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PubMed2002

Influence of wetness on the ultraviolet protection factor (UPF) of textiles: in vitro and in vivo measurements.

BACKGROUND/PURPOSE: Clothing is an important product for sunburn protection and skin cancer prevention. The moisture content of a fabric, which can increase during its wearing, may decrease the fabric's capability of protecting the skin from solar UV radiation, that is, lower its UPF (ultraviolet protection factor). Due to limited data about the effect of fabric wetness on UPF, this study was undertaken to investigate the following: (a) the effect of saturating a variety of fabrics with tap water and with salt water on fabric UPF and (b) whether wetted-fabric UPF values reflect only the fact that the fabric is wet during testing or the fact that the skin is hydrated and the fabric is wet. METHODS: For objective a, 69 summer fabrics were spectrophotometrically (in vitro) assessed when "dry" and when saturated with tap and salt water. In vitro UPFs, percent UVA transmission and percent UVB transmission values were calculated from the transmission data. For objective b, 100% cotton and 100% polyester fabrics were tested in vivo to determine in vivo UPF values. The minimal erythema dose (MED) was determined for each of the 12 subjects on unprotected "dry" skin and on "hydrated" unprotected skin. MEDprotected was determined when the subject's skin was covered with "dry" and with saturated fabric. In vivo UPFs were calculated using this data. Student's paired t-tests were used to determine the effect of wetting. RESULTS: With one exception, in vitro UPF values were the same when the fabrics were saturated with tap water and when they were saturated with salt water. However, saturating the fabrics with water had different effects on the UPF, UVA transmission, and UVB transmission values. For linen, viscose and polyester fabrics, UPF significantly increased. For the cotton fabrics and the polyester + TiO2 fabrics, UPF significantly decreased. For the modal + TiO2 fabrics and the polyester crepe + TiO2 fabrics, UPF significantly increased. From the in vivo testing, the MED of the "hydrated unprotected" skin was not different than the MED of "dry unprotected skin." Values obtained from subtracting dry-fabric in vivo UPF values from dry-fabric in vitro values and subtracting wet-fabric in vivo UPF values from wet-fabric in vitro values are not different. CONCLUSION: Fabrics do not need to be tested when saturated with tap and with salt water. Testing fabrics wet and dry should be done, as the effect of saturating fabric on UPF value varies. Fortunately, UPF values for wetted fabrics reveal only the effect of increased moisture content in the fabric and have nothing to do with wetting of the skin by the fabric.

Adult↗

PubMed2006

Environmentally degradable, high-performance thermoplastics from phenolic phytomonomers.

Aliphatic polyesters, such as poly(lactic acid), which degrade by hydrolysis, from naturally occurring molecules form the main components of biodegradable plastics. However, these polyesters have become substitutes for only a small percentage of the currently used plastic materials because of their poor thermal and mechanical properties. Polymers that degrade into natural molecules and have a performance closer to that of engineering plastics would be highly desirable. Although the use of a high-strength filler such as a bacterial cellulose or modified lignin greatly increases the plastic properties, it is the matrix polymer that determines the intrinsic properties of the composite. The introduction of an aromatic component into the thermoplastic polymer backbone is an efficient method to intrinsically improve the material performance. Here, we report the preparation of environmentally degradable, liquid crystalline, wholly aromatic polyesters. The polyesters were derived from polymerizable plant-derived chemicals--in other words, 'phytomonomers' that are widely present as lignin biosynthetic precursors. The mechanical performance of these materials surpasses that of current biodegradable plastics, with a mechanical strength, sigma, of 63 MPa, a Young's modulus, E, of 16 GPa, and a maximum softening temperature of 169 degrees C. On light irradiation, their mechanical properties improved further and the rate of hydrolysis accelerated.

Journal Article↗

PubMedDate not supplied

Comparison of adhesive properties of five different prosthetic materials used in hernioplasty.

