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  • Life and Medical Sciences  (6)
  • Life Sciences (General)  (4)
  • 1985-1989  (10)
  • 1988  (10)
  • 1
    Electronic Resource
    Electronic Resource
    ERV3 Human endogenous provirus mRNAs are expressed in normal and malignant tissues and cells, but not in choriocarcinoma tumor cells (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 36 (1988), S. 121-128 
    Details
    ISSN: 0730-2312
    Keywords: human endogenous provirus ; choriocarcinoma ; proviral mRNA expression ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Messenger RNA expression of a human endogenous provirus, ERV3, has been characterized in 170 specimens of normal and malignant human tissues and cells. In contrast to the high expression in first-trimester and full-term placental chorionic villi, most other human tissues expressed ERV3 mRNAs at a level of 2-30% of placenta. However, ERV3 mRNAs were not detected in choriocarcinoma tumor cell lines. These studies suggest that the ERV3 provirus may have been preempted for a biological function and disruption of its mRNA expression results in choriocarcinoma.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240360203
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  • 2
    Electronic Resource
    Electronic Resource
    Inhibition of the proliferation of Nb2 cells by femtomolar concentrations of cholera toxin and partial reversal of the effect by 12-O-tetradecanoyl-phorbol-13-acetate (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 37 (1988), S. 119-129 
    Details
    ISSN: 0730-2312
    Keywords: Nb2lymphoma cells ; phorbol ester ; cAMP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: One hour of exposure to cholera toxin is sufficient to elicit a significant delay in the initiation of DNA synthesis and cell division in lactogenic hormone-dependent Nb2-11C lymphoma cells. The inhibitory effect occurs already at very low concentrations of cholera toxin (5-50 fM), at which it is not accompanied by a detectable increase in intracellular cAMP, or ADP-ribosylation of the alpha subunit of Gs, the stimulatory guanine nucleotide binding protein of adenylate cyclase; IBMX, the phosphodies-terase inhibitor, acts synergistically to cholera toxin, indicating that a minute increase in cAMP may be sufficient for the inhibition. This indication is substantiated by the finding that dibutyryl cAMP also inhibits cell proliferation. Phorbol diester reverses partially the inhibitory activity of cholera toxin. It is most likely that this effect does not result from blocking the increase in cAMP, but rather from some subsequent, yet unidentified, events. The inhibitory effect of cholera toxin is not dependent on the concentration of the proliferation-stimulating lactogenic hormone and cannot be abolished or reduced by excess of the hormone. Cholera toxin also inhibits the autonomous proliferation of a lactogenic hormone-independent cell line (Nb2-SP); however, in this case the inhibition is not affected by TPA.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240370111
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  • 3
    Electronic Resource
    Electronic Resource
    Actin depolymerization and inhibition of capping induced by pentoxifylline in human lymphocytes and neutrophils (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 137 (1988), S. 577-582 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Pentoxifylline is used clinically for the treatment of intermittent claudication. It is believed to exert its effect by altering the rheologic properties of blood. The cytoskeleton plays an important role in the maintenance of cell structure and function. In particular, alterations in the state of actin seem to play an important role in cell motility. Therefore, we examined the effect of pentoxifylline on the actin state in human polymorphonuclear leukocytes (PMN) and mononuclear cells. Pentoxifylline (10 mM final concentration) decreased F-actin content in both PMN and mononuclear cells. Pentoxifylline also inhibited concanavalin A-induced capping in PMN and mononuclear cells. Similarly, surface immunoglobulin capping in B lymphocytes was also inhibited. Pretreatment of cells with pertussis toxin did not inhibit pentoxifylline-induced decrease in F-actin, suggesting pentoxifylline does not act through pertussis toxin-sensitive G-proteins. Dibutyryl cyclic AMP failed to show any significant effect on the F-actin content in PMN. Therefore, the effect of pentoxifylline cannot be attributed to changes in cyclic AMP levels. Chemotactic peptide-induced actin polymerization was unaffected in PMN when expressed as percent change in F-actin. The observations reported here suggest that the rheological effects of pentoxifylline might be due to its effects on the actin state in the cellular elements of the blood. Further studies on the mechanism of action of pentoxifylline on actin state in leukocytes will prove useful in delineating the physiological mechanisms regulating actin state in leukocytes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041370326
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  • 4
    Electronic Resource
    Electronic Resource
