PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Polyesters”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources
PubMed1997

Oligosaccharide polyesters from roots of Polygala fallax.

Five new oligosaccharide polyesters, fallaxoses A-E, along with four known ones, reiniose D, senegose G, tenuifolioses C and P, were isolated from the roots of Polygala fallax. Fallaxoses A-E were elucidated as 3-O-{4-O-[beta-D-glucopyranosyl-(1-->4)- alpha-L-rhamnopyranosyl]-feruloyl}-beta-D-fructofuranosyl- (2-->1)-(4,6-di-O-benzoyl)-alpha-D-glucopyranoside, 3-O-{4-O-[beta-D-glucocopyranosyl-(1-->3)-(2-O-acetyl)- alpha-L-rhamnopyranosyl]-feruloyl}-beta-D-fructofuranosyl-(2-->1)- (4, 6-di-O-benzoyl)-alpha-D-glucopyranoside, 1-O-p-coumaroyl-(3-O-benzoyl)-beta-D-fructofuranosyl-(2-->1)- [beta-D-glucopyranosyl-(1-->2)]-[6-O-acetyl-beta-D-glucopyranosyl- (1-->3)]-(4-O-p-coumaroyl)-alpha-D-glucopyranoside, 1-O-p-coumaroyl-(3-O-benzoyl)-beta-D-fructofuranosyl-(2-->1)- [beta-D-glucopyranosyl-(1-->2)]-[6-O-acetyl-beta-D-glucopyranosyl-(1-->3 )]-(4-O-feruloyl)-alpha-D-glucopyranoside, 1-O-feruloyl-(3-O-benzoyl)-beta-D-fructofuranosyl-(2-->1)- [beta-D-glucopyranosyl-(1-->2)]-[beta-D-glucopyranosyl- (1-->3)-(6-O-acetyl)-beta-D-glucopyranosyl-(1-->3)]- (6-O-feruloyl)-alpha-D-glucopyranoside, respectively, by spectroscopic and chemical means.

Carbohydrate Conformation↗
PubMed1999

Adsorption of proteins from plasma at polyester non-wovens.

Polyester non-wovens in filters for the removal of leukocytes from platelet concentrates (PCs) must be platelet compatible. In PC filtration, the adsorption of proteins at the plasma-non-woven interface can be of great importance with respect to the yield of platelets. Unmodified and radio frequency glow discharge (RFGD) treated poly(ethylene terephthalate) non-woven (NW-PET) and two commercial surface-modified non-wovens were contacted with human plasma. Protein desorption by sodium dodecyl sulphate (SDS) was evaluated by X-ray photoelectron spectroscopy (XPS). The desorbed proteins were characterized by gel electrophoresis and immunoblotting. Compared to the commercial surface-modified non-wovens, unmodified and RFGD-treated NW-PETs adsorbed a relatively high amount of protein. Significantly more protein was removed from the hydrophobic NW-PET by SDS than from the hydrophilic RFGD-treated non-wovens. RFGD treatment of NW-PET reduces the reversibility of protein adsorption. Less albumin and fibrinogen were removed from the RFGD-treated non-wovens than from NW-PET. In addition, a large amount of histidine-rich glycoprotein was removed from RFGD-treated non-wovens, but not from NW-PET. The different behaviour of RFGFD-treated non-wovens towards protein adsorption is probably caused by differences in the chemical reactivity of the non-woven surfaces.

Adsorption↗
PubMed2004

Cardiac heart disease in the era of sucrose polyester, Helicobacter pylori and Chlamydia pneumoniae.

Recent evidence associates inflammatory mediators with coronary heart disease. Elevation of acute-phase reaction (APR) proteins such as serum amyloid A, fibrinogen, CRP and haptoglobin in response to Helicobacter pylori (H. pylori) infection was shown to initiate gastritis and ischemic heart disease. Positive Chlamydia pneumoniae (C. pneumoniae) serology is associated with increased levels of inflammatory cytokines and tumor necrosis factor-alpha (TNF-alpha), which stimulates endothelial cell activation, procoagulant activity and angiogenesis in patients with coronary heart disease. As a final example, interleukin-6 (IL-6) has been proposed to mediate cardiovascular disorders. Public awareness of risks of excessive body weight and high levels of serum cholesterol propelled the development of synthetic dietary components such as sucrose polyester (SPE) to substitute for natural lipids. SPE is a synthetic lipid whose physical properties are similar to a natural triacylglycerol with a similar assortment of fatty acids and is resistant to lipolysis by gastric and pancreatic enzymes. Intake of SPE in lieu of natural lipids is expected to decrease absorption of essential fatty acids (EFA) and fat-soluble vitamins among other essentials. Deficiency of EFA leads to the formation of faulty cellular membranes, which is manifested as skin lesions, growth failure, erythrocyte fragility, impairment of fertility and uncoupling of oxidation and phosphorylation. Possibilities of absorption of these synthetic lipids into the circulation may represent an unexpected health hazard. We have shown that subcutaneous (sc) administration to rabbits of a range of lipolysis-resistant lipid-like sorbitol, mannitol and arabitol esters of palmitic (P) and lauric (L) acids was found to evoke a mild APR, which in humans could contribute to CHD incidence. We suggest a reversal in the commonly accepted role of SPE as a sequestor of dietary lipid: SPE may be the lipophilic solute contained within the dietary lipid solvent micelle. An alternative conclusion regarding the biological effects of excessive dose of SPE in human and pig for a short time span should be considered.

Chlamydophila Infections↗
PubMedDate not supplied

The individuality of fibres used to provide forensic evidence--not all blue polyesters are the same.

Fibres used in forensic casework suffer from a disadvantage common to other forms of trace evidence--it is not possible to state with absolute certainty that they originate from a specific source. Target fibre studies, population studies and research on 'blocks of colour' have effectively demonstrated the polymorphism of textile fibres (particularly man-made ones) and have shown that when a fibre is believed to have a specific putative source, the chance that it has originated from a different source purely by coincidence is extremely remote. A study by Houck MM (Houck MM, Inter-comparison of unrelated fibre evidence. Forensic Science International 2003; 135: 146-149) has shown that no coincidental matching fibres were recovered from items of clothing examined in 20 unrelated crimes. The study involved over two million comparisons. This work goes a step further, and using the example of blue polyester fibres shows that even within a very narrow segment of the whole general fibre population, many examples of a specific colour/type of man-made fibre taken from random sources can be compared and the chance of any two being the same is very low. These studies should help to show the specificity and value of transferred fibres in providing forensic evidence.

Journal Article↗
PubMed1998

A 3-month, double-blind, controlled trial of feeding with sucrose polyester in human volunteers.

Sucrose polyester (SPE) is a tasteless, odourless substance which reduces plasma cholesterol concentrations and may therefore be valuable as a fat substitute in human foodstuffs. It has recently been approved for use in snack foods by the United States Federal Drug Administration. The current study was designed to investigate its effects on gastrointestinal physiology and nutrient absorption in human subjects. A 6-month (2 x 3-month periods) double-blind, placebo-controlled, randomized, cross-over trial of SPE and control fat was performed in healthy free-living volunteers. Subjects consumed 20-40 g of SPE daily (mean 26.8 (SE 6.8) g) which reduced the intake of total and saturated fat but had no effect on energy intake or body weight. Plasma cholesterol and triacylglycerols were reduced. The frequency of bowel movements and their urgency were increased and anal leakage occurred in 7.2% of subjects. Abdominal pain was more frequent in subjects receiving SPE and was significantly greater than in the control group after 8 weeks feeding. The plasma concentrations of vitamin E and six carotenoids were significantly reduced. Routine haematology and biochemistry, other vitamins, intestinal biopsies, bile-salt retention, rectal prostaglandins, fractional Ca absorption and aminopyrine metabolism were unaffected. The ingestion of foods containing 20-40 g SPE daily provoked significant gastrointestinal problems. This intake is greater than that to be expected from the use of SPE in savoury snack foods, for which it has been approved by the United States Federal Drug Administration. However, the favourable effects on lipid profiles must be balanced against the reduction in the concentrations of vitamins and carotenoids, as these compounds may have beneficial effects on health through protection from free-radical oxidative stress.

Adult↗
PubMed2002

The cobalt-catalyzed alternating copolymerization of epoxides and carbon monoxide: a novel approach to polyesters.

The metal-catalyzed synthesis of polyolefins, polyketones, and polycarbonates is well-known in academia and is already successfully applied in industrial processes. Still missing, however, is the metal-catalyzed synthesis of aliphatic polyesters, as one of the most important biodegradeable polymer families. We report here on the cobalt-catalyzed alternating copolymerization of propylene oxide and carbon monoxide, affording atactic and isotactic polyhydroxybutyrates (PHB). The postulated mechanism is supported by online ATR-IR analytics.

Journal Article↗
PubMed2006

Thermally induced phase transition of carborane-functionalized aliphatic polyester dendrimers in aqueous media.

Three recently reported aliphatic polyester dendrimers of generations 3, 4, and 5, having 4, 8, and 16 carborane cages within their interior, respectively, were found to exhibit thermally induced, reversible precipitation in aqueous solution. The cloud-point temperatures for these molecules were observed to be between 40 and 80 degrees C, depending on the dendrimer generation. The three dendrimers investigated have a hydroxyl-to-carborane ratio of 8:1, which provides the ideal balance between the hydrophobic interior and the hydrophilic exterior to enable the thermally induced phase transition to occur. It was found that repeated heating/cooling cycles resulted in a decreasing cloud-point temperature and increased dendrimer solubility. Additionally, the effect of pH on the cloud point was investigated, indicating no significant changes as long as the dendrimers remained stable. Size-exclusion chromatography indicated that dendrimer degradation was occurring at pH above 7.0.

Journal Article↗
PubMed1998

Diterpene polyesters from euphorbia seguieriana

An Me2CO extract of Euphorbia seguieriana (Euphorbiaceae) afforded seven new diterpene polyesters (1-7). Five of them (1-5), having a new parent alcohol that was named 17-hydroxymyrsinol, were structurally related to myrsinol. The other two compounds (6, 7) were new derivatives of the known parent alcohols cyclomyrsinol and lathyrane. The structure elucidations of the new compounds by highfield spectroscopic methods, including 1D and 2D NMR techniques, are described.

Journal Article↗
PubMed2002

New insight into the synthesis of a novel azo-based optically active polyamidoamine side chain dendritic polyester architectural photoswitch.

[reaction: see text] A novel chiral polyamidoamine side chain dendritic polyester 4 has been synthesized and found to be a photoresponsive system undergoing reversible E/Z photochemical/thermal isomerization of azo units. Thorough characterization (IR,UV-vis, NMR, FAB-MS, elemental analysis, optical rotation, etc.) were performed to ascertain the structures of dendrimers 2, 3, and 4. The intrinsic viscosity of 4 at 36 degrees C in CHCl(3) was found to be 0.48 dl/g.

Journal Article↗
PubMed2000

Biodegradable polyester, poly[alpha-(4-aminobutyl)-L-glycolic acid], as a non-toxic gene carrier.

PURPOSE: The aim of this study was to develop a non-toxic polymeric gene carrier. For this purpose, biodegradable cationic polymer, poly[alpha-(4-aminobutyl)-L-glycolic acid] (PAGA) was synthesized. PAGA was designed to have ester linkage because polyesters usually show biodegradability. METHODS: Degradation of PAGA in an aqueous solution was followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). PAGA/DNA complexes were characterized by gel electrophoresis, atomic force microscopy (AFM), dynamic light scattering (DLS). The transfection was measured by using the beta-galactosidase reporter gene. RESULTS: PAGA was degraded in aqueous solution very quickly and the final degradation product was a monomer (L-oxylysine). Formation of self-assembling biodegradable complexes between PAGA and DNA at a charge ratio 1:1 (+/-) was confirmed by gel band shift assay and AFM. In these studies, controlled release of DNA from the complexes could be seen. The complexes showed about 2-fold higher transfection efficiency than DNA complexes of poly-L-lysine (PLL), a structural analogue of PAGA, which is the most commonly used poly-cation for gene delivery. The polymer did not show cytotoxicity, possibly because of its degradability and the biocompatibility of the monomer. CONCLUSIONS: The use of the biodegradable poly-cation, PAGA, as a DNA condensing agent will be useful in safe gene delivery.

