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  • Chemistry  (75)
  • Peyer's patches  (3)
  • Two-dimensional polyacrylamide gel electrophoresis  (3)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 707-710 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The design and use of an experimental device for investigating the time-dependent structure of an electrospray current is described. Various electrolytes, including aqueous solutions, were submitted to electrospray and the instantaneous current intensities were monitored by means of a fast current measurer. The intensity proved discontinuous and roughly periodic in almost every case. By recording the intensity pattern on a fast oscilloscope, an estimate of the ‘period’ was obtained. A typical structure (obtained from a 10 mM NaBr methanolic solution, ‘reduction mode’) consists of series of groups of peaks. The charge per peak is approximately 10-10C and does not change much with the experimental parameters (electrolyte concentration, nature of the solvent, value of the high voltage). The current variation seems to be mainly related to the number of peaks rather than to the heights of the peaks. These results are consistent with commonly observed averaged spray intensities (0.1 to 1 μA) and suggest a pulsed droplet emission frequency of the order of 300 kHz.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 14 (1997), S. 613-618 
    ISSN: 1573-904X
    Keywords: tomato lectin ; Peyer's patches ; nanoparticles ; oral uptake ; bioadhesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To investigate the usefulness of a surface-conjugated, bioadhesive molecule, tomato lectin, to augment intestinal uptake of orally administered inert nanoparticles. Methods. Fluorescent 500 nm polystyrene nanoparticles with tomato lectin covalently surface coupled using a carbodiimide reaction were administered to female Wistar rats by oral gavage daily for 5 days. Results. Analysis of tissue extracted polymer by gel permeation chromatography revealed a 23% systemic uptake of tomato lectin conjugated nanoparticles compared to 〈 0.5% of TL nanoparticles blocked with N-acetylchitotetraose thus representing an increase of almost 50 fold across the intestine. Intestinal uptake of tomato lectin-conjugated nanoparticles via the villous tissue was 15 times higher than uptake by the gut-associated lymphoid tissue. Conclusions. The application of tomato lectin as a bioadhesive agent in vivo has been demonstrated to enhance subsequent intestinal transcytosis of colloidal particulates to which it is bound.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 14 (1997), S. 259-266 
    ISSN: 1573-904X
    Keywords: microparticles ; Peyer's patches ; GALT ; particle absorption ; oral delivery ; lymphatics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This mini-review covers some of the historical and recent arguments over the experimental evidence on the uptake by and translocation from the intestinal mucosa of microparticulates after oral administration. It is concluded that there is now no dispute over the fact that this is a normal occurrence. Particulate uptake does take place, not only via the M-cells in the Peyer's patches and the isolated follicles of the gut-associated lymphoid tissue, but also via the normal intestinal enterocytes. Factors affecting uptake include particle size, surface charge and hydrophobicity and the presence or absence of surface ligands. The covalent attachment of lectin or invasin molecules to the surface of carrier particles leads to greater systemic uptake. Whether or not the route can be utilized for the routine administration of therapeutic agents which are not normally absorbed from the gut is not yet proven. Many studies show that 2−3% of the ingested dose of submicron particles can be absorbed. The increasing diversity of carrier systems, which includes dendrimers and liposomes, needs to be exploited fully. More also must be learned about the inter- and intra-subject variability of lymphoid tissue so that appropriate selectivity can be achieved through the design of specific carriers.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Combination of a receptor unit with a rigid shaping unit produces a new type of receptor molecules of the cryptand class, hollow macropolycyclic molecules termed speleands, capable of substrate inclusion. Two members of this category of compounds 1 and 2, have been synthesized by connecting in a single step, a macro-cyclic [18]-N3O3 binding unit with a rigid cyclotriveratrylene unit via three bridges. Compound 1 binds the rnethylammonium cation forming both external and internal complexes; for the latter a ‘speleme’ structure, schematically represented by 15, may be proposed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of new ‘bridged’ β-cyclodextrin (β-CD) ‘dimers’ 7-12 was successfully achieved by two one-pot reactions from β-CD (3) and 6A-azido-6A-deoxy-β-CD (4). The ‘phosphine imine’ reaction was shown to be a superior approach compared to the Mitsunobu reaction as coupling strategy for the preparation of these ‘dimers’. NMR Data, along with molecular-modelling calculations, suggest a ‘helical-like’ arrangement for the phenanthroline-diyl-linked ‘dimer’ derivative 9. Complexation properties of 9 were established by UV-VIS-spectrophotometric titration toward four metals. Among them CuII or EuIII ions were complexed selectively by 9, but no complexation occurred with LaIII and ZnII. In addition a specific and interesting esterase activity toward the phosphodiester bond of bis(4-nitrophenyl) phosphate anion was found in the case of the CuII complex of 9.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1739-1746 
