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At least 37 records · Page 2Linked to original sources

PubMed1990

Formation of polyesters consisting of medium-chain-length 3-hydroxyalkanoic acids from gluconate by Pseudomonas aeruginosa and other fluorescent pseudomonads.

Pseudomonas aeruginosa PAO and 15 other strains of this species synthesized a polyester with 3-hydroxydecanoate as the main constituent (55 to 76 mol%) if the cells were cultivated in the presence of gluconate and if the nitrogen source was exhausted; 3-hydroxyhexanoate, 3-hydroxyoctanoate, and 3-hydroxydodecanoate were minor constituents of the polymer. The polymer was deposited in granules within the cell and amounted to 70% of the cell dry matter in some strains. Among 55 different strains of 41 Pseudomonas species tested, P. aureofaciens (21.6% of cellular dry matter), P. citronellolis (78.0%), P. chlororaphis (8.5%), P. marginalis (11.4%), P. mendocina (50.7%), P. putida (33.5%), and Pseudomonas sp. strain DSM 1650 (54.6%) accumulated this type of polymer at significant levels (greater than 5%) during cultivation on gluconate. In two strains of P. facilis and P. fluorescens, as well as in one strain of P. syringae, this polymer was detected as a minor constituent (much less than 5%). All other strains accumulated either poly(3-hydroxybutyrate) or a polymer consisting mainly of 3-hydroxyoctanoate with octanoate but no polyester with gluconate as the carbon source. Only a few species (e.g., P. stutzeri) were unable to accumulate poly(hydroxyalkanoic acids) (PHA) at all. These results indicated that the formation of PHA depends on a pathway which is distinct from all other known PHA-biosynthetic pathways. The polyesters accumulated by gluconate- or octanoate-grown cells of recombinant strains of P. aeruginosa and P. putida, which harbored the Alcaligenes eutrophus poly(3-hydroxybutyrate)biosynthetic genes, contained 3-hydroxybutyrate as an additional constituent.

Gluconates↗

PubMed1988

Anterior cruciate ligament replacement. Biocompatibility and biomechanics of polyester and carbon fibre in rabbits.

The anterior cruciate ligament was replaced in rabbits, using implants of carbon or polyester filaments with known mechanical properties. The biocompatibility of the implants was assessed in detail using light microscopy, and scanning and transmission electron microscopy. Mechanical tests were made of stability, in comparison with normal joints and controls after excision of the ligament. Some carbon fibre implants broke down in vivo, allowing instability; the fragments caused chronic inflammation. Intact carbon implants did not induce the formation of neoligaments; they were covered by tissue, but there was no ingrowth. Polyester did not degrade mechanically and supported early collagenous ingrowth within the implant, even in the mid-joint space. It was concluded that there was no justification for the use of carbon fibres as anterior cruciate replacements; polyester appeared to be suitable.

Animals↗

PubMed1992

[Polyester treatment in rats with a dorsal air pouch: chemotaxis in lavage fluid from the pouch].

Minced polyester threads introduced into peritoneal cavity of rats cause a granulomatous inflammation with evidence of macrophage stimulation. Chemotactic agents play an important role in the inflammatory reaction; they are released locally by cells involved in inflammation. In this paper the chemotactic effect of the peritoneal and subcutaneous air pouch fluids from rats bearing the polyester inflammatory process, have been studied on PMN cells "in vitro". The fluids were obtained by washing the cavity of untreated rats or rats injected with polyester, 7 days after the injection. The chemotactic response was assayed by employing modified chemotaxis Boyden chambers (Blind Well Neuro Probe) and polymorphonuclear cells from normal rats. Quantification of the migration was calculated by chemotactic index (A/B) (B = random migration, A = chemotaxis). The results demonstrate that a chemotactic activity is present in peritoneal and subcutaneous air pouch fluids following the inflammatory process. In conclusion the chronic inflammation determines the appearance of chemotactic factors for PMN cells, in the peritoneal cavity and in the air pouch, and the air pouch is a very convenient experimental system with the particular advantage that it permits easy repeated sampling of exudate during the course of an inflammatory response.