Absorbable Implants↗
PubMed1998

Polyacids as bonding agents in hydroxyapatite polyester-ether (Polyactive 30/70) composites.

A previously developed method to improve the interface between hydroxyapatite (HA) and a polyester-ether (Polyactive 70/30) by using polyacrylic acid or poly(ethylene-co-maleic acid) has been applied to HA/Polyactive 30/70 composites noting that polyactive 30/70 contains less polyethylene glycol (PEG) segments and a higher concentration of rigid poly(butylene terephthalate) (PBT) segments. The mobility of the PEG segments is significantly affected by the existence of a high concentration of rigid PBT segments. Our experimental results show that this method is indeed suitable for making HA/Polyactive 30/70 composites. The hydrogen bond/dipole interaction forming ability of the PEG segment is not affected by the existence of relatively large amounts of PBT segments. By using these coupling agents, the mechanical properties of the composite can be significantly improved both in dry and wet states. A fractographical study of the fracture surfaces revealed that the surface modified HA particles maintain better contact at fracture. It also showed that larger HA particles may initiate cracks and that such particles may be responsible for a decrease in the tensile strength of the composites.

Journal Article↗
PubMed1997

Up-regulation of thrombomodulin is inducible on an endothelialized polyester.

The concept of endothelial cell seeding of vascular prostheses is designed as a method for improving long-term patency substitutes because endothelium is considered as the haemocompatible surface of reference. The assessment of the functionality of cells lining a biomaterial is thus of crucial importance. We have reported encouraging results concerning the ability of a polyester coated with albumin and chitosan (M 11) to be lined by a confluent monolayer of cultured human endothelial cells (EC). The aim of the present work was to study the expression of thrombomodulin (membrane glycoprotein responsible for anticoagulant activity) in EC lying on M.11 by anticoagulant activity and mRNA level with and without stimulation. Results obtained in basal conditions showed that EC on M.11 have a comparable expression of TM mRNA when compared to control (EC on tissue culture plates) despite a lower TM surface activity for EC on the biomaterial. In terms of ratio (stimulated cells to unstimulated ones) the response in activity for EC on M.11 is comparable to that of the control. These results indicate that cells lying on M.11 are able to respond to physiological-like stimuli, despite a tendency for these cells to express a procoagulant phenotype when compared with control EC.

Journal Article↗
PubMed1994

Cyclosporin absorption is impaired by the fat substitutes, sucrose polyester and tricarballylate triester, in the rat.

The effect of non-absorbable fat substitutes (sucrose polyester (SPE) and tricarballylate triester (TCTE)) on cyclosporin A (CsA) intestinal absorption was studied in the rat using in situ perfusion and gastric intubation techniques. A first experiment using the recirculating intestinal perfusion model showed that emulsions of either 5% SPE or TCTE significantly reduced (p < 0.0008) CsA absorption, whereas no difference was found between results for saline and 5% olive oil emulsion. In single-pass intestinal perfusion experiments SPE dose-dependently inhibited CsA absorption at SPE concentrations of 0.31% (p < 0.0004) and higher. Using gastric intubation, whole blood CsA concentrations significantly decreased when administered with SPE and TCTE in comparison with olive oil (p < 0.04). These results confirm that the CsA fraction dissolved in the undigested oil phase, constituted by the undigested and nonabsorbed fat substitute, is unavailable for intestinal absorption.

Animals↗
PubMed1994

In situ degradation of 11/0 polyester (mersilene) suture material following cataract surgery.

