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  • Cell & Developmental Biology  (6)
  • Chemical Engineering  (6)
  • 1990-1994  (11)
  • 1960-1964  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Two distinct isoforms of sea urchin egg dynein (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 21 (1992), S. 281-292 
    Details
    ISSN: 0886-1544
    Keywords: ATPase ; CTPase ; minus-end-directed microtubule motility ; cytoplasmic dynein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Extracts of unfertilized sea urchin eggs contain at least two isoforms of cytoplasmic dynein. One exhibits a weak affinity for microtubules and is primarily soluble. The other isoform, HMr-3, binds to microtubules in an ATP-sensitive manner, but is immunologically distinct from the soluble egg dynein (Porter et al.: Journal of Biological Chemistry 263:6759-6771, 1988). We have now further distinguished these egg dynein isoforms based on differences in NTPase activity. HMr-3 copurifies with NTPase activity, but it hydrolyzes CTP at 10 times the rate of ATP. The soluble egg dynein is similar to flagellar dynein in its nucleotide specificity; its MgCTPase activity is ca. 60% of its MgATPase activity. Non-ionic detergents and salt activate the MgATPase activities of both enzymes relative to their MgCTPase activities, but this effect is more pronounced for the soluble egg dynein than for HMr-3. Sucrose gradient-purified HMr-3 promotes an ATP-sensitive microtubule bundling, as seen with darkfield optics. We have also isolated a 20 S microtubule translocating activity by sucrose gradient fractionation of egg extracts, followed by microtubule affinity and ATP release. This 20 S fraction, which contains the HMr-3 isoform, induces a microtubule gliding activity that is distinct from kinesin. Our observations suggest that soluble dynein resembles axonemal dynein, but that HMr-3 is related to the dynein-like enzymes isolated from a variety of cell types and may represent the cytoplasmic dynein of sea urchin eggs.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970210404
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  • 2
    Electronic Resource
    Electronic Resource
    Spray-to-bubbly transition for distillation systems containing two liquid phases (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 597-606 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The tray hydrodynamics were determined for a system containing water and kerosene as immiscible liquids. Plates with hole diameters ranging from 3.18 to 12.70 mm were used in a 44.5-cm2 perspex air-water-kerosene simulator. Experiments were also carried out in a 50-mm-ID column using different depths of oil and water mixtures to study the drop and bubble mechanisms. A spray-to-bubble transition occurred for the two liquid-phase system experiments. The liquid holdup at the transition increased directly with gas velocity and hole diameter, and decreased with increasing free area. At the same hole velocity, the presence of two liquid phases caused the transition to occur at different liquid holdups than for the single pure liquid. Two different modes of coalescence were observed in the small column work. New correlations have been proposed for the liquid holdup at the transition which allow for the presence of two liquid phases.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690370413
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  • 3
    Electronic Resource
    Electronic Resource
    A macromolecular deformation model to estimate viscoelastic flow effects in polymer melts (1993)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 33 (1993), S. 437-444 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The elastic deformation of polymer macromolecules in a shear field is used as the basis for quantitative predictions of viscoelastic flow effects in a polymer melt. Non-Newtonian viscosity, capillary end correction factor, maximum die swell, and die swell profile of a polymer melt are predicted by the model. All these effects can be reduced to generic master curves, which are independent of polymer type. Macromolecular deformation also influences the brittle failure strength of a processed polymer glass. The model gives simple and accurate estimates of practically important processing effects, and uses fitting parameters with the clear physical identity of viscoelastic constants, which follow well established trends with respect to changes in polymer composition or processing conditions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760330710
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  • 4
    Electronic Resource
    Electronic Resource
    Phase and crystallization behavior of solution-blended poly(ether ether ketone) and poly(ether imide) (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 1870-1875 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Results on solution-blended poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) blends are reported. Dichloroacetic acid was used as the cosolvent for blending. PEEK and PEI are confirmed to be miscible in the melt. The glass transition, Tg, behavior obeys the simple Fox equation or the Gordon-Taylor equation with the adjustable coefficient k = 0.86. This agrees with prior data on melt-blended PEEK/PEI blends. The Tg width of the amorphous PEEK/PEI blends was found to be broader than that of the pure components. The maximum broadening is about 10°C. The specific volume of the amorphous PEEK/PEI blends shows a slight negative deviation from linearity, indicating favorable interaction between PEEK and PEI. The spherulitic growth and resultant blend morphology at 270°C were studied by a cross-polarized optical microscope. The radial growth rate of PEEK spherulites formed from the miscible melt at 270°C decreases from 3.04 μm/min for PEEK/PEI 90/10 blend to 0.77 μm/min for PEEK/PEI 70/30 blend. The decrease in crystalization rate of PEEK from PEEK/PEI blends is attributable to the increase in blend Tg. A linear growth was observed for PEEK spherulites formed from miscible melt at 270°C in the early growth stage. The spherulitic growth deviated from linearity in the late stage of growth. PEEK spherulites formed from the miscible PEEK/PEI melt at 270°C are essentially volume-filling. The branches of the spherulites become more clear for PEEK spherulites formed from the blend than that formed from pure PEEK melt.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760322410
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  • 5
    Electronic Resource
    Electronic Resource
    A review on the tensile strength of polyethylene fibers (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 266-268 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340406
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  • 6
    Electronic Resource
    Electronic Resource
    A Tribute to William P. (Bill) Gergen (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1-2 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340102
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  • 7
    Electronic Resource
    Electronic Resource
