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At least 1,639 records · Page 91Linked to original sources

PubMed2006

Facile synthesis of a D-galactono-1,6-lactone derivative, a precursor of a copolyester.

2,3,4,6-Tetra-O-methyl-d-galactonic acid (5) was readily prepared from d-galactono-1,4-lactone (1) in 47% yield. The sequence involves tritylation of HO-6 of 1, followed by O-permethylation and deprotection. Lactonization of 5 led to the per-O-methyl-d-galactono-1,6-lactone, which was copolymerized with epsilon-caprolactone by ring-opening polymerization catalyzed by scandium triflate. The incorporation of the sugar comonomer into the polyester chain was about 10%.

Caproates↗

PubMed2006

Glycerol-derived ester oligomers from cork suberin.

The cork suberin polyester was partially depolymerized by a methanolysis reaction catalyzed by calcium hydroxide. The methanolisate was analysed by ESI-MS/MS in the form of [M+Li](+) adduct-ions. This reaction solubilized a mixture of monomers and oligomers, including a set of glycerol-derived dimeric and trimeric esters. Four types of glycerol esters were identified: monoacylglycerols of alpha,omega-diacids, of omega-hydroxyacids and of monoacids; diglycerol diesters of alpha,omega-diacids; diacylglycerols of alpha,omega-diacids; monoacylglycerols of linear dimeric esters of alpha,omega-diacids and omega-hydroxyacids. The alpha,omega-diacids and omega-hydroxyacids found as monomer residues in the glycerol esters are the main ones found as cork suberin monomers. It is concluded that suberin is a glycerol-derived lipid of polymeric dimensions. Due to the protective and insulating role that it plays in plants, suberin should be considered together with the other known glycerolipids that build up biological membranes.

Dimerization↗

PubMed2005

Laparoscopic sacral colpopexy approach for genito-urinary prolapse: experience with 363 cases.

OBJECTIVE: To evaluate the surgical outcome, complications and benefits of laparoscopic double promonto-fixation for patients with pelvic prolapse. METHODS: Women with genito-urinary prolapse underwent a transperitoneal placement of a 100% polyester mesh on the anterior vaginal wall and a posterior mesh on the levator ani muscle. Both of these were anchored to the sacral promontory. A TVT was placed simultaneously in patients who had concurrent stress urinary incontinence. RESULTS: A total of 363 patients were operated upon between 1996 and 2002. Their mean age was 63 (range 35-78), average follow-up was 14.6 months, the mean operating time was 97 minutes. There were 8 conversions due to anesthetic or surgical difficulties. Follow up was done by a postal questionnaire and physical examination at 6 months and then yearly. 96% were satisfied with the results of their operation and no patients complained of sexual dysfunction. There was a 4% recurrence rate of prolapse, 3 vaginal erosions, 2 urinary retentions that required TVT section, 1 bowel incarcerations, 1 spondylitis and 2 mesh infection. CONCLUSIONS: Laparoscopic promonto-fixation is feasible and highly effective technique that offers good long-term results with complication rates similar to open surgery, with the added benefits of minimally invasive surgery.

Adult↗

PubMed2006

Novel polymeric micelles for hydrophobic drug delivery based on biodegradable poly(hexyl-substituted lactides).

Novel amphiphilic methoxy-poly(ethylene glycol)-poly(hexyl-substituted lactides) block copolymers were synthesized by ring-opening polymerization (ROP) of mono and dihexyl-substituted lactide (mHLA and diHLA) in bulk at 100 degrees C in the presence of tin(II) 2-ethylhexanoate (Sn(Oct)(2)) as catalyst and methoxy-poly(ethylene glycol) (MPEG) as initiator. MPEG-PmHLA and MPEG-PdiHLA copolymers of predictable molecular weights and narrow polydispersities were obtained, as shown by (1)H NMR and GPC. DSC experiments showed that the MPEG-PHLA block-copolymer presents a bulk microstructure containing MPEG domains segregated from the PHLA domains. Micelles were successfully prepared from these block copolymers, with sizes ranging from 30 to 80 nm. The critical micellar concentration (CMC) was found to decrease with the increasing number of hexyl groups on the polyester block (MPEG-PLA > MPEG-PmHLA > MPEG-PdiHLA) for copolymers of the same composition and molecular weight. The hydrophobicity of the micelle core in dependence of the number of hexyl groups along the PLA chain was evidenced by absorbance experiments with the incorporation of the dye Nile Red. These novel amphiphilic copolymers are interesting for micellar drug delivery and especially in regard to optimized hydrophobic drug loadings, as it was shown for griseofulvin as a model drug.

