Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prosthetic valve endocarditis is an infrequent, but serious complication of cardiac valve replacement. The infection is caused by the adherence of bacteria to the prosthetic valve or to tissue at the site of implantation. Recently it was shown that antibacterial peptides from blood platelets are involved in clearance and killing of bacteria adhering to vegetations induced in a model for prosthetic valve endocarditis using rabbits. The application of these antibacterial proteins in a release system, incorporated in the Dacron sewing ring of the prosthetic heart valve would diminish the incidence of endocarditis. In this study a release system for small cationic proteins based on cross-linked gelatin was developed and characterised. Furthermore, the system was evaluated with respect to the uptake and in vitro release of lysozyme, a small cationic protein that was chosen as a model protein for small cationic antibacterial proteins. Variation of gelatin type (A and B), and cross-link density resulted in differences in swelling, thermal behaviour, and number of charged groups. Lysozyme uptake was proportional to swelling, but was governed by the number of anionic groups. The latter was also observed for the release profiles: when the amount of free carboxylic acids is higher (gelatin B compared to gelatin A), the lysozyme release lasts for a longer time period. The release into solidified agarose medium, as a model for heart muscle tissue, was measured. After 50 h, 40-100% of the lysozyme was released, which is in accordance with the aimed release period of 24-48 h. The adsorption experiments in vitro suggest an influence of the electrostatic interactions between lysozyme and gelatin. This hypothesis was validated with a mathematical model which takes both diffusion and adsorption interactions into account.
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PMID:Controlled delivery of antibacterial proteins from biodegradable matrices. 974 31

Prosthetic valve endocarditis may be reduced by the local delivery of antibacterial proteins from the Dacron sewing ring of a prosthetic heart valve. Dacron discs were treated with a carbon dioxide gas plasma to improve the hydrophilicity and thereby enabling homogeneous impregnation with gelatin type B. The gelatin samples were cross-linked to different degrees using various amounts of water-soluble carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Lysozyme, a model protein for antibacterial proteins, was loaded into (non)-cross-linked gelatin gels incorporated in Dacron, or adsorbed onto non-treated and gas plasma-treated Dacron. The in vivo lysozyme release was measured after subcutaneous implantation of lysozyme-loaded samples in rats. The lysozyme content of the samples, and the lysozyme level of the surrounding tissue were determined at different explantation times (ranging from 6 h up to 1 week). For cross-linked gelatin gels, the lysozyme tissue level was elevated up to 2 days after implantation. In vitro release was measured using agarose medium or phosphate buffer. Lysozyme release in buffer solution under sink conditions was in good agreement with the in vivo lysozyme release profiles, and therefore considered a good model to describe in vivo release characteristics. The release was modelled with a solution of Fick's second law of diffusion using the appropriate boundary conditions. In this way the lysozyme concentration in the gel and the surrounding tissue as a function of time and distance was obtained. The presence of cross-linked gelatin in Dacron did lead to an increased uptake of lysozyme and a delayed release during 30 h after implantation, whereas a burst release took place from Dacron, gas plasma-treated Dacron, or Dacron containing non-cross-linked gelatin.
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PMID:In vivo and in vitro release of lysozyme from cross-linked gelatin hydrogels: a model system for the delivery of antibacterial proteins from prosthetic heart valves. 1082 64