    ISSN: 0009-2940
    Keywords: Nitrilimines ; Phosphorus heterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions involving the λ3-phosphorus atom of N-[bis(diisopropylamino)phosphanyl)]-C-[(bis(diisopropylamino) -thio-phosphoranyl)nitrilimine (1) are reported. Addition of elemental sulfur or selenium to 1 leads, by a formal [1 + 4] cycloaddition, to 1,3,4,2λ5-thiadiazaphosphole 3a or 1,3,4,2λ5-selenodiazaphosphole 3b in 85 and 84% yield, respectively. Reactions of 1 with dimethyl acetylenedicarboxylate and tetracyanoethylene afford the corresponding [2 + 4] adducts 1,2,3λ5-diazaphosphinine 6 (80% yield) and 1,2,4,3λ5-triazaphosphinine 10 (80% yield). Phenyl azide reacts with 1 with loss of nitrogen to give 1,2,4,3λ5-triazaphosphole 15 (74% yield), while the reaction of 1 with α-diazo ketone 17 leads with conservation of the N2 grouping to the formation of 1,2,4,3λ5-triazaphosphole 20 (85% yield). Addition of methyl trifluoromethanesulfonate to 1 affords N-[bis(diisopropylamino)methylphosphonioyl]-C-[bis(diisopropylamino)thiophosphoranyl]nitrilimine 22. In contrast to 1, the new stable nitrilimine 22 is strongly electrophilic. [2 + 3] cycloadditions are observed with ethyl vinyl ether, styrene, methyl acrylate and phenylacetylene to furnish the corresponding pyrazolines 23 - 25 and pyrazole 26 in good yields. Water adds to 22 by a 1,3-addition process to give hydrazine 27 (88% yield). The lithium salt 30 of [bis(diisopropyl-amino)thiophosphoranyl](diazo)methane reacts with [bis(pentafluorophenyl)](chloro)phosphane to afford the corresponding diazo compound 32 (50% yield) while the reaction with (chloro)(phenyl)[2,4,6-tris(trifluoromethyl)phenyl]phosphane furnishes nitrilimine 33 in 82% yield. Only 1,3-addition reactions with water or diisopropylamine leading to hydrazine 34 (65% yield) and hydrazone 35 (54% yield) are observed on treatment with this new poorly reactive nitrilimine.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Among the methods to introduce functional groups in macromolecular compounds, the initiation of free radical polymerization by functional peroxyesters was investigated. m- and p-tert-butyldioxycarbonylbenzoic acids (3 and 8) were synthetized and their properties were studied. Differential scanning enthalpimetric study of the thermolysis kinetics of 3 and 8 led to the conclusion that these compounds are a little more stable than O,O-tert-butyl hydrogen monoperoxyphthalate (1). Thus, they could be applied under similar conditions. Solution and bulk polymerizations of styrene initiated by 3 or 8 were found to be efficient methods to obtain polystyrene substituted by carboxylic functions.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1855-1869 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mechanism and kinetics of the polycondensation of 4,4′-sulfonyldianiline (2) with 2,3-epoxy-1-phenoxypropane (1) were analysed in the absence or presence of a catalyst [N,N-(dimethyl)-benzylamine or BF3 complex]. Chemical data obtained by 13C NMR and HPLC show that secondary reactions (homopolymerisation, reaction of hydroxyl groups with the epoxy groups) take a prominent part.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mechanism and kinetics of the reactions of N-(2,3-epoxypropyl)-N-methylaniline (1) with aniline or 4,4′-sulfonyldianiline (3) were investigated using high performance liquid chromatography and 13C FT NMR under different conditions (110-172°C). Comparison of 1 with its derivatives shows that the activity of the 2,3-epoxypropyl group in such epoxides depends on the structure and the substituents at the benzene ring; etherification may occur already before the secondary amine is consumed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The early stage of cationic polymerization of 1,2-epoxy-3-nitropropane in the presence of ethylene glycol and borontrifluoride etherate is examined. It is shown that the reaction proceeds according to the Activated Monomer Mechanism: initiation and propagation involve the nucleophilic attack of an hydroxyl end-group moiety onto a protonated monomer molecule; this attack takes place on the carbon atom located in the β-position with regard to the —CH2NO2 group.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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