbohydrates by means of peroxidase and ferritin complexes of the Lens culinaris lection.

The use of Lens culinaris lectin for electron microscopic detection of D-mannose,- D-glucose and N-acetyl-D-glucosamine like sites on tumor cells, erythrocytes, erythrocyte ghosts, cultured rat liver cells and various tissues of mice is demonstrated. In addition to Lens culinaris lectin-peroxidase reaction (LeL-po reaction) the preparation of active Lens culinaris lectin-ferritin conjugate are described and the specificity of cytochemical reactions are demonstrated. Furthermore experiments by immuno freeze-etching are reported for topological analysis of the lectin receptors.

Acetylglucosamine↗
PubMed1975

Ultrastructural detection of lectin receptors by cytochemical affinity reaction using mannan-iron complex.

A two-step affinity reaction is described for electron microscopic demonstration of the Concanavalin A as well as the Lens culinaris lectin receptors by means of the yeast mannan-iron complex. First the tissue was incubated in the lectin. Afterwards the incubation in the yeast mannan-iron complex was performed and reaction takes place between the still free second sugar binding site of membrane bound lectin molecules and the polysaccharides. This membrane receptor-lectin-polysaccharide complex is revealed by the electron dense iron core of the yeast mannan-iron complex. The specificity of the reactions could be demonstrated by addition of the hapten or by incubation in the yeast mannan-iron complex only. The proposed technique has proved useful for demonstration of lectin receptors in the small intestine.

Animals↗
PubMed1975

[Studies on the Concanavalin A-receptors of rabbit erythrocytes and of erythyrocyte shadows using immunoelectron microscopy].

The authors report on the immuno electron microscopic demonstration of Concanavalin A-receptors on the erythrocyte membrane. Immuno freeze-etching studies evidenced a focal arrangement of Concanavalin A-receptors on intact erythrocytes as well as on erythrocyte ghosts. Obviously hemolysis by distilled water does not produce changes in the pattern of distribution of Concanavalin A-receptors whereas slight aggregation of plasma membrane intramembraneous particles occured. No unambigous spatial relationship between Concanavalin A-receptors and the plasma membrane intramembraneous particles (intrinsic proteins) of erythrocytes could be observed.

Animals↗
PubMed1975

Electron microscopic demonstration of a saccharide moieties in the hypophase of the alveolar surfactant system.

For electron microscopic demonstration of complex carbohydrates and simple sugars in the mouse lung, anionic dye and lectins were used. After immersion fixation of small lung tissue blocks, the alveolar surfactant system was destroyed and only membrane bound carbohydrates (cell coat) could be demonstrated by means of colloidal iron and ruthenium red. Fixation of the whole lung via the visceral pleura preserved the alveolar surfactant system. Only this technique afforded a distinction between cell coat components and hypophase components. After performance of the Concanavalin A-peroxidase technique and after incubation in ferritin-labed Concanavalin A, Lens culinaris lectin or Ricinus communis lectin, various saccharide moieties were demonstrable by immune electron microscopy in the hypophase of the alveolar surfactant system.

Animals↗
PubMed1975

Concanavalin A receptors in the plasma membrane of rat liver cells: comparative electron microscopic studies on normal cells and on cells in vivo transformed by diethylnitrosamine.

The Concanavalin A receptors at the cell surface of normal rat liver cells and of those in vivo transformed by diethylnitrosamine were comparatively studied by electron microscopic cytochemistry. Besides different agglutinability of the cells a variable surface staining of the cells by the Con A-peroxidase reaction (BERNHARD and AVRAMEAS 1971) was observed. After performance of the cytochemical reaction on living normal rat liver cells in situ a continuous cell surface staining was seen. In transformed rat liver cells a marked tendency for patchy distribution of the Con A label at the cell surface occurred. Furthermore, internalisation of Con A-peroxidase labeled plasma membrane segments was visible in the transformed cells. A similar variable labeling by Con A-peroxidase reaction occured also in the "basal" plasma membrane of normal and transformed rat liver cells. The results are discussed with respect to the importance concerning the mobility of lectin receptors and membrane stability.

Animals↗
PubMed1975

Interaction of Lens culinaris lectin, concanavalin A, Ricinus communis agglutinin and wheat germ agglutinin with the cell surface of normal and transformed rat liver cells.

