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  • Polymer and Materials Science  (28)
  • Metastasis  (1)
  • Na+/Ca2+ exchange  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Galectins-1 and -3 and their ligands in tumor biology (1999)
    Springer
    Journal of cancer research and clinical oncology 125 (1999), S. 461-474 
    Details
    ISSN: 1432-1335
    Keywords: Key words Cell adhesion ; Galectin ; Lectin ; Liposome ; Matrix glycoproteins ; Metastasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Protein (lectin)-carbohydrate (cellular glycoconjugate) recognition is operative in biochemical information transfer. Galectins constitute a family of endogenous galactoside-binding lectins with conserved features in the binding site. The members of this lectin category are assumed to be involved in cell adhesion and growth regulation. To assess to what extent the different modes of binding-site presentation and/or carbohydrate fine-specificities will affect aspects of galectin behavior, homodimeric cross-linking galectin-1 and monomeric chimeric galectin-3, with its collagenase-sensitive stalk linked to the carbohydrate-recognition domain, were investigated. Cell-surface expression of the two galectins and accessible galectin-binding sites on various tumor cell lines was ascertained by FACScan analysis. In particular, ligand accessibility for the two galectins differed for the tested cell line types. Binding of tumor cells to laminin and plasma or placental fibronectin was generally reduced by treatment of cells or matrix with galectins. Galectin-3 was more efficient than galectin 1 at impairing laminin's potency as matrix. Cell binding of galectin-1, on the other hand, proved on average more effective for blocking cell association to fibronectins after its preincubation with cell suspensions. Differences were also apparent in the biodistribution of the galectins, where an avian homolog of galectin-1 served as the control to distinguish effects of spatial and sugar-binding features. Histopathological analysis of lymph-node-negative and -positive breast and colorectal carcinomas (n = 180 including 60 metastatic lesions) indicated a correlation of either increased galectin-1 binding and reduced galectin-3 expression or reduced binding of both galectins with the occurrence of lymph node lesions. Together with data on the heparin-binding lectin, revealing reduced expression to be associated with a positive lymph-node status in the breast cancer group, these results can be interpreted to reflect cell-type-dependent requirements of galectin ligand presentation during the metastatic cascade. By introducing mammalian lectins to lectin-histochemical studies, the detection of quantitative differences in glycosylation brings an understanding of its cell biological significance one step closer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004320050303
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  • 2
    Electronic Resource
    Electronic Resource
    Oxygen free radicals and calcium homeostasis in the heart (1994)
    Springer
    Molecular and cellular biochemistry 135 (1994), S. 99-108 
    Details
    ISSN: 1573-4919
    Keywords: sarcolemma ; myofibrils ; Na+/Ca2+ exchange ; sarcoplasmic reticulum ; cardiac contraction ; Ca2+ pump
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Many experiments have been done to clarify the effects of oxygen free radicals on Ca2+ homeostasis in the hearts. A burst of oxygen free radicals occurs immediately after reperfusion, but we have to be reminded that the exact levels of oxygen free radicals in the hearts are yet unknown in both physiological and pathophysiological conditions. Therefore, we should give careful consideration to this point when we perform the experiments and analayze the results. It is, however, evident that Ca2+ overload occurs when the hearts are exposed to an excess amount of oxygen free radicals. Though ATP-independent Ca2+ binding is increased, Ca2+ influx through Ca2+ channel does not increase in the presence of oxygen free radicals. Another possible pathway through which Ca2+ can enter the myocytes is Na+−Ca2+ exchanger. Although, the activities of Na+−K+ ATPase and Na+−Ca2+ exchanger. Although, the activities of Na+−H+ exchange are inhibited by oxygen free radicals, it is not known whether intracellular Na+ level increases under oxidative stress or not. The question has to be solved for the understanding of the importance of Na+−Ca2+ exchange in Ca2+ influx process from extracellular space. Another question is ‘which way does Na+−Ca2+ exchange work under oxidative stress? Net influx or efflux of Ca2+?’ Membrane permeability for Ca2+ may be maintained in a relatively early phase of free radical injury. Since sarcolemmal Ca2+-pump ATPase activity is depressed by oxygen free radicals, Ca2+ extrusion from cytosol to extracellular space is considered to be reduced. It has also been shown that oxygen free radicals promote Ca2+ release from sarcoplasmic reticulum and inhibit Ca2+ sequestration to sarcoplasmic reticulum. Thus, these changes in Ca2+ handling systems could cause the Ca2+ overload due to oxygen free radicals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00925965
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  • 3
    Electronic Resource
    Electronic Resource
    Additive effect of poly(ethylene oxide), 3.Part 2: cf. Akira Hirao, Seiichi Nakahama, Mitsuru Takahashi, and Noboru Yamazaki, Makromol. Chem. 179, 1735 (1978). Retardation effect of poly(ethylene oxide) in the reduction of aldehydes and ketones with sodium borohydride (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 2343-2347 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790923
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  • 4
    Electronic Resource
    Electronic Resource
    Acceleration effect of acids on the co-dimer formation from 1-(4-chlorophenyl)ethyl esters and styrene (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 1-7 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A linear unsaturated co-dimer of styrene and p-chlorostyrene, 1-phenyl-3-(4-chlorophenyl)-1-butene (2), was preferentially produced by reaction of 1-(4-chlorophenyl)ethyl diphenyl phosphate (1) with styrene. The reaction was found to be extraordinarily accelerated by addition of trifluoromethanesulfonic acid. 1-(4-chlorophenyl)ethyl acetate reacts readily with styrene in the presence of trifluoromethanesulfonic acid to afford 2 in good yields, whereas the acetate is inert toward styrene in the absence of a super acid.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021850101
