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  • 1
    Electronic Resource
    Electronic Resource
    Conformational aspects of polypeptides. XXV. Solvent and temperature effects on the conformations of copolymers of benzyl and methyl L-aspartate with nitrobenzyl L-aspartateFor previous paper in this series, see Mark and Goodman. (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1579-1603 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of copolymers of β-p-nitrobenzyl L-aspartate with β-benzyl L-aspartate and with β-mcthyl L-aspartatc in helix-supporting and helix-breaking conditions have been reexamined by using ultraviolet isotropic, absorption, optical rotatory dispersion, and circular dichroism techniques. Many different conformations are apparent, depending on solvent and temperature. Chloroform, trifluoroethanol, and methylene dichloride support the left-handed helical conformation of the copolymers containing less than about 20 mole-% nitroaromatic residues and the right-handed helical conformation of the copolymers containing more than approximately 30 mole-% nitroaromatic residues. In trifluoroacetic acid all the copolymers are in a random-coil conformation. In hexa-fluoroacetone trihydrate and in trimethyl phosphate, the copolypeptides with low nitroaromatic residues content are predominantly in a disordered conformation, while those with high nitroaromatic residues content show a right-handed helical array. Reversible helix-ramlom-coil transitions are observed with increasing temperature in trimethyl phosphate. An example of right-handed-left-handed helix reversible transition with temperature is reported in a chloroform-trimethyl phosphate (2:1) mixture. Nitrobenzyl-nilrobenzyl side-chain interactions in chloroform, but not in trifluoroacetic acid or in trimethyl phosphate, have been confirmed. For the first time we report the circular dichroism spectra in which the n-π* peptide band of a left-handed helical conformation is almost completely evident.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1968.360061106
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  • 2
    Electronic Resource
    Electronic Resource
    Carbon combinations. Rapid thermal processing. Edited by Richard B. Fair, Academic Press, San Deigo 1993, XII, 430 pp., hardcover, ISBN 0-12-247690-5 (1994)
    Weinheim : Wiley-Blackwell
    Advanced Materials 6 (1994), S. 178-178 
    Details
    ISSN: 0935-9648
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19940060226
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  • 3
    Electronic Resource
    Electronic Resource
    Determining molecular weight distributions of antigen-antibody complex by quasi-elastic light scattering (1991)
    New York : Wiley-Blackwell
    Biopolymers 31 (1991), S. 1289-1295 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Physiological properties of soluble antigen-antibody (Ag-Ab) complexes depend in part on the size of the complexes. In previous work, the size distribution and structure of model Ag-Ab complexes were determined by electron microscopy. In this study, we used constrained regularization analysis of quasi-elastic light scattering data to estimate molecular weight distributions of model Ag-Ab complexes. A conformational model was necessary to determine appropriate correlations between molecular weight and diffusion coefficient, and to estimate particle structure factors. Porod-Kratky theory proved to be an adequate conformational model for these purposes. The molecular weight distributions determined by constrained regularization compared favorably with distributions obtained either by electron microscopy or by thermodynamic modeling.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360311107
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  • 4
    Electronic Resource
    Electronic Resource
    Selective peptidic and peptidomimetic inhibitors of Candida albicans myristoylCoA: Protein N-myristoyltransferase: A new approach to antifungal therapy (1997)
    New York : Wiley-Blackwell
    Biopolymers 43 (1997), S. 43-71 
    Details
    ISSN: 0006-3525
    Keywords: antifungal therapy ; Candida albicans ; peptidic inhibitors ; peptidomimetic inhibitors ; myristoylCoA ; protein N-myristoyltransferase ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: MyristoylCoA: protein N-myristoyltransferase (NMT) catalyzes the cotranslational covalent attachment of a rare cellular fatty acid, myristate, to the N-terminal Gly residue of a variety of eukaryotic proteins. The myristoyl moiety is often essential for expression of the biological functions for these proteins. Attachment of C14:0 alone provides barely enough hydrophobicity to allow stable association with membranes. The partitioning of N-myrisotyl-proteins is therefore often modulated by “switches” that function through additional covalent or noncovalent modifications.Candida albicans, the principal cause of systemic fungal infection in immunocompromised humans, contains a single NMT gene that is essential for its viability. The functional properties of the acylCoA binding site of human and C. albicans NMT are very similar. However, there are distinct differences in their peptide binding sites. An ADP ribosylation factor (Arf) is included among the few cellular protein substrates of the fungal enzyme. Alanine scanning mutagenesis of an octapeptide derived from an N-terminal Arf sequence (GLYASKLS-NH2) disclosed that Gly1, Ser5, and Lys6 play predominant roles in binding. ALYASKLS-NH2 is an inhibitor competitive for peptide [Ki(app) = 15.3±6.4 μM] and noncompetitive for myristoylCoA. Remarkably, replacement of the N-terminal tetrapeptide with an 11-aminoundecanoyl group results in a competitive inhibitor (11-aminoundecanoyl-SKLS-NH2) that is ∼ 40-fold more potent [Ki(app) = 0.40 ± 0.03 μM] than the starting octapeptide. Removal of Leu-Ser from the C-terminus generates a competitive dipeptide inhibitor (11-aminoundecanoyl-SK-NH2) with a Ki(app) of 11.7 ± 0.4 μM, equivalent to that of the starting octapeptide. A derivative dipeptide inhibitor containing a C-terminal N-cyclohexylethyl lysinamide moiety has the advantage of being more potent (IC50 = 0.11 ± 0.03 μM) and resistant to digestion by cellular carboxypeptidases. Rigidifying the flexible aminoundecanoyl chain results in very potent general NMT inhibitors (IC50 = 40-50 nM). Substituting a 2-methylimidazole for the N-terminal amine and adding a benzylic α-methyl group with R streochemistry to the rigidifying element produces even more potent inhibitors (IC50 = 20-50 nM) that are up to 500-fold selective for the fungal compared to human enzyme. A related less potent member of this series of compounds in fungistatic. Its growth inhibitory effects are associated with a reduction in cellular protein N-myristoylation, judged using cellular Arf as a reporter. These studies establish that NMT is a new antifungal target. © 1997 John Wiley & Sons, Inc. Biopoly 43: 43-71, 1997
    Additional Material: 75 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Interaction of poly(methyl methacrylate) and manganese chloride (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1133-1141 
    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: The thermal degradation of poly(methyl methacrylate) (PMMA), in the presence of manganese chloride has been studied by sealed tube reactions and thermogravimetric analysis coupled to FT-IR spectroscopy. From sealed tube reactions it was found that the degree of mixing of the MnCl2 and PMMA has an important effect on monomer formation. In systems where the two components are simply poured together, the amount of monomer is about half that observed for the thermolysis of PMMA alone; when the two components are thoroughly mixed by dissolution in solvent, the monomer yield fails to zero. The TGA-FT-IR experiment on solvent mixed material does show the presence of monomer. In sealed tubes, monomer may not escape and must repolymerize, while in the TGA experiment the monomer is swept out before reaction may occur. Monomer production also commences at temperatures lower than those for degradation of PMMA alone. It is apparent that manganese chloride catalyzes both the degradation of polymer to monomer and the reoligomerization of this monomer. The gases that are produced include CO, CO2, CH3Cl, HCl, and CH4. A mechanism is proposed to account for all of these products and a manganese ionomer is the final product of the reaction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420427
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  • 6
    Electronic Resource
    Electronic Resource
    The interaction of poly(methyl methacrylate) and chromium chloride: Transfer of methyl groups from the ester to the main chain (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1095-1102 
    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: The interaction of transition-metal halides with poly(methyl methacrylate) (PMMA) has been studied in the past and methyl halides are always observed as a product of the reaction. When CrCl3 is used as an additive for PMMA, only traces of methyl-containing products are seen and these only at quite high temperatures. The principal volatile products consist of carbon dioxide, carbon monoxide, and monomer, while the nonvolatile residue contains a multitude of methylene and methine carbons. A mechanism is invoked by which the ester methyl is transferred to the polymer backbone in a concerted process.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460618
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  • 7
    Electronic Resource
    Electronic Resource
    Interaction of poly(methyl methacrylate) and nafions (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 901-909 
    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: The thermal degradation of Nafion-H, Nafion-K, and the mixture of each of these with poly(methyl methacrylate) (PMMA) has been studied. A mechanism is proposed for the thermal degradation of Nafion-H that involves an initial cleavage of the carbon-sulfur bond leading to SO2 and OH radical and a carbon-based radical. This carbon-based radical then undergoes further degradation. The addition of PMMA to Nafion-H inhibits further degradation of the Nafion carbon-based radical and instead radical recombination reactions between PMMA fragments and this Nafion radical dominate the reaction scheme. The replacement of the hydrogen in Nafion-H with a potassium (i.e., Nafion-K) produces a much more robust material that does not degrade under conditions similar to those used for Nafion-H. Nafion-K has little effect on the degradation of PMMA.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420404
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  • 8
    Electronic Resource
    Electronic Resource
    Polyester prostheses as substitutes in the thoracic aorta of dogs. II. Evaluation of albuminated polyester grafts stored in ethanol (1984)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 18 (1984), S. 1059-1072 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In an attempt to find an alternative procedure to the preclotting of porous textile vascular prostheses, the feasibility of an albumin coating and ethanol preservation technique has been evaluated by implanting albuminated polyester prostheses as substitutes in the thoracic aorta of dogs. Nine different grafts representing woven, knitted, and velour constructions were implanted for periods ranging from 4 h to 6 months. At the sacrifice, the grafts were excized for measurement of the thrombogenicity of the flow surface, for pathological examination by light microscopy and SEM, and for quantifying the changes in the textile structure during implantation. Also the kidneys were removed and examined for infarcts caused by trapped circulating emboli. The healing characteristics of the nine different grafts proved similar and followed the same sequence of events as preclotted control grafts. The albumin coating and ethanol preservation resulted in a somewhat slower rate of healing. Yet, given sufficient time, a more completely healed graft was achieved as evidenced by the presence of endothelial-like cells throughout the length of the graft. In addition, the albumin is believed to reinforce the textile structure by reducing the tendency to stretch and dilate in vivo.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820180909
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  • 9
    Electronic Resource
    Electronic Resource
    Polyester prostheses as substitutes in the thoracic aorta of dogs. I. Evaluation of commercial prostheses (1983)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 17 (1983), S. 1049-1077 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Using canine models, a representative selection of polyester or Dacron vascular prostheses, including woven, knitted, and velour types, were evaluated for their relative healing characteristics and for their structural changes during implantation. Following residence periods ranging from 4 h to 6 months at the site of the thoracic aorta, the dogs were sacrified, and the grafts were excized for measurement of the thrombogenicity of the flow surface and for pathological examination by light microscopy and SEM. The kidneys were also removed and examined for infarcts caused by any trapped circulating emboli. The extent of healing, the presence of embolizing nuclei, and the thrombogenicity and morphology of the lumen surface were also assessed. The healing characteristics of each type of device proved similar. Velour fabrics exhibited more extensive encapsulation, but frequently their internal capsules failed to incorporate all the fibers. In all cases, cellular development on the lumen was limited to areas contiguous to the anastomoses. The initial porosity of the devices as measured by water permeability did not appear to influence the healing sequence to a significant extent. The grafts did exhibit differences in structural stability depending on whether they were of a knitted or woven construction. We suggest that users consider these different mechanical and structural properties when making their choice of a graft. Despite these differences, we believe that the healing process is far more host dependent than graft dependent.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820170614
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  • 10
    Electronic Resource
    Electronic Resource
    Controlling cell interactions by micropatterning in co-cultures: Hepatocytes and 3T3 fibroblasts (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 34 (1997), S. 189-199 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The repair or replacement of damaged tissues using in vitro strategies has focused on manipulation of the cell environment by modulation of cell-extracellular matrix interactions, cell-cell interactions, or soluble stimuli. Many of these environmental influences are easily controlled using macroscopic techniques; however, in co-culture systems with two or more cell types, cell-cell interactions have been difficult to manipulate precisely using similar methods. Although microfabrication has been widely utilized for the spatial control of cells in culture, these methods have never been adapted to the simultaneous co-cultivation of more than one cell type. We have developed a versatile technique for micropatterning of two different cell types based on existing strategies for surface modification with aminosilanes linked to biomolecules and the manipulation of serum content of cell culture media. This co-culture technique allowed manipulation of the initial cellular microenvironment without variation of cell number. Specifically, we were able to control the level of homotypic interaction in cultures of a single cell type and the degree of heterotypic contact in co-cultures over a wide range. This methodology has potential applications in tissue engineering, implant biology, and developmental biology, both in the arena of basic science and optimization of function for technological applications. © 1997 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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