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  • 1
    Electronic Resource
    Electronic Resource
    Thermomechanical properties of blends of pectin and poly(vinyl alcohol) (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 71-79 
    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: Blends of citrus pectin and several types of poly(vinyl alcohol) were investigated to determine the effects of compositional variables and polymer type on film properties. Some films were also plasticized with glycerol. Films were cast from water onto Lexan™ plates, dried, and removed. Thermomechanical properties were obtained using a dynamic mechanical analyzer, and thermodynamic transitions were also obtained using a differential scanning calorimeter. Increasing the amount of poly(vinyl alcohol) in the blends reduced the storage and loss modulus of the films above the glass transition temperature (Tg). The Tg values observed decreased as the amount of PVOH in the blend increased. Addition of glycerol depressed the PVOH Tg and merged it into the Tg of the pectin/glycerol blend. Changes in the molecular weight and degree of ester hydrolysis of poly(vinyl alcohol) exerted a rather small effect on the blends. © 1996 John Wiley & Sons, Inc.Reference to a brand or firm name does not constitute an endorsement by the U.S. Department of Agriculture over others of a similar nature.
    Additional Material: 8 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Physical and mechanical properties of highly plasticized pectin/starch films (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 1311-1320 
    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: Blends of citrus pectin and high amylose starch plasticized with glycerine were investigated to determine the effect of compositional variables on film properties. Several films with representative compositions were made from sugar beet and almond pectin, and tested for comparison. The films were cast from water onto glass plates, dried, and removed. Mechanical analysis was done using a Rheometrics RSA II solids analyzer. Increasing the glycerine concentration led to decreases in static modulus, dynamic modulus, and tensile strength, but to increases in elongation. Increasing levels of starch in the blend lowered the effect of glycerine on mechanical properties. Oxygen permeability of the films was extremely low. Sugar-beet pectin and almond pectin gave films with mechanical properties comparable to those made with citrus pectin. © 1994 John Wiley & Sons, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070540913
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanical and microstructural properties of pectin/starch films (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 57 (1995), S. 663-670 
    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: Films were made from blends of high methoxy pectin and high amylose starch gelatinized in a microwave oven in the presence and absence of glycerol at times ranging from 10 to 105 s. Three thermodynamic transitions were observed when storage modulus, loss modulus, and loss tangent were plotted against temperature. All three transitions gave minima when the transition temperature was plotted against time of gelatinization. Overall, there were only modest changes in these moduli over the range of gelatinization times studied, with little difference between films made with the starch gelatinized in either the presence or absence of glycerol. Starch granules were found to disappear at gelatinization times between 20 and 30 s, although much smaller starch particles seemed to recur at gelatinization times of 75 s and above. The minima found in the transition temperature and modulus plots were believed to result from a minimum in the amount of intermolecular interactions between the starch molecules. © 1995 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070570602
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  • 4
    Electronic Resource
    Electronic Resource
    The vasculature of the gills in the aquatic and aestivating lungfish (Protopterus aethiopicus) (1978)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 156 (1978), S. 173-208 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Studies were undertaken of the microcirculation and histology of the gill of Protopterus aethiopicus as a prerequisite for elucidating the function of the gills in a bimodal respiratory system. The lamellae of the gill-bearing arches (I, IV, V, VI) resembles the arborescent external gill of the larval amphibian rather than the gill of the teleost or selachian.The arterio-arterial system (a-a) of the gill consists of an afferent artery, a series of large capillaries, and an efferent artery on each of the primary, secondary and tertiary lamellae. There are no pillar cells and the loose capillaries are covered with a multilayered epithelium. While living in water, the minimum distance for gas exchange is of the order of 5 μ. An afferent-efferent arterial shunt at the base of each primary lamella may be involved in control of lamellar blood flow and the resistance of the gill vasculature.The arterio-venous system originates primarily from the efferent side of the arterio-arterial system and drains into large branchial veins. Numerous contractile cisternae, interposed between intercellular channels and veins, presumably function as micropumps that collect fluid from intercellular epithelial spaces and inject it into the venous circulation.During aestivation, the epithelial layer of the gill lamellae becomes thinner. The entire gill vasculature, including the capillaries and afferent-efferent shunts on arches IV-VI, are very dilated which presumably promotes blood flow through these gill arches to the lungs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051560205