Antifungal Agents↗

PubMed2004

A new surgical technique for ocular fixation in congenital third nerve palsy.

PURPOSE: To present a new technique of ocular fixation to restore and maintain the ocular alignment in primary position for patients with total third nerve paralysis. METHOD: We fixated the globe (medial rectus muscle insertion) to the medial palpebral ligament insertion at the anterior lacrimal crest by using nonabsorbable 5-0 polyester sutures in a prospective study of 5 patients (5 eyes) with congenital total third nerve paralysis. A large recession of the lateral rectus muscle (12 to 16 mm) was also performed in four patients. RESULTS: Four patients achieved satisfactory ocular alignment and one patient had residual exotropia. After an initial exotropic shift, no significant change in ocular alignment was observed during the follow-up period of 6 to 9 months. Mild fullness and congestion over the medial rectus muscle area was observed in the immediate postoperative period in all the patients, which resolved in about two months time. CONCLUSION: This technique of ocular fixation is easy, safe, and effective for the management of exotropia secondary to total third nerve paralysis.

Adolescent↗

PubMed2006

Design features to enhance external hip protector adherence in the nursing home setting.

OBJECTIVE: To determine the preferences for external hip protector (EHP) design features of both certified nursing assistants (CNAs) and nursing home laundry personnel, and to test the durability of favored model features. DESIGN: Cross-sectional descriptive study of CNAs' and laundry personnels' preferences and a prospective experimental study of EHP fastener durability under institutional laundry conditions. SETTING: Three urban nursing homes and a hospital-based laundry service. PARTICIPANTS: Twenty-seven CNAs, 4 laundry service supervisors. INTERVENTION: Five focus groups with CNAs and a survey of laundry supervisors were conducted to elicit preferences of EHP design features with an emphasis on convenience and durability. A laundry test of 20 EHPs was conducted to compare these design features. RESULTS: There was wide agreement among CNAs and laundry personnel that EHPs with soft pads in garments of light neutral colors, and cotton-blend fabrics were most preferred. CNAs preferred sewn-in pads to removeable ones, but laundry personnel had no consensus on this issue. For dependent residents, wraparound (front opening) garments using Velcro were preferred by CNAs, whereas laundry supervisors preferred snap closures. When EHP underwent repeated washing in the laundry test, Velcro and snaps were functionally comparable at 52 cycles. Garments constructed of heavyweight cotton blends, polyester, or cotton with spandex maintained elasticity at 52 weeks, whereas the lightweight cotton blend stretched significantly. CONCLUSIONS: Based on CNAs' preferences, laundry personnels' input, and a laundry test, EHP design features that could enhance both caregiver efficiency and resident comfort include soft pads sewn into a light-colored (but non-white) heavier weight cotton-blend garment, with the availability of both a pull-up style and a wraparound style using Velcro fasteners. Snaps did not demonstrate superior durability in the laundry test, but further comparison with Velcro under clinical conditions is indicated. Education and inclusion of CNAs in EHP decision making are important ways to improve EHP adherence.

Accidental Falls↗

PubMed2005

Possibilities for controlling a PHB accumulation process using various analytical methods.

