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PubMed2004

Clinical results with an ePTFE inflow conduit for mechanical circulatory support.

BACKGROUND: Neurologic complication is an adverse event associated with mechanical circulatory support. To decrease the incidence of embolic cerebrovascular accidents (CVA) during support with the Novacor left ventricular assist system (LVAS), an expanded polytetrafluoroethylene (ePTFE) inflow conduit has been developed and introduced clinically. METHODS: Using clinical data from Europe and Canada, we conducted a retrospective analysis of the incidence of embolic CVA with the ePTFE inflow conduit (n=88) in comparison with the previously used polyester inflow conduits (n=310, including Vascutek n=155 and Cooley n=155). We calculated freedom from embolic CVA, risk reduction for embolic CVA, and linearized rates of embolic CVA. RESULTS: A significant decrease in the incidence of embolic CVA was demonstrated with the ePTFE conduit (ePTFE 10% vs polyester 23%, p=0.002). Kaplan-Meier analysis of freedom from embolic CVA at 180 days after implantation was 86% for the ePTFE group vs 72% for the polyester group (log-rank test, 0.0185). We also found an associated risk reduction of 55% in CVA occurrence in the ePTFE group when compared with the Polyester group (hazard ratio, 0.445; 95% confidence limit, 0.222-0.890; p=0.0221). Linearized CVA rates also were decreased at all time intervals after implantation in the ePTFE group. CONCLUSIONS: Preliminary clinical results with the newly introduced ePTFE inflow conduit provide compelling evidence that the ePTFE conduit material significantly decreases thromboembolic complications during mechanical circulatory support with the Novacor LVAS.

Adolescent↗

PubMed1999

Substrate and binding specificities of bacterial polyhydroxybutyrate depolymerases.

The substrate specificities of three extracellular polyhydroxybutyrate (PHB) depolymerases from Alcaligenes faecalis (PhaZ Afa), Pseudomonas stutzeri (PhaZ Pst), and Comamonas acidovorans (PhaZ Cac), which are grouped into types A and B based on the position of a lipase box sequence in the catalytic domain, were examined for films of 12 different aliphatic polyesters. Each of these PHB depolymerases used was capable of hydrolyzing poly(3-hydroxybutyrate) (P(3HB)), poly(3-hydroxypropionate) (P(3HP)), poly(4-hydroxybutyrate) (P(4HB)), poly(ethylene succinate) (PESU), and poly(ethylene adipate) (PEA) but could not hydrolyze another seven polyesters. In addition, the binding characteristics of substrate binding domains from PhaZ Afa, PhaZ Cac, and PHB depolymerase from Comamonas testosteroni (PhaZ Cte) were studied by using fusions with glutathione S-transferase (GST). All of fusion proteins adsorbed strongly on the surfaces of polyester granules of P(3HB), P(3HP), and poly(2-hydroxypropionate) (P(2HP)) which was not hydrolyzed by the PHB depolymerases used in this study, while they did not bind on Avicel and chitin granules. The adsorption kinetics of the fusion proteins to the surface of P(3HB) and P(2HP) granules were found to obey the Langmuir isotherm. The cross-area per molecule of fusion protein bound to P(3HB) granules was estimated to be 12+/-4 nm2/molecule. It has been suggested that the active sites in catalytic domains of PHB depolymerases have a similar conformational structure, and that several amino acids in substrate-binding domains of PHB depolymerases interact specifically with the surface of polyesters.

Adsorption↗

PubMed1997

Drug migration from the adhesive matrix to the polymer film laminate facestock in a transdermal nitroglycerin system.

The apparent loss of nitroglycerin in a prototype transdermal nitroglycerin system was investigated by attenuated total reflectance infrared (ATR-IR) microspectroscopy and high performance liquid chromatography (HPLC). Several transdermal nitroglycerin lots placed under controlled storage conditions exhibited loss of drug potency (up to 10%) along with the appearance of a defect in the polymer film laminate facestock. A significant loss of nitroglycerin from the transdermal drug/adhesive matrix may reduce the bioavailabilty of nitroglycerin to the patient. ATR-IR analysis confirmed that nitroglycerin migrated from the drug/adhesive matrix to the facestock polyester layer under storage conditions and that nitroglycerin was retained in the facestock polyester layer. An alternate sample extraction solution successfully removed the nitroglycerin from both the adhesive matrix and facestock polyester layer with nearly 100% labeled strength recovered. The relationship between the migration of nitroglycerin into the facestock polyester layer and the appearance of the defect in the facestock aluminum layer is discussed and a nitroglycerin-aluminum metal reaction mechanism is proposed.