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  • 5
    Electronic Resource
    Electronic Resource
    Down-regulation of gonadotropin and β-adrenergic receptors by hormones and cyclic AMP (1985)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 27 (1985), S. 231-239 
    Details
    ISSN: 0730-2312
    Keywords: adenylate cyclase ; hormone receptors ; cyclic AMP ; down-regulation ; desensitization ; β-adrenergic receptors ; gonadotropin receptors ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Loss of gonadotropin receptors in murine Leydig tumor cells and of β-adrenergic receptors in rat glioma C6 cells occurred following exposure of the cells to human chorionic gonadotropin and isoproterenol, respectively. Down-regulation of receptors was mimicked in part by other agents that elevated cyclic AMP levels in the cells such as cholera toxin and dibutyryl cyclic AMP. Whereas agonist-mediated receptor loss was rapid and almost total, down-regulation by cyclic AMP was slower and less extensive. Down-regulation of receptors did not appear to be accompanied by loss of the regulatory and catalytic components of adenylate cyclase. Hormone-mediated down-regulation was preceded by desensitization of hormone-stimulated adenylate cyclase. In contrast, there was no evidence that cyclic AMP caused desensitization. Finally, loss of receptors induced either by agonists or cyclic AMP required protein synthesis as cycloheximide inhibited down-regulation. We conclude that down-regulation of receptors in these cells is a complex process involving both cyclic AMP-independent and -dependent events.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240270305
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  • 6
    Electronic Resource
    Electronic Resource
    Stimulation of phospholipase A2 activity by oxygen-derived free radicals in isolated brain capillaries (1985)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 27 (1985), S. 449-453 
    Details
    ISSN: 0730-2312
    Keywords: phospholipid degradation ; phospholipase A2 ; free radicals ; brain capillaries ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: An exogenous free radical generating system added to isolated brain capillaries induces degradation of phospholipids. This inductive effect reflects increased phospholipase activities as measured by fatty acid composition of various phospholipid fractions. The correlation of phospholipid degradation with stimulation of phospholipases was further investigated by using cationic amphiphilic agents, which are known to be phospholipase A2 inhibitors. The breakdown of phospholipids was inhibited by the pretreatment of isolated capillaries with these drugs.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240270413
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  • 7
    Electronic Resource
    Electronic Resource
    Estivation in Protopterus (1986)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 190 (1986), S. 237-248 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Estivation in Protopterus is an episodic event characterized by elaboration of a cocoon as ambient water is withdrawn, a state of torpor, and distinctive cardiorespiratory and metabolic changes. Among the more striking of these features is a decrease in oxygen consumption, a complete reliance on air breathing to satisfy metabolic need, a slowing of the heart rate, and a drop in blood pressure. The initiating mechanism for these dramatic changes is not known. As yet, specific “estivating factors” have not been identified. However, the pattern of decrease in oxygen uptake during estivation and starvation are quite similar, suggesting that a common factor may be involved in both. Attempts to implicate suppression of thyroid function in the onset of estivation have been unconvincing. Although initiating mechanisms for estivation in Protopterus remain uncertain, once estivation sets in a variety of adaptive changes occur that enable the estivating lungfish to survive for months to years without ingesting food or water. Among these are oliguria and a shift in metabolic pathways. Although estivation in Protopterus has been characterized with respect to cardiorespiratory and metabolic parameters, no attempt is made to extrapolate from the biologic processes in Protopterus to other lepidosirenid lungfish or to other genera.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051900416
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  • 8
    Electronic Resource
    Electronic Resource
    A critical examination of the reaction of pyridoxal 5-phosphate with human hemoglobin AoThe opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense (AR 360-5). (1989)
