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  • 1975-1979  (7)
  • Cell & Developmental Biology  (4)
  • Molecular Cell Biology  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Transport enhancement and reversal: Glucose and 3-O-methyl glucose (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 91 (1977), S. 155-168 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In chick embryo fibroblast cultures the 15- to 30-fold enhancement of D-glucose uptake observed when cells are starved of glucose for 24 hours is not duplicated for derivatives of glucose that compete effectively for uptake and have generally been considered to use the same carrier. 2-deoxy-D-glucose, D-mannose, D-galactose and D-glucosamine are derepressed progressively less sharply in that order with glucosamine uptake never more than doubled by starvation. D-glucose at a concentration of 5.5 mM in the 24-hour conditioning medium is a strong “repressor” resulting in low “transport” behavior for each of the five sugars cited. D-glucosamine is equally effective at the same concentration. A 10-fold reduction in the concentration of glucosamine (0.55 mM) allows for the escape from repression of mannose, glucose, and deoxyglucose uptake while the others remain repressed. Mannose uptake escapes as well when the glucose concentration in the “conditioning” medium is similarly reduced.Under certain conditions of starvation and cell density dramatic effects of supplemental stimulation by insulin can be achieved. Insulin withdrawal interrupts the supplemental stimulation process. Cycloheximide, actinomycin D and cordycepin block both non-insulin and insulin-induced derepression. Short exposure (15-30 minutes) of 24-hour starved cells to glucose (5.5 mM) reduces glucose sharply but does not affect 3-O-methyl glucose uptake. If the exposure is to 2-deoxyglucose (5.5 mM) further derepression of glucose uptake results.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040910202
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  • 2
    Electronic Resource
    Electronic Resource
    Observations on the development of the human atrioventricular node and bundleSupported by N.I.H. Grant HL07047. (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 192 (1978), S. 337-350 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This light microscopic study of the cardiac junctional tissues was based on 27 human embryos, fetuses and postnatal hearts. Evidence was presented that superficial and deep portions of the postnatal AV node were derived from two cellular primordia in the posterior wall of the common atrium at the 6-mm stage. The small right primordia was associated with the right venous valve and gave rise to the loosely organized superficial AV node that extended posteriorly to the coronary sinus ostium. A larger left primordia formed the more compact deep subdivision of the AV node located against the anulus fibrosus. In most postnatal hearts the two subdivisions are partially or completely fused to form the adult AV node. Failure of the nodal primordia to fuse during cardiogenesis may result in two separate nodal cell aggregates above the anulus. The present observations provide a rational explanation for the two AV nodal masses described in the literature and an additional specimen that is illustrated in this communication.An AV bundle was first identified in a 13-mm embryo and appeared to be derived from large clear cells of the posterior AV canal. At 25 mm the bundle formed a broad band across the top of the IV septum and continued into both ventricles. At this stage multiple cell strands penetrated the endocardial cushion to connect the AV bundle to the two nodal primordia. Failure of normal fusion between the AV node primordia and AV bundle can result in a variety of junctional anomalies including congenital heart block.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091920302
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  • 3
    Electronic Resource
    Electronic Resource
    The development of the atrioventricular node and bundle in the ferret heartThis work is supported by N.I.H. Grant HL07047. (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 135-150 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The development of the atrioventricular (AV) node and bundle in the ferret heart was examined at the light microscopic level. The AV node develops from two primordia which were first observed in the posterior wall of the common atrium during the stage when the single heart tube convolutes. During septation of the heart, the AV nodal primordia eventually fuse and come to lie at the base of the interatrial septum. The right AV nodal primordium is located below the attachment of the right venous valve to the interatrial septum. The left AV nodal primordium maintains a position anterior to the prospective ostium of the coronary sinus. At 16 days of gestation, large pale cells were seen in the dorsal AV canal. By 21 days of gestation these AV canal cells have been replaced by AV bundle cells. At this time the bundle is continuous with both nodal primordia. At birth the AV bundle is continuous mainly with the component of the AV node that is derived from the right AV node primordium. The anulus fibrosus begins to undergo the greatest developmental change after the AV node and bundle attain their final position in the AV junction. However, the anulus does not completely separate the atria from the ventricles during the later stages of development nor at birth, so that accessory AV pathways are present in the newborn ferret heart. Both the AV node and the AV bundle also demonstrated continuity with the myocardial cells of the interventricular septum in the neonatal heart. During development there was no evidence that rings of specialized tissues at the junctions of the cardiac chambers give rise to any component of the cardiac conduction system.