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A H Dutton

Publications and source records attributed to A H Dutton.

13 recordsLinked to original sources
PubMed1990

Transfer of secretory proteins from the endoplasmic reticulum to the Golgi apparatus: discrimination between homologous and heterologous transfer in intact heterokaryons.

To examine aspects of the transfer of secretory proteins from the endoplasmic reticulum to the Golgi apparatus in situ, heterokaryons were formed between Hep G2 human hepatoma cells and WI-38 human fibroblasts. The cells were appropriately treated with cycloheximide before fusion, which emptied them of their respective secretory proteins, serum albumin for the Hep G2 cells and procollagen I for the WI-38 cells. After fusion was complete, the cycloheximide was washed out, protein synthesis was resumed, and the rates of reappearance of serum albumin and procollagen I in the two separated Golgi apparatuses within each heterokaryon were followed by immunofluorescence microscopy. Serum albumin was found to always reappear first in the Golgi apparatus contributed by the Hep G2 half of the heterokaryon, and procollagen I in the Golgi apparatus of the WI-38 half. These results suggest that the endoplasmic reticulum-to-Golgi apparatus transfer in situ is not simply a stochastic process but is either spatially restricted or exhibits cell-type specificity or both.

Carcinoma, Hepatocellular↗
PubMed1986

Occult malignancy presenting as acute fulminant hepatic failure.

Only six cases of hepatic metastatic disease presenting as acute fulminant liver failure have been recorded in the literature. A seventh case is reported here where, after presenting in acute liver failure, it was not possible to establish a tissue diagnosis but evidence of massive liver replacement by tumour was provided by ultrasound imaging and radionuclide scintiscanning.

Female↗
PubMed1984

An improved procedure for immunoelectron microscopy: ultrathin plastic embedding of immunolabeled ultrathin frozen sections.

Ultrathin frozen sections are ideal substrates with which to carry out immunolabeling experiments in electron microscopy. However, the ultrastructural delineation in positively stained frozen sections has not been as detailed as in conventionally osmium-stained and plastic-embedded sections. We now describe a simple technique in which immunolabeled ultrathin frozen sections are subsequently treated with osmium tetroxide, dehydrated, and then embedded in plastic by impregnation with a monomer to the thickness of the section, followed by polymerization of the monomer. By this technique ultrastructural definition as good as that of conventional plastic sections is achieved, while the high density and specificity of immunolabeling characteristic of ultrathin frozen sections are retained.

Animals↗
PubMed1983

Immunoelectron microscopic studies of desmin (skeletin) localization and intermediate filament organization in chicken skeletal muscle.

We studied the localization of desmin (skeletin), the major subunit of muscle-type intermediate filaments, by high resolution immunoelectron microscopy in adult chicken skeletal muscle. Immunoferritin labeling of ultrathin frozen sections of intact fixed sartorius muscle showed the presence of desmin between adjacent Z-bands and as strands peripheral to Z-bands, forming apparent connections between the Z-bands with adjacent sarcolemma, mitochondria, and nuclei. We observed no desmin labeling, however, in the vicinity of the T-tubules. In addition, intermediate filaments were morphologically discernible at the level of the Z-bands in plastic sections of glycerol-extracted muscle that had been infused with unlabeled antidesmin antibodies. Our results indicate that the desmin present in adult skeletal muscle, that had previously been detected by immunofluorescence light microscopy, is largely if not entirely in the form of intermediate filaments. The results provide evidence that these filaments serve to interconnect myofibrils at the level of their Z-bands, and to connect Z-bands with other specific structures and organelles in the myotube, but not with the T-tubule system.

Animals↗
PubMed1983

Immunoelectron microscopic studies of desmin (skeletin) localization and intermediate filament organization in chicken cardiac muscle.

We studied the localization of desmin (skeletin), the major protein subunit of muscle-type intermediate filaments, in adult chicken cardiac muscle by high resolution immunoelectron microscopic labeling of ultrathin frozen sections of the intact fixed tissues. We carried out single labeling for desmin and double labeling for both desmin and either vinculin or alpha-actinin. In areas removed from the intercalated disk membranes, we observed desmin labeling between adjacent Z-bands in every interfibrillar space. Where these spaces were wide and contained mitochondria, convoluted strands of desmin labeling bridged between the periphery of neighboring Z-bands and the mitochondria. The intermediate filaments appeared to be organized in a more three-dimensional manner within the interfibrillar spaces of cardiac as compared to skeletal muscle. Near the intercalated disks, desmin labeling was intense within the interfibrillar spaces, but was completely segregated from the microfilament attachment sites (fascia adherens) where vinculin and alpha-actinin were localized. Desmin therefore appears to play no role in the attachment of microfilaments to the intercalated disk membrane. We discuss the role of intermediate filaments in the organization of cardiac and skeletal striated muscle in the light of these and other results.

Actinin↗
PubMed1981

Ultrastructure of chicken cardiac muscle as studied by double immunolabeling in electron microscopy.

The ultrastructural localization of alpha-actinin and vinculin in chicken cardiac muscle was studied by double indirect immunoelectron microscopy, using ferritin and iron-dextran (Imposil) as the electron-dense markers conjugated to the secondary antibodies, on ultrathin frozen sections of fixed tissue. Fixation and immunolabeling procedures were developed that permitted maximal retention of the two proteins at their natural sites as well as their adequate labeling. alpha-Actinin was found both on the Z-bands, as expected, and near the fascia adherens of the intercalated discs, whereas vinculin was confined to the latter sites. At the fascia adherens, the double labeling results clearly showed that vinculin was situated closer to the membrane than was alpha-actinin. These results, coupled with earlier observations, suggest that vinculin may participate in the linkage of actin-containing microfilament bundles to membranes in a variety of cell types.

Actinin↗
PubMed1981

Immunoelectron microscope studies of membrane-microfilament interactions: distributions of alpha-actinin, tropomyosin, and vinculin in intestinal epithelial brush border and chicken gizzard smooth muscle cells.

The ultrastructural localization of three cytoskeletal proteins, alpha-actinin, tropomyosin, and vinculin, in the brush border of epithelial cells of chicken small intestine and the smooth muscle cells of chicken gizzard was studied by immunofluorescence and immunonelectron microscope labeling of frozen sections of lightly fixed, intact tissues. In the immunoelectron microscope studies, a recently described new type of electron-dense antibody conjugate, imposil-antibody, has been successfully used, along with ferritin-antibody conjugates, in single and double immunolabeling experiments. In the intestinal brush border shows that vinvulin is sharply confined to the junctional complex close to the membrane region of the zonula adherens, in distinct contrast to the more diffuse distributions of the other two proteins. In the smooth muscle cells, the labeling patterns show that vinculin is sharply confined to the membrane-associated dense plaques, closer to the membrane than the alpha-Actinin is also present in the cytoplastic dense bodies, from which vinculin is absent. Tropomyosin is present diffusely distributed in the cytoplasm, but absent from both dense plaques and dense bodies. These findings with the muscle cells demonstrate, therefore, that the dense plaques and dense bodies are chemically and structurally distinct entities. The results with both tissues, along with those in previous papers (Geiger, 1979, Cell. 18:193-205.; Geiger et al., 1980, Proc. Natl. Acad. Sci. U. S. A. 77:4127-4131), suggest that vinculin may play an important and widespread role in the linkage of actin-containing microfilament bundles to membranes.

Actinin↗
PubMed1980

Vinculin, an intracellular protein localized at specialized sites where microfilament bundles terminate at cell membranes.

As intracellular protein of 130,000 molecular weight was recently isolated in this laboratory from chicken gizzard smooth muscle. By immunofluorescence observations of cultured chicken fibroblasts, it was shown to be concentrated on the ventral surfaces of the cells where they formed focal adhesions to the substratum [Geiger, B. (1979) Cell 18, 193-205]. Focal adhesions are sites where, inside the fibroblast, microfilament bundles are known to terminate at the cell membrane. The suggestion was made that this new protein (herein named "vinculin") might be involved in the linkage of the termini of microfilament bundles to membranes in various cell types. To explore this possibility, in the present study we examined several chicken tissues, including intestinal epithelium, gizzard smooth muscle, and cardiac striated muscle, by immunoelectron microscopic labeling for vinculin on ultrathin frozen sections of the specimens. In each case, the immunolabeling for vinculin was concentrated close to membrane sites where microfilament bundles terminate: at the zonula adherens in the junctional complex of the brush border of epithelial cells; at the membrane-associated sense plaques of smooth cells; and at the fascia adherens of the intercalated disk membranes of cardiac muscle cells. These results suggest therefore that vinculin may participate in the anchoring of microfilament bundles to specific membrane sites in various cells.

Animals↗
PubMed1979

Iron-dextran antibody conjugates: General method for simultaneous staining of two components in high-resolution immunoelectron microscopy.

We report the preparation and properties of an electron-dense antibody conjugate, made by the covalent bonding of an iron-dextran (Imposil) particle to an antibody molecule. Transmission electron microscopic experiments with the Imposil-antibody conjugates demonstrate their suitability as specific immunostains at high resolution, particularly for simultaneous double staining experiments in conjunction with ferritin-antibody conjugates.

Journal Article↗