Air↗

PubMed1992

[Efficacy of leukocyte-depleted platelet concentrates for prevention of HLA-alloimmunization in patients with frequent platelet transfusions: a prospective multi-institutional study using a polyester platelet filter].

A prospective multi-institutional study was conducted to assess the efficacy of leukocyte-depleted platelet concentrates, prepared by a method using a newly developed polyester filter, in the prevention of HLA-alloimmunization in patients with hematological disorders. Patients who were expected frequent platelet transfusions, were assigned into two groups, receiving either standard platelet concentrates (control group) or leukocyte-depleted platelet concentrates prepared through a polyester platelet filter, Sepacell-PL (filtered group). All patients received leukocyte-depleted red cell products. Of III patients enrolled, 72 were evaluable, 23 in the control and 49 in the filtered group. Both groups were comparable according to age, sex ratio, underlying disorders, previous exposure to alloantigens by transfusion and/or pregnancy. There was no statistically significant difference in the number and duration of transfusion in the two groups. There were significant differences in HLA-alloimmunization rate (9 cases out of 23, 39% in the control group versus 4 cases out of 49, 8% in the filtered group; p less than 0.01) and refractoriness to platelet transfusion from random donors (6 cases out of 23, 26% in the control group versus 2 cases out of 49, 4% in the filtered group; p less than 0.05). These results indicated that leukocyte-depleted platelet concentrates prepared through the polyester platelet filter are beneficial to reduce HLA-alloimmunization in patients with frequent platelet transfusions.

Adolescent↗

PubMed1989

[Bassini operation with polyglycolic acid or polyester. A prospective randomized study of 300 cases].

In a prospectively randomized trial polyglycolic acid (PGA) was tested against polyester for recurrence rate in Bassini hernia repair. After a median observation period of 2 years a distinct but statistically insignificant difference was found (12.0% recurrence for PGA against 7.0% for polyester). Within prospectively defined risk groups statistically significant differences were found for men (15.4% PGA, 6.4% polyester) and in the presence of at least one of the risk factors obesity, bronchitis, recurrent hernia, size of hernial sac greater than 8 cm, the last of which being the strongest unfavourable variable for PGA.

Aged↗

PubMed1978

[Histological and cytological studies of the inflammatory process induced by polyesters in the guinea pig].

The inflammatory process caused in the omentum of the guinea pig by the intraperitoneal injection of minced polyester threads is characterized by an increasing number of mononuclear and giant cells surrounding polyester fragments. Lymphocytes and plasma cells have been found to participate in the process when the animals are treated for longer times. The cells obtained from the peritoneal cavity have a large lysosomal apparatus as stained by acridine orange, although the colour is taken up to a lesser degree when the cells are in the presence of the polyester.

Animals↗

PubMed1976

Filtration characteristics of polyester mesh (Pall) micropore blood transfusion filter.

Stored human blood of varying age was passed through polyester mesh (Pall) micropore blood transfusion (pore size, 40 mu). Passage through the filter resulted in decreased screen filtration pressure (SFP) of the blood and increased filter weight. Mumerous microaggregates were removed, but SFP did not return to normal after filtration. On the basis of this research, we conclude that polyester mesh micropore blood transfusion filters are not as effective as Dacron wool (Swank) transfusion filters in removal of micro-aggregates from stored human blood. If a polyester mesh filter must be used, it is recommended that once occlusion of the filter has occurred, the filter should then be discarded and another inserted.

Blood Preservation↗

PubMed1976

The biostability of silicone rubbers, a polyamide, and a polyester.

