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  • 1
    Electronic Resource
    Electronic Resource
    Regulation of gamma-glutamyl transpeptidase and alkaline phosphatase activities in immortalized rat brain microvessel endothelial cells (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 159 (1994), S. 101-113 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rat brain microvessel endothelial cells were immortalized by transfection with a plasmid containing the E1A adenovirus gene. One clone, called RBE4, was further characterized. These cells display a nontransformed phenotype and express typical endothelial markers, Factor VIII-related antigen and Bandeiraea simplicifolia binding sites. When RBE4 cells were grown in the presence of bFGF and on collagen-coated dishes, confluent cultures developed sprouts that extend above the monolayer and organized into three-dimensional structures. The activity of the blood-brain barrier-associated enzyme, gamma-glutamyl transpeptidase (γGTP), was expressed in these structures, not in the surrounding monolayer. Similar results were obtained with the microvessel-related enzyme alkaline phosphatase (ALP). Addition of agents that elevate intracellular cAMP reduced the formation of three-dimensional structures, but every cell inside the aggregates still expressed γCTP and ALP activities. Such structures, associated with high levels of γCTP and ALP activities, were also induced by astroglial factors, including (1) plasma membranes from newborn rat primary astrocytes or rat glioma C6 cells, (2) C6 conditioned media, or (3) diffusible factors produced by primary astrocytes grown in the presence of, but not in contact with RBE4 cells. RBE4 cells thus remain sensitive to angiogenic and astroglial factors for the expression of the blood-brain barrier-related γCTP activity, as well as for ALP activity, and could constitute the basis of a valuable in vitro model of the blood-brain barrier. © 1994 wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041590114
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  • 2
    Electronic Resource
    Electronic Resource
    Programmed cell death (apoptosis) is induced rapidly and with positive cooperativity by activation of cyclic adenosine monophosphate-kinase I in a myeloid leukemia cell line (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 146 (1991), S. 73-80 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Programmed death (apoptosis) of the rat myelocytic leukemic cell line IPC-81 was triggered by cyclic adenosine monophosphate (cAMP) analogs or by agents (cholera toxin, prostaglandins) increasing the endogenous cAMP level. The induction of cell death by cholera toxin was preceded by increased activation of cAMP-kinase. Cell lysis started already 5 hr after cAMP challenge and was preceded by internucleosomal DNA fragmentation and morphological changes characteristic of apoptosis. The cell suicide could be prevented by inhibitors of macromolecular synthesis. cAMP analogs induced cell death in a positively cooperative manner (apparent Hill coefficient of 2.9), indicating that triggering of the apoptotic process was under stringent control. There was a strong synergism between cAMP analogs complementing each other in the activation of cAMP-dependent protein kinase I (cAKI). No such synergism was noted for analogs complementing each other in the activation of cAKII. It is concluded that apoptosis can be induced solely by activation of cAKI. The IPC-81 cells expressed about four times more cAKI than cAKII. The expression of cAK subunits, on the protein and mRNA levels, was only minimally affected by cholera toxin treatment.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041460110
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  • 3
    Electronic Resource
    Electronic Resource
    Nitric oxide and endothelin secretion by brain microvessel endothelial cells: Regulation by cyclic nucleotides (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 155 (1993), S. 104-111 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Endothelin (ET)-1 was originally characterized as a potent vasoconstrictor peptide secreted by vascular endothelial cells. It possesses a wide range of biological activities within the cardiovascular system and in other organs, including the brain. Also secreted by endothelial cells, nitric oxide (NO), has recently been identified as a relaxing factor, as well as a pleiotropic mediator, second messenger, immune defence molecule, and neurotransmitter. Most of the data concerning the secretion of these two agents in vitro has been collected from studies on macrovascular endothelial cells. Given the remarkable heterogeneity of endothelia in terms of morphology and function, we have analyzed the ability of brain microvessel endothelial cells in vitro to release ET-1 and NO, which, at the level of the blood-brain barrier, have perivascular astrocytes as potential targets. The present study was performed with immortalized rat brain microvessel endothelial cells, which display in culture a non transformed phenotype. Our data demonstrate that: (1) these cells release NO when induced by IFNγ and TNFα, (2) they constitutively secrete ET-1, and (3) cAMP potentiates the cytokine-induced NO release and exerts a biphasic regulation on ET-1 secretion: micromolar concentrations of 8-Br-cAMP inhibit and higher doses stimulate ET-1 secretion. This stimulation is blocked by EGTA and the calmodulin antagonist W7, but not by protein kinase C inhibitors, suggesting the involvement of the calmodulin branch of the calcium messenger system. These results suggest that cerebral microvessel endothelial cells may participate in vivo to the regulation of glial activity in the brain through the release of NO and ET-1. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041550114
