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  • 1
    Electronic Resource
    Electronic Resource
    Endoplasmic microtubules connect the advancing nucleus to the tip of legume root hairs, but F-actin is involved in basipetal migration (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 27-36 
    Details
    ISSN: 0886-1544
    Keywords: nuclear migration ; microtubules ; F-actin ; root hairs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A prominent feature of tip growth in filamentous plant cells is that the nucleus often migrates in step with the tip as it extends. We have studied this long-recognized but unexplained relationship in root hairs of the legume Vicia hirsuta by a variety of microscopic techniques. Using rhodaminyl lysine phallotoxin, and antitubulin antibodies, root hairs are shown to contain axial bundles of F-actin and a complex microtubular system. To the basal side of the nucleus the microtubules are cortical and net axial but in the region between nucleus and tip the arrangement is more complicated. Electron microscopic thin sections demonstrate that internal bundles of microtubles exist in addition to the plasma membrane-associated kind. Computerized deblurring of through-focal series of antitubulin stained hairs clarifies the three-dimensional organization: bundles of endoplasmic microtubules progress from the nuclear region toward the apical dome where they can be seen to fountain out upon the cortex.The relationship between nucleus and tip can be uncoupled with antimicrotubule herbicides. Time lapse video microscopy shows that these agents cause the nucleus to migrate toward the base. This contrary migration can be inhibited by adding cytochalasin D, which fragments the F-actin bundles.It is concluded that microtubules connect the nucleus to the tip but that F-actin is involved in basipetal migration as is known to occur when symbiotic bacteria uncouple the nucleus from the tip.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970080105
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  • 2
    Electronic Resource
    Electronic Resource
    Post-gamma-irradiation grafting of polypropylene. Part II. Butadiene: E.S.R. experiments (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 3089-3099 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ESR spectra of gamma irradiated annealed and quenched forms of polypropylene film have been studied at the temperatures used for post-irradiation grafting experiments with butadiene, described in Part I. On warming from low temperature there is radical loss by termination and some radical transformation to radicals with optimum stability in annealed polypropylene at approximately 45°C. These radicals, which may be allyl type, are sited at the crystal faces, and decay more rapidly at higher temperatures in annealed polypropylene; in quenced polypropylene their concentration never exceeds one third the optimum observed in annealed polypropylene. Correlation with the grafting experiments suggests that allyl radicals are important for long-term grafting. Effects on the ESR spectrum of adding butadiene to the system show that in the long-term butadiene adds exclusively to the allyl radicals and that alkyl radicals still present at that stage are precursors to the allyl radicals. They do not react directly with butadiene presumably because they are sited in the inaccessible crystal core. Experiments at lower temperature show that butadiene does react with alkyl radicals in accessible regions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080241133
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  • 3
    Electronic Resource
    Electronic Resource
    Water immersion of polysulfide sealants. II. An interpretation of the influence of curing systems on water resistancePresented at Adhesives, Sealants and Encapsulants 85 (Network Events), London, U.K., November 1985. (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 5415-5429 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Dichromate cured polysulfide sealants have superior resistance to swelling in hot water than those cured with manganese dioxide and examinations to identify the reasons for this difference were undertaken. The commercial sealants PR-1422, PR-1750, and Pro-Seal 899 were shown to contain similar types and loading of fillers. Crosslink densities were compared through a procedure involving an oscillating disc cure meter modified to accommodate mobile mixtures. No relationship between stability and crosslinking was observed. Formation of large voids in MnO2-cured sealants after prolonged immersion at 70-90°C, suggests the formation of a water-soluble acid which then reacts with the CaCO3 filler, and this was supported by pH measurements. The acid was shown to arise through autoxidation of formal groups in the polysulfide, and this process can be suppressed by radical scavengers (including ammonium dichromate). When PR-1750 was examined under nitrogen or with carbon black as filler, a similar time-swell curve to that of PR-1422 was produced. It was concluded that abnormal swell does not result simply from autoxidation: a filler capable of reacting with the acid must also be present.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320614
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  • 4
    Electronic Resource
    Electronic Resource
