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  • Analytical Chemistry and Spectroscopy  (9)
  • Peyer's patches  (3)
  • Two-dimensional polyacrylamide gel electrophoresis  (3)
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  • 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
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 15 (1998), S. 153-156 
    ISSN: 1573-904X
    Keywords: nanoparticles ; oral uptake ; invasin ; Peyer's patches
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 29 (1994), S. 366-371 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase ion - molecule reactions between ionized vinylamine ([CH2 = CHNH2]+.) as a set of conjugated and unconjugated dienes were studied by Fourier transform is observed. Conjugated dienes lead to the elimination of NH3 or of an hydrocarbon radical from the adduct [M + CH2 = CHNH2]+.. In the case of unconjugated dienes a regiospecific cyclobutanation-cycloreversion process is observed. Reaction mechanisms are proposed to explain these experimental findings.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 4 (1990), S. 476-480 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Reactions between CX2=CXOX+· (X = H or D) and alkenes, an alkyne, benzene, aldehydes and ketones have been studied by Fourier transform mass spectrometry. Most of the neutral species undergo charge exchange or proton transfer reactions with high rates; l-alkenes lead to slower cycloaddition reactions. The thermochemistry and considerations on the reaction specificities are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Unimolecular dissociation of the molecular cations of 1,2-expoxybutane (1), 1-methoxypropene (2), 2,3-epoxybutane (3), ethyl-vinyl ether (4), 1,2-epoxy-2-methylpropene (5), and 2-methoxypropene (6)have been investigated. Different behaviour of pairs of [C4H8O]+· isomers (1+·/2+·), (3+·/4+·) and (5+·/6+·) have been demonstrated. Isomerization by epoxide ring opening and 1,4-hydrogen migration is suggested to explain the similar unimolecular chemistry observed for the two partners of each pair of isomers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0173-0835
    Keywords: Melanie ; Computer analysis ; Two-dimensional polyacrylamide gel electrophoresis ; World Wide Web ; Federated database ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Although two-dimensional electrophoresis (2-DE) computer analysis software packages have existed ever since 2-DE technology was developed, it is only now that the hardware and software technology allows large-scale studies to be performed on low-cost personal computers or workstations, and that setting up a 2-DE computer analysis system in a small laboratory is no longer considered a luxury. After a first attempt in the seventies and early eighties to develop 2-DE analysis software systems on hardware that had poor or even no graphical capabilities, followed in the late eighties by a wave of innovative software developments that were possible thanks to new graphical interface standards such as XWindows, a third generation of 2-DE analysis software packages has now come to maturity. It can be run on a variety of low-cost, general-purpose personal computers, thus making the purchase of a 2-DE analysis system easily attainable for even the smallest laboratory that is involved in proteome research. Melanie II 2-D PAGE, developed at the University Hospital of Geneva, is such a third-generation software system for 2-DE analysis. Based on unique image processing algorithms, this user-friendly object-oriented software package runs on multiple platforms, including Unix, MS-Windows 95 and NT, and Power Macintosh. It provides efficient spot detection and quantitation, state-of-the-art image comparison, statistical data analysis facilities, and is Internet-ready. Linked to proteome databases such as those available on the World Wide Web, it represents a valuable tool for the “Virtual Lab” of the postgenome area.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rates of proton transfer and hydrogen atom abstraction between ionized enols [CH2=CHOH]+· and [CH2=C(CH3)OH]+· were measured by Fourier transform ion cyclotron resonance Spectrometry. It was observed that proton transfer is favoured by its high rate even when it does not reach the limiting collision rate. When a competition is in principle possible between H+, H· and H- transfers, only the former process is observed. This phenomenon and the low efficiency of hydrogen atom abstraction are discussed in terms of the potential energy profile, where the stability of the intermediate complexes plays a critical role.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 271-278 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrogen atom abstraction and cycloaddition-cycloreversion reactions between ionized vinylamine and neutral olefins were studied in a Fourier transform ion cyclotron resonance spectrometer. The efficiencies of both processes are appreciably less than unity. The trend in reaction efficiencies is consistent with the presence of a substantial intrinsic barrier but interpretation based on constraints inherent to the approach of the reactants cannot be discarded. The regioselectivity observed during the cycloaddition-cycloreversion reactions closely parallels the nucleophilic attack of an olefin by a free radical. The thermochemistry of these reactions and partial potential energy surfaces were examined with the help of experimental data and molecular orbital calculations (MP2/6-31G*//3-21G).
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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