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  • 4
    Electronic Resource
    Electronic Resource
    Microinjection of fluorescent brain tubulin reveals dynamic properties of cortical microtubules in living plant cells (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 24 (1993), S. 205-213 
    Details
    ISSN: 0886-1544
    Keywords: microtubule dynamics ; cell morphogenesis ; Nitella pseudoflabelatta ; plant cytoskeleton ; Tradescantia virginiana ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fluorescent brain tubulin, injected into living cells of the green alga Nitella pseudoflabellata and the higher plant Tradescantia virginiana, incorporates into the cortical microtubules, allowing these structures to be observed. With confocal laser scanning microscopy, clear images of microtubules were recorded and changes in microtubule patterns documented. After injection, fluorescent lengths of microtubules appeared within a few minutes and their number and length increased rapidly to a “steady state” over the first 15 min. In many instances, fluorescent microtubules could still be detected several hours after injection. In the cells examined, microtubules are arranged as an array of separate units only occasionally displaying close association or accurate co-alignment with neighboring microtubules. In what we perceive to be the steady state condition, some microtubules remain relatively static, while others undergo rapid changes in length or small translocations. We also document what appears to be bidirectional microtubule elongation during postdepolymerization assembly. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970240308
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  • 5
    Electronic Resource
    Electronic Resource
    Recent insights into the assembly, dynamics, and function of intermediate filament networks (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 19 (1991), S. 67-79 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970190202
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  • 6
    Electronic Resource
    Electronic Resource
    Switching of the dominant calcium sequestering protein during skeletal muscle differentiation (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 29 (1994), S. 259-270 
    Details
    ISSN: 0886-1544
    Keywords: calsequestrin ; calreticulin ; sarcoplasmic reticulum ; skeletal muscle ; myofibril ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A major Ca2+-storing protein in endoplasmic reticulum (ER) of non-muscle cells is calreticulin (CR), which is considered to be functionally homologous to calsequestrin. Calsequestrin is a Ca2+-binding protein in sarcoplasmic reticulum (SR) of striated muscle, which stores Ca2+ during muscle relaxation. In order to investigate the expression and distribution of calsequestrin and calreticulin during skeletal muscle differentiation, cultured chick embryonic skeletal muscles were observed by immunofluorescence using anti-calsequestrin, anti-calreticulin, antidesmin, and anti-sarcomeric myosin antibodies and rhodamine-phalloidin. Within 6 hours in culture, myoblasts started to express desmin. Desmin-positive cells demonstrated the reticular staining of calreticulin, as did desmin-negative cells. Around fusion, calsequestrin and sarcomeric myosin started to appear in desmin-positive cells. The expression of calsequestrin slightly preceded that of sarcomeric myosin. As the myotubes matured, the fluorescent dots of calsequestrin increased and spread to the cell periphery along the myofibrils, while the reticular pattern of calreticulin gradually disappeared. Double labeling showed that calsequestrin colocalized with calreticulin. In mature myotubes, anti-calsequestrin staining demonstrated many dots along myofibrils, whereas calreticulin was barely seen except at the perinuclear region. These results suggest that the expression of calsequestrin and calreticulin are switched during skeletal muscle differentiation. © 1994 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970290309
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  • 7
    Electronic Resource
    Electronic Resource
    Lung myofibroblasts (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 22 (1992), S. 92-98 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970220203
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  • 8
    Electronic Resource
    Electronic Resource
