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PubMed2005

Comparison of primary monoatomic with primary polyatomic ions for the characterisation of polyesters with static secondary ion mass spectrometry.

Static secondary ion mass spectrometry (S-SIMS) emerges as one of the most adequate methods for the surface characterisation of polymers with an information depth of essentially one monolayer. The continuing search for increased analytical sensitivity and specificity has led to exploring the use of polyatomic primary ions as an alternative to the traditionally applied monoatomic projectiles. As part of a systematic investigation on polyatomic bombardment of organic and inorganic solids, this paper focuses on selected polyesters. Mass spectra and ion yields are compared for layers deposited on silicon wafers by spincoating solutions with different concentrations of poly(epsilon-caprolactone) (PCL), poly(butylene adipate) (PBA) and poly(ethylene adipate) (PEA). Accurate mass measurements have been used to support the assignment of the ions and link the composition of the detected ions to the analyte structure. Use of polyatomic projectiles increases the yield of structural ions with a factor of +/-15, +/-30 and +/-10 for PCL, PBA and PEA, respectively, in comparison to bombardment with Ga+ primary ions, while the molecular specificity is improved by the detection of additional high m/z ions.

Adipates↗

PubMed1999

On the suitability of fiberglass reinforced polyester as building material for mesocosms.

Gel- and topcoat surface layers on fiberglass [glass-reinforced plastic (GRP)] made of unsaturated resin based on isophthalic acid polyester and neopentyl glycol (ISO-NPG) were tested for leaching, ecotoxicity of water eluates, and abrasion by river sediments at a current speed of 0.5 m * s-1. Leaching from topcoat tempered at low temperature was significant, whereas it was negligible from highly tempered gelcoat. Water eluates from both gel-and topcoat were nontoxic in routinely employed biotests (bacteria, algae, daphnids). No abrasion by river sediments was detectable. Based on these results, GRP with gelcoat made of ISO-NPG is considered a suitable building material for mesocosms.

Acetone↗

PubMed2001

Production of polyesters in transgenic plants.

Polyhydroxyalkanoates (PHAs) are bacterial polyesters having the properties of biodegradable thermoplastics and elastomers. Synthesis of PHAs has been demonstrated in transgenic plants. Both polyhydroxybutyrate and the co-polymer poly(hydroxybutyrate-co-hydroxyvalerate) have been synthesized in the plastids of Arabidopsis thaliana and Brassica napus. Furthermore, a range of medium-chain-length PHAs has also been produced in plant peroxisomes. Development of agricultural crops to produce PHA on a large scale and at low cost will be a challenging task requiring a coordinated and stable expression of several genes. Novel extraction methods designed to maximize the use of harvested plants for PHA, oil, carbohydrate, and feed production will be needed. In addition to their use as plastics, PHAs can also be used to modify fiber properties in plants such as cotton. Furthermore, PHA can be exploited as a novel tool to study the carbon flux through various metabolic pathways, such as the fatty acid beta-oxidation cycle.

Arabidopsis↗

PubMed1982

Human exposure to styrene. IV. Industrial hygiene investigations and biological monitoring in the polyester industry.

An industrial hygiene study of 10 glassfiber reinforced polyester plants (including 90 workers) was undertaken to investigate the styrene exposure in this industry and to estimate biological limit values (BLV's) for the urinary metabolites of styrene: mandelic (MA) and phenylglyoxylic acids (PGA). Time weighted average (TWA) styrene exposures were found ranging from 2 to 200 ppm. The urinary elimination of metabolites correlated well with exposure and the BLV's corresponding to an 8-h exposure at 100 ppm were consistent with earlier laboratory findings (end-of-shift sample: MA 1640, PGA 510, MA + PGA 2150; next-morning sample: MA 330, PGA 330, MA + PGA 660 mg/g creat.). Total metabolites (MA + PGA) in the next-morning sample or mandelic acid in the end-of-shift sample are recommended for routine monitoring of exposure to styrene. The study revealed the need for further research on how to reduce styrene exposure in this industry.

Air↗

PubMed1998

Endothelial cells lining polyester fabric express pro-coagulant phenotype in vitro.

The paper deals with the in vitro assessment of endothelial cell (EC) phenotype covering an albumin- and chitosan-coated polyester fabric and shows that resting ECs express a pro-coagulant phenotype by releasing a high von Willebrand factor level and expressing low thrombomodulin surface activity, despite maintaining an adequate response to stimulating agents.

Biocompatible Materials↗

PubMed1984

Calorimetrical comparison of insulative properties of metalized plastic, clear polyethylene, and polyester blanket.