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  • 5
    Electronic Resource
    Electronic Resource
    Additive effect of poly(ethylene oxide), 2.Part 1: cf.6a. An acceleration effect of poly(ethylene oxide) in a williamson reaction (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 1735-1741 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The additive effect of poly(ethylene oxide) (PEO) in the Williamson reaction between sodium phenolate and butyl bromide was investigated. Under certain conditions a remarkable rate acceleration by PEO was observed in this reaction, which is explained by the fact that a cooperative coordination of oxygen atoms of PEO with metal cations promotes ion dissociation. The relationship between the formation of a PEO-sodium phenolate complex and the reaction rate, and also the dependency of the reaction rate on the molecular weight of PEO were examined.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790708
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  • 6
    Electronic Resource
    Electronic Resource
    Polycondensation of amino acids by means of diphenyl phosphite in the presence of pyridineStudies on Reactions of the N-Phosphonium Salts of Pyridines, Part 9. (1974)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 1825-1831 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Bei der direkten Polykondensation von freien α-Aminosäuren und Dipeptiden mit Diphenylphosphit (1) in Pyridin wurden lineare Polypeptide mit hohen Molekulargewichten erhalten. Die Reaktion wurde beeinflußt durch Lösungsmittel, tertiäre Amine, Aminosäurekonzentration und Temperatur. Die Copolykondensation wurde ebenfalls mit verschiedenen optisch aktiven oder inaktiven Aminosäuren ausgeführt. Die Zusammensetzungen der Copolypeptide wurden mit denen, die nach der NCA-Methode erhalten werden, verglichen.
    Notes: Linear polypeptides of high molecular weights were obtained by the direct polycondensation reactions of free α-amino acids and dipeptides with diphenyl phosphite (1) in pyridine. The reaction was affected by solvent, tertiary amine, amino acid concentration, and temperature. The copolycondensation was also carried out using various couples of optically active or inactive amino acids. The compositions of the copolypeptides were compared with those by the NCA method.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1974.021750611
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  • 7
    Electronic Resource
    Electronic Resource
    Additive effect of poly(ethylene oxide), 1 acceleration effect of poly(ethylene oxide) in several nucleophilic reactions (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 915-925 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The additive effect of poly(ethylene oxide) (PEO) in several nucleophilic reactions, such as the oxidation of trans-stilbene with potassium permanganate, the alkylation of potassium acetate and diethyl benzylsodiomalonate as well as the Williamson reaction of sodium phenoxide with alkyl bromides was investigated and compared with that of dibenzo-18-crown-6 (crown ether). A marked effect by PEO was observed under certain conditions, which was explained by a cooperative coordination of the oxygen atoms of PEO with metal cations promoting ion dissociation and resulting in the observed remarkable rate acceleration.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790406
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  • 8
    Electronic Resource
    Electronic Resource
    Anionic and radical polymerization of p-triphenyl- and p-tributylgermyl-styrenes (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 961-967 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Anionic polymerization of p-triphenylgermylstyrene (1a) and p-tributylgermylstyrene (1b) were investigated under high vacuum conditions (≈10-6 mbar). Both 1a and 1b were readily polymerized with sodium naphthalide, potassium naphthalide, or α-methylstyrylsodium oligomers to form “living polymers”. The addition of α-methylstyrene to these living systems gave the triblock copolymer, poly(α-methylstyrene-b-p-triphenylgermylstyrene-b-α-methylstyrene). Both monomers were also polymerized radically with AIBN as initiator. Some physical properties of the resulting polymers were examined.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840508
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of polymers with primary amino end groups, 2Part 1: cf.6.. Synthesis of polyisoprene with primary amino end groups and poly(isoprene-b-γ-benzyl-L-glutamate)s (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1355-1362 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Primary amine terminated polyisoprene 2 was produced by reaction of anionic living polyisoprene with one of the following protected aminating reagents: N-(benzylidene)trimethylsilylamine (1a). N-(1-phenylpentylidene)trimethylsilylamine (1b), N-benzylidenebenzenesulfeneamide (1c), or N,N-bis(trimethylsilyl)-2-bromoethylamine (3). Especially with 1a, the terminal amino group was quantitatively introduced at the end of the polymer chain. 2 was found to initiate the polymerization of the N-carboxy anhydride of γ-benzyl-L-glutamate 5 to afford poly(isoprene-b-γ-benzyl-L-glutamate) (6).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840704
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  • 10
    Electronic Resource
    Electronic Resource
    Peptide synthesis by using polymer-supported N-acylphosphoramidites (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 1803-1810 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Diethoxyphosphino-substituted acetamides (1 and 2) and the polymer gel bearing dialkoxy-phosphino groups (3,4, and 5) were prepared by reaction of chlorophosphites with acetamide and crosslinked polyacrylamides, respectively, in the presence of triethylamine. By using 1,2 and the polymer as condensing reagents, various peptides were synthesized directly from N-protected amino acids and amino acid esters in high yields with little racemization. The highly crosslinked polymeric reagents simplified the procedure and were recycled by treatment with chlorophosphites.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860909
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