Poly-beta-hydroxybutyrate (PHB) and other polyesters can be produced by various species of bacteria. Of the possible carbon sources, methane could prove to be one of the most suitable substrates for the manufacture of PHB. The methanotrophic strain Methylocystis sp. GB 25 DSM 7674 was applied in order to accumulate PHB in a rapid, non-sterile process. Cultivation was performed in two stages: a continuous growth phase (dilution rate 0.17 h(-1)) and a PHB accumulation phase under deficiency conditions of an essential nutrient (e.g. phosphorus) in batch culture. The PHB content of the biomass was as high as 51%; efficiency was the highest during the first 5 h of the product formation process. The PHB produced is of very high quality, having a high molecular mass of up to 2.5 x 10(6) Da. In order to monitor and control the process, a rapid analysis method based upon turbidimetry in the visible range (438 nm) was applied. Moreover, the PHB content of the biomass was determined using an FT-IR-spectroscopic method with ATR sampling and multivariate calibration. We achieved a value of 1.4% as the best standard error of cross validation. The nitrogen content of the PHB final product (a product quality parameter) was estimated by spectroscopic method in the visible range.

Biomass↗

PubMed2005

Biodegradable polymersomes as a basis for artificial cells: encapsulation, release and targeting.

The encapsulation of biofunctional compounds, release properties and targetability of polymersomes of amphiphilic block-copolymers based on poly(ethylene glycol) (PEG) and biodegradable polyesters or polycarbonate are described. Carboxyfluorescein (CF), as a model for hydrophilic biofunctional compounds, could be readily incorporated in the polymersomes by adding the compound to the aqueous phase during polymersome preparation. The release of encapsulated material from the polymersomes can be adjusted by changing the copolymer composition, especially the molecular weight and type of hydrophobic block of the copolymer. The presence of plasma proteins other than albumin suppressed the release of CF. CF release in PBS both at room temperature and at 60 degrees C followed first order kinetics, confirming that the CF containing polymersome system is a membrane controlled reservoir system. These biodegradable polymersomes have the potential to be targeted to specific sites in the body as shown by the specific interaction of anti-human serum albumin immobilized polymersomes with a human serum albumin coated sensor surface.

Biodegradation, Environmental↗

PubMed2005

Ketoprofen controlled release from composite microcapsules for cell encapsulation: effect on post-transplant acute inflammation.

Cell encapsulation technology raises hopes in medicine and biotechnology. Encapsulated pancreatic islets is a promising approach for the final solution of Type 1 diabetes. Unfortunately, evidence of long-term encapsulated islet graft survival and functional competence lies behind expectancy. Failure was often ascribed to the lack of biocompatibility generating inflammatory response, or limited immunobarrier competence or hypoxia or finally, low beta-cell replication. In order to prevent severe inflammation at early stages after implantation, composite microcapsules were designed. Biodegradable microspheres containing ketoprofen were enveloped into the well established alginate/poly-L-ornithine/alginate capsules. Polyester microspheres were prepared, by solvent evaporation, and characterized for encapsulation efficiency, particle size and in vitro release. Biocompatibility and efficacy to prevent the inflammatory response were studied in vivo. Good encapsulation efficiency and the desired particle size were achieved. In vitro release studies evidenced a high burst effect probably due to a plasticizing effect of both water and ketoprofen. The composite systems showed good biocompatibility and capacity to completely avoid the inflammatory response and the pericapsular cell overgrowth. In conclusion, the inflammatory response in the immediate post-transplant period can be circumvented using multicompartment microcapsules releasing non-steroidal anti inflammatory drugs.

Animals↗

PubMed2006

Oral bioavailability of a low molecular weight heparin using a polymeric delivery system.