The thermal insulation properties of metalized plastic sheeting (MPS), clear polyethylene sheeting (CPS) and 100 per cent polyester thermal bed blanket (TBB) were tested and compared quantitatively using direct calorimetry. The experiments were carried out on individual subjects sitting in a whole body calorimeter and covered first with a TBB bag up to the neck. Then the three materials were tested, one at a time, over the original TBB up to the neck. The temperature of the calorimeter was set at normal operating room temperature of 18 degrees C. MPS provided the greatest reduction in sensible heat loss (SHL) of all three materials tested. The total SHL saving provided by an MPS over TBB was 29.7 per cent and was statistically highly significantly different from that provided by a CPS or TBB over TBB (the difference is 9.6 and 9.9 per cent, respectively, p less than 0.001 for both). While the SHL saving provided by a CPS over TBB was 20.1 per cent, and a TBB over TBB was 19.8 percent, the difference of 0.3 per cent is statistically not significant (p greater than 0.5). An additional finding was that MPS is electrically conductive on one side. Precautions must be taken when it is used on patients connected to electrical devices. Also, insensible perspiration trapped inside the bag can be as much as 10 g X hour-1 and may become a problem when the patient is wrapped in MPS for an extended period of time.

Body Temperature Regulation↗

PubMed2003

Carbon paste electrode modified with copper (II) phosphate immobilized in a polyester resin for voltammetric determination of L-ascorbic acid in pharmaceutical formulations.

A carbon paste electrode modified with copper(II) phosphate immobilized in a polyester resin (CuP-Poly) is proposed for voltammetric determination of L-ascorbic acid in pharmaceutical formulations. The modified electrode allows the detection of L-ascorbic acid at lower anodic potentials than observed at unmodified electrodes. Several parameters that can influence the voltammetric response of the proposed electrode such as carbon paste composition, pH, scan rate, and possible interference were investigated. The peak current was proportional to the concentration of ascorbic acid in the range 2.0 x 10(-5) to 3.2 x 10(-3) mol L(-1) with a detection limit of 1.0 x 10(-5) mol L(-1). The stability and repeatability of the electrode for the determination of L-ascorbic acid are also discussed. Amperometric response was also recorded for electrocatalytic oxidation of the L-ascorbic acid. Concentrations of the vitamin C in pharmaceutical formulations (tablets) measured using the modified electrode and a titrimetric method are in agreement at the 95% confidence level and within an acceptable range of error.

Ascorbic Acid↗

PubMed2001

Polyester microchannel chip for electrophoresis--incorporation of a blue LED as light source.

A blue-light-emitting diode was incorporated as a fluorescence-excitation light source into a polyester microchannel chip fabricated by in situ polymerization. Placing the light-emitting facet of the diode close to the microchannel obviated any need for an additional optical arrangement. Fluorescence from the sample was transmitted by an optical fiber incorporated into the microchip perpendicular to the LED. FITC labeled amino acids were separated in the presence of 5 mM SDS by using the microchip and were detected by LED-induced fluorescence.

Amino Acids↗

PubMed2001

Polyester and polycarbonate synthesis by in vitro enzyme catalysis.

Enzyme technology has significantly expanded in scope and impact over the past 10 years to include organic transformations in non-traditional environments. This is in part due to an increased understanding and capability of using enzyme catalysis in a wide variety of organic solvents, at interfaces, and at high temperatures and pressures. This review focuses on a relatively new but rapidly expanding research activity where in vitro enzyme catalysis is used for the synthesis of non-natural polyesters and polycarbonates. The inclination to use of enzymes for polymer synthesis has been fueled by a desire to carry out these reactions in the absence of heavy metals, at lower temperatures, and with increased selectivity. Aspects of this work that include enzyme-catalyzed step-growth condensation reactions, chain-growth ring-opening polymerizations, and corresponding transesterification of macromolecular substrates are discussed.

Acylation↗

PubMedDate not supplied

Assessment of a polyester-covered nitinol stent in the canine aorta and iliac arteries.

PURPOSE: To evaluate the patency and healing characteristics of a woven polyester fabric-covered stent in the canine model. METHODS: Twenty-four self-expanding covered stents were placed in the infrarenal aorta and bilateral common iliac arteries of eight dogs and evaluated at 1 (n = 2), 3 (n = 2), and 6 (n = 4) months. Stent assessment was done using angiography prior to euthanasia, and light and scanning electron microscopy. RESULTS: Angiographically, just prior to euthanasia, 8 of 8 aortic and 14 of 16 iliac endovascular covered stents were patent. Histologically, the stented regions showed complete endothelialization 6 months after graft implantation. A neointima had formed inside the stented vessel regions resulting in complete encasement of the fabric-covered stent by 3 months after graft implantation. Medial compression with smooth muscle cell atrophy was present in all stented regions. Explanted stent wires, examined by scanning electron microscopy, showed pitting but no cracks or breakage. CONCLUSION: The covered stent demonstrated predictable healing and is effective in preventing stenosis in vessels 10.0 mm or greater in diameter but does not completely preclude stenosis in vessels 6.0 mm or less in diameter.

Alloys↗

PubMed2002

Biological properties of jatrophane polyesters, new microtubule-interacting agents.

PURPOSE: The biological activities of macrocyclic jatrophane polyesters 1-3 from the Sardinian endemism Euphorbia semiperfoliata Viv. have not been evaluated in depth. We investigated the microtubule-interacting and antiproliferative activities of these drugs and the molecular mechanisms underlying their effects. METHODS: We tested jatrophanes for their interaction with purified bovine brain tubulin by an in vitro polymerization assay and by electron microscopy. At a cellular level, the effects of jatrophanes on microtubular architecture, nuclear morphology, cell viability, cell cycle perturbations, and p53 and Raf-1/Bcl-2 involvement were investigated. RESULTS: Jatrophanes exhibited microtubule-interacting activity. They stimulated purified tubulin assembly in vitro, and induced paclitaxel-like microtubules, as revealed by electron microscopy. In the cells, rearrangement of microtubule architecture was in contrast to the bundling produced by paclitaxel. Jatrophanes inhibited the growth of some human cancer cell lines without inducing cell cycle arrest in the G2/M phase. Moreover, they influenced p53 expression and Raf-1/Bcl-2 activation. CONCLUSIONS: Despite their structural difference from paclitaxel and other microtubule-interacting agents, jatrophanes may represent a new type of tubulin binder.

3T3 Cells↗

PubMed1997

The Dialine II graft: a new collagen-impregnated warp-knitted polyester arterial prosthesis.

The Dialine graft, a new prototype of knitted vascular prosthesis that uses a different brand of polyester fibers as an alternative to Dacron fibers, has been shown to offer excellent in vitro physical performance and in vivo healing. Although it still requires preclotting, the Dialine prosthesis was made impervious by impregnation of bovine type I collagen cross-linked with vapors of formalin. The purpose of the present investigation was to compare the in vitro physical characteristics of the Dialine II graft with those of the collagen-impregnated Hemashield graft. In addition, we studied the healing performance as a thoracoabdominal bypass in dogs for prescheduled periods of implantation ranging from 4 hours to 6 months. In vitro, the bursting strength, resistance to dilatation, and suture retention strength properties of the Dialine II prosthesis were all shown to exceed those of the Hemashield control graft. In the first weeks after implantation, the Dialine II grafts induced a discrete inflammatory response, as shown by the constant leukocyte counts observed both before implantation and when the animals were killed, as well as by the histologic observation of a few inflammatory cells in contact with the collagen. Consequently, the Dialine II grafts showed a slow rate of bioresorption of cross-linked collagen. At 1 month, a thin internal collagenous capsule was present at both anastomoses, laying over the original collagen coating. At 3 and 6 months, areas of thrombotic deposits and endothelialized areas were observed on the luminal surface. Because results of early clinical trials have been highly satisfactory, this prosthesis may be recommended for use without restriction as a medium- and large-diameter blood conduit.

Animals↗

PubMed1999

Impregnated polyester arterial prostheses: performance and prospects.

Impregnated polyester arterial prostheses have gained wide acceptance by most vascular surgery teams, probably because these prostheses are easy to use, without any preclotting. We offer here a synthesis of the main studies that have appraised the experimental and clinical performance of these prostheses, and we delineate their major prospects.

Animals↗

PubMed2006

The production of a new extracellular putative long-chain saturated polyester by smooth variants of Mycobacterium vaccae interferes with Th1-cytokine production.

