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  • 1
    Digitale Medien
    Digitale Medien
    Regulation of transferrin receptor expression in concanavalin a stimulated and gross virus transformed rat lymphoblasts (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 113 (1982), S. 40-46 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Expression of the cell surface receptor for the serum glycoprotein transferrin has been correlated with cellular proliferation in normal lymphocytes undergoing mitogen or antigen induced proliferative responses. In the present study, the expression of transferrin receptor in Concanavalin A stimulated rat lymphocytes or Gross virus transformed lymphoma cells has been examined with respect to the following questions: (1) is expression of receptor activity related to blastogenesis or to the subsequent IL-2 dependent DNA synthetic activity, and (2) is transferrin receptor expression regulated in similar fashion in both normal and malignant lymphoblasts? Scatchard analysis of saturation binding data illustrated that binding site number increased and subsequently decreased during the response while the receptor affinity for transferrin remained constant. These findings were confirmed by SDS-polyacrylamide gel electrophoretic analysis of radiolabeled cell surface proteins which specifically interact with transferrin. Examination of nonproliferating normal lymphoblasts (96 hr post Con A stimulation) compared with the same population of cells stimulated to reinitiate DNA synthesis with a partially purified preparation of Interleukin 2 (IL-2) showed that transferrin receptor expression was tightly linked to the IL-2 dependent stimulation of DNA replication. This coordinate regulation of receptor expression was markedly less stringent in retrovirus transformed thymic lymphoma cells.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041130109
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  • 2
    Digitale Medien
    Digitale Medien
    Receptor-mediated endocytosis and exocytosis of transferrin in concanavalin A-stimulated rat lymphoblasts (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 114 (1983), S. 222-228 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Iron-loaded transferrin has been shown to be necessary for the support of cell proliferation in culture. This function depends upon interaction of transferrin with a specific high-affinity cell surface receptor. The present report is directed toward determining the consequences of the interaction of transferrin with this receptor on Concanavalin A-stimulated rat lymphocytes. Three specific questions have been posed: (a) Is transferrin endocytosed following binding to its specific receptor in a temperature-dependent fashion? (b) Following endocytosis, is the carrier protein released from the cell in a structurally and functionally intact form? and (c) Is the cell surface transferrin receptor also endocytosed following ligand binding? The results provide affirmative answers to all questions. Using two independent probes of the cell surface versus intracellular location of transferrin we observed that cell-bound transferrin moved from the cell surface to the inside of the cell and subsequently back to the medium. This process occurred in a temperature-dependent fashion. When cells containing only intracellular transferrin were further incubated at 37°C approximately 80% of cell-bound transferrin was released to the medium. Nearly all of this material retained reactivity with antibody to transferrin. In addition, exocytosed transferrin exhibited qualitatively and quantitatively equivalent binding reactivity with the transferrin receptor and showed identical electophoretic mobility on SDS gel electrophoresis. Finally, using similar methodology to that employed with transferrin itself, we provide evidence that the specific receptor is also endocytosed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041140212
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  • 3
    Digitale Medien
    Digitale Medien
    Developing innervation of the chick heart: A histofluorescence and light microscopic study of sympathetic innervation (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 196 (1980), S. 333-340 
    Details
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The available descriptions of the development of sympathetic innervation of the chick heart conflict with the known sympathetic innervation of the adult chicken heart. The adult heart is innervated by bilateral sympathetic cardiac nerves originating from the first thoracic sympathetic ganglia. These nerves travel lateral and anterior to the lung and join the vagi just before entering the pericardium along the great vessels. Using catecholamine histofluorescence techniques and silver preparations, we have observed the development of the sympathetic cardiac nerves. The sympathetic cardiac nerves arise from the first thoracic sympathetic ganglia on the 7th day of incubation. They grow lateral and then ventral to the developing lungs to join the vagi, and are found in the bulbar region of the heart and atrium on the 10th day of incubation. Fluorescent cells without processes mark the course of the sympathetic cardiac nerves and are present in the bulbar region on the 10th day and thereafter. Sympathetic ganglion cells lose their fluorescence between day 8 and day 16 of incubation. This is presumably due to dilution of the transmitter in the rapidly increasing volume of cytoplasm in the sprouting neurons. Small intensely fluorescent (SIF) and adrenal medullary cells do not undergo a diminution of fluorescence during this period. SIF cells appear well differentiated at 16 days.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ar.1091960309
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  • 4