    Differentiation of HL-60 cells is associated with an increase in the 35-kDa protein lipocortin I (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 137 (1988), S. 402-410 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Lipocortin I, a 35-kDa protein, has been detected in terminally differentiated monocytes and neutrophils. This calcium-phospholipid binding protein appears to be identical to a 35-kDa protein that can serve as a substrate for the EGF-receptor/tryosine kinase. We have used the human myelocytic cell line HL-60 to explore whether differentiation of hematopoietic cells is associated with changes in the level of lipocortin I. We find that differentiation of HL-60 cells toward the macrophage lineage by the addition of phorbol esters or vitamin D3 or toward neutrophils with dibutyryl cyclic AMP or dimethyl sulfoxide is accompanied by an increase in the cellular content of lipocortin I. In comparison, treatment of HL-60 cells with bryostatin 1, a compound that activates protein kinase C but does not differentiate HL-60 cells, did not effect the level of 35 kDa protein. We have developed a radioimmunoassay to quantitate this protein by using a polyclonal antibody to a synthetic amino terminal peptide of the 35-kDa protein. This antibody recognizes purified pig lung 35-kDa protein as well as a single 35-kDa protein in HL-60 and A-431 cells as determined by Western blotting and immune precipitation. Differentiated HL-60 cells contain 2.6-fold the amount of 35-kDa protein found in undifferentiated HL-60 cells. Our findings that the addition of phorbol esters to HL-60 cells results in an increase in the mRNA for the 35-kDa protein and in an increase in the incorporation of 35S-methionine into the protein suggest that transcriptional activation or increased stability of the mRNA is responsible for the increased rate of synthesis and accumulation of lipocortin I during differentiation of these cells. In the absence of added divalent cations, we have determined that in differentiated HL-60 cells 79% of lipocortin I protein is located in the cytosol while 21% of the total cellular protein is bound to the particulate fraction. The 35-kDa protein can be removed from the particulate fraction by incubation with chelators or treatment with phospholipase A2 or phospholipase C. Addition of the calcium ionophore A23187 to intact differentiated HL-60 cells causes the 35-kDa protein to associate with the particulate fraction of the cell, suggesting that modulation of intracellular calcium levels may play a role in changing the intracellular location of this protein.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041370303
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  • 5
    Electronic Resource
    Electronic Resource
    Recombinant gibbon interleukin-3 stimulates megakaryocyte colony growth in vitro from human peripheral blood progenitor cells (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 136 (1988), S. 439-446 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gibbon interleukin-3 (rlL-3) has recently been cloned and found to have a high degree of homology with the human IL-3 molecule. In this investigation, we evaluated the effects of gibbon rlL-3 on normal human peripheral blood megakaryocyte progenitor cell growth in vitro. Gibbon rlL-3 exhibited substantial megakaryocyte colony stimulatory activity (Meg-CSA), supporting peak colony numbers at a concentration of 1 U/ml. Megakaryocyte colony growth induced by rlL-3 reached 58% of the maximum achieved with the active, Meg-CSA-containing protein fraction of aplastic canine serum. Increasing gibbon rlL-3 concentrations also stimulated a 4-5-fold increase in megakaryocyte colony size and resulted in a decrease in geometric mean megakaryocyte ploidy. Ploidy values fell from 8.5N ± 1.4 (±SEM) at an rlL-3 concentration of 0.1 U/ml to a minimum of 2.9N ± 0.3 at 10 U/ml. In the presence of rlL-3 at 1.0 U/ml, megakaryocyte colony growth was linear with cell plating density and the regression line passed approximately through the origin. The effects of rlL-3 on megakaryocyte colony growth were independent of the presence of T-lymphocytes in the cultures. Cross-species evaluation of murine and gibbon lL-3 indicated that its bioactivity is species restricted. Murine lL-3 did not support colony growth from human megakaryocyte progenitors and gibbon rlL-3 showed no activity in stimulating acetylcholinesterase production by murine bone marrow cells. Gibbon rlL-3 is a potent stimulator of the early events of human megakaryocyte progenitor cell development promoting predominantly mitosis and early megakaryocytic differentiation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041360307
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  • 6
    Electronic Resource
    Electronic Resource
    Human endogenous retroviruses (1988)
    New York, NY : Wiley-Blackwell
    BioEssays 9 (1988), S. 191-196 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Several studies have revealed the presence in human DNA of thousands of endogenous retrovirus genomes, or HERVs. Many HERVs are related to extant retroviruses that infect other vertebrates and some have been present in the germ line of primates for millions of years. Although the HERVs that have been isolated are defective and thus do not encode infectious retroviruses, there may be HERVs that are capable of infection. In addition, because HERVs are so ancient in the human lineage, evolution of the human genome may have included the acquisition of some HERV genes for strictly cellular functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950090603
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  • 7