Mycobacterium vaccae is of major pharmaceutical interest as an immunotherapeutic agent. Although M. vaccae 15483 ATCC(T) strain displays smooth and rough colonial morphologies on solid culture media, it is not known in which conditions M. vaccae switches from one colonial morphotype to the other or whether there are biological differences, especially immunological, between them. We have found that the change from a smooth to rough stable variant occurs spontaneously at 30 degrees C. The analysis of the composition of the cell wall in both variants showed that the smooth morphotype presents an extracellular material that has never previously been described and was identified as a long-chain saturated polyester that, interestingly, is not produced by the rough morphotype. Our results also indicate that this compound could be implicated in the spreading ability of smooth colonies. Proliferation, IFN-gamma and IL-12(p40) production by splenocyte cultures was significantly higher in mice immunised with the rough variant compared with those immunised with the smooth one. This latter finding suggests that the different colonial morphology of M. vaccae may affect the immunomodulatory effects induced from M. vaccae preparations.

Animals↗

PubMed2005

Hydrolysis of polyesters by serine proteases.

The substrate specificity of alpha-chymotrypsin and other serine proteases, trypsin, elastase, proteinase K and subtilisin, towards hydrolysis of various polyesters was examined using poly(L-lactide) (PLA), poly(beta-hydroxybutyrate) (PHB), poly(ethylene succinate) (PES), poly(ethylene adipate) (PEA), poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBS/A), poly[oligo(tetramethylene succinate)-co-(tetramethylane carbonate)] (PBS/C), and poly(epsilon-caprolactone) (PCL). alpha-Chymotrypsin could degrade PLA and PEA with a lower activity on PBS/A. Proteinase K and subtilisin degraded almost all substrates other than PHB. Trypsin and elastase had similar substrate specificities to alpha-chymotrypsin.

Adipates↗

PubMed2006

Material and knot properties of braided polyester (Ticron) and bioabsorbable poly-L/D-lactide (PLDLA) 96/4 sutures.

The purpose of the present study was to investigate in vitro the biomechanical material and knot properties and histomorphometrical knot properties of 3-0 braided polyester suture (Ticron) and bioabsorbable poly-L/D-lactide (PLDLA) 96/4 suture. In Ticron five throws are needed to form a secure knot, and the 1 = 1 = 1 = 1 = 1 and the 2 = 1 = 1 = 1 configurations are recommended. For PLDLA several granny and square knots formed a secure knot, but the 1 = 1 and 1 = 1 = 1 knots were the best. These PLDLA knots had lower yield force and strain at yield point, but higher stiffness than the recommended Ticron knots. The ultimate force values did not differ, but PLDLA knots had significantly higher strain at ultimate point. In the histomorphometrical analysis of the recommended knots, the PLDLA knots had a significantly smaller knot surface area than the Ticron knots. According to these results, PLDLA suture proved to be suitable for flexor tendon repair.

Absorbable Implants↗

PubMed1985

Nerve regeneration through biodegradable polyester tubes.

One approach to repair of transected nerves is to attempt extrinsic guidance of axons across the gaps. We inserted the proximal and distal stumps of severed mouse sciatic nerves into opposite ends of biodegradable polyester tubes. The nerves and ensheathing tubes were examined after postoperative survival times of as long as 2 years. Myelinated fiber number in each successfully regenerated nerve was measured and correlated with the tube's residual lumen size. In selected regenerated nerves axonal sizes and myelin sheath widths were sampled and compared with control values. Swelling and deformation of tube walls occurred in nearly all tubes. Successful regeneration was obtained through more than half of the implants, and was more probable in tubes with larger initial lumens. Myelinated fiber number in regenerated nerves ranged from 231 to 3561 (normally 3900 to 4200); larger values again were found in tubes with larger initial lumens. Mean axonal areas in regenerated nerves were roughly half of normal, though myelin sheaths became appropriately thick. We concluded that the more biodegradable a tube, the more likely it was to incur distortion and luminal narrowing. Tube composition per se seemed of importance mainly as it related to maintenance of adequate luminal size over the length of the degrading tubes; luminal adequacy, not tube composition, seemed paramount in determining the extent of nerve regeneration.

Animals↗

PubMed1990

Evidence for microbial polysaccharide preparations containing polyester substituents.

CPMAS 13C-n.m.r. spectroscopy was employed to characterize the composition and solid phase morphology of gellan, welan, rhamsan and NW11. Spectra indicated that commercial preparations of these polysaccharides, which share a similar molecular backbone, contain a non-carbohydrate component exhibiting four inequivalent carbon atoms. Isolation of this component, followed by 13C-n.m.r. in CHCl3 and MS analysis, revealed its structure to be poly(beta-hydroxybutyrate). Evidence is presented which suggests that this polyester may be a covalent adduct to the above polysaccharides, although this cannot be unambiguously determined at this time. Further experimentation is in progress.

Hydroxybutyrates↗