Adhesives↗

PubMed1998

Drug microencapsulation by PLA/PLGA coacervation in the light of thermodynamics. 1. Overview and theoretical considerations.

Phase separation of poly(lactide) (PLA) and poly(lactide-co-glycolide) (PLGA), often called "coacervation" in the pharmaceutical field, is one of the classical methods for peptide drug microencapsulation in biodegradable polyesters. Although numerous studies have used this technique, the underlying physicochemical mechanisms of polyester coacervation under conditions of microsphere production have not been well-described yet. Moreover, the quality of microencapsulation in terms of drug loading efficiency and residual organic solvents is often not entirely satisfactory and depends greatly on the specific drug and polymer used. The first part of this contribution reviews briefly the scientific and patent literature on PLA/PLGA coacervation. Then, the underlying physicochemical principles of polyester coacervation are discussed and relevant thermodynamic models presented. More specifically, attempts were made to clarify the necessary characteristics of polymers, solvents, and coacervating and hardening agents for successful phase separation and microsphere formation. These basic considerations may contribute to a better understanding of the boundary conditions crucial for efficient drug microencapsulation by polyester coacervation.

Drug Compounding↗

PubMedDate not supplied

Effect of different types of textile fabric on spermatogenesis. I. Electrostatic potentials generated on surface of human scrotum by wearing different types of fabric.

This paper comprises a study of the electrostatic potentials generated on the surface of the scrotal area when different types of textile fabric were worn. 21 healthy volunteers were divided into 3 equal groups. The first group was dressed in underpants made of 100% polyester, the second of 100% cotton, and the third of a 50:50% polyester:cotton mixture. With an electrostatic kilovoltmeter, the electrostatic potentials were measured 1 h after wearing the pants once at daytime and a second time at night. The test was repeated 4 times, each on a separate day. No electrostatic potentials were detected on the cotton underpants. The polyester pants showed the highest potentials (mean 338.9 +/- 25 SD Volt cm-2) while the mixed polyester:cotton pants produced less than half that level (mean 148.3 +/- 16 SD Volt cm-2). The readings at daytime were higher than at night, probably due to the higher temperature during the day. The accumulated electrostatic charges on the pants are due to the friction of the pants with the skin. As a result of friction, equal and opposite charges are accumulated on the skin surface and on the inner surface of the pants facing the skin. Eventually, an 'electrostatic field' is produced traversing the scrotal contents and may disturb the testicles and/or epididymis leading to disordered spermatogenesis.

Adult↗

PubMed1997

Mechanical comparison of materials used for extra-capsular stabilisation of the stifle joint in dogs.

OBJECTIVE: The mechanical properties of three materials (No. 2 polypropylene, No. 5 polybutilate-coated multifilament polyester and 18, 27 and 36 kg test monofilament nylon leader material) commonly used for extra-capsular stabilisation of the stifle in dogs with cranial cruciate ligament insufficiency were determined. The ability of No. 5 polybutilate-coated multifilament polyester and 36 kg test monofilament nylon leader material, when placed as extra-capsular sutures, to mitigate cranial drawer was evaluated in hindlimbs of cadavers. DESIGN: An in vitro mechanical study. ANIMALS: Seven pairs of hindlimbs harvested from adult greyhound dogs recently euthanased for other reasons. PROCEDURE: Samples of each material, including samples of 27 kg test leader material that had been sterilised by one of three methods (ethylene oxide, one or five cycles in an auto-clave), were loaded to determine tensile and stress relaxation properties. The effect of cyclic loading on a No. 5 polybutilate-coated multifilament polyester and 36 kg test leader material was also determined. Using the harvested hindlimbs, cranial drawer was measured before and after transection of the cranial cruciate ligament and on the first and twelfth cycle following extra-capsular stabilisation with either No. 5 polybutilate-coated multifilament suture or 36 kg test leader material. RESULTS: Leader material was found to have the most suitable mechanical characteristics for use as extracapsular stabilisation of the cranial cruciate ligament deficient stifle. Of the sterilisation methods, ethylene oxide was found to have the least detrimental effects on the handling and material characteristics of the leader material. Stifles stabilised with 36 kg test leader material had significantly less drawer than those stabilised with No. 5 polybutilate-coated multifilament polyester suture. CLINICAL IMPLICATIONS: Monofilament nylon leader material would appear to have suitable mechanical properties for extra-capsular stabilisation of the cranial cruciate ligament deficient stifle. If possible the material should be sterilised using ethylene oxide.