    Localization of 3H-estradiol in the reproductive organs of male and female baboons (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 172 (1982), S. 151-157 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The uptake and retention of radiolabeled estradiol by both the male and female reproductive organs were examined in the baboon. Two male and two female baboons were injected intracardially with 1 μg/kg body weight of 3H-estradiol and two animals, one male and one female, were injected with both labeled and 100 μg/kg body weight of unlabeled estradiol. One and a half hours after the injections, the animals were sacrificed and the uterus, cervix, vagina, oviduct, seminal vesicles, and prostate gland were removed and processed for autoradiography. The stratified squamous epithelia of the cervix and vagina demonstrated a light uptake of the label in the germinative, but not in the superficial cell layers. The columnar cells lining the oviduct and uterine glands were labeled, whereas the luminal epithelium of the uterus and the glandular epithelia of the seminal vesicles and prostate gland did not sequester the tritiated steroid. The interstitial cells of all the organs studied demonstrated a moderate to heavy uptake of the radioactivity, whereas the smooth muscle cells were lightly labeled except in the vagina, in which these cells displayed a moderate number of silver grains.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051720203
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  • 5
    Electronic Resource
    Electronic Resource
    Protein-reactive, molded polystyrene surfaces having applications to immunoassay formats (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 1917-1924 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Injection-molded polystyrene surfaces were chemically modified rendering them protein reactive. The process involves chlorosulfonation of the aromatic ring, sulfonamide formation with excess di- and triamines, and reaction of the residual pendant amines with various bifunctional molecules. Surfaces possessing pendant bromoacetyl, iodoacetyl, fluorodinitrophenyl, and trimellitic anhydride were prepared and can exhibit up to ten times more protein immobilization capability compared to unfunctionalized polystyrene, where the coupling takes place presumably via hydrophobic interaction.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070340510
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  • 6
    Electronic Resource
    Electronic Resource
    Selenium deficiency in cultured adrenocortical cells: Restoration of glutathione peroxidase and resistance to hydroperoxides on addition of selenium (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 123 (1985), S. 33-38 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultured bovine adrenocortical cells were previously shown to be functionally deficient in selenium and vitamin E when grown in medium supplemented with fetal bovine serum. In the present experiments, the lack of significant bioavailable amounts of selenium in the medium was demonstrated by the finding of only low levels of glutathione peroxidase in the cultured cells (0.008 U/mg protein compared with 0.045 U/mg protein in fresh adrenocortical tissue). When 20 nM selenium as selenite was added to the cultured adrenocortical cells, glutathione peroxidase activity increased continuously over 72 h, with a total increase of about eightfold over this period. Over the same time-course, the highest concentration of cumene hydroperoxide tolerated by the cells without cell death increased progressively from 10 μM to 50 μM. Addition of 1μM α-tocopherol also increased the amount of cumene hydroperoxide tolerated to 50 μM. Cell death was measured by cloning efficiency after removal of cumene hydroperoxide. Addition of either selenium or α-tocopherol had little effect on the growth rate of the cells over six passages, even when residual vitamin E was removed from the serum by extraction with ether and residual low molecular weight selenium compounds were removed by dialysis. It is concluded that combined deficiency of selenium and vitamin E, at least in the presence of other components of fetal bovine serum, has little effect on the ability of the cells to survive under normal conditions, as evidenced by continued long-term proliferation. However, the low levels of glutathione peroxidase resulting from selenium deficiency cause an increase susceptibility to peroxide-mediated toxicity. The combined deficiency of selenium and vitamin E impairs the ability of cells to survive under adverse conditions, as well as altering mitochondrial functions, as previously demonstrated.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041230106
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  • 7
    Electronic Resource
    Electronic Resource
    Molecular sieving characteristics of the cultured endothelial monolayer (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 132 (1987), S. 111-117 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We examined the selectivity of the bovine pulmonary artery endothelial monolayer in vitro to molecules of different sizes. The cultured bovine pulmonary endothelial monolayer was grown on a gelatinized filter and the transendothelial transport was studied by determining the permeability of molecules ranging from 182 to 340,000 daltons under diffusion conditions. The permeabilities across the cultured bovine endothelium were modeled according to cylindrical pore theory. The data were best fit by a two-pore model with radii 65 Å and 304 Å and a ratio of small to large pores of 160:1. The results indicate that the cultured endothelial monolayer is a selective barrier to molecules of different sizes and that the molecular selectivity is consistent with a diffusional pathway through endothelial pore equivalents. The cultured endothelial monolayer is a useful system for studying the permeability characteristics of the endothelial barrier.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041320115
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  • 8
    Electronic Resource
    Electronic Resource