Low molecular weight heparins (LMWHs) are the standards of anticoagulant for the prevention of deep vein thrombosis (DVT) in patients undergoing arthroplasty and abdominal surgery. However, LMWHs are so far only administered by parenteral route. Thus, they are usually replaced by oral warfarin for outpatient therapy. Since warfarin has a slow onset and high incidence of drug-drug interaction, there is a great need for the development of an oral LMWH formulation. LMWH (tinzaparin)-loaded nanoparticles prepared with a blend of a polyester and a polycationic polymethacrylate by the double emulsion method were administered orally in fasted rabbits. The plasma tinzaparin concentration was measured by a chromogenic anti-factor Xa assay. After oral administration of two doses of tinzaparin-loaded nanoparticles (200 and 600 anti-Xa U/kg), the oral absorption was observed between 4 and 10 or 12 h, with a delayed onset of action ranging from 3 to 4 h. Mean absolute bioavailabilities were 51% and 59% for the two tested doses. We now report that the encapsulation of tinzaparin into nanoparticles is likely to contribute to its oral efficacy with an anticoagulant effect prolonged up to 8 h.

Absorption↗

PubMed2006

Oral delivery of insulin associated to polymeric nanoparticles in diabetic rats.

Nanoparticles prepared with a blend of a biodegradable polyester (poly(-epsilon-caprolactone)) and a polycationic non-biodegradable acrylic polymer (Eudragit RS) have been used as a drug carrier for oral administration of insulin. The rate of encapsulation of insulin was around 96%. The therapeutic efficiency of oral insulin nanoparticles (25, 50 and 100 IU/kg) in diabetic rats and the intestinal uptake of fluorescein isothiocyanate (FITC) labelled insulin were studied. When administered orally by force-feeding to diabetic rats, insulin nanoparticles decreased fasted glycemia in a dose dependant manner with a maximal effect observed with 100 IU/kg. These insulin nanoparticles also increased serum insulin levels and improved the glycemic response to an oral glucose challenge for a prolonged period of time. FITC-Insulin-loaded nanoparticles strongly adhered to the intestinal mucosa and labeled insulin, either released and/or still inside nanoparticles, was mainly taken up by the Peyer's patches. It is concluded that polymeric nanoparticles allows the preservation of insulin's biological activity. In addition, the antidiabetic effect can be explained by the mucoadhesive properties of the polycationic polymer (Eudragit) RS) allowing the intestinal uptake of insulin.

Acrylic Resins↗

PubMed2006

The physical characterization of a thermoplastic polymer for endodontic obturation.

OBJECTIVE: To analyze a new endodontic sealer material commercially known as Resilon and to describe in detail the experimental techniques employed that lead to the identification of the composite material. METHODS: An extensive structural, thermal, and physical characterization was used to identify a new endodontic sealer material using the following techniques: Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) analysis, X-ray fluorescence spectrometry (XRF) technique, X-ray diffraction (XRD) measurement, thermo-gravimetric analysis (TGA) and a differential scanning calorimeter (DSC). The surface morphology was analyzed using a scanning electron microscope (SEM). RESULTS: The material was identified as a composite of polycaprolactone, which is a polymer of the polyester family and bioactive glass, which is radiopaque filler. CONCLUSIONS: The Resilon sealer material is a thermoplastic synthetic degradable polymer (polycaprolactone), it contains bioactive glass. Its properties, such as strength, modulus, shape-memory effect and biodegradability depend on the crystalline fraction, which is affected in turn by conditions of crystallization. Investigation of the crystallization kinetics of PCL is of practical significance. It is especially necessary to study its the dynamic and non-isothermal crystallization process.

Calorimetry, Differential Scanning↗

PubMed2005

A biomechanical analysis of suture materials and their influence on a four-strand flexor tendon repair.

