Polymer carrier

Imaging plates are exposed similar to radiographic films. They are read out by a LASER-scanner to a digital image without any developing process. After optical erasing of the virtual picture the same IP can be used cyclic up to more than 1000 times. The life time is limited by the mechanical stability of the IP s. An IP consists of a flexible polymer carrier which is coated with the sensitive layer. This layer is covered with a thin transparent protective foil. 

Combinatorial Chemistry. Figure 2 Chemical libraries are prepared either by parallel synthesis or by the split-and-recombine method. In the latter case, coupling m building blocks in m separated reaction flasks through n synthetic cycles on a beaded polymer carrier generates a combinatorial library with nf individual compounds and one compound per bead. 

One of the most successful conjugate polymer systems was developed by Duncan and Kopecek (25). The polymer carrier used in their system is poly [N(2-hydroxypropyl) methacrylamide] a biocompatible polymer that was originally developed as a plasma extender. They have evaluated a number of polymer conjugated drugs for cancer chemotherapy with interesting results. The attachment of the drug is through a peptidyl spacer pendent to the polymer backbone. These peptides links are stable in aqueous media but are readily hydrolyzed intracellularly... 

A detailed theoretical characterization of the network structure of the polymer carrier in terms of the correlation length, , in combination with... 

In Eq. (17), Dip(Ci) is the concentration-dependent diffusion coefficient its form of concentration dependence is affected by the structural characteristics of the polymer carrier. A selective summary of the various forms of the diffusion coefficient is provided in Table I. 

One of earliest approaches of estimating the diffusion coefficient through a polymer carrier is that of Eyring (1936). In this theory, diffusion of a solute through a medium is presented as a series of jumps instead of a continuous process. Therefore, in Eq. (18) in Table I, which comes from the Eyring analysis, X is the diffusional jump of the drug in the polymer and v is the frequency of jumping. 

Enzymes can be immobilized by matrix entrapment, by microencapsulation, by physical or ionic adsorption, by covalent binding to organic or inorganic polymer-carriers, or by whole cell immobilization (5 ). Particularly impressive is the great number of chemical reactions developed for the covalent binding of enzymes to inorganic carriers such as glass, to natural polymers such as cellulose or Sepharose, and to synthetic polymers such as nylon, polyacrylamide, and other vinyl polymers and... 

M.R. Buchmeiser, R. Tessadri, F. Sinner, and G.K. Bonn, Dipyridylam-ine ligand bound to a polymer carrier for extracting metal ions, AT Patent 405056B, May 25,1999. 

For some applications, it is important to use protein particles of a specific size. When drugs are released within the body there is an initial boost followed by an exponential decay in the concentration over time. Sometimes it is desirable or necessary to minimize the variation of concentration within patients and one of the ways to accomplish this is by using microparticles distributed within a polymer carrier. Tom et al. (1993) used... 

Polymer carriers 4-hydroxy-L-proline In vivo—rats... 

The importance of preclinical models in the selection of polymer carriers... 

Overall, key takeaways from the nonpoly meric paclitaxel delivery studies were that despite their improvement of angiographic parameters, paclitaxel-eluting stents without a polymer carrier did not demonstrate a positive effect on clinical outcomes, as seen with polymer-based paclitaxel elution (65), discussed in the next section. Potential reasons for the failure of such an approach could be loss of drug to the systemic circulation prior to reaching the target site during the stent deployment procedure, variability associated with the dose delivered to the lesion, and lack of control over drug-release kinetics due to the absence of a polymer carrier. 

The polymer carrier should remain stable and durable during coating, crimping, sterilization, packaging, shelf-storage, and implantation, Physical stability of the polymer is necessary to... 

An alternative approach places the Pt electrodes directly on a flexible polymer carrier [80]. Eh Lilly developed a three-electrode transducing system based on a polyimide carrier with electroadsorbed enzyme and a highly oxygen-permeable membrane covering the sensor. Such a system was tested in vivo and published results seem encouraging although the company cancelled the project. 

Pro-drugs are systems comprising drug molecules chemically bonded to a polymer carrier. The drug converts to the active compound at a specific tissue site, often through the agency of an enzyme or receptor [53-56]. 

Polymer carriers with a grafted functional surface layer (i.e., the soluble functional covering on an insoluble substrate) occupies an intermediate position between soluble and cross-linked macroligands. Such polyligands present interest due to the fact that the functional groups localized on the surface facilitate the... 

B. Narashinhan and N. A. Peppas, Molecular Analysis of Drug Delivery Systems Controlled by Dissolution of the Polymer Carrier, J. Pharm. Sci., 86, 297 (1997). 

Narasimhan, B. and Peppas, N., Molecular analysis of drug delivery systems controlled by dissolution of the polymer carrier, Journal of Pharmaceutical Sciences, Vol. 86, No. 3, 1997, pp. 297-304. 

Cone and drum plasticators as well as two- and three-roll mills are other ways of making concentrates. These along with Z mixers are probably best suited for low-viscosity polymer carriers, plastisols, or paste concentrates. Some concentrates based on wax and stabilizer carriers are produced on this type of mixer. 

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