This experimental study was designed to assess and to compare intra-abdominal adhesions following the use of five commercially available prosthetic mesh grafts in the repair if abdominal wall defects. Sixty Wistar albino rats were randomly divided into six groups (n = 10). A 2 x 1 cm defect at abdominal wall was created and defects were closed either primarily or with one of the following prosthetic mesh grafts: monofilament polypropylene, polytetrafluoroethylene, sodium hyaluronate/carboxymethylcellulose-coated polypropylene, polypropylene/polyglactin 910 composite, or resorbable hydrophilic collagen-coated multifiber polyester. The severity of adhesions was graded, tensile strengths of adhesions were measured, and histopathological grades of inflammation and fibrosis were evaluated. Polypropylene mesh resulted in more adhesion formation in comparison to primary repair and other grafts used in this study, except polypropylene/polyglactin 910 composite mesh. In addition, the highest tensile strength of omental adhesions was detected in the polypropylene group (chi2 = 26.249; p = .0001). Polyester composite mesh caused the least adhesion formation among the groups. Sodium hyaluronate/carboxymethylcellulose-coated polypropylene and polyester composite meshes revealed the highest fibrosis scores (chi2 = 50.776; p = .0001). The highest inflammatory activity was detected in the polytetrafluoroethylene mesh group (chi2 = 16.564; p = .005). Thus, sodium hyaluronate/carboxymethylcellulose-coated polypropylene and polytetrafluoroethylene meshes following polyester composite mesh were the minimal adhesion-forming grafts in this study. Disadvantages of the polytetrafluoroethylene mesh were lower fibrotic activity and higher inflammatory reaction to the graft.

Abdomen↗

PubMed1965

Studies on nucleic acid metachromasy. II. Metachromatic and orthochromatic staining by toluidine blue of nucleic acids in tissue sections.

Acrolein-fixed, polyester wax-embedded tissue sections showed excellent preservation of light microscopic architecture and, when stained with toluidine blue, intense color contrast between DNA, which stained orthochromatically, and RNA, which stained metachromatically. This method has practical value for differentiating DNA from RNA in the same section. The color contrast was impaired by substituting formaldehyde for acrolein or paraffin for polyester wax, and was negligible in tissues fixed in formaldehyde or Carnoy's fluid and embedded in paraffin. Quality of structural preservation paralleled degree of color contrast. Metachromatic staining can be analysed, by the quantitative parameters of Bradley and colleagues, to provide inferences regarding the conformation of biopolymers in tissue sections. Comparison of the nucleic acid color contrasts in toluidine blue-stained sections with titrations of fixative-treated nucleic acids against toluidine blue in solution indicated a greater difference in conformation between DNA- and RNA-protein in acrolein-polyester sections than between acrolein-treated free DNA and RNA in solution. This is supported by recent evidence that the conformation of ribosomal RNA is quite different in whole ribosomes from that assumed by the same RNA free in solution. The acrolein-polyester method may enhance color contrast by providing superior preservation of ordered nucleoprotein conformations.

Acetates↗

PubMed1992

Development of a polymer endovascular prosthesis and its implantation in porcine arteries.