A biostability test program was designed after evaluation of the relevant literature on in vivo aging phenomena in plastics and elastomers. The program comprised macroscopic, microscopic, mechanical, and physicochemical investigations. Five silicone rubbers, one polyester, and one polyamid were tested as to their aging behavior and their suitability for long-term implantation in the human body was assessed. In order to be able to state the applicability of materials used for endotheses, the various aging phenomena had to be divided into three groups, viz. unspecific, relative, and absolute indications of aging or unserviceability. Changes due to aging were found in all types of implanted plastics and elastomers. Thus, the formation of layers on inlay surfaces occurred regularly and the same would apply to changes in mechanical characteristics during the tensile test. Aging processes resulting in total unserviceability were fragmentation and crazing in the polyester and polyamide sheetings. Other aging phenomena which will easily fit into the classification given above are changes in electrical test values, protein, and lipid depositions without stronger absorptive adhesion, crystallizations on the surface of silicone vulcanizates, and chemical changes in the polyester and polyamide sheetings. Following the assessment of the materials used for endotheses, the test methods used have been evaluated with regard to their suitability for the testing of biostability.

Amides↗

PubMed1975

[Studies concerning the usefulness of catgut, PGA and polyester for abdominal fascia closure (author's transl)].

The abdominal fascia incisions of 133 rabbits were closed either with plain gut, chromic gut, PGA or polyester threads. The breaking strength of the wounds were determined tensiometrically at different time intervals and the tissue was examined histologically. For a three-week period the strength of the abdominal wall depends significantly on the intactness of the threads. PGA produces minimal inflammatory reactions, but loses its strength after a fortnight. Since longitudinal incisions are endangered by severe muscle pull, this material cannot be recommended because of the possibility of wound disruption and the formation of hernias. The loss of strength of catgut plain and catgut chromic starts later. Catgut causes inflammatory reactions within the wound area leading to loss of strength of the sutured tissue. Thus incisions of the abdominal fascia should not be closed with catgut. The non-resorbable suture material polyester shows satisfactory strength and minimal tissue reaction. As long as there is no synthetic suture material with mild tissue reaction and late resorption the fascial closure should be sutured with polyester.

Abdominal Muscles↗

PubMed1990

Production of unsaturated polyesters by Pseudomonas oleovorans.

Pseudomonas oleovorans was grown separately on 3-hydroxy-6-octenoic acid and 3-hydroxy-7-octenoic acid as the only carbon source and under ammonium nutrient-limiting conditions to produce storage polyesters. The polyesters produced contained mainly unsaturated C8 units. Small amounts of both the saturated and the unsaturated C6 units were also present, but only about 1% of the saturated 3-hydroxyoctanoate units was detected. The polyester obtained from 3-hydroxy-6-octenoic acid, which was a mixture of the cis and trans isomers, also contained units with cis and trans double bonds. The weight average molecular weights of the polymers produced were in the range of 339,000-383,000 as determined by g.p.c. relative to polystyrene, with Mw/Mn ratios of 1.8-2.1. The mechanism of PHA formation from n-octene previously reported is discussed in relation to the present results, and the two were found to be in good agreement.

Culture Media↗

PubMed2026

Broad-spectrum biodegradation of aliphatic and aliphatic-aromatic polyesters by Papiliotrema laurentii isolated from locust frass.

Biodegradable aliphatic and aliphatic-aromatic polyesters, such as poly(butylene adipate-co-terephthalate) (PBAT), polylactic acid (PLA), polycaprolactone (PCL), polybutylene succinate (PBS), and polyhydroxyalkanoates (PHA), are increasingly used as sustainable alternatives to petrochemical plastics. However, their depolymerization outside industrial composting facilities is often incomplete. This study characterized Papiliotrema laurentii strain 62UF-13, isolated from migratory locust frass, for broad-spectrum polyester hydrolysis. Emulsion assays demonstrated hydrolytic activity across all five polymers, with PCL and PBS showing the highest clearance rates. Solid-film assays revealed substantial gravimetric mass loss of PCL, PLA, and PHA cast films, whereas a commercial PBAT-PLA mulch film in minimal medium, underwent progressive fragmentation/disintegration, as assessed by the remaining film area. Incubation with the PBAT-PLA film was accompanied by the release of adipic acid (49.60 mg/L, week 1) and terephthalic acid (maximum 21.62 mg/L, week 4), followed by a decrease to 0.26 mg/L by week 8, coinciding with the emergence of putative 3,4-dihydroxymandelic acid and a putative acetylated derivative. Scanning electron microscopy (SEM) revealed pronounced pitting and erosion, while Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) indicated ester-bond scission and changes in crystallinity/melting behavior. Whole-genome sequencing identified eight candidate polyesterases, including cutinases and esterases, with ≥ 60% amino acid identity to known hydrolases active on PCL, PBS, PHA, and PLA. This study is the first report of P. laurentii degrading a broad range of aliphatic and aliphatic-aromatic polyesters, including partial biotransformation of terephthalate moieties from PBAT. Integration of phenotypic assays and genomic evidence positions P. laurentii 62UF-13 as a viable biocatalyst for decentralized management of biodegradable plastic waste under mild environmental conditions.

