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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 507 (1987), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1573-904X
    Schlagwort(e): poly(lactide-co-glycolide) ; biodegradable microparticles ; (water-in-oil)-in-water emulsion ; solvent evaporation ; controlled-release vaccine ; ovalbumin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Poly(lactide-co-glycolide) (PLG) microparticles with entrapped antigens have recently been investigated as controlled-release vaccines. This paper describes the preparation of PLG microparticles with an entrapped model antigen, ovalbumin (OVA), using a (water-in-oil)-in-water emulsion solvent evaporation technique. In a series of experiments, the effects of process parameters on particle size and OVA entrapment were investigated. It was found that smooth, spherical microparticles 1–2 µm in diameter containing up to 10% (w/w) OVA could be produced using a small volume of external aqueous phase containing a high concentration of emulsion stabilizer and a 1:5 antigen:polymer ratio. PAGE analysis, isoelectric focusing, and Western blotting of OVA released from the microparticles in vitro confirmed that the molecular weight and antigenicity of the protein remained largely unaltered by the entrapment procedure.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Pharmaceutical research 10 (1993), S. 583-587 
    ISSN: 1573-904X
    Schlagwort(e): diamorphine ; percutaneous ; transdermal drug delivery ; human neonatal skin ; premature newborn ; skin esterases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The permeation kinetics of diamorphine through human premature neonatal cadaver skin over a range of gestational ages between 24 and 36 weeks was investigated using small diffusion cells. A strong inverse correlation was noted between the apparent permeability coefficient and the gestational age of the skin (P 〈 0.01; n = 26). The calculated apparent permeability coefficients decreased with gestational age from 6.0 × 10 −2 cm · hr−1 at 24 weeks' gestation to 5.2 × 10−6 cm · hr−1 at 36 weeks' gestation. The amount of diamorphine remaining bound within the skin at the end of the in vitro experiments did not change significantly with gestational age of the skin. Diamorphine was subject to degradation over the course of the in vitro experiments to produce significant amounts of 6-mono-acetylmorphine and evidence is presented to suggest that this was due to residual skin esterase activity. It is calculated that the steady-state flux rate of diamorphine through neonatal skin observed in these experiments would be sufficient to obtain a therapeutic plasma concentration of morphine assuming a 2-cm2 area for application and a delivery rate of 15 µg hr −1 kg−1. However, the prolonged half-life of morphine in the premature neonate would result in a delay of some hours before the attainment of this level.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 1573-904X
    Schlagwort(e): gastrocolonic response ; gamma scintigraphy ; drug delivery to the colon ; tablets
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The response of the colon to eating, the gastrocolonic response (GCR), may have important implications for the design of drug dosage forms for selective delivery to the colon. Therefore, the effect of meal composition on the GCR and its relation to the transit of non-disintegrating tablets has been investigated. Eight healthy male volunteers each received 5 × 6-mm radiolabeled nondisintegrating tablets, and the transit was followed using a gamma camera. When the tablets reached the ileocolonic region, each volunteer received a test meal (1000 kcal) containing 70% carbohydrate, 15% fat, and 15% protein. The subsequent movement of the tablets was then monitored. The study was repeated using a 70% fat meal and a 70% protein meal, so that the effects of a high-carbohydrate, a high-fat, and a high-protein meal on the GCR could be compared. The incidence of GCRs was similar after all meals. Thus, there appeared to be no effect of meal composition on the movement of the tablets into the colon. This implies that the ingestion of food may not necessarily stimulate the passage of material across the ileocecal junction and that other factors may also be involved.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Pharmaceutical research 13 (1996), S. 1008-1014 
    ISSN: 1573-904X
    Schlagwort(e): amphotericin B ; lecithin ; emulsion ; stability ; monolayer ; low-dimensional structures
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Purpose. To study the interaction of the polyene antifungal amphotericin B with phospholipid Langmuir monolayers and to correlate with stability of phospholipid-stabilized drug emulsions. Methods. Pressure—area isotherms of mixed monolayers of amphotericin B (0–20 mol%) and different phospholipid types were recorded using conventional Langmuir trough methods. Emulsion stability of amphotericin B-containing lipid emulsions was measured using dynamic light scattering. Results. Incorporation of amphotericin B into monolayers composed of saturated phospholipids (Lipoid E80-3) had a profound effect on the shape of the isotherm. This effect was directly related to the concentration of amphotericin B in the monolayer. At high drug concentrations, the shape of the isotherms became progressively similar to that of pure DPPC, thus exhibiting regions attributable to phospholipid in different phase states. This effect on isotherm shape was not observed following incorporation of the drug into monolayers composed of the equivalent unsaturated lecithin (Lipoid E80). Conclusions. These results are interpreted as indicating the formation of an amphotericin B-phospholipid complex, resulting in phase separation within the monolayer. The extent and nature of this phase separation was dependent on both the concentration of drug in the system, and the saturation state of the phospholipid component. The relevance of these observations to the stability of amphotericin B drug emulsions stabilised by saturated and unsaturated phospholipid emulsifiers is discussed. These observations may also be relevant to the toxicity of these, and other novel amphotericin B formulations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 1573-904X
    Schlagwort(e): lymph node targeting ; subcutaneous administration ; poly(lactide-co-glycolide) ; poly(lactide)-poly(ethylene glycol) copolymers ; polystyrene ; nanospheres
