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155 results on '"Bult, Auke"'

4. Interaction between plasmid DNA and cationic polymers studied by surface plasmon resonance spectrometry

Author

Wink, Thijs, Beer, Joris de, Henniik, Wim E., Bult, Auke, and Bennkom, Wouter P. van

Subjects
Plasmids -- Genetic aspects, Extrachromosomal DNA -- Genetic aspects, Addition polymerization -- Research, Polymers -- Research, Binding energy -- Research, Chemistry
Abstract

A universal and novel strategy for the immobilization of polymers has been developed for studying the interaction between plasmid DNA and synthetic polymers with surface plasmon resonance spectrometry. The introduction of thiol moieties in polymers has been applied for a reliable determination of apparent kinetic rate constants between plasmid DNA and the nonviral carrier polymers. Thiolated poly(L-lysine) and poly[(2-dimethylamino)ethyl methacrylate] yielded reproducible sensor surfaces, contrary to the nonthiolated polymers. The knowledge of the kinetic parameters may play a crucial role in the development of nonviral carrier systems for gene therapy, because the dissociation rate constant is strongly correlated to the effectiveness of cell transfection.

Published
1999

6. Liposome-mediated enhancement of the sensitivity in immunoassays of proteins and peptides in surface plasmon resonance spectrometry

Author

Wink, Thijs, Zuilen, Steven J. van, Bult, Auke, and Bennekom, Wouter P. van

Subjects
Immunoassay -- Research, Spectrum analysis -- Equipment and supplies, Liposomes -- Usage, Resonance ionization spectroscopy -- Methods, Chemistry
Abstract

A recently developed liposome sandwich immunoassay for interferon-[Gamma] (IFN-[Gamma]), to be applied in microtiter plates, is tailored for surface plasmon resonance (SPR) spectrometry. The assay is performed on a thin ([approximately]20 nm) polystyrene layer that covers a gold surface. This way, analytical data obtained from microtiter plate technology can directly be extrapolated toward SPR. For assaying the antigen IFN-[Gamma], a 16-kDa cytokine, a capture monoclonal antibody is physically adsorbed onto the polystyrene surface. After addition of the sample containing IFN[Gamma], a biotinylated detecting antibody is added. Avidin is used as a bridging molecule between the biotinylated antibody and the biotinylated liposomes. All solutions are prepared with PBS buffer (10 mM, pH 7.4). This avoids additional changes in index of refraction caused by the use of various buffer solutions in immunoassays on microtiter plates for coating, binding, and washing procedures. It is shown that, when liposomes are used, a substantial enhancement of the detection limit is achieved. The 'liposome' strategy improves the sensitivity for the IFN-[Gamma] assay [approximately] 4 x [10.sup.4] times and the detection limit to low picomolar. The method is generally applicable to other sandwich immunoassays.

Published
1998

10. Identification of the degradation products of gonadorelin and three analogues in aqueous solution

Author

Hoitink, Marnix A., Beijnen, Jos H., Boschma, Marcel U.S., Bult, Auke, Hop, Ed, Nijholt, Jack, Versluis, Cees, Wiese, Gerard, and Underberg, Willy J.M.

Subjects
Peptides -- Analysis, Biodegradation -- Analysis, Chemistry
Abstract

Degradation products of the peptides gonadorelin and its analogues buserelin, goserelin, and triptorelin were characterized with LC/MS, chiral amino acid analysis, and FAB-MS(-MS). Differences in chemical structures of gonadorelin, its analogues, and their respective decomposition products were evaluated in relation to the putative degradation mechanisms. In acidic solution, gonadorelin and triptorelin are deamidated, whereas buserelin and goserelin undergo debutylation. In the pH range 5-6, the peptide backbone of all four analogues is hydrolyzed at the N-terminal side of the 4serine residue. The hydroxyl moiety of the 4serine residue catalyzes this hydrolysis. Goserelin possesses an azaglycinamide residue, which is also subject to degradation in the neutral pH region. At pH > 7, 4serine epimerization is the main pathway of degradation of all four peptides. Parallel to the epimersation, hydrolysis of gonadorelin, goserelin, and triptorelin occurs.