Papiliotrema laurentii↗

PubMed1978

[Styrene migration into wine contained in polyester resin tanks].

The use of polyester resins in wine tanks manufacture or coating has widely spread during the past five years; this type of material has been and is still the source of organoleptic damage due to non polymerized sytrene migration into urine. Sytrene is a solvant often used in resin polymerization: it act as a reticulation agent of insaturated linear polyester. Polymerization at room temperature is allowed gy additives but has to be completed in warm air or in steam. An excess of styrene is often used for a polymerisation as complete as possible and remains on a free form. Then it migrates from the tank walls into the wine. For a better understanding of the styrene migration mechanism studies were performed on two levels: from small containers (4 l) kept in the laboratory and from tanks (30 hl) set up in an I.N.R.A. wine estate in all conditions usually realized in practice. Influence of time, temperature and alcohol content were studied. Styrene migration was interpreted as a diffusion phenomenom and styrene diffusion coefficients were calculated for several temperatures. Knowledge of these coefficients and of styrene content of the tank walls allow the prediction of a tank behaviour in time. Other substances that styrene were detected in wine and in tank walls, they are impurities either from resins like ethylbenzene, or from the catalyst like mesityl oxide. The lattest has never been mentioned in the litterature. From the results obtained it is possible to give some advices to manufacturers and users of polyester resin tanks, about the quality of raw materials, resins and additives along with the conditions carried and for their use and about the control of monomer styrene content in the walls of just manufactured tank.

Food Contamination↗

PubMed1990

Plastics from bacteria and for bacteria: poly(beta-hydroxyalkanoates) as natural, biocompatible, and biodegradable polyesters.

Hence, PHB belongs to the family of poly(beta-hydroxyalkanoates), PHA, all of which are usually formed as intracellular inclusions under unbalanced growth conditions. Recently, it became of industrial interest to evaluate PHA polyesters as natural, biodegradable, and biocompatible plastics for a wide range of possible applications such as surgical sutures or packaging containers. For industrial applications, the controlled incorporation of repeating units with different chain lengths into a series of copolymers is desirable in order to produce polyesters with a range of material properties because physical and chemical characteristics depend strongly on the polymer composition. Such "tailormade" copolymers can be produced under controlled growth conditions, in that if a defined mixture of substrates for a certain type of microorganisms is supplied, a well defined and reproducible copolymer is formed.

Bacteria↗

PubMed1986

Silver staining of proteins: standardized procedure for two-dimensional gels bound to polyester sheets.

A system for the simultaneous silver staining of numerous two-dimensional gels bound to polyester sheets is proposed. Under controlled conditions, a very good reproducibility of staining can be obtained, even between different experiments. Procedures to avoid artifacts due to polyester sheets (background, silver mirror, and vertical streaking) are described.

Electrophoresis, Polyacrylamide Gel↗

PubMed1985

A compound arterial prosthesis: the importance of the sterilization procedure on the healing and stability of albuminated polyester grafts.

