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PubMed1991

Skull bone defects. Preliminary results using a new prosthesis.

The use of a new prosthetic material (110 DTEX F 33 Propylene and Medical Polyester Torlen 165 DTEX) in the reconstruction of bone defects of the skull, even of large dimension, is described by the authors. The material has good biologic tolerance, is already pre-moulded, can be easily adapted to the exact size of the defect and offers remarkable aesthetic and functional results. EEG, X-ray, MRI and CT can be performed without artefact and interferences.

Adolescent↗

PubMed1980

Fibrocollagenous tissue tube as a small arterial substitute.

A new arterial graft, a fibrocollagenous tissue tube supported by polyester mesh, was evaluated as a substitute for a small caliber artery. The graft of 3 mm in internal diameter and 3.5 to 5.7 cm in length were implanted into the external iliac arteries of 24 dogs. The patency rate of the graft was 73% from 0 to 7 months following the operation. The newly formed vascular wall was soft and stable. The graft showed good endothelization of the neointima.

Animals↗

PubMed1998

Accumulation of biodegradable copolyesters of 3-hydroxy-butyrate and 3-hydroxyvalerate in Alcaligenes eutrophus.

Biodegradable copolyesters of 3-hydroxybutyrate-co-3-hydroxyvalerate (3HB-3HV) were produced by Alcaligenes eutrophus in a two-staged process, namely growth stage and nitrogen-deficient polyester-accumulation stage. When C5 was used as the sole carbon source, the copolyester contained 43 mol % of 3HV. A range of copolyesters with 0-43 mol % of 3HV could be produced by using a medium containing different concentration ratios of butyric acid C4 and C5. Tm of PHB homopolymer was 177.6 degrees C and that of copolyester with highest 3HV mol fraction of 43% was 99.0 degrees C. C5 concentration in the medium could be an effective means to control the polymeric composition and mechanical properties of the copolyesters accumulated in A. eutrophus.

3-Hydroxybