The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform
Claudio Airoldi - One of the best experts on this subject based on the ideXlab platform.
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New generation of sterically protected C18 stationary phases containing embedded urea groups for use in high-performance liquid chromatography
Journal of Chromatography A, 2002Co-Authors: César R. Silva, Isabel Cristina Sales Fontes Jardim, Claudio AiroldiAbstract:Abstract New monofunctional C18 urea stationary phases with sterically protecting dimethyl and diisopropyl groups were prepared by a single step modification process. Prontosil spherical silica (3 μm) was chemically modified with the monofunctional ethoxysilanes, [(3-octadecylurea)propyl]dimethyl and [(3-octadecylurea)propyl]diisopropyl ethoxysilanes. The phases were characterized by elemental analysis, infrared and solid-state 29Si and 13C NMR spectroscopies. Chromatographic characterizations of the new phases in 50×3.9 mm HPLC columns were performed by the separation of two different test mixtures, containing nonpolar, polar and highly basic compounds.
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Preparation of a new C18 stationary phase containing embedded urea groups for use in high-performance liquid chromatography.
Journal of chromatography. A, 2002Co-Authors: César R. Silva, Isabel Cristina Sales Fontes Jardim, Stefan Bachmann, Renata Rabelo Schefer, Klaus Albert, Claudio AiroldiAbstract:A new C18 urea stationary phase was prepared by a single-step modification process through the reaction of Prontosil spherical silica (3 microm, Bischoff) with the trifunctional alkoxysilane (CH3CH2O)3-Si-(CH2)3-NH-C(O)-NH-(CH2)17-CH3, prepared in our laboratory. The phase was characterized by elemental analysis and solid-state 29Si and 13C nuclear mangnetic resonance spectrometry. Chromatographic evaluations of the new phase in 150 x 3.9 mm HPLC columns involving the separation of different test mixtures, indicate good performance for both polar and basic mixtures and also show promising results for further applications.
Jette E. Kristiansen - One of the best experts on this subject based on the ideXlab platform.
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On the 75th anniversary of Prontosil
Dyes and Pigments, 2011Co-Authors: Mark Wainwright, Jette E. KristiansenAbstract:Abstract While much of the credit for the beginning of the “antibiotic era” is given to Fleming, the first clinically available antibacterial agents were the sulphonamides, discovered as by-products of the azo dye, Prontosil. This was given its general release, i.e., outside Germany, in 1935 and rapidly became associated with “miracle” cures, particularly in skin diseases, pneumonia and childbed fever. While the discovery of sulphanilamide as the active agent in Prontosil led to the explosion in “sulpha” drugs other, related, agents such as Marfanil and the thiosemicarbazides were also developed by the Bayer chemists, and knowledge of the breakdown of the azoic bond specifically in the colon has also led to the introduction of drug delivery approaches to that organ.
Peter Elsner - One of the best experts on this subject based on the ideXlab platform.
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Sulfonamides in dermatology.
Clinics in dermatology, 2003Co-Authors: S. Fuchs, Peter ElsnerAbstract:The first sulfonamide therapy was discovered by Domagk, who, in 1932, discovered that an orange-red sulfonamide dye named Prontosil rubrum was safe and effective in curing streptococcal infections in mice. He confirmed the effectiveness of the dye through various experiments The discovery of the sulfonamides represented the first real breakthrough in selective antimicrobial therapy. The sulfonamides (Fig 1) are synthetic bacteriostatic antimicrobials with a wide spectrum against most Gram-positive and many Gram-negative organisms. The widespread use of sulfonamides as a result of their low cost has resulted in the development of many sulfonamide-resistant strains of bacteria. In general, the sulfonamides exert only a bacteristatic effect, and cellular and humoral defense mechanisms of the host are essential for the final eradication of the infection. The earliest report on the use of sulfapyridine in a noninfectious dermatologic disease was in 1939, when it was used to treat a patient with acrodermatitis of Hallopeau. 1 The age of antibacterial chemotherapy started in 1935 when Gerhard Domagk published his successful application of “Prontosil rubrum” in animals and humans to fight streptococcal infections. The chemical agent was the azo dye sulfachrysoidine. Shortly thereafter, it was shown by another European group that this dye is metabolized to the therapeutically active, colorless sulfanilamide. 2 Various chemical modifications of this parent sulfonamide compound yielded a great number of sulfonamides with a relatively constant antibacterial spectrum yet with a widely varying number of pharmacokinetic and toxicological properties. In the beginning, sulfonamides were grouped according to their half-time of elimination. Today, we distinguish middle- and long-acting and poorly absorbed sulfonamides. Typical middle-acting sulfonamides are sulfadiazine and sulfamethoxazole, and long-acting ones are sulfalene and sulfadoxine.
César R. Silva - One of the best experts on this subject based on the ideXlab platform.
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New generation of sterically protected C18 stationary phases containing embedded urea groups for use in high-performance liquid chromatography
Journal of Chromatography A, 2002Co-Authors: César R. Silva, Isabel Cristina Sales Fontes Jardim, Claudio AiroldiAbstract:Abstract New monofunctional C18 urea stationary phases with sterically protecting dimethyl and diisopropyl groups were prepared by a single step modification process. Prontosil spherical silica (3 μm) was chemically modified with the monofunctional ethoxysilanes, [(3-octadecylurea)propyl]dimethyl and [(3-octadecylurea)propyl]diisopropyl ethoxysilanes. The phases were characterized by elemental analysis, infrared and solid-state 29Si and 13C NMR spectroscopies. Chromatographic characterizations of the new phases in 50×3.9 mm HPLC columns were performed by the separation of two different test mixtures, containing nonpolar, polar and highly basic compounds.
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Preparation of a new C18 stationary phase containing embedded urea groups for use in high-performance liquid chromatography.
Journal of chromatography. A, 2002Co-Authors: César R. Silva, Isabel Cristina Sales Fontes Jardim, Stefan Bachmann, Renata Rabelo Schefer, Klaus Albert, Claudio AiroldiAbstract:A new C18 urea stationary phase was prepared by a single-step modification process through the reaction of Prontosil spherical silica (3 microm, Bischoff) with the trifunctional alkoxysilane (CH3CH2O)3-Si-(CH2)3-NH-C(O)-NH-(CH2)17-CH3, prepared in our laboratory. The phase was characterized by elemental analysis and solid-state 29Si and 13C nuclear mangnetic resonance spectrometry. Chromatographic evaluations of the new phase in 150 x 3.9 mm HPLC columns involving the separation of different test mixtures, indicate good performance for both polar and basic mixtures and also show promising results for further applications.
Mark Wainwright - One of the best experts on this subject based on the ideXlab platform.
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On the 75th anniversary of Prontosil
Dyes and Pigments, 2011Co-Authors: Mark Wainwright, Jette E. KristiansenAbstract:Abstract While much of the credit for the beginning of the “antibiotic era” is given to Fleming, the first clinically available antibacterial agents were the sulphonamides, discovered as by-products of the azo dye, Prontosil. This was given its general release, i.e., outside Germany, in 1935 and rapidly became associated with “miracle” cures, particularly in skin diseases, pneumonia and childbed fever. While the discovery of sulphanilamide as the active agent in Prontosil led to the explosion in “sulpha” drugs other, related, agents such as Marfanil and the thiosemicarbazides were also developed by the Bayer chemists, and knowledge of the breakdown of the azoic bond specifically in the colon has also led to the introduction of drug delivery approaches to that organ.