The observation of BOREK et al. (1973) on nonagglutinability of transformed rat liver cells by Lens culinaris lectin and our ultrastructural findings of a greater mobility of the Lens culinaris lectin receptors on transformed rat liver cells as compared to normal rat liver cells (ROTH 1975) initiated the present agglutination experiments on liver cells with lectins. For agglutination assay the microhemadsorption technique after FURMANSKI et al. (1973) was used with exception of several tests on EDTA-detached cells. The transformed rat liver cells exhibited, in contrast to the findings of BOREK et al. (1973), a positive microhemadsorption with Lens culinaris lectin as well as with Concanavalin A, Ricinus communis lectin and wheat germ agglutinin whereas the normal rat liver cells became positive only after a brief trypsin treatment. The significance of the difference in agglutinability of rat liver cells with Lens culinaris lectin and the other lectins used is discussed with regard to the cell-cell interaction mediated by lectins.

Agglutination Tests↗
PubMed1975

Lens culinaris lectin receptors in the plasma membrane of rat liver cells: comparative electron microscopic studies on normal cells, on cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells.

The distribution of the Lens culinaris lectin receptors on normal rat liver cells, on rat liver cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells of the rat is investigated by means of the Lens culinaris lectin-peroxidase method and by ferritin conjugated Lens culinaris lectin. The normal rat liver cells show a continuous labeling at the outer membrane surface by the lectin complexes, whereas the transformed rat liver cells exhibit a strong tendency for patchy distribution of the cell surface label. The discontinuous cell surface label in the transformed rat liver cells is obviously caused by an internalization of plasma membrane areas. The importance of these morphological findings in their relationship to Lens culinaris lectin mediated agglutination of rat liver cells and the membrane fluidity in general are discussed. In the experiments no hints to a rotation of the Lens culinaris lectin receptors from the outer membrane surface to the inner membrane surface of rat liver cells can be found.

Animals↗
PubMed1975

The use of fluorescein isothiocyanate labelled lectins for immunohistochemical demonstration of saccharides.

Cryostat sections of various tissues from man, rat, mice, hamster, rabbit, guinea pig, sparrow and carp were examined by fluorescence microscopy after incubation with fluorescein isothiocyanate labelled Concanavalin A and Lens culinaris lectin. In the same tissue of various species no basic differences in the pattern of fluorescence were observed. In general, connective tissue structures were stained by both lectins in the same degree, whereas by fluorescein isothiocyanate labelled Concanavalin A additionally a varying staining of the cell surface and of cytoplasmic structures occurred. The results show the general presence of Concanavalin A and Lens culinaris lectin receptors in normal animal tissues.

Animals↗
PubMed1975

Wheat germ agglutinin and Ticinus communis agglutinin as specific saccharide stains in light and electron microscopy.

Two plant agglutinins, wheat germ agglutinin and Ricinus communis agglutinin, were used for light and electron microscopic detection of certain carbohydrate-containing cell surface components and extracellular polysaccharides. For light microscopic studies on various tissues fluorescein isothiocyanate coupled lectins were prepared. The ferritin coupling of the lectins for electron microscopy was performed by glutarldehyde in the presence of the specific hapten. The specificity of the reactions was demonstrated by blocking with the hapten.

Antibody Formation↗
PubMed1975

Concanavalin A receptors on normal rat liver cells, on rat liver cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells of the rat: morphokinetic analysis of cell surface dynamics.

Comparative electron microscopic investigations were performed in living cultures of normal rat liver cells, of rat liver cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells of the rat concerning the mobility of the Concanavalin A cell surface receptors. The cells were incubated in Concanavalin A and peroxidase and subsequently washed. They were then reincubated for various periods at +37 degrees C in PBS prior to fixation. In the case of the Zajdela ascites hepatoma cells the cells were reincubated after Concanavalin A incubation followed by fixation and peroxidase incubation. The cytochemical procedure allowed us to show differences in the mobility of Concanavalin A surface receptors between normal and transformed rat liver cells. The cell surface label disappeared completely within 15 min of reincubation in the transformed cells, whereas in normal cells the same degree of loss in surface label was visible after 120 min reincubation. In both cases an internalization of labelled plasma membrane areas occurred. After complete disappearance of cell surface label in diethylnitrosamine transformed cells a complete relabelling of the cell surface occurred after 60 min reincubation caused by an exocytosis.

Animals↗