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 2071-2083 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyridoxylated normal adult human hemoglobin (HbAo) has been prepared using both oxygenated and deoxygenated HbAo at pH 6.8 and room temperature without the addition of Tris to produce a mixture with P50 of 30 ± 2 torr and a Hill coefficient of 2.3 ± 0.1 similar to that of the isolated adult human hemoglobin from the red blood cell. Reduction of the pyridoxylated HbAo in the oxygen-ligated form by sodium borohydride gives unacceptable levels of methemoglobin (i.e., 〉 10%). Exessive foaming and methemoglobin formation can be partially avoided using deoxyHbAo. Reduction with sodium cyanoborohydride is much gentler and gives solutions with 〈 5% methemoglobin. Both reducing agents give products with multiple components as shown by analytical chromatography. Radioautography on the isoelectric focusing gels of HbAo treated with 14C pyridoxal 5-phosphate (PLP) shows three major bands for the cyanoborohydride-reduced derivatives and a much more complex mixture of labeled molecules after the sodium borohydride reduction. When pyridoxylated hemoglobin is prepared without reduction, the preparation, after passage through a mixed-bed resin, contains 0.4 equivalents of PLP per heme, and has a P50 of 30 ± 2 torr and an n value of 2.3 similar to the values found after reduction. Upon anion exchange resin chromatography, the PLP is removed, indicating that the reaction forms a reversible Schiff base. On standing at 4°C for one month, this preparation produces a mixture of HbAo and pyridoxylated HbAo with the original P50. Methemoglobin increased to 3% during this incubation. After four months in the cold, the yield of a single chromatographic species is 70% with 20% methemoglobin. This fraction appears to be stable and can be passed through an anion exchange column without release of the PLP. Separation of the individual chains by reverse-phase chromatography indicates that the addition of PLP to HbAo is directed solely to the β-chains. This is also the case for the cyanoborohydride reduced derivatives. When NaBH4 is used for the reduction, radioactively labeled PLP is found on both the α- and β-chains.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360281204
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  • 9
    Electronic Resource
    Electronic Resource
    Reexamination of the polymerization of pyridoxylated hemoglobin with glutaraldehydeThe opinions or assertions contained herein are the private views of the authors, and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 871-882 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyridoxylated adult human hemoglobin (HbAo) was prepared using a one molar equivalent of pyridoxal 5-phosphate (PLP) per heme and reduced with either NaCNBH3 or NaBH4. A separate sample was pyridoxylated and passed through a mixed-bed ion exchange column without reduction. All three preparations had a P50 of 29 ± 2 torr and a cooperativity of n = 2.4 ± 0.1. These preparations, in both the oxy and deoxy forms, were then treated with 7 equivalents of glutaraldehyde per tetramer at pH 6.8 at 4°C and at room temperature. The polymerization invariably reduced the P50 to 18 ± 2 torr with Hill coefficients of less than 2. These solutions, with or without further reduction using NaCNBH3, all retained the PLP in differing amounts (2-3 moles/tetramer). Methemoglobin concentrations were increased during the polymerization reaction. The normal pyridoxylation procedure, using sodium borohydride reduction, resulted in a number of different molecular species. Polymerization with glutaraldehyde caused a further proliferation of molecular species that could not be separated by anion exchange chromatography or by isoelectric focusing. The extent of polymerization, estimated by gel exclusion chromatography and SDS polyacrylamide gel electrophoresis, was from 40 to 50%. Analysis of the reverse phase chromatograms, which separate the heme and the α- and β-chains, showed extensive polymerization and distribution of the radioactively labeled PLP on the protein for all preparations. All of the polymerized and pyridoxylated samples were unstable, and showed different chromatographic patterns after storage at 4°C for 1 month. Attempts to stabilize these preparations by further reduction with NaCNBH3 gave products with a lower P50 and lower cooperativity. When the reactions were conducted with a purified HbAo, heterogeneity was somewhat decreased compared to the normally used stroma-free hemoglobin, but a large number of molecular species were still formed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290602
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  • 10
    Electronic Resource
    Electronic Resource
    Polynucleotide synthesis at oligomeric templates (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 77-84 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of kinetics of polynucleotide synthesis at oligomeric templates is developed. It is shown that the dependence of oligomer efficacy on its size cannot be explained without taking into account the probability of separation of the oligomer from the growing chain. If such a possibility exists, the maximal size which can be achieved by the growing chain is determined by the ratio of the probability of proposed propagation and of the probability of separation. Without any models of the separation mechanism, the study of experimental kinetic data shows that two such mechanisms exist. Very short oligomers can be easily separated from the growing chain, but there is a critical size of oligomer after which the probability of separation is much smaller. The oligomers whose size is equal to or greater than the critical one form helices with growing chains.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1966.360040108
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