PURPOSE: Flexor tendon repair strength depends on the suture technique and the suture material used. Configurations that incorporate locking loops prevent sutures from pulling through the tendon but typically fail because of suture breakage. The choice of suture material therefore influences repair strength. This study investigated the mechanical properties of 5 nonabsorbable 4-0 suture materials (monofilament nylon, monofilament polypropylene, braided polyester, braided stainless steel wire, and braided polyethylene) and evaluated their performance when used in a locking 4-strand flexor tendon repair configuration. METHODS: Five samples of 2 strands of each suture type were tested mechanically to determine the material stiffness and ultimate load. In addition, 50 fresh porcine flexor tendons were divided and repaired with each of the 5 suture materials using a 4-strand single-cross technique. Gap force, ultimate strength, and stiffness were measured to compare biomechanical performance. RESULTS: All repairs failed by suture rupture at the locking loop. Fibrewire and stainless-steel sutures and repairs were significantly stronger and stiffer than the other suture types. The results for Prolene and Ethibond were similar in the tendon repair groups with respect to gap and ultimate forces although Ethibond provided significantly increased repair stiffness. Nylon sutures and repairs consistently produced the poorest mechanical performance in all outcome measures. CONCLUSIONS: Suture material strongly influences the biomechanical performance of multistrand tendon repairs and is an important consideration for the surgeon. Fibrewire and stainless steel are the most biomechanically suitable suture materials for flexor tendon repair whereas nylon is the least suitable. Further developments in suture materials are important for advancements in flexor tendon repair strength.

Animals↗

PubMed2004

A comparative analysis of the biomechanical behaviour of five flexor tendon core sutures.

Five core suture techniques were compared by static tensile testing in vitro. Fifty porcine tendons were used. The core sutures were performed with 3-0 or 4-0 braided polyester suture (Ticron) and the over-and-over running peripheral sutures with 6-0 monofilament polypropylene (Prolene). The core sutures were: (1) Pennington modified Kessler (3-0), (2) Double Pennington modified Kessler (3-0), (3) 4-strand Savage (3-0), (4) 4-strand Savage (4-0), and (5) 6-strand Savage (4-0). Repairs were compared as paired in regard to one variable: the number of core suture strands, the suture calibre, or the suture configuration. Biomechanical differences between the repair groups started during the linear region, with the yield force and stiffness increasing along with the number of core suture strands. All three variables influenced the strain at the yield point. Thus, the strength of the intact repair can be improved by modifying the core suture. In all repairs gap formation started near the yield point after failure of the peripheral suture. The yield force represents the strength of the intact repair composite and should be considered the strength of the tendon repair.

Animals↗

PubMed2026

Multiomic insights into fungal polylactic acid degradation: Metabolic adaptation and hydrolytic mechanisms of Sporobolomyces pararoseus.

Polylactic acid (PLA), a biodegradable polyester from renewable resources, is a sustainable alternative to petrochemical plastics. However, its environmental degradation is inefficient naturally, requiring specific microbial activities. While bacterial PLA-degrading mechanisms are well documented, fungal degrading systems-particularly their molecular mechanisms-are underexplored.We isolated Sporobolomyces pararoseus ZRQ01 from the gut microbiota of PLA-fed mealworms. This fungal strain noticeably degraded PLA in PLA-containing medium supplemented with 2% glucose. Biodegradation assays revealed 22.8% loss of the PLA film weight after 35 days of incubation, and scanning electron microscopy confirmed extensive surface erosion and pore formation. Integrated transcriptomic and proteomic analyses, together with the reference genome of S. pararoseus ZRQ01, revealed that S. pararoseus ZRQ01 upregulates hydrolytic enzymes at both transcript and protein levels to cleave PLA into lactic acid. After lactic acid is transferred into S. pararoseus ZRQ01 cells by monocarboxylate transporters with increased abundance, it is assimilated by pathways of pyruvate metabolism and the TCA cycle with increased protein abundance. Intriguingly, upregulation of genes in autophagy-related and MAPK signaling pathways underscores an adaptive stress response potentially supporting cellular homeostasis and degradation-related gene expression. Our results highlight S. pararoseus ZRQ01's metabolic potential for bioremediation and offer insights into fungal bioplastic degradation pathways.

Polyesters↗

PubMed2005

Comparison of the ovine and porcine animal models for biocompatibility testing of vascular prostheses.