A polyethylene-terephthalate braided mesh stent has been developed for application in the (coronary) arterial tree. In vitro measurements showed that the radial pressure delivered by this device was in the same range as that of a stainless steel stent. Hysteresis-like behavior, however, occurred after constraining the polyester stent for a period of only 15 minutes on a delivery system for percutaneous implantation. This implies that the polymer stent must be mounted on this delivery system immediately before the placement procedure, and that either a diameter in the unconstrained condition must be selected, which is considerably larger than the diameter of the target vessel, or stent expansion has to be enhanced by balloon expansion. Taking into account the results obtained during the in vitro studies, we investigated the angiographic patency and histologic features after implantation of this polyester stent in peripheral arteries of pigs. In four animals eight stents were placed. Except for heparin during the implantation procedure only, antithrombotic or antiplatelet drugs were not administered. After 4 weeks repeat angiography was performed. Angiography revealed that five of the six correctly placed stents were patent. At autopsy, two additional patent stents proved to be located in the aortic bifurcation, probably due to failure of the delivery system. Quantitative assessment showed that the mean luminal diameters of the site of stent placement were 3.3 +/- 0.2 mm before, 3.2 +/- 0.2 mm immediately after, and 3.1 +/- 0.3 mm at 4 weeks after implantation. Histology demonstrated an inflammatory reaction of variable severity around the stent fibers. Quantitative histologic measurements showed that the thickness of the neointima was 114 +/- 38 mum after 4 weeks. In conclusion, polyester stents can be constructed with mechanical properties similar to stainless steel stents. Hysteresis-like behavior of polyester stents, however, influences the selection of the nominal stent diameter as well as the forces exerted to the vessel wall. After implantation in porcine peripheral arteries, five of six correctly placed stents were patent at 4 weeks. The extent of neointimal proliferation was similar to that observed after placement of metal stents in swine, despite the presence of a more pronounced inflammatory reaction.

Angioplasty, Balloon, Coronary↗

PubMed1975

The use of monofilament suture in vascular surgery.

The blood lost through the suture line holes of vessels closed with braided polyester sutures is compared with that lost when a monofilament polypropylene suture is employed. In a retrospective analysis of blood replacement during saphenous vein aortorenal bypasses, twice as much blood replacement was required when the braided polyester suture was used. Further, ten dogs had one femoral artery reanastomosed with braided polyester suture and the other with monofilament polypropylene. Bleeding was three times greater and lasted six times longer when the braided polyester suture material was utilized.

Animals↗

PubMedDate not supplied

Development of a growable vascular graft.

A vascular graft that can grow with the growth of its recipient was developed. The graft implanted in the thoracic descending aorta grew slowly to the expected size within a year after implantation in puppies. Human saphenous vein was used as the substrate material. It was dipped into distilled water and sonicated, resulting in cell destruction, and followed by cross-linking with a polyepoxy compound to give both controlled biodegradability, hydrophilicity, and antithrombogenic properties. Four millimeter inner diameter (ID) grafts, enveloped with polyester mesh tubes of 10 mm ID, were implanted in 11 puppies. The diameter of the grafts grew to 9.5 mm from their original 4 mm. After 1 year, the graft walls that were reinforced with polyester mesh were covered with endothelial cells. The following requirements were provided in a growable graft: 1) antithrombogenicity in a small caliber graft; 2) ability to grow as well as to terminate growth. The polyester mesh tube, which was larger than the graft, caused arrest of growth at the expected diameter, whereas the growth rate was controlled by the degree of graft cross-linking. With this method, any size graft can be made by changing the size of the original graft and the polyester mesh tube around it.

Animals↗

PubMed1996

A comparison of the strength of knots tied by hand and at laparoscopy.

BACKGROUND: The strength of knots tied at laparoscopy was compared with that of hand-tied knots. STUDY DESIGN: The force needed to undo or break eight types of knots that were tied in fresh postmortem human stomachs was measured. The knotting performance of nylon, polyglactin 910, braided silk, polytetrafluoroethylene, braided polyester fiber, braided polyester suture, polyamide 66, and polydiaxone was also compared. RESULTS: Measurements of knot strength of two to six half hitches (hand tied) showed that four half hitches were necessary to tie a secure nonslipping knot with most monofilament threads (nylon, polytetrafluoroethylene, braided polyester suture, and polyamide 66), while three half hitches were adequate to secure a knot when polyglactin 910, braided polyester fiber, silk, and polydiaxone were used. Additional throws did not increase knot strength once the knot no longer slipped (p = NS). Some commonly tied knots, three half hitches and surgical knots at laparoscopy were weaker than the same hand-tied knots (p < 0.05) but an additional throw increased knot security (p < 0.01). Differences between laparoscopic and hand-tied knot strengths were greater for monofilament than multifilament threads. There was a wider distribution of strengths for laparoscopically tied than hand-tied knots. Four half hitches were the most secure configuration for laparoscopically tied knots and were significantly stronger than three half hitches and surgical knots (p < 0.01). The extracorporeally tied slipknot (Roeder loop) was significantly less secure than four half hitches (p < 0.05). CONCLUSIONS: This study demonstrates that laparoscopically formed knots may be weaker than those tied by hand and shows that improvements in knot strength at laparoscopy can be achieved by choice of optimal knot configuration for different suture materials.