    Evidence for control of protein synthesis in HeLa cells via the elongation rate (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 104 (1980), S. 269-281 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of fresh medium and serum on protein synthesis in suspension-cultured HeLa cells after growth to high cell density (〉5 × 105 cells/ml) were studied. Cells which were resuspended in fresh medium plus serum and grown for 24 hours (control) were compared with cells grown for 2 hours after resuspension (stimulated). The spectrum of proteins being synthesized by control and stimulated cells does not appear to be grossly different; that is, the weight and number average molecular weights of newly synthesized whole-cell protein are about the same in both cultures. Also, no significant differences were observed in the number of ribosomes per polysome or in the fraction of total ribosomes in polysomes. However, the transit times (combined elongation and termination times) were found to differ significantly; the average transit time for control cells was 2.24 minutes, while the average transit time for stimulated cells was 1.26 minutes. (An appendex evaluating the methodology involved in measuring the transit time is included.) In agreement with the difference in transit time, the absolute rate of protein synthesis in stimulated cells was approximately 1.8 times the rate measured in control cells. These data are taken as evidence that under certain conditions, the rate of elongtion and/or termination of polypeptide chains limits the overall rate of translation, and that cells can respond to growth conditions by changing the elongation and/or termination rate of protein synthesis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041040302
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  • 9
    Electronic Resource
    Electronic Resource
    The role of vitamin E in cellular energy metabolism in cultured adrenocortical cells (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 112 (1982), S. 207-216 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: AC1 cells, a bovine adrenocortical cell clone, are rapidly arrested and killed by 2 mM aminooxyacetate, an inhibitor of transmination reactions. Toxicity of aminooxyacetate to cultured bovine adrenocortical cells was previously linked to a high ratio of capacity for oxidation of glutamine relative to pyruvate and was reversible by adding excess glutamine. The toxic effects of aminooxyacetate were shown in the present study to be completely prevented by the simultaneous addition of low concentrations (〈100 nM) of d-α-tocopherol (vitamin E) or selenious acid or higher concentration of other tocopherols, antioxidants, and ubiquinones (coenzymes Q6 and Q10). When antioxidant analogs were tested, it was found that structural features of the molecules that increase antioxidant potency increased potency for prevention of aminooxyacetate toxicity. α-Tocopherol-supplemented AC1 cells were found to be significantly less sensitive than nonsupplemented cells to growth inhibition by rotenone but not by fluorocitrate or dinitrophenol. Dinitrophenol (100 m̈M) stimulated substrate oxidation fivefold but had relatively slight effects on growth, either with or without α-tocopherol, indicating that limitation of the maximal activity of the tricarboxylic acid cycle and respiratory chain is probably not responsible for the sensitivity to aminooxyacetate and rotenone in cells not supplemented with α-tocopherol. Sensitivity to growth inhibition by rotenone and the prevention by ubiquinones of aminooxyacetate toxicity suggest a restriction of electron flow at the NADH-ubiquinone step. The resultant higher NADH/NAD+ ratio would result in a lowered capacity for metabolism of pyruvate with consequent dependence for tricarboxylic acid cycle function and energy production on 2-oxoglutarate from glutamine by the transmination pathway. Vitamin E and other antioxidants may restore efficient function of ubiquinone by preventing side reactions involving lipid peroxidation. Selenium may have a similar effect as cofactor for glutathione peroxidase. A high ratio of capacity for oxidation of glutamine relative to pyruvate and accompanying sensitivity to aminooxyacetate may reflect a deficiency of vitamin E and selenium in adrenocortical cells in culture.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041120208
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  • 10
    Electronic Resource
    Electronic Resource
    Expression of angiotensin-converting enzyme activity in cultured pulmonary artery endothelial cells (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 108 (1981), S. 337-345 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Angiotensin-converting enzyme (EC 3.4.15.1) is a carboxyterminal dipeptidyl peptidase. The enzyme catalyzes the conversion of the decapeptide angiotensin I to the octapeptide angiotensin II. In addition, the enzyme catabolizes bradykinin. Because of these actions, the enzyme is of pivotal importance in blood pressure homeostasis. Numerous investigators have demonstrated the presence of the enzyme in association with endothelial cells but relatively little is known concerning the factors controlling the expression of enzyme activity by endothelial cells in culture. We have demonstrated that endothelial cells in culture do not express significant amounts of enzyme activity until several days after growth ceases due to high cell density. This is important because it demonstrates a change in function with stage of growth in culture and a possible difference in functional capabilities between nondividing endothelial cells and cells that are dividing in response to injury. Since density-dependent expression of differentiated traits does not appear to be unique to endothelial cells an understanding of the mechanisms underlying this phenomenon may provide a general explanation for the expression of differentiated traits by cultured cells.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041080307
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