Vascularization, implantation

Health Safety. PET fibers pose no health risk to humans or animals. Eibers have been used extensively iu textiles with no adverse physiological effects from prolonged skin contact. PET has been approved by the U.S. Eood and Dmg Administration for food packagiug and botties. PET is considered biologically iuert and has been widely used iu medical iaserts such as vascular implants and artificial blood vessels, artificial bone, and eye sutures (19). Other polyester homopolymers including polylactide and polyglycoHde are used iu resorbable sutures (19,47). 

Shwarkawy et al. (1997, 1998a,b) also demonstrated that changes in pore size not only effected vascular density but also the response to systemic uptake of drug through a vascularized implant. It was demonstrated that the 60 pm pore material delivered the drug in almost half the time it took for a subcutaneous injection to be taken up systemically. This is due to the increased vascular density as well as increased vascular permeability at these pore sizes (Shwarkawy et al., 1997, 1998a,b). 

Although short-term implantation studies do give an analysis of the biocompatibility of a material at a local site systemic effects can also be observed from corrosion products that develop from vascular implants that migrate to other sites (26). 

The surface morphologies of these block copolyurethanes differ from their bulk morphologies (4-6). Because the surface controls the interaction of a vascular implant with blood, the surface structure and its relation to the bulk structure of the same material was determined also. Originally, ESCA was explored to study the surface structure because the depth of penetration was within the first 100 A. The low surface depth of penetration and subtle shifts in binding energies that result in peak splittings of the elemental spectra appeared to make this an attractive method to study the chemical and bonding environments of the elements (40). 

Cell-adsorptive coatings of PTFE with laminin, coUagen IV, and Bbronectin have been described in the Hterature to improve the growth of endothehal cells on vascular implants, but these methods did not show satisfactory results when ap-pHed to vessels with a small diameter. 

Schumann DA, Wippermaim J, Klemm DO et al (2009) Artificial vascular implants frran bacterial cellulose preliminary results of small arterial substitutes. Cellulose 16 877-885 Seydibeyoglu MO, Oksman K (2008) Novel nanocomposites based on polyurethane and micro-fibrillated cellulose. Compos Sci Technol 68 908-914 Shoda M, Sugano Y (2005) Recent advances in bacterial cellulose production. Biotechnol Bioprocess Eng 10 1-8... 

Normal and satisfactory healing of a vascular implant involves the following sequence of events. Initially, immediately after exposure to the blood... 

It has been evident for some time that passive implantation for a short time cannot be sufficient by itself to establish biological acceptance. Long term studies are essential since effects are possibly oriy realisable after tissues and implatji have been in intimate contact for periods in excess of one year. These are presently in progress. Functional implantation is also necessary to study the effects of load-bearing or movement in the same way that vascular implantation is necessary for evaluation of thrombo-genetic activity. In this context, it may be noted that the... 

Sukavaneshvar S. Assessment and management of vascular implant thrombogenecity. In Thrombus and Stroke, p. 57-78. 

Polyamide, In vascular implants, syringes, clamps, blood transfusion sets. 

Polymers can also be used to prevent the adsorption of proteins to surfaces. For example, polyvinylpyrrolidone can prevent protein adsorbing onto a variety of surfaces and it can also displace adsorbed protein [ 18]. This has led, for example, to its application in the coating of filtration membranes in order to reduce biofouling. Polymers are also used to inhibit the adhesion of bacteria or water-borne micro-organisms onto siufaces [19,20]. Bacteria are usually surrounded by exoceUular polysaccharides that can aid adhesion to clean surfaces. Thus prosthetic devices and vascular implants carrying blood suffer from the build up of biofilms, leading to blockages and infection. This build up can be markedly reduced... 

Polymeric materials are used in a wide range of medical applications, because of their unique physical properties such as strength, elasticity, and pliability. A potential application could include small diameter vascular implants if one of the major problems of polymeric biomaterials in contact with blood, thrombus formation, could be overcome. Although the underlying processes are not completely understood, an initial step in the thrombogenic sequence is the adsorption of plasma proteins to the surface of a material followed by adhesion of platelets and/or leukocytes.2 3 The extent of thrombosis, in turn, is related to the... 

The very surface chemical and morphological structures can be different from that of the bulk structures. Since it is the surface that controls the interaction of a vascular implant with blood, it was important to explore techniques to determine this surface structure as related to the bulk (21). ESCA was originally explored in an attempt to determine the surface structures as compared with the bulk. This technique involves the excitation of inner shell electrons by X-rays and the analysis of the kinetic energies of these excited... 

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