Entrapment model

Entrapment model of drug incorporation. Drugs are incorporated into hair from the bloodstream during the growth phase. Their concentration in the hair reflects that present in the bloodstream. A central dogma of the entrapment model is that hair is resistant to incorporation of drugs from outside contamination. 

FIGURE 7.32 Schematic diagram of the single pore entrapment model. 

As shown in Figure 9, the gels showed a release of the entrapped model proteins (IgG and lysozyme) over 6 days. 

We used QDC to simulate a GFP-synthesizing PS encapsulated into liposomes, with the solute partition inside the vesicles obtained by the two entrapment models a pure Poisson process or a power law. The protein s mthesis in... 

Erythrocyte Entrapment of Enzymes. Erythrocytes have been used as carriers for therapeutic enzymes in the treatment of inborn errors (249). Exogenous enzymes encapsulated in erythrocytes may be useful both for dehvery of a given enzyme to the site of its intended function and for the degradation of pathologically elevated, diffusible substances in the plasma. In the use of this approach, it is important to determine that the enzyme is completely internalized without adsorption to the erythrocyte membrane. Since exposed protein on the erythrocyte surface may ehcit an immune response following repeated sensitization with enzyme loaded erythrocytes, an immunologic assessment of each potential system in animal models is required prior to human trials (250). 

A theoretical model whereby maximum peak capacity could be achieved by the use of 3-D planar chromatographic separation was proposed by Guiochon and coworkers (23-27). Unfortunately, until now, because of technical problems, this idea could not be realized in practice. Very recently, however, a special stationary phase, namely Empore silica TLC sheets, has now become available for realization of 3-D PC. This stationary phase, developed as a new separation medium for planar chromatography, contains silica entrapped in an inert matrix of polytetrafluoroethy-lene (PTFE) microfibrils. It has been established that the separating power is only ca. 60% of that of conventional TLC (28) this has been attributed to the very slow solvent migration velocity resulting from capillary action. 

The application of modified electrodes for the assay of antibodies in senun preparations using redox indicators encapsuled into antigene marked liposomes attached to an electrode surface was suggested First model studies towards this goal make use of ferricyanide ions entrapped in synthetic vesicles. 

In addition to solubilization, entrapment of polymers inside reversed micelles can be achieved by performing in situ suitable polymerization reactions. This methodology has some specific peculiarities, such as easy control of the polymerization degree and synthesis of a distinct variety of polymeric structures. The size and shape of polymers could be modulated by the appropriate selection of the reversed micellar system and of synthesis conditions [31,191]. This kind of control of polymerization could model and/or mimic some aspects of that occurring in biological systems. 

The models proposed by Wu et al. [36] and by Lin and Leu [45] refer to continuous conversion processes by immobilized bacteria the first to a fixed mixed culture entrapped into PVA beads operated in a fluidized bed, and the second to BAC of P. luteola operated in a packed bed. Results of these models highlight the role of mass transport phenomena and biophase granule size on reactor performance. 

The fluorescent labels reported for investigation of intracellular uptake and distribution by CLSM comprise Nile red [13], Texas Red, and 6-coumarin [14]. Not only for fluorescence microscopy but also for transmission electron microscopy (TEM), the loading of markers proved to be useful. Osmium tetroxid as an electron dense marker and bovine serum albumin (BSA) as a model protein were entrapped in PLGA-nanoparticles to elucidate their uptake and intracellular distribution in human vascular smooth muscle cells [15]. 

Corvo ML, Boerman OC, Oyen WJ, et al. Intravenous administration of superoxide dismutase entrapped in long circulating liposomes. II. In vivo fate in a rat model of adjuvant arthritis. Biochim Biophys Acta 1999 1419 325. 

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