    The status of non-Newtonian polymer flow (1963)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 3 (1963), S. 18-20 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This study summarizes the flow behavior of concentrated and melt systems of linear amorphous polymer. For low molecular weight polymer, viscosity increases regularly with a lower power dependence on molecular weight. This dependence decreases towards first power with increasing temperature but is independent of shear, with viscosities being constant up to the highest attainable steady state stresses, about 106 dynes/cm2. At a higher molecular weight, 2,000-40,000, depending on polymer type, the viscosity dependence on molecular weight changes abruptly to a high power which is generally about 3.4. Above the transition, this high power function is independent of temperature but depends markedly on shear. Non-Newtonian flow sets in abruptly and predictably above the transitional molecular weight.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760030105
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  • 8
    Electronic Resource
    Electronic Resource
    Novel monoclonal antibodies identify antigenic determinants unique to cellular senescence (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 142 (1990), S. 425-433 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Normal human diploid fibroblasts exhibit a limited lifespan in vitro and are used as a model to study in vivo aging. Monoclonal antibodies were generated against partially purified surface membranes from human diploid fibroblasts at the end of their lifespan (senescent). Three hybridomas were isolated that secreted antibodies reacting to cellular determinants expressed specifically on senescent human fibroblasts of different origin, including neonatal foreskin, embryonic lung, and adult skin punch biopsy, but not expressed on matched young cells. The antibodies did not bind to immortal human cells and normal young cells made reversibly nondividing, indicating the antigens are not expressed in cells that are not senescent. The antibodies identified senescent cells in a mixed cell population and expression of the senescent cell antigens correlated strongly with the cells inability to synthesize DNA at the onset of senescence. The antigens appeared to be cell surface or extracellular matrix associated, and the epitopes were destroyed by mild trypsin treatment. Western analysis indicated all three antibodies reacted with fibronectin. Though the antigenic determinants on the fibronectir molecule were not accessible in the intact young cell, the epitopes were present in fibronectin extracted from both senescent and young cells, as well as purified human plasma fibronectin. These antibodies and the senescent specific expression of the antigens provide powerful tools to investigate the mechanisms leading to in vitro senescence. This may enable us to investigate directly the relationship between cellular aging and aging of the individual.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041420228
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  • 9
    Electronic Resource
    Electronic Resource
    Regulation of polyamine transport by polyamines and polyamine analogs (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 155 (1993), S. 399-407 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Regulation of polyamine transport in murine L1210 leukemia cells was characterized in order to better understand its relationship to specific intracellular polyamines and their analogs and to quantitate the sensitivity by which it is controlled. Up-regulation of polyamine uptake was evaluated following a 48-hr treatment with a combination of biosynthetic enzyme inhibitors to deplete intracellular polyamine pools. The latter declined gradually over 48 hr and was accompanied by a steady increase in spermidine (SPD) and spermine (SPM) transport as indicated by rises in Vmax to levels ∼4.5 times higher than control values. Restoration of individual polyamine pools during a 6-hr period following inhibitor treatment revealed that SPD and SPM uptake could not be selectively affected by specific pool changes. The effectiveness of individual polyamines in reversing inhibitor-induced stimulation of uptake was as follows: putrescine 〈 SPD 〈 SPM = the SPM analog, N1, N12-bis(ethyl)spermine (BESPM). In contrast to stimulation of transport, down-regulation by exogenous polyamines or analogs occurred rapidly and in response to subtle increases in intracellular pools. Following a 1-hr exposure to 10 μM BESPM, Vmax values for SPD and SPM fell by 70%, whereas the analog pool increased to only 400-500 pmol/106 cells - about 15-20% of the total polyamine pool (∼2.8 nmol/106 cells). SPM produced nearly identical regulatory effects on transport kinetics. Both BESPM and SPM were even more effective at down-regulating transport that had been previously stimulated four to fivefold by polyamine depletion achieved with enzyme inhibitors. A dose response with BESPM at 48 hr revealed a biphasic effect on uptake whereby concentrations of analog 〈 3 μM produced an increase in SPD and SPM Vmax values, whereas concentrations 3 μM and higher produced a marked suppression of these values. Cells treated with 3 μM BESPM for 2 hr and placed in analog-free medium recovered transport capability in only 3 hr. Thus, whereas stimulation of polyamine transport is a relatively insensitive and slowly responsive process that tends to parallel polyamine depletion, down-regulation of polyamine transport by exogenous polyamines and analogs and its reversal are rapidly responsive events that correlate with relatively small (i.e., 15-20%) changes in intracellular polyamine pools.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041550222
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  • 10
    Electronic Resource
    Electronic Resource
    Vanadate reduces sodium-dependent glucose transport and increases glycolytic activity in LLC-PK1 epithelia (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 158 (1994), S. 459-466 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of vanadate pentoxide on apical sodium-dependent glucose transport in LLC-PK1 epithelia was examined. Epithelia grown in the presence or absence of 1 μM vanadate formed confluent monolayers and exhibited no differences in DNA, protein, or ultrastructure. Vanadate-supplemented epithelia demonstrated a lower steady-state α-methyl-D-glucopyranoside (AMG) concentrating capacity and a twofold reduction in apical AMG uptake Jmax. This decreased AMG transport occurred as a consequence of a reduction in the number of transport carriers and was not associated with a change in the sodium electrochemical gradient. The vanadate-induced reduction in apical glucose carrier functional activity and expression was accompanied by a stimulation of intracellular glycolytic flux activity, as evidenced by increased glucose consumption, lactate production, PFK-1 activity, and intracellular ATP. There was no difference in intracellular cAMP levels between vanadate-supplemented and non-supplemented epithelia. These results demonstrate an association between stimulation of glycolytic pathway activity and an adaptive response in the form of a reduction in the function and expression of the sodium-dependent apical glucose transporter in LLC-PK1 epithelia. © 1994 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041580310
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