Evaluation Studies as Topic↗

PubMed1990

Fabric-reinforced ultrathin polyacrylamide gels for sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing.

The suitability of four different fabric materials for the preparation of ultrathin rein-forced polyacrylamide gels was investigated. With all fabric-reinforced gels, a good separation of proteins by isoelectric focusing and sodium dodecyl sulfate-electrophoresis could be achieved. Semi-dry electrophoretic blotting of proteins was possible with all types of fabric-reinforced gels. Two polyester fabrics (a net and a fleece) were decidedly superior in handling and dimensional stability on drying to a nylon fabric and another polyester fleece material. Only gels prepared with the former materials withstood further treatment, such as fixation, staining, destaining, and drying. One of the polyester fleece fabrics had poor handling properties and the nylon fabric was unsuitable for direct staining procedures employing concentrated (20% w/v) trichloroacetic acid as fixative.

Electrophoresis, Polyacrylamide Gel↗

PubMed1993

Enzyme-biomaterial interactions: effect of biosystems on degradation of polyurethanes.

Enzyme-induced liberation of hard-segment-containing components from polyurethanes was evaluated using two 14C-labeled polyurethanes. A polyester urea-urethane and polyether urea-urethane were synthesized from toluene-2,4-diisocyanate (TDI)/polycaprolactone diol (PCL) or TDI/polyethylene glycol (PEO) with 14C-labeled ethylene diamine. Both materials were characterized using electron spectroscopy for chemical analysis (ESCA), differential scanning calorimetry (DSC), size exclusion chromatography, and material chemistry by Fourier transform infrared (FTIR) spectroscopy. Biodegradation assays were carried out using cholesterol esterase (CE), collagenase (CO), cathepsin B (CB), and xanthine oxidase (XO) at the pH optimum conditions for each enzyme at 37 degrees C. Biodegradation was analyzed by monitoring the release of radiolabel, by weight change, and by surface analysis using scanning electron microscopy. The polyester urea-urethane was shown to be susceptible to enzymatic degradation above the effect of the buffer control solution by the CE but not by the other enzyme systems as monitored by radiolabel released. In the initial period of incubation, the rate of degradation was increased for all systems, including buffer controls; however, the rates dropped off rapidly by day 28. The change in weight data for the polyester urea-urethane and polyether urea-urethane showed no enzyme-dependent biodegradation above the buffer controls. However, in sodium acetate buffer at pH = 5, the polymers showed a significant weight loss relative to other buffers. In conclusion, this study showed that the biological component responsible for the onset of the biodegradation process is more likely the result of a multitude of biologically mediated compounds acting synergistically, with the process being enhanced by physical parameters such as material dissolution. In addition characterization of surface and bulk chemistry as well as material structure evaluation have been shown to be essential to interpret degradation data.

Biocompatible Materials↗

PubMed1993

Development and implementation of a safety evaluation program for chemical fibers.