OBJECTIVE: Evaluation of the pig and sheep models for biocompatibility investigations of vascular prostheses (VP). DESIGN: Comparative analysis of animal experimental investigations involving two different animal models. MATERIALS AND METHODS: Commercially available polyester vascular prostheses (PET-VP) were implanted into two different animal models (infrarenal porcine aorta and ovine carotid artery). The costs, surgical handling, patency rate, and healing on the basis of macroscopic, microscopic, and immunohistochemical criteria were analyzed over a period of 3 months. RESULTS: Handling and operating times (63 +/- 10 versus 76 +/- 16 min; P = 0.125) did not differ significantly. The cost of the two animal models was comparable. Integration of the VP was complete in the sheep model, but varied in the pig model (two complete, four incomplete). Complete endothelialization of all VPs was observed in the pig, which contrasted with the sheep with complete (circular) endothelialization only in the region of the anastomosis. The thickness of neointima in the region of the anastomosis differed insignificantly; immunohistochemically, only periprosthetic Ki67 was significantly reduced (28.7 +/- 9.9 versus 6 +/- 0.9%; P = 0.002) in the sheep. CONCLUSIONS: In the porcine model, extremely good endothelialization of the VP was observed, with formation of a rapid neointimal hyperplasia. The ovine model was characterized by the fact that postoperative follow-up investigations were easy to perform. Complete endothelialization was not observed.

Animals↗

PubMed2004

Effect of ultrasonic energy in washing of medical surgery gowns.

Today, the use of medical textiles is very important for health and hygienic purposes. Although some of medical textile materials are disposable, surgery gowns are usually laundered and re-used. After the laundering it is desirable to have these gowns keeping some of their properties such as anti-microbial and tenacity properties. For this in mind, different surgery gowns were washed and compared. In this work, a special blend of polyester carbon anti-microbial and other surgery gowns were stained with blood and later washed with both conventional method and with ultrasonic energy. The results were also analysed spectrophotometrically and the tenacity of the fabrics were determined.

Carbon↗

PubMed1994

Shouldice is superior to Bassini inguinal herniorrhaphy.

The original Bassini and Shouldice methods for inguinal herniorrhaphy were tested against each other and against their respective variants that avoid permanent suturing of the internal oblique muscle. Seven hundred fifty inguinal hernia repairs were prospectively allocated to 1 of 4 groups: group A: Bassini with absorbable sutures (polyglycolic acid); group B: Bassini with nonabsorbable sutures (polyester); group C: Shouldice with four rows of polypropylene sutures; and group D: Shouldice with two rows of polypropylene sutures. Outcome was correlated to prospectively defined types and risk factors such as direct hernia, repair for recurrent hernia, hernial sac diameter greater than 8 cm, age greater than 70 years, overweight, and chronic bronchitis. Actual (not actuarial) recurrence rates were determined through clinical examination by hospital staff surgeons (not through information by letter or phone) for 93.6% of surviving patients. Local complications exclusive of recurrence, but including the redoubtable and litigious sequelae of testicular atrophy and chronic ilioinguinal pain, were significantly reduced from 6.3% (group B and C) to 2.3% by omitting permanent muscle sutures (groups A and D; P < 0.05). However, the use of slowly absorbable suture material resulted in a disproportionately high recurrence rate of 12.8% in the modified Bassini group A. The original Bassini method, ie, division of the transversalis fascia and repair with nonabsorbable sutures, as was used in group B, had an actual 2-year recurrence rate of 8.7%, still a highly significant difference compared with 3.6% and 2.3% for Shouldice groups C and D, respectively (P = 0.012). For repair of recurrent hernia, the superiority of the Shouldice technique was not statistically significant: re-recurrence rate 7.6% versus 13.5% for the original Bassini group B. Repair of recurrent hernia was the only patient-related risk factor of equal significance as the method of repair. The Shouldice technique is superior to and more than merely a reinvention of Bassini's original method. The omission of muscle sutures is physiologically sound and recommended for the Shouldice operation.

Actuarial Analysis↗