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    Variability in surface ECG morphology: signal or noise? (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Using data collected from canine models of acute myocardial ischemia, we investigated two issues of major relevance to electrocardiographic signal averaging: ECG epoch alignment, and the spectral characteristics of the beat-to-beat variability in ECG morphology. With initial digitization rates of 1 kHz, an iterative a posteriori matched filtering alignment scheme, and linear interpolation, we demonstrated that there is sufficient information in the body surface ECG to merit alignment to a precision of 0.1 msecs. Applying this technique to align QRS complexes and atrial pacing artifacts independently, we demonstrated that the conduction delay from atrial stimulus to ventricular activation may be so variable as to preclude using atrial pacing as an alignment mechanism, and that this variability in conduction time be modulated at the frequency of respiration and at a much lower frequency (0.02-0.03Hz). Using a multidimensional spectral technique, we investigated the beat-to-beat variability in ECG morphology, demonstrating that the frequency spectrum of ECG morphological variation reveals a readily discernable modulation at the frequency of respiration. In addition, this technique detects a subtle beat-to-beat alternation in surface ECG morphology which accompanies transient coronary artery occlusion. We conclude that physiologically important information may be stored in the variability in the surface electrocardiogram, and that this information is lost by conventional averaging techniques.
    Keywords: Life Sciences (General)
    Type: Computers in cardiology (ISSN 0276-6574); 14; 257-60
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    NASA TECHNICAL REPORTS
  • 8
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    On the precision of automated activation time estimation (1988)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: We examined how the assignment of local activation times in epicardial and endocardial electrograms is affected by sampling rate, ambient signal-to-noise ratio, and sinx/x waveform interpolation. Algorithms used for the estimation of fiducial point locations included dV/dtmax, and a matched filter detection algorithm. Test signals included epicardial and endocardial electrograms overlying both normal and infarcted regions of dog myocardium. Signal-to-noise levels were adjusted by combining known data sets with white noise "colored" to match the spectral characteristics of experimentally recorded noise. For typical signal-to-noise ratios and sampling rates, the template-matching algorithm provided the greatest precision in reproducibly estimating fiducial point location, and sinx/x interpolation allowed for an additional significant improvement. With few restrictions, combining these two techniques may allow for use of digitization rates below the Nyquist rate without significant loss of precision.
    Keywords: Life Sciences (General)
    Type: Computers in cardiology (ISSN 0276-6574); 14; 101-4
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    NASA TECHNICAL REPORTS
  • 9
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    Analysis of long term heart rate variability: methods, 1/f scaling and implications (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The use of spectral techniques to quantify short term heart rate fluctuations on the order of seconds to minutes has helped define the autonomic contributions to beat-to-beat control of heart rate. We used similar techniques to quantify the entire spectrum (0.00003-1.0 Hz) of heart rate variability during 24 hour ambulatory ECG monitoring. The ECG from standard Holter monitor recordings from normal subjects was sampled with the use of a phase locked loop, and a heart rate time series was constructed at 3 Hz. Frequency analysis of the heart rate signal was performed after a nonlinear filtering algorithm was used to eliminate artifacts. A power spectrum of the entire 24 hour record revealed power that was inversely proportional to frequency, 1/f, over 4 decades from 0.00003 to 0.1 Hz (period approximately 10 hours to 10 seconds). Displaying consecutive spectra calculated at 5 minute intervals revealed marked variability in the peaks at all frequencies throughout the 24 hours, probably accounting for the lack of distinct peaks in the spectra of the entire records.
    Keywords: Life Sciences (General)
    Type: Computers in cardiology (ISSN 0276-6574); 14; 419-22
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  • 10
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    Nonlinear dynamics in cardiac conduction (1988)
    In:  Other Sources
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    Publication Date: 2019-08-15
    Description: Electrical conduction in the heart shows many phenomena familiar from nonlinear dynamics. Among these phenomena are multiple basins of attraction, phase locking, and perhaps period-doubling bifurcations and chaos. We describe a simple cellular-automation model of electrical conduction which simulates normal conduction patterns in the heart as well as a wide range of disturbances of heart rhythm. In addition, we review the application of percolation theory to the analysis of the development of complex, self-sustaining conduction patterns.
    Keywords: Life Sciences (General)
    Type: Mathematical biosciences (ISSN 0025-5564); 90; 19-48
    Format: text
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