    Digitale Medien
    Digitale Medien
    A quantitative morphological analysis of interatrial muscle cells in the ferret heart (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 201 (1981), S. 31-42 
    Details
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Cells located in the interatrial septum of the ferret heart were examined and mean cell volume, surface area, length, width, as well as cell length/width and surface area/volume ratios were obtained. The muscle cells were from two different regions. One region was the area of the middle internodal tract while the other was from the area where the anterior and middle internodal tracts intermingled. Based on the data obtained, at least two different subpopulations of interatrial muscle cells could be defined. The larger cells had a mean cell length of 109.7 μm, a mean cell width of 13.1 μm, a length/width ratio of 8.61, a mean cell surface area of 5,057.6 μm2, a mean cell volume of 5960.8 μm3, and a surface area/volume ratio of 0.87. The smaller cells had a mean cell length of 58.0 μm, a mean cell width of 12.2 μm, a length/width ratio of 4.85, a mean cell surface area of 2494.1 μm2, a mean cell volume of 2553.6 μm3, and a surface area/volume ratio of 1.00. The large cell population had cells that were myofibril rich and also others that were myofibril poor. These quantitative data indicate that the regions of internodal pathways are not composed of a single specialized cell type, but rather are composed of at least two, if not more, cell types that intermingle with each other.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ar.1092010105
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  • 5
    Digitale Medien
    Digitale Medien
    Early morphological alterations of pressure-overloaded cat right ventricular myocardium (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 207 (1983), S. 417-426 
    Details
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Pressure overload of the right ventricle results in an increase in ventricular mass. It also results in abnormal in vitro contractile function in advance of the onset of congestive heart failure as determined in papillary muscles removed from these ventricles. To correlate these functional abnormalities with any early underlying morphological changes, a band was placed around the proximal pulmonary artery of cats. This band restricted the lumen to 20% of normal and was left in place for 2 weeks. At that time, hemodynamic variables were measured to insure that right ventricular pressure overload had been produced. The hearts were then perfusion fixed, and papillary muscles from the right ventricle were prepared for light and transmission electron microscopy. Quantitative morphological data were obtained for the volume density both of several tissue components and of several organelles. It was found that there are significant increases in myocyte cross-sectional area and diameter in hypertrophied tissue with a concurrent increase in the volume density of interstitial tissue. There are no alterations in the volume density of organelles in the hypertrophied myocytes. We suggest that the substantial increase in the proportion of connective tissue and the decrease in the surface area to volume ratio that accompany pressure overload cardiac hypertrophy may be early underlying structural changes that relate directly to the abnormal contractile function found in this type of hypertrophy.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ar.1092070304
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  • 6
    Digitale Medien
    Digitale Medien
    The use of computer imaging techniques to visualize cardiac muscle cells in three dimensions (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 198 (1980), S. 537-546 
    Details
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Atrial muscle cells and atrioventricular bundle cells were reconstructed using a computer-assisted three-dimensional reconstruction system. This reconstruction technique permitted these cells to be viewed from any direction. The cell surfaces were approximated using triangular tiles, and this optimization technique for cell reconstruction allowed for the computation of cell surface area and cell volume. A transparent mode is described which enables the investigator to examine internal cellular features such as the shape and location of the nucleus. In addition, more than one cell can be displayed simultaneously, and, therefore, spatial relationships are preserved and intercellular relationships viewed directly. The use of computer imaging techniques allows for a more complete collection of quantitative morphological data and also the visualization of the morphological information gathered.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ar.1091980314
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  • 7
    Digitale Medien
    Digitale Medien
    The ultrastructure of the atrioventricular junctional tissues in the newborn ferret heart (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 161 (1981), S. 383-392 
    Details
    ISSN: 0002-9106