Polyester and acrylic fibers often have prolonged contact with human skin: the sucking of childrens' toys may lead to ingestion. During manufacture, occupational exposure to fiber components may occur. An evaluation of these possible hazards was undertaken by data appraisal, chemical analyses, and animal plus human testing. Occupational exposure limits have already been set for the chemicals used in polymer manufacture. Finishing agents (applied to the fibers) were examined in bacterial mutation and rat acute oral toxicity tests. Finished fibers were tested for acute toxicity and then for sensitizing potential (on guinea pig skin). Human volunteer trials for skin irritance and sensitization followed. No adverse reactions were seen. Only when fibers were burnt was toxicity seen: smoke from acrylic fiber proved more toxic than that from polyester fiber (due principally to hydrogen cyanide release). Migration tests showed that little material leached out from the fibers: < 1 mg/dm2 surface area in saline, 0.4 mg/dm2 from acrylic fibers in methanol, 3.6 mg/dm2 from polyester fibers in chloroform. Analysis showed only fiber polymer components and finish in saline and methanol leachates. Whilst further testing may be required for areas of special concern, since only a limited range of biological endpoints have been addressed, it is concluded that current and foreseeable future uses of these chemical fibers pose little or no toxicological hazard.

Acrylonitrile↗

PubMed1999

Hamstring graft motion in the femoral bone tunnel when using titanium button/polyester tape fixation.

The objective of this study was to determine the relative motion of a quadruple hamstring graft within the femoral bone tunnel (graft-tunnel motion) under tensile loading. Six graft constructs were prepared from the semitendinosus and gracilis tendons of human cadavers and were fixed with a titanium button and polyester tape within a bone tunnel in a cadaveric femur. Three different lengths of polyester tape (15, 25, and 35 mm loops) were evaluated. The femur was held stationary and uniaxial tensile loads were applied to the distal end of the graft using a materials testing machine. Each construct was subjected to loading for ten cycles with upper limits of 50 N, 100 N, 200 N and 300 N. Graft-tunnel motion was then determined using the distances between reflective tape markers placed on the hamstring graft and at the entrance to the femoral bone tunnel, which were tracked with a high-resolution video system. Graft-tunnel motion was found to range from 0.7 +/- 0.2 mm to 3.3 +/- 0.2 mm, and significant increases in graft-tunnel motion were observed with increasing tensile loads (P < 0.05). Shorter tape length (15 mm) resulted in significantly less motion when compared to longer tape length (35 mm) (P < 0.05). We conclude that graft-tunnel motion is significant and should be considered when using this fixation technique. Early stress on the graft, as seen in postoperative rehabilitation exercises and athletic activities, may cause large graft-tunnel motion before graft incorporation is complete. A shorter distance between the tendon tissue and the titanium button is recommended to minimize the amount of graft-tunnel motion. Alternative fixation materials to polyester tape, or different fixation techniques, need to be developed such that graft-tunnel motion can be reduced. Further studies are needed to evaluate the effect of graft-tunnel motion on graft incorporation in the bone tunnel.

Biomechanical Phenomena↗

PubMed2006

Increased diversification of polyhydroxyalkanoates by modification reactions for industrial and medical applications.

A wide range of diverse polyhydroxyalkanoates, PHAs, is currently available due to the low substrate specificity of PHA synthases and subsequent modifications by chemical reactions. These polymers are promising materials for a number of different applications due to their biocompatibility and biodegradability. This review summarizes the large variability of PHAs regarding chemical structure and material properties that can be currently produced. In the first part, in vivo and in vitro biosynthesis processes for production of a large variety of different PHAs will be summarized with regard to obtaining saturated and unsaturated copolyesters and side chain functionalized polyesters, including brominated, hydroxylated, methyl-branched polyesters, and phenyl derivatives of polyesters. In the second part, established chemical modifications of PHAs will be summarized as that by means of grafting reactions and graft/block copolymerizations, as well as by chlorination, cross-linking, epoxidation, hydroxylation, and carboxylation, reactions yield further functionalized PHAs.

Acyltransferases↗

PubMed2000

Polyhydroxyalkanoate accumulation in Burkholderia sp.: a molecular approach to elucidate the genes involved in the formation of two homopolymers consisting of short-chain-length 3-hydroxyalkanoic acids.