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001540202
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  • 4
    Electronic Resource
    Electronic Resource
    The atrioventricular node and bundle in the ferret heart: A light and quantitative electron microscopic studyThis work was supported in part by N.I.H. grants HL07047, HL19425, HL19606, CA08231. (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 154 (1979), S. 365-391 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The cells of the atrioventricular (AV) junction in the ferret heart were examined using light microscopy, a wax-model reconstruction and quantitative electron microscopy to determine their organization and characteristics. A series of subdivisions of the specialized tissues of the AV junction was apparent at both the light and electron microscopic levels. A transitional zone was observed interposed between the atrial muscle cells and the AV node. The AV node consisted of a coronary sinus portion, a superficial portion and a deep portion. The AV bundle had a segment above the anulus fibrosus, a segment which penetrated the right fibrous trigone, a non-branching segment below the anulus fibrosus and a branched segment. At the ultrastructural level the AV junctional conduction tissues had fewer irregularly oriented myofibrils than did working atrial myocardial cells. T-tubules, present in atrial muscle cells, were not observed in the modified muscle cells of the AV node and bundle. Conventional intercalated discs also were not observed between the cells of the AV node or the AV bundle.Atrial myocardial cells had the highest percentage of the plasma membrane occupied by desmosomes, fasciae adherentes and gap junctions. The AV bundle cells had the highest percentage of appositional surface membrane and a relatively large fraction of plasma membrane occupied by gap junctions. Cells of the superficial portion of the AV node had the smallest percentage of the plasma membrane composed of gap junctions, desmosomes or fasciae adherentes, as well as the smallest fraction of the cell membrane apposed to adjacent cells. The stereological data indicate that the most useful distinguishing characteristic between atrial muscle cells and conduction cells was that a smaller percentage of the conduction cell sarcoplasm was occupied by mitochondria and myofibrils. The most useful characteristics that could be used to differentiate between the regions of the AV junctional conduction tissues were the amounts and types of surface membrane specializations in the respective cell types.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001540305
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  • 5
    Electronic Resource
    Electronic Resource
    Activation of cyclic AMP-dependent protein kinase and stimulation of protein phosphorylation in response to adenosine in C-1300 murine neuroblastoma (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 125-135 
    Details
    ISSN: 0091-7419
    Keywords: protein phosphorylation ; cAMP-dependent protein kinases ; adenosine on cyclic AMP ; C1300 neuroblastoma ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: DEAE-cellulose chromatography of the 20,000g supernatant fraction of homogenates of C-1300 murine neuroblastoma (clone N2a) yields one major and two minor peaks of cyclic AMP-dependent protein kinase activity. Assessment of the endogenous activation state of the enzyme(s) reveals that the enzyme is fully activated by the treatment of whole cells with adenosine (10 μM) in the presence of the phosphodiesterase inhibitor Ro 20 1724 (0.7 mM). This treatment produces a large elevation in the cyclic AMP content of the cells. The treatment of whole cells with adenosine alone (1-100 μM) or Ro 20 1724 alone (0.1-0.7 mM) produces minimal elevations in cyclic AMP but nevertheless causes significant activations of cyclic AMP-dependent protein kinase. The autophosphorylation of whole homogenates of treated and untreated cells was studied using [γ-32P] ATP, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Treatments which activate cyclic AMP-dependent protein kinase selectively stimulate the incorporation of 32P into several proteins. This stimulation is most prominent in the 15,000-dalton protein band. The addition of cyclic AMP to phosphorylation reactions containing homogenate of untreated cells stimulates the phosphorylation of the same protein bands. These results indicate that adenosine may have regulatory functions through its effect on the cyclic AMP: cyclic AMP-dependent protein kinase system.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400100203
