Browsing by Subject "Cardiac"

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    The cytoskeleton in skeletal, cardiac and smooth muscle cells
    (F. Hernández y Juan F. Madrid. Universidad de Murcia. Departamento de Biología Celular e Histología, 1998) Stromer, M. H.
    The muscle cell cytoskeleton consists of proteins or structures whose primary function is to link, anchor or tether structural components inside the cell. Two important attributes of the cytoskeleton are strength of the various attachments and flexibility to accommodate the changes in cell geometry that occur during contraction. In striated muscle cells, extramyofibrillar and intramyofibrillar domains of the cytoskeleton have been identifi ed , Evidence of the extramyofibrillar cytoskeleton is seen at the cytoplasmic face of the sa rcolemma in striated muscle where vinculin- and dystrophin-rich costameres adjacent to sarcomeric Z lines anchor intermedi a te filaments that span from peripheral myofibrils to the sarcolemma. Intermediate filaments also link Z lines of adjacent myofibrils and may, in some muscles, link successive Z lines within a myofibril at the surface of the myofibril. The intramyofibrillar cytoskeletal domain includes elastic titin filaments from adjacent sarcomeres that are anchored in the Z line and continue through the M line at the center of the sa rcomere; inelastic nebulin filaments also anchored in the Z line and co-extensible with thin filaments; the Z line, which also anchors thin filaments from adjacent sarcomeres; and the M line, which forms bridges between the centers of adjacent thick filaments, In smooth muscle, the cytoskeleton includes adherens junctions at the cytoplasmic face of the sarcolemma, which a nchor B-actin filaments and intermediate filaments of the cytoskeleton, and dense bodies in the cytoplasm, which also anchor actin filaments and intermediate filaments and which may be the interface between cytoskeletal and contractile elements.
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    Ultrastructure of murine cardiac ganglia in experimental Chagas's disease
    (Murcia : F. Hernández, 1992) Wong, W. C.; Tan, C.K.; Singh, M.; Yick, T. Y.
    Albino mice, infected with Trypanosoma cruzi (Tulahuen strain) were sacrificed on days 7, 9, 12, 14, 16, 18, 21, 32 and 39 following infection. Transmission electron microscopic examination of the cardiac ganglia revealed no ultrastructural change at day 7. At day 9 there was peri- and intraganglionic monocytic infiltration but parasites were absent. Between days 12 and 16 there was intense monocytic infiltration, with intra-ganglionic presence of parasites within fibroblasts, monocytes and macrophages. None were seen within capsular cells, endothelial cells, Schwann cells, statellite cells and ganglion cells. The Schwann cells and satellite cells, however, showed phagocytic activity. Satellite cells were also reactive with proliferative pseudopodia which encircled neuronal processes. By day 18, parasites were absent in the ganglia. But monocytes were still present up to day 39, some of them still engulfing satellite cell and neuronal processes. Satellite cells continued to be reactive and Schwann cells phagocytic. Ganglion cells remained normal throughout the experiment.The results suggest that infection of Schwann cells, satellite cells and ganglion cells may depend upon the tissue tropism of the strain of the parasite used and its concentration in the inoculum. The results are consistent with the view that any parasympathetic dysfunction in experimental Chaga's disease in the mouse may be of a transient nature.