    An N-cadherin-like protein contributes to solute barrier maintenance in cultured endothelium (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 156 (1993), S. 610-618 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We investigated the role of cadherins in the solute barrier maintained by endothelial cells in vitro. Cell-column chromatographic measurement of endothelial barrier showed that reducing normal extracellular calcium from 1.2 to 0.12 mM increased endothelial permeability to 250% of baseline after 20 min. Restoring normal calcium restored the barrier within 15 min which remained stable for at least 60 min. We used sulfo-NHS-biotin and anti-cadherin antibodies to characterize endothelial proteins with possible roles in the maintenance of endothelial barrier. The non-specific probe sulfo-NHS-biotin identified at least ten endothelial cell surface proteins, with greatest labelling occurring at molecular weights of 125 and 145 kD. Six proteins, including the 125 and 145 kD proteins, associated with the cytoskeleton. Western blotting for the presence of classical cadherins containing the conserved cytoplasmic sequence CDPTAPPYDSLLVFDYEG detected two bands at 145 and 125 kD which associated with the cytoskeleton. Western blotting with an antibody, which recognizes FHLRAHAVDINGNQV, an extracellular homotypic binding region of N-cadherin, detects three bands. Of these three, one protein had a molecular weight of 125 kD and was associated with the cytoskeleton. Immunofluorescence with both N-cadherin and anti-peptide 1 antibodies found staining at endothelial cell borders. The utility of a newly developed cell-column calcium switch assay was tested by verifying the functional role of the previously described epithelial cadherin, uvomorulin, in epithelial barrier. We then applied this method to endothelial cell columns and found the N-cadherin antibody interfered with the reforming of interendothelial junctions. These results suggest that, as in epithelial cells, cadherins in bovine endothelial cells have a functional role in forming the calcium sensitive endothelial junction and may play an important role in the formation of normal barrier. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041560321
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  • 9
    Electronic Resource
    Electronic Resource
    Human Co115 colon carcinoma cells potentiate the degradation of laminin mediated by tissue-type plasminogen activator (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 161 (1994), S. 285-292 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The plasminogen activation (PA) system of human Co 115 colon carcinoma cells was investigated. Analysis at the levels of protein and mRNA of cultured cells and of histozymography of tumor xenografts in nude mice showed that Co 115 cells produce only tissue type PA (t-PA) and no urokinase (u-PA). Also, mRNA for the u-PA receptor and for PA inhibitorr type 2 (PAI-2), but not for PAI-I, were detected. We developed a quantitative degradation assay using glutaraldehyde-immobilized125I-Iaminin to investigate the capacity of Co 115 cells to degrade laminin. Laminin degradation by Co 115 cells was completely inhibited by 100 μg/ml of polyclonal anti-t-PA IgG, by the plasmin inhibitors aprotinin (100μg/ml) or ε-aminocaproic acid (EACA; at 0.3 M), but not by antibodies against u-PA or u-PAR nor by nonimmune IgG. Cycloheximide-treated Co 115 cells were unable to degrade laminin but increased laminin degradation induced by conditioned medium of Co 115 cells or recombinant t-PA. No potentiation was observed when Co 115 cells and laminin were kept separated by Transwell™ inserts. Our results suggest that Co 115 human colon carcinoma cells degrade laminin by potentiating t-PA-mediated plasminogen activaton at the cells surface which requires close contact between tumor cells and laminin substrate. © 1994 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041610213
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  • 10
    Electronic Resource
    Electronic Resource
    Organization of calsequestrin-positive sarcoplasmic reticulum in rat cardiomyocytes in culture (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 158 (1994), S. 87-96 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sarcoplasmic reticulum (SR) regulates the levels of cytoplasmic free Ca2+ ions in muscle cells. Calsequestrin is a major Ca2+ -storing protein and is localized at special sites in the SR. To investigate the development of calsequestrin-positive SR and its interaction with the cytoskeleton, we examined the distribution of calsequestrin in cultured cardiomyocytes from newborn rats by immunofluorescence with anticalsequestrin and antitubulin antibodies and rhodamine-phalloidin. In frozen sections of neonatal rat heart, anticalsequestrin immunostaining was apparent as cross-striations at Z-lines. When newborn cardiomyocytes were isolated, calsequestrin-positive SR was disorganized and was apparent as small vesicles beneath the sarcolemma, whereas myofibrils accumulated in the center of the cells. As the cells spread in culture, calsequestrin-positive vesicles spread to the periphery of the cytoplasm, becoming associated with the developing myofibrils. In mature cells, calsequestrin was closely associated with myofibrils, showing cross-striations at the Z-lines. Double-labeling using anticalsequestrin and antitubulin antibodies demonstrated that the distribution of calsequestrin-positive structures was similar to that of the microtubular arrays. When the microtubules were depolymerized by nocodazole at an early stage, the extension of the SR to the cell periphery was inhibited. In mature cardiomyocytes, nocodazole appeared not to affect the distribution of the SR. These results indicate that the calsequestrin-positive SR in cardiomyocytes is organized at the proper sites of myofibrils during myofibrillogenesis and that the microtubules might serve as tracts for the transport of components of the SR. © 1994 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041580112
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