In response to the demand for a vascular prosthesis which achieves reliable haemostasis without preclotting, a new compound albumin/polyester prosthesis has been developed. In order to optimize the sterilization procedures for this device, two series of implantations in the thoracic aorta of dogs were undertaken to compare the effects of ethylene oxide (EtO) and gamma-radiation. Preclotted polyester prostheses were implanted in two additional control series. Pathological analysis of the explanted grafts indicated that gamma-radiation is to be preferred over EtO because it results in faster rates of healing. While the albumin coating delayed the thrombotic response and fibrinolytic activity, the extent of healing of the radiation sterilized graft was equivalent to that achieved by preclotted polyester prostheses in the medium and long term. Measurements of the strength and dimensional changes of the graft demonstrated that, in addition to reducing the risks of acute thrombosis and postoperative haemorrhage, the albumin coating improves the dimensional stability of the knitted structure.

Albumins↗

PubMed1986

Degradability of crosslinked albumin as an arterial polyester prosthesis coating in in vitro and in vivo rat studies.

In order to avoid the preclotting procedure in knitted polyester arterial prostheses and in woven models, compound polyester grafts have been proposed, containing preadsorbed collagen or albumin. Since we are currently investigating grafts impregnated with crosslinked albumin, it was decided to establish the degradation rate of this coating after stabilization with either glutaraldehyde (GA) or carbodiimide (CDI). Tests were performed in vitro by incubation in either PBS, plasma or pancreatin and in vivo by implantation in the abdominal cavity of rats. In PBS or plasma in vitro, the coatings were very stable (2% degradation after 144 h incubation), however, in pancreatin the CDI crosslinked albumin degraded much faster than the GA crosslinked albumin (more than 50% degradation in 12 h compared to less than 30% in 48 h). In vivo the degradation rates of the two types of crosslinked albumin were similar (almost all of the albumin having been lost after 4 weeks) but the cellular response was very different: a mild tissue reaction was observed with the CDI crosslinked coating whereas many foreign body giant cells were present on the GA crosslinked material.

Albumins↗

PubMed1987

In vitro and in vivo characterization of an impervious polyester arterial prosthesis: the Gelseal Triaxial graft.

Over the years, textile polyester arterial prostheses have acquired an excellent reputation for easy handling and good healing characteristics. Until recently, the main drawback in using them was the need for preclotting. This, however, is no longer true. Nonporous polyester grafts which have been coated with an impervious bioerodible layer during manufacture are now commercially available. The Gelseal Triaxial prosthesis is one of this new generation of grafts. It is manufactured by impregnating a Triaxial prosthesis with a gelatin coating. An in vivo and in vitro evaluation of this new device has found that its water permeability is almost zero. It has good handling and conformability characteristics, and its bursting strength is slightly greater than that of the uncoated prosthesis due, no doubt, to the presence of the gel. The rates of degradation of the gelatin coating have proven to be rapid under both in vitro and in vivo conditions. In fact, only a few traces of the gel were found remaining on the graft after 2 wk in the canine thoracic aorta. In addition, this study has demonstrated that the use of a bioerodible gelatin coating, with its ability to promote cellular regeneration, is a feasible approach with which to achieve earlier and more complete biological healing.

Animals↗

PubMed1991

Soft filamentous woven polyester arterial prosthesis from China.

Woven polyester arterial prostheses have traditionally been known for their tight construction and smooth surface which has limited their healing capacity and resulted in poor attachment of their internal and external capsules. A new woven prototype has recently been developed in the Peoples' Republic of China. Among its unique features are its high physical porosity, softness and flexibility. This study undertook a series of in vitro tests to characterize its structure and physical properties in comparison with four commercial polyester grafts of North American origin. In addition, an animal trial was completed in which the new prototype was implanted as an infrarenal aortic substitute in 20 dogs for periods ranging from 4 h to 12 month. The in vitro tests confirmed a unique lightweight, highly porous, satin weave construction. Because of its high water permeability, preclotting was necessary before implantation. Once preclotted and installed, no significant blood loss was observed, and 19 of the 20 grafts remained patent at the sacrifice. Rapid full-width healing was achieved with tightly bound capsules, and more extensive tissue ingrowth was observed. Further work is needed to evaluate its long-term durability as an arterial substitute.

Animals↗