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Purpose. Nanospheres can be utilised for the targeting of drugs and diagnostic agents to the regional lymph nodes. The surface modification of model polystyrene, (PS), and poly(lactide-co-glycolide),(PLGA), nanospheres by poly(lactide)-poly(ethylene glycol), (PLA:PEG), copolymers has been assessed by in vitro characterisation and in vivobiodistribution studies following subcutaneous administration of the nanospheres to the rat. Methods. Three PLA: PEG copolymers were investigated, with PEG chain lengths of 750, 2000 and 5000 Da. The PLA:PEG copolymers were either coated onto the surface of PS and PLGA nanospheres or used as a co-precipitate in the formation of PLGA-PLA:PEG nanospheres. Coating of the nanospheres was confirmed by an increase in their particle size and a corresponding decrease in the surface potential. The kinetics of injection site drainage and lymph node retention was determined over a 24 hour time course for naked, coated and co-precipitated nanosphere systems. Results. Dependent on the surface characteristics, the distribution of the nanospheres can be significantly modified and the lymph node localisation dramatically enhanced by coating their surfaces with PLA:PEG copolymers or by producing co-precipitate nanospheres of PLGA and PLA:PEG. Conclusions. A fully biodegradable nanosphere system has been developed with excellent lymph node targeting characteristics.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 1573-904X
    Schlagwort(e): polystyrene ; polyethylene glycol ; particles ; rats ; non-parenchymal liver cells ; blood clearance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The effect of differing densities of poly (ethylene glycol-2000) (PEG2000) at the particle surface of polystyrene-poly (ethylene glycol-2000) (PS-PEG2000) particles was assessed in terms of hydrophobic interaction chromatography (HIC) and the in vitro and in vivo behaviour of the particles. The particles, with different surface densities of PEG, were prepared by varying the copolymerizing reaction of styrene with a PEG macromonomer. There is a clear relationship between the surface density of PEG as determined by X-ray photoelectron spectroscopy and surface hydrophobicity as assessed by hydrophobic interaction chromatography (HIC). Similarly, the interaction of the particles with non-parenchymal liver cells in in vitro studies was shown to decrease as the surface density of PEG increases. The in vivo study investigating the biodistribution of the PS-PEG particles after intravenous injection into rats reveals that a relationship exists between the surface density of PEG and the extent to which the particles remain in the circulation, avoiding recognition by the reticuloendothelial system. Particles with the higher surface densities show increased circulatory times which compared well with data for particles prepared with the surface adsorbed PEO-PPO block copolymer, Poloxamine 908.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 1573-904X
    Schlagwort(e): mannitol ; small intestinal transit ; drug absorption ; gamma scintigraphy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The aim of the present study was to investigate the effect that different concentrations of mannitol have on small intestinal transit, and whether any observed effect was concentration dependent. Eight, healthy male subjects each received 200ml of radiolabelled purified water, or a 200ml solution of mannitol at three different concentrations; 0.755g/200ml, 1.509g/200ml and 2.264g/200ml, in a randomised, four way cross-over study. Transit of the radiolabelled solutions was followed by gamma scintigraphy. The study demonstrated no significant differences between the gastric emptying times of the four solutions. Rapid gastric emptying was observed in most cases. The mean small intestinal transit times for the 0.755g/200ml, 1.509g/200ml and 2.264g/200ml mannitol solutions was reduced by 11%, 23% and 34% respectively, when compared to the control solution. The intestinal transit data of the four solutions demonstrate that mannitol has a concentration dependent effect on small intestinal transit. Small concentrations of mannitol included in a pharmaceutical formulation could therefore lead to reduced uptake with any drug exclusively absorbed from the small intestine.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Pharmaceutical research 2 (1985), S. 225-230 
    ISSN: 1573-904X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The distribution behavior of salicylic acid and its various esters (methyl, ethyl, phenyl, and glycol) between different semisolid vehicles (PEG, Carbopol 940, Plastibase) and non-miscible second phases has been examined over a range of temperature. The derived thermodynamics data can be used to discuss drug-vehicle interactions and changes in the thermodynamic activity of the solute. Salicylic acid interacts little, if at all, with inert materials such as Plastibase (mineral oil thickened with polyethylene) but together with its esters shows strong interaction with PEG. An increased interaction with increase in molecular weight (ethylene oxide content) of PEG is demonstrated. The salicylate esters have a lower affinity for Carbopol gels than for PEG because of entropy effects. Glycol salicylate in Carbopol gels demonstrates anomalous behavior. The relevance of the data to studies on drug release, and in particular the evaluation of rheological factors, is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    ISSN: 1573-904X
    Schlagwort(e): Progabide ; reversed phase ; high-performance liquid chromatography (HPLC) ; plasma ; analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A reversed-phase high-performance liquid chromatography (HPLC) assay procedure for Progabide, its active acid metabolite (PGA), and its hydrolytic degradation product (SL79.182) has been developed. This highly specific technique has allowed the simultaneous determination of these drugs in aqueous samples, and when coupled with a single and easy extraction step, spiked plasma samples could also be analyzed. The method had a sensitivity of about 30, 45, and 100 ng/ml for Progabide, SL79.182, and PGA, respectively.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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