Two hundred and ten patients (231 eyes) had their cataract sections closed with 11/0 polyester suture material over a 4 year period. Their case sheets were assessed to determine the number of eyes from which sutures had been removed prior to discharge, and for what reasons these sutures were removed. Ninety-seven patients (107 eyes) with sutures left in situ were further assessed to determine whether they were suffering from any suture-related symptoms and examined to determine the degree of clinical biodegradation experienced by the sutures. Six of these sutures were removed for electron microscopic examination. Of the 231 eyes initially included, 61 sutures (26.4%) had been removed prior to discharge. None of the 107 sutures examined showed evidence of clinical biodegradation; this was confirmed by electron microscopic analysis which showed only minimal erosion of sutures even after 48 months in situ.

Biodegradation, Environmental↗
PubMed2001

Headspace gas chromatographic determination of 2-alkyl-5,5-dimethyl-1,3-dioxane derivatives in wastewaters of a polyester resin plant.

The static headspace gas chromatographic technique can be conveniently employed to check the presence and amount of the odorous side-products, 2-R-1,3-dioxanes (R = H, CH3, C2H5, i-C3H7, n-C3H7), directly from the wastewaters flowing from the reactors during the synthesis of polyester resins. By the optimisation of a simple and direct analytical method, the amounts of these compounds may be continuously monitored and controlled. This method is characterized by good repeatability (3-4%) and does not seem to suffer from matrix effects. The detection limits for the determination of the five dioxanes fall in the range 400-700 micrograms dm-3 (alpha = beta = 0.05).

Journal Article↗
PubMed2000

Biostability, inflammatory response, and healing characteristics of a fluoropassivated polyester-knit mesh in the repair of experimental abdominal hernias.

The present study was undertaken to validate the benefits of a fluoropolymer treatment on the biostability, inflammatory response, and healing characteristics of a polyester mesh used for hernia repair, the Fluoromesh, as compared to a commercial monofilament-knit polypropylene mesh, Marlex, used as the control. Both were implanted for the repair of surgically induced abdominal hernias in piglets for prescheduled durations of implantation of 4, 15, and 60 days. The mesh and surrounding tissue were harvested at the sacrifice for the bursting strength and inflammatory response measurements in terms of alkaline and acid phosphatase secretion in the tissue, and for histological observations of the healing sequence and tissue thickness measurements by histomorphometric techniques. After cleaning to remove adherent tissue, the presence of the fluoropolymer at the surface of the mesh was detected using SEM and ESCA. The results demonstrated greater mechanical reinforcement and tissue development for the Fluoromesh than for the polypropylene mesh. The healing performance of the Fluoromesh was attributed to a more intense chronic inflammatory reaction early after implantation that stimulated significantly greater tissue ingrowth and integration. The concentration of fluoropolymer at the surface of the mesh was masked as a result of biological species adsorption. Textile analysis revealed that the Fluoromesh was dimensionally more stable in vivo than the polypropylene control mesh, which demonstrated stretching in the weft direction and shrinking in the warp direction during implantation.

Acid Phosphatase↗
PubMed1995

Short-term satiating effect of the fat replacer sucrose polyester (SPE) in man.

The effects of different amounts of the non-absorbable fat replacer sucrose polyester (SPE), water, and fat added to six warm preload lunches on feelings of appetite and food intake were investigated in two studies that were replicates of each other. In the first study thirty-nine subjects consumed rice preloads; in the second study thirty-five subjects consumed macaroni preloads. The six preloads were fixed on three energy levels: 1.8, 2.7, or 3.7 MJ. At 2 h after preload consumption a test-meal buffet of thirty-one products was presented. Food intake was recorded on the study day, and the day after the study day. For women no energy compensation occurred in either study. Men showed a tendency to compensate for the energy differences between the preloads. However, when the fat of the preloads was replaced by SPE, energy compensation was less than 50% and non-significant. Statistically significant energy compensation (66%) was found when fat was replaced by water. No macronutrient-specific compensation occurred in men or women in either study. Lower total fat and energy intakes were found with the preloads where fat was replaced by SPE compared with the preloads containing fat. The appetite ratings were in line with the energy intake values, with no differences in women, and higher appetite ratings after the lower energy preloads in men. This short-term study indicates that SPE may be a useful aid to reduce fat and energy intakes.

Adult↗