Burkholderia sp. accumulates polyhydrox-yalkanoates (PHAs) containing 3-hydroxybutyrate and 3-hydroxy-4-pentenoic acid when grown on mineral media under limited phosphate or nitrogen, and using sucrose or gluconate as a carbon and energy source. Solvent fractionation and NMR spectroscopic characterization of these polyesters revealed the simultaneous accumulation of two homopolyesters rather than a co-polyester with random sequence distribution of the monomers [Valentin HE, Berger PA, Gruys KJ, Rodrigues MFA, Steinbuchel A, Tran M, Asrar J (1999) Macromolecules 32: 7389-7395]. To understand the genetic requirements for such unusual polyester accumulation, we probed total genomic DNA from Burkholderia sp. by Southern hybridization experiments using phaC-specific probes. These experiments indicated the presence of more than one PHA synthase gene within the genome of Burkholderia sp. However, when total genomic DNA from Burkholderia sp. was used to complement a PHA-negative mutant of Ralstonia eutropha for PHA accumulation, only one PHA synthase gene was obtained resembling the R. eutropha type of PHA synthases, based on amino acid sequence similarity. In addition to the PHA synthase gene, based on high sequence homology, genes encoding a beta-ketothiolase and acetoacetyl-CoA reductase were identified in a gene cluster with the PHA synthase gene. The arrangement of the three genes is quite similar to the R. eutropha poly-beta-hydroxybutyrate biosynthesis operon.

Acyltransferases↗

PubMed2006

Flexible ex vivo phantoms for validation of diffusion tensor tractography on a clinical scanner.

PURPOSE: The aim of this study was to develop ex vivo diffusion tensor (DT) flexible phantoms. MATERIALS AND METHODS: Materials were bundles of textile threads of cotton, monofilament nylon, rayon, and polyester bunched with spiral wrapping bands and immersed in water. DT images were acquired on a 1.5-Tesla clinical magnetic resonance scanner using echo planar imaging sequences with 15 motion probing gradient directions. DT tractography with seeding and a line-tracking method was carried out by software originally developed on a PC-based workstation. RESULTS: We observed relatively high fractional anisotropy on the polyester phantom and were able to reconstruct tractography. Straight tracts along the bundle were displayed when it was arranged linearly. It was easy to bend arcuately or bifurcate at one end; and tracts followed the course of the bundle, whether it was curved or branched and had good agreement with direct visual observation. Tractography with the other fibers was unsuccessful. CONCLUSION: The polyester phantom revealed a diffusion anisotropic structure according to its shape and would be utilizable repeatedly under the same conditions, differently from living central neuronal system. It would be useful to validate DT sequences and to optimize an algorithm or parameters of DT tractography software. Additionally, the flexibility of the phantom would enable us to model human axonal projections.

Anisotropy↗

PubMed1994

Biosynthesis from gluconate of a random copolyester consisting of 3-hydroxybutyrate and medium-chain-length 3-hydroxyalkanoates by Pseudomonas sp. 61-3.

Pseudomonas sp. 61-3 isolated from soil was found to produce a polyester consisting of 3-hydroxyalkanoic acids of even carbon numbers C4, C6, C8, C10 and C12 when sodium gluconate was fed as the sole carbon source. The polyester produced was fractionated with boiling acetone. The acetone-insoluble fraction (28 wt%) of the polyester was a poly(3-hydroxybutyrate) homopolymer, while the acetone-soluble fraction (72 wt%) was composed of seven different 3-hydroxyalkanoate (3HA) units ranging from C4 to C12: 40 mol% 3-hydroxybutyrate (3HB), 5 mol% 3-hydroxyhexanoate (3HH), 20 mol% 3-hydroxyoctanoate (3HO), 24 mol% 3-hydroxydecanoate (3HD), 1 mol% 3-hydroxy-5-cis-decenoate (3H5D), 4 mol% 3-hydroxydodecanoate (3HDD) and 6 mol% 3-hydroxy-5-cis- dodecenoate (3H5DD). The copolymer was characterized by nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography and differential scanning calorimetry. The acetone-soluble fraction of this amorphous copolymer was shown to have a random sequence distribution of the seven 3HA units of C4 to C12 by analysis of the 150 MHz 13C-NMR spectrum. This is the first example of microbial synthesis of a random copolyester consisting of 3HB and medium-chain-length 3HA units.