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: In this study the structure of the atrioventricular (AV) node and bundle in the newborn ferret heart was examined by light and electron microscopy. At the light microscopic level the AV node could be subdivided into deep and superficial portions. Electron microscopy revealed that both superficial and deep AV nodal cells were characterized by a paucity of myofibrils, desmosomes, fasciae adherentes and gap junctions. Deep AV nodal cells, however, had more surface specializations than did superficial AV nodal cells. In both subdivisions the constituent cells were ellipsoid with tapering end-processes. In contrast to the nodal cells, the newborn AV bundle cells were round to ovoid. The AV bundle cells were organized into large fascicles, and there was a high frequency of anastomosing intercommunication between fascicles. These bundle cells had few myofibrils and a high incidence of apposed plasma membrane. The present morphological findings support the concept that there are significant postnatal morphological changes that occur in the region of the AV junction. These results are also consistent with findings in other species that AV nodal conduction time is similar in newborns and adults, while conduction through the AV bundle increases with age.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1001610404
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  • 8
    Digitale Medien
    Digitale Medien
    A scanning electron microscopic study of the ferret atrioventricular node (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 158 (1980), S. 345-353 
    Details
    ISSN: 0002-9106
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The atrioventricular (AV) node and surrounding transitional zone in the ferret heart were examined with scanning electron microscopy. This permitted the direct visualization of the three-dimensional cell shape, as well as intercellular relationships. Transitional cells were roughly cylindrical with extensively branching end processes. These cells were apposed to many adjacent transitional cells. The superficial AV nodal cells were smaller than transitional cells and were fusiform in shape. Most of the cell contacts between superficial AV nodal cells were between overlapping end processes, and there was very little branching of these cells. The deep AV nodal cells were similar to the superficial AV nodal cells, but were slightly larger and also had more cell contacts with adjacent cells. The possible significance of cell size and shape and intercellular relationships as they relate to atrioventricular impulse propagation and AV nodal delay are discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1001580308
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  • 9
    Digitale Medien
    Digitale Medien
    The early development of the AV node and bundle in the ferret heart (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 167 (1983), S. 299-312 
    Details
    ISSN: 0002-9106
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The development of the atrioventricular (AV) junctional tissues in the ferret embryonic heart was studied on days 16, 18, and 21 of gestation. This important region of the heart was examined with PAS and toluidine-blue staining at the light microscope level and with transmission electron microscopy at the ultrastructural level. By day 16 of gestation the ferret heart was in the initial stages of convolution. The heart was at the primitive four-chamber stage by 18 days postcoitum. On day 21 of gestation the heart was in the process of being septated. The AV nodal primordia were first observed as two clusters of cells in the dorsal wall of the common atrium of the 16 day ferret embryo heart. These nodal primordial cells were morphologically different from working myocardial cells or cells of the AV canal. The AV canal cells were particularly numerous in the dorsal wall of the canal and eventually gave rise to the AV bundle in this region. On day 18 of gestation the morphological differences between the AV nodal, AV canal, and myocardial cells were readily apparent. By 21 days postcoitum, the AV node with its two regions had reached its definitive anatomic position. The AV bundle was also present in its normal adult location. The AV nodal cells were distinctly different when compared to the ventricular or atrial myocytes at this stage in development. In addition, the AV bundle cells were morphologically different from the AV nodal cells and working myocardial cells. A discussion of these findings relates this information to current descriptions of how the AV node and bundle develop.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1001670303
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  • 10
    Digitale Medien
    Digitale Medien
    Binding of isolated 3T3 surface membranes to growing 3T3 cells and their effect on cell growth (1982)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 20 (1982), S. 81-93 
    Details
    ISSN: 0730-2312
    Schlagwort(e): 3T3 cells ; 3T3 surface membranes ; growth inhibition ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: We have quantitated by autoradiography the binding of [125I]labeled 3T3 plasma membrane fragments to 3T3 cells growing on the surface of plastic dishes; ie, the same conditions in which these membranes specifically arrest the growth of 3T3 cells early in the G1 phase of the cell cycle. We have been able to demonstrate that binding of membranes to cells is coincidental with the expression of the growth inhibitory activity of protein(s) present in the membrane fragments. Treatments that reduce binding (heat denaturation of the membranes or culture in the presence of high scrum) also reduce growth inhibitory activity. [125I]labeled membranes bound to cells are located primarily on the cell surface (as determined by electron microscope autoradiography) and are exchangeable with unlabeled membranes. We conclude that binding of membranes to cells is necessary but may not be sufficient for the expression of the growth inhibitory activity of these membranes. This approach provides information not only on the average level of binding of membranes to cells, but also provides a quantitative assessment of the variation of the level of membrane to cell binding between different cells in the population.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcb.240200109
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