Animals↗

PubMed1998

Experimental study of the histocompatibility of covered expandable metallic stents in the trachea.

STUDY OBJECTIVES: To evaluate the histocompatibility of four different materials used to cover expandable metallic stents. DESIGN: Prospective, randomized, unblinded study. SETTING: Animal research laboratory of Kurume University. PATIENTS OR PARTICIPANTS: Twenty 12- to 18-kg mongrel dogs. INTERVENTIONS: Handmade Gianturco-type stents with six bends, 20 mm in length, and 15 to 20 mm in diameter were covered using four different materials: polypropylene mesh, silicone-coated mesh, polyester mesh, and ePTFE. Covered stents were inserted into the trachea after i.v. anesthesia. Five animals were used in each group. MEASUREMENTS AND RESULTS: Postinsertion status was observed using clinical and bronchoscopy measures 7, 14, 28, and 56 days after intervention. Eight weeks after stent insertion, the tracheal specimens were studied pathologically. A scoring system was used to evaluate the histocompatibility of covered stents in each study group. The mean of clinical scores in the polypropylene group was 1.84+/-0.36, which was significantly higher than those in the groups of silicone, polyester, and ePTFE. The means of histopathologic scores in the polypropylene group and the silicone group were 1.60+/-0.55, which were significantly higher than those in groups of polyester and ePTFE. CONCLUSIONS: Polypropylene mesh cover was more suitable than silicone-coated mesh, polyester mesh, and ePTFE because of its excellent histocompatibility.

Anesthesia, Intravenous↗

PubMedDate not supplied

Effect of different types of textile fabric on spermatogenesis: electrostatic potentials generated on the surface of the human scrotum by wearing different types of fabric.

This study was conducted to evaluate the effect of the electrostatic potentials generated on the surface of the scrotal area when different types of textile fabric were worn. Twenty-one healthy volunteers were divided into three equal groups. The first group was dressed in underpants made of 100% polyester, the second wore underpants of 100% cotton, and the third wore a 50/50% polyester/cotton mixture. With an electrostatic kilovoltmeter, the electrostatic potentials were measured 1 h after wearing the pants once during the day and a second time at night. The test was repeated 4 times, each on a separate day. No electrostatic potentials were detected on the cotton underpants. The polyester pants showed the highest potentials (mean 338.9 +/- 25 SD V/cm2), while the mixed polyester/cotton pants produced less than half that level (mean 148.3 +/- 16 SD V/cm2). The readings during the day were higher than those at night, probably due to the higher temperature during the day. This study could explain the cause of diminished spermatogenesis in dogs dressed in polyester pants. A new theory is put forward holding that the polyester underpants create an "electrostatic field" across the scrotal sac that disturbs the testicular and/or epididymal function.

Adult↗

PubMed1999

Morphological and functional evaluation of isolated rat hepatocytes in three dimensional culture systems.

Various three-dimensional configurations, such as polyester tissue and woven-nonwoven, hydrophilic polyester fabric, either collagen-coated or uncoated, were investigated as potential scaffold for hepatocyte culture, in view of their use in bioreactors for hybrid liver support systems. Attachment, morphology and ultrastructure of primary adult rat hepatocytes were evaluated, as well as urea production and ammonium detoxification during a 24h incubation period in serum-free tissue culture medium. As control, hepatocytes were also plated onto collagen-coated dextran microcarriers and on plastic petri dishes, either collagen-coated or uncoated. In all the three-dimensional cultures, hepatocytes appeared morphologically intact without any statistically significant difference in metabolic activity. Collagen-coating did not influence cell attachment to polyester substrates, whereas woven-nonwoven hydrophilic polyester fabric may offer some potential advantages as three-dimensional system for hepatocyte culture in hybrid liver support systems.

Animals↗

PubMedDate not supplied

Plastination of whole brain specimen and brain slices.