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation of glucose carriers in chick fibroblasts (1977)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 7 (1977), S. 499-513 
    Details
    ISSN: 0091-7419
    Keywords: glucose ; carrier ; regulation ; transport ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The derepression of glucose transport initiated by removing glucose from the incubation medium requires both protein and RNA synthesis. The synthesis and accumulation of putative mRNA for the carrier protein(s) can be demonstrated by inhibiting protein synthesis with cycloheximide (2 μg/ml). Release from inhibition with simulataneous addition of actionmycin D (1-5 μg/ml) results in a burst of carrier synthesis that achieves virtually maximal derepression in 4-6 h. An external energy source provided by a “nonrepressive” sugar (D-fructose, D-xylose) or by pyruvate is required to accomplish carrier synthesis. Previous failure to demonstrate mRNA accumulation was due to the depletion of energy in the starved cells. Glucose acts as a repressor at a posttranscriptional step, probably at the level of turnover of formed carrier.The protection of formed carrier in the absence of glucose and by inhibitors of protein synthesis even in the presence of glucose has encouraged conjecture that a protease is activated by a metabolic product of glucose that is analogous to a co-repressor. The glucose metabolite either activates the protease by direct interaction with it or alters the conformation of the carrier to expose a critical region to protease attack. Indeed the regulation of carrier density in the membrane of chick fibroblasts may be achieved entirely by carrier inactivation, the rate of which is a function of glucose concentration in the culture medium.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400070319
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  • 7
    Electronic Resource
    Electronic Resource
    Human placental cell surface antigens: Expression by cultured cells of diverse phenotypic origin (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 503-515 
    Details
    ISSN: 0091-7419
    Keywords: glycoproteins ; two-dimensional electrophoresis ; differentiation ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The present work examined the expression of cell surface glycoprotein antigens in cultured human cell lines. The set of glycoproteins studied was defined by their immunoreactivity with antiserum developed to Triton-solubilized extracts of placental brush border membranes. Studies were performed using cell lines of trophoblastic (BeWo, JEG-3) and nontrophoblastic (Chang liver cells) origin, as well as diploid fibroblast cell lines (WI-38, GM-38).Antiplacental brush border antiserum reacts with at least 19 distinct antigens present in placental membrane preparations, each of which can be resolved and identified in two-dimensional electrophoresis. The subunit molecular weight and isoelectric point for all components were defined by their positions in the two-dimensional matrix. Thirteen of these could be detected among the five cell lines examined by lactoperoxidase-catalyzed cell surface iodination. One of these 13 antigens has been identified as the placental isoenzyme of alkaline phosphatase (PAP). The expression of this component is limited to choriocarcinonia cells and Chang liver cells and it is not present in diploid fibroblasts. Under normal circumstances expression of PAP is unique to the differentiated placenta but has been frequently demonstrated in both trophoblastic and nontrophoblastic neoplasms.Two other antigens are variably expressed among the different cell types examined in the present study and their presence or absence was independent of the trophoblastic, epithelial nontrophoblastic, or fibroblastic origin of the cells.Ten surface antigens were expressed in all five cell lines. Six of these had previously been found common to membranes from three adult differentiated tissues, including liver and kidney, as well as placenta (Wada et al, J Supramol Struc 10(3):287-305, 1979). The presence of this set of antigens in cultured cells as well extends the possibility that these are ubiquitously expressed on human cell surfaces. Two other antigens observed in all cultured cells had been found in both placental and either kidney or liver membranes and may represent common functions shared by many tissues which are also necessary for growth in vitro. The two remaining placental antigens seen in all cultured cells have previously been shown to be absent in adult tissues. Their presence in cultured cells but not in the membranes of resting differentiated tissues may signify the expression of glycoproteins characteristic of trophoblasts in all cells adapted to growth in culture.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110409
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