Published
1997

11. Abstracts of lectures and posters pharmaceutical and biomedical analysis meeting

Author

Ackermans, Mariëtte, Endert, Erik, Aluoch, J., Ouintens, I., Roets, E., Hoogmartens, J., Barka, G., Opper, C., Kerkdijk, H., Witte, D. T., Bruggeman, F. J., Franke, J. P., Copinga, S., Jansen, J. M., de Zeeuw, R. A., Bosman, I. J., Ensing, K., Dekker, I., Dams, Ir. A. B. J. M., de Pooter, Ch. M. J., Fichtinger-Schepman, A. M. J., Scalliet, P. G., Maes, R. A., Berends, F., Van Oosterom, A. T., de Bruijn, E. A., Fay, L. A., Verstappen, C. J., Pluijms, W., Irth, H., Oosterkamp, A. J., van der Welle, W., Khan, K., Paesen, J., Jacobs, Peter L., de Vries, Marcel P., Lammers, Norbert, Biermans, Frans, de Witte, Eric, Mussche, Philippe, Lamoree, M. H., Reinhoud, N. J., Tjaden, U. R., Niessen, W. M. A., van der Greef, J., Solie, A., Paulus, Aran, Klockow, Antje, Bruin, Gerard J. M., Reubsaet, J. L. E., Beijnen, J. H., Bult, A., Teeuwsen, J., Koster, E. H. M., Waterval, J. C. M., Underberg, W. J. M., Cypers, W., Claeys, P., Simonian, M. H., Rongen, Herman A. H., van der Horst, Helma M., Bult, Auke, van Bennekom, Wout P., Šmisterová, J., Thoithi, G., Van Schepdael, A., Wouters, K., Herdewijn, P., Vendrig, D., Gout, E., van Santvoort, P. M. J., Hamelinck, R. L. A. E., van Zeeland, M. J. M., Janssen, P. S. L., Vervoort, R. J. M., Derksen, M. W. J., Maris, F. A., Yongxin, Zhu, Hendrix, C., Busson, R., and Janssen, G.

Published
1994
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14. Structural identification of the degradation products of the antitumor peptide antagonist (Arg6, D-Trp7,9, MePhe8)substance P(6-11)

Author

Reubsaet, J. Leon E., Beijnen, Jos H., Bult, Auke, Vermaas, Raymond, Kellekule, Yunus, Kettenes-van den Bosch, J. Jantien, Underberg, Willy J.M., and Hop, Ed

Subjects
Antineoplastic agents -- Research, Peptides -- Research, Substance P -- Antagonists, Chemistry
Abstract

The basic hexapeptide antagonist [Arg6,D-Trp7,9,MePhe8]substance P (6-11) was degraded in acid and alkaline media. In acid solution, only one degradation product is found whereas in alkaline solution at least six products are formed. These compounds were analytically characterized and structurally identified by reversed-phase high-performance liquid chromatography, capillary electrophoresis, liquid chromatography/mass spectrometry, fast atom bombardment tandem mass spectrometry, optical rotation analysis, and chiral gas chromatography. The product formed in acidic solution is the terminally deamidated antagonist [[Arg.sup.6],D-[Trp.sup.7,9],Me[Phe.sup.8]]substance P (6-11); this product was also found in alkaline degradation mixtures. Other important degradation products originate from racemization of the amino acid residue L-Met, formation of ornithine from Arg, and the oxidation of Met to its sulfoxide form.

Published
1995

16. Etoposide

Author

Holthuis, Joost J.M., primary, Kettenes-van den Bosch, J. Jantina, additional, and Bult, Auke, additional

Published
1990
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17. Teniposide

Author

Kettenes-Van Den Bosch, J.Jantina, primary, Holthuis, Joost J.M., additional, and Bult, Auke, additional

Published
1990
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19. Substitution of didanosine sachets by chewable tablets: a pharmacokinetic study in patients with AIDS

Author

Burger, David, Meenhorst, Pieter, Mulder, Jan, Henrichs, Jeanette, Frissen, Jos, Kroon, Frank, Napel, Chris ten, Koks, Kees, Bult, Auke, and Beijnen, Jos

Subjects
Didanosine -- Dosage and administration, AIDS (Disease) -- Drug therapy, Health
Abstract

A tablet form of the AIDS drug didanosine (ddI) may be just as effective as a previously used sachet form of the drug. Researchers analyzed the differences in absorption into the blood of the tablet and sachet forms of ddI in 15 AIDS patients. The tablet form was better absorbed into the blood than was the sachet form, and the lower dosage of the tablets was as effective as the higher dose sachets. Patients with low body weights of less than 60 kg were given lower doses of ddI to match their low weight. They experienced low plasma levels of ddI, so ddI dosage may need to have a lower limit of 60 kg of body weight. The tablet form of ddI was created to increase patient acceptance and absorption into the blood.

Published
1995

26. Mitomycin C

Author

Beijnen, Jos H., primary, Bult, Auke, additional, and Underberg, Willy J.M., additional

Published
1987
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31. On‐line coupling of size‐exclusion chromatography and capillary zone electrophoresis via a reversed‐phase C18 trapping column for the determination of peptides in biological samples

Author

Stroink, Thom, primary, Schravendijk, Pim, additional, Wiese, Gerard, additional, Teeuwsen, Jan, additional, Lingeman, Henk, additional, Waterval, Joop C. M., additional, Bult, Auke, additional, de Jong, Gerhardus J., additional, and Underberg, Willy J. M., additional

Published
2003
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