BACKGROUND: The human dead body specimens are plastinated for teaching purposes in medical institutions, using silicone. The silicone impregnated whole brain specimens and brain slices do not give satisfactory results. METHODS: In the present study the brain specimens were plastinated with another polymer known as Polyester-Copolymer. The brain specimens were first preserved and then fixed with 5% formalin. The specimens were then dehydrated and degreased in a volatile solvent acetone. The specimens were placed in Polyester-Copolymer solution which penetrated the brain tissue both intracellulary and intercelluraly. The specimens were then cured by gas method. RESULTS: The whole brain specimens and brain slices plastinated with Polyester-Copolymer were dry, odorless, handy and durable. It also gives a clear visual contrast between grey and white matter in brain slices whereas the brain specimens plastinated with silicone are flexible and sticky. There was no color contrast between grey and white matter. CONCLUSION: The polyester impregnated brain specimens and slices are non-toxic and ideal for teaching purposes and examinations. They require minimal aftercare. The whole organ serial sections of plastinated brain specimens will help 3-dimensional study of the normal brain and will improve the assessment of brain pathology.

Brain↗

PubMed1985

Infectivity of vascular sutures.

Bacterial adherence to vascular sutures was evaluated in vitro using radioactively labeled Staphylococcus aureus. The following suture materials were tested: polypropylene, silicone-treated braided polyester, and Teflon-treated braided polyester. Significantly fewer bacteria adhered to the monofilament polypropylene than either of the braided polyester sutures. There was no significant difference between silicone-treated and Teflon-treated polyester from the standpoint of bacterial adherence. Vascular sutures were evaluated in vivo using a mouse wound model. Sutures were tested with and without knots. When tested without knots, fewer bacteria were recovered from wounds containing polypropylene suture compared to either of the braided materials, although this apparent advantage did not prove to be statistically significant. When studied with knots, the differences among types of suture were much less marked and, again, not significant. The purported contribution of the monofilament structure of a suture to its infection resistance may have been overstated.

Adhesiveness↗

PubMed1993

Evaluation of evacuated blood-collection tubes: effects of three types of polymeric separators on therapeutic drug-monitoring specimens.

The potential of three types of separator materials found in conventional blood-collection tubes for interference in therapeutic drug measurements was assessed. None of the separators (based on acrylic, silicone, or polyester polymers) had any significant effect on the concentrations of seven drugs (theophylline, digoxin, phenytoin, phenobarbital, gentamicin, ethanol, and cyclosporine) in blood specimens that were processed and analyzed promptly. Storage of specimens for 24 h resulted in an average 2.4% increase in theophylline values in specimens collected in tubes with the acrylic separator (P = 0.024); an average 8.1% decrease in phenytoin in specimens collected in tubes with the polyester-based separator (P < 0.001); and an average 4.2% decrease in phenobarbital in specimens collected in tubes with the polyester-based separator (P = 0.02). All other drug concentrations were not significantly affected. A small decrease in phenytoin (7.9%; P < 0.01) was seen when the specimen volume in 7-mL tubes containing polyester-based separator was reduced to 1.0 mL; all other drug concentrations were unaffected by partial filling of tubes. Paired blood specimens from pediatric patients, when collected in plain tubes and tubes containing acrylic separator, yielded no significant differences for theophylline, digoxin, tobramycin, phenytoin, or phenobarbital concentrations. The three commercially available separators had only small effects on therapeutic drug concentrations, and a newly developed separator based on an acrylic resin was suitably inert.

Acrylic Resins↗

PubMed1988

Biocompatibility of six elastomers in vitro.

The biocompatibility of two silicone rubbers, Silastic and Dow Corning Elastomer, and of a polyether and a polyester urethane, a polyether polyester copolymer, and polypropylene oxide was assessed in vitro. These elastomers were selected for assessment as a possible alloplastic tympanic membrane. For these studies use was made of rat middle ear mucosa explants and serially cultured epithelium. The quantitative results were based on epithelial growth curves, the morphological picture was based on the findings in epithelium, and the aging of a biomaterial was simulated. Epithelium morphology was investigated by scanning and transmission electron microscopy and x-ray microanalysis. Quantitative results showed that on Dow Corning Elastomer and polypropylene oxide, cell proliferation was significantly lower compared to normal growth curves. The morphological findings were negative for polypropylene oxide, and did not discriminate between the other biomaterials under study. The simulation results indicated better biocompatibility for the polyurethanes and the polyether polyester copolymer compared with that of polypropylene oxide and both silicone rubbers. Under the simulation conditions, cells exposed to Silastic showed silicon-containing inclusions. These in vitro results suggest that the biocompatibility of the polyurethanes and the polyether polyester copolymer is better than that of both silicone rubbers and polypropylene oxide.