3-Hydroxybutyric Acid↗

PubMed1996

Intracellular depolymerase functionality and location in Pseudomonas oleovorans inclusions containing polyhydroxyoctanoate.

Microbial poly-3-hydroxyoctanoate inclusion bodies produced by Pseudomonas oleovorans when grown on n-octanoic acid, are complex macromolecular structures consisting of polyester, organized paracrystalline lattice arrays and lipids. While it is known that the polymer in the granules maintains its native, amorphous state while it is surrounded by the components of this complex, the precise functions of the various components during polymer production and utilization have yet to be established. By utilizing electron microscopy, SDS-PAGE, and gel filtration chromatography along with in vitro assays for depolymerase activity, the present study demonstrates that a protein species with molecular weight of approximately 32 kDa is the depolymerase protein of the polymer inclusion. When exogenous carbon was exhausted, cell viability required utilization of the stored polyester. Under these conditions, the concentration of the depolymerase increased while the concentrations of the polymerase decreased. Thus, the association of the depolymerase with the granules was shown to be under metabolic regulation relative to the polymerase. The results from the present studies show that careful manipulation of the substrate concentration can selectively, and differentially, alter the level of inclusion associated proteins as well as the quantity and quality of the polyester which is accumulated.

Bacterial Proteins↗

PubMed2007

In vivo h-VEGF165 gene transfer improves early endothelialisation and patency in synthetic vascular grafts.

OBJECTIVES: Small-diameter synthetic vascular graft performance is inferior to autologous vein grafts. This study tested the hypotheses that local in vivo administration of plasmids encoding for human vascular endothelial growth factor (VEGF), or co-administration of plasmids encoding for human vascular endothelial growth factor/plasmids encoding for fibroblast growth factor-2 in the tissues surrounding a porous synthetic vascular graft would enhance graft endothelialisation and, consecutively, graft patency. METHODS: First, optimal gene for small-diameter synthetic graft endothelialisation was studied in rat abdominal aorta model (n=132): plasmids encoding for human vascular endothelial growth factor; co-administration of plasmids encoding for human vascular endothelial growth factor/plasmids encoding for fibroblast growth factor-2; or control plasmids were injected around 60 microm ePTFE graft. Second, optimal small-diameter synthetic graft design for endothelialisation was explored in rabbit abdominal aorta model (n=90). Various ePTFE grafts or pre-clotted polyester grafts were used with/without plasmids encoding for human vascular endothelial growth factor. Third, clinically used medium-size synthetic grafts were investigated with/without plasmids encoding for human vascular endothelial growth factor in dog carotid (n=20) and femoral arteries (n=15). Endothelialisation was assessed in midgraft area with scanning electron microscopy. RESULTS: In rats, plasmids encoding for human vascular endothelial growth factor enhanced endothelialisation; whereas co-administration of plasmids encoding for human vascular endothelial growth factor/plasmids encoding for fibroblast growth factor-2 had worst outcome at 1 week (NS), 2 weeks (P=0.01) and 4 weeks (P=0.02). In rabbits, pre-clotted polyester grafts had a trend for faster endothelialisation than ePTFE grafts (P=0.08); whereas plasmids encoding for human vascular endothelial growth factor enhanced endothelialisation compared to controls at 2 weeks (P=0.06), however, the effect reversed at 4 weeks (P=0.03). In dogs, synthetic graft patency was improved by plasmids encoding for human vascular endothelial growth factor in femoral position (P=0.103); whereas all carotid grafts were patent at 6 weeks. CONCLUSIONS: Thus, these data suggested that endothelialisation was fastest in pre-clotted polyester grafts; and that local application of plasmids encoding for human vascular endothelial growth factor had a potential to improve early endothelialisation and patency in synthetic vascular grafts.

Animals↗