Animals↗

PubMed2002

Hamstring graft tibial fixation: biomechanical properties of different linkage systems.

This biomechanical study analyzed the mechanical properties of different linkage systems commonly used in hamstring tendon ACL reconstruction. Two kinds of tapes, 5-mm braided polyester (Mersilene) and 3-mm woven polyester (Orthotape), were connected to a particular staple in bovine bone sections in single- and double-loop constructs with five replicates of each. These constructs underwent straight pull tensile tests, residual tensile tests, and fatigue tests at a loading regime of 540,000 cycles at 25 Hz frequency, using an Instron tensile test machine. Protrusion heights of the constructs were measured. The double-loop Mersilene-Fastlok construct was weaker than either single-loop or double-loop Orthotape-Fastlok construct. The mean failure strength of double-loop Orthotape-Fastlok was 93% higher and its mean stiffness was 40% greater at failure than that of Mersilene-Fastlok. At a 150-N load Mersilene-Fastlok was stiffer, while at 300 N Orthotape-Fastlok was stiffer. The thickness of Orthotape-Fastlok resulted in 1 mm more device protrusion. In hamstring tendon ACL reconstructions with indirect fixation we advocate the use of woven polyester (Orthotape) with Fastlok as a linkage material over braided polyester (Mersilene) with Fastlok because of its superior strength and stiffness.

Animals↗

PubMed2006

Genetic and biochemical evidence for involvement of HOTHEAD in the biosynthesis of long-chain alpha-,omega-dicarboxylic fatty acids and formation of extracellular matrix.

In plants, extracellular matrix polymers built from polysaccharides and cuticular lipids have structural and protective functions. The cuticle is found to be ten times thinner in Arabidopsis thaliana (L.) Heynh than in many other plants, and there is evidence that it is unusual in having a high content of alpha-,omega-dicarboxylic fatty acids (FAs) in its polyesters. We designated the new organ fusion mutant hth-12 after it appeared to be allelic to adhesion of calyx edges (ace) and hothead (hth), upon molecular cloning of the gene by transposon tagging. This mutant is deficient in its ability to oxidize long-chain omega-hydroxy FAs to omega-oxo FAs, which results in leaf polyesters in decreased alpha-,omega-dicarboxylic FAs and increased omega-hydroxy FAs. These chemical phenotypes lead to disorder of the cuticle membrane structure in hth-12. ACE/HTH is a single-domain protein showing sequence similarity to long-chain FA omega-alcohol dehydrogenases from Candida species, and we hypothesize that it may catalyze the next step after cytochrome P450 FA omega-hydroxylases in the omega-oxidation pathway. We show that ACE/HTH is specifically expressed in epidermal cells. It appears very likely therefore that the changes in the amount of alpha-,omega-dicarboxylic FAs in hth-12 reflect the different composition of cuticular polyesters. The ACE/HTH gene is also expressed in root epidermal cells which do not form a polyester membrane on the exterior surface, thereby making it possible that the end products of the pathway, alpha-,omega-dicarboxylic FAs, are generally required for the cross-linking that ensures the integrity of the outer epidermal cell wall.

Alleles↗

PubMedDate not supplied

Aneurysm shrinkage after endovascular repair of aortic diseases.

BACKGROUND: There are two graft materials for endovascular repair of aortic diseases, i.e., polyester and expanded polytetrafluoroethylene (ePTFE). The latest reports have suggested that there is graft-specific difference in outcomes. The purpose of this article was to evaluate the difference in terms of aneurysm shrinkage. PATIENTS AND METHODS: Eighty-six patients who underwent endovascular repair of aortic diseases were included. Forty patients had true aortic aneurysms, 8 had aortic pseudoaneurysms, and 38 had aortic dissections. Eighteen patients with true aortic aneurysms were treated with stent grafts fabricated with polyester, while the other 68 patients, including 22 patients with true aneurysms, 8 patients with pseudoaneurysms, and 38 patients with aortic dissections, were treated with stent grafts fabricated with ePTFE. All patients were followed-up by computed tomography (CT) for more than 1 year. The mean follow-up term was 28 months. Computed tomography confirmed that there were sufficiently long necks, and the aneurysm or the entry tear was completely excluded without any endoleak in all patients. The diameter of the preoperative lesion was compared with that measured on follow-up CT at 1 year and at the end of the follow-up term. Increase or decrease in the diameter by more than 5 mm was defined as a significant diameter change. RESULTS: Aneurysm shrinkage was observed in 40% of patients with true aneurysms, 88% of patients with pseudoaneurysms, and 55% of patients with aortic dissections at 1 year. There was no significant increase in patients with aneurysm shrinkage at the end of follow-up in any groups. In the case of true aortic aneurysms, shrinkage of aneurysms was observed more frequently with polyester-fabricated stent grafts (67%, 13/18) than with ePTFE-fabricated ones (18%, 4/22) at 1 year (P<.01). In contrast, expansion of aneurysms was observed only in patients treated with ePTFE (14%, 3/22). Shrinkage of the descending aorta was observed in 55% of patients with acute aortic dissections and 36% of patients with chronic aortic dissections. There was no case with aortic enlargement in either group. There was no significant difference between acute and chronic dissection in terms of shrinkage of the descending aorta. CONCLUSION: Expanded polytetrafluoroethylene appears to be effective for the treatment of pseudoaneurysms and aortic dissections. However, polyester seems to be more effective than ePTFE when true aneurysms are to be treated.

Aortic Dissection↗

PubMed2006

"Artificial lotus leaf" prepared using a 1945 patent and a commercial textile.

Two polyester textiles, conventional polyester and microfiber polyester fabrics, were hydrophobized using a simple, patented water-repellent silicone coating procedure. Water contact angles on these two surfaces are theta(A)/theta(R) = 151 degrees/140 degrees and theta(A)/theta(R) = 170 degrees/165 degrees, respectively. A smooth surface of this of this coating exhibits theta(A)/theta(R) = 110 degrees/100 degrees. The binary length scale topography (approximately 2 microm/ approximately 50 microm) of the microfiber polyester is responsible for relieving receding contact line pinning and promoting water repellency that is superior to that of the lotus leaf. The recent literature on superhydrophobic surfaces is criticized for neglecting literature of the 1940s.

Journal Article↗

PubMed1997

Multiblock copolyesters as biomaterials: in vitro biocompatibility testing.

Cell adhesion, cell growth and cell activities of macrophages and fibroblasts, cultured on newly developed degradable multiblock-copolyesters were studied to examine the biocompatibility and the possible use of these polymers for medical applications. The biocompatibility and the biodegradability of the polymers were confirmed by subcutaneous implantation of polymer foils in rats. The newly developed polymers, two polyesters (DegraPol/bsc43 and DegraPol/bsd43) and a polyesterether (DegraPol/bst41), were found to exhibit good cell compatibility; the cell-to-substrate interactions induced neither cytotoxic effects nor activation of macrophages. The adhesion and growth of fibroblasts and macrophages were different among the substrate. Fibroblasts adhered on the polyesters to about 60% of control cell cultured on tissue culture polystyrene (TCPS) and proliferated in the same doubling time as on TCPS. On the polyetherester cells exhibited weak adhesion; however, they proliferated up to day 4 after plating at the same doubling time as on TCPS (of about 42 h), and then decreased their doubling time to 27 h. Macrophages attached to the polyesters to about 40-60% of TCPS but no significant change was seen in the doubling time of cells cultured on TCPS and the polyesters. Again on the polyetherester, macrophages exhibited relatively low adhesion (25% of TCPS) and high doubling time (about 100 h). Fibroblasts produced high amounts (up to 500% of control cells) of collagen type I and type IV, and fibronectin. Macrophages responded to lipopolysaccharide treatment by the production of nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha), indicating that the cell-to-polymer interactions allow fibroblasts and macrophages to maintain their phenotype. All three test polymers exhibit favourable tissue compatibility. The formed capsule was just a few cell layers thick (<30 microm). After 2 months implanted subcutaneously in rats, the molecular weight of the test polymers was reduced by >20% depending on their chemical structure. Taken collectively, the present data demonstrate that the newly developed multiblock copolyesters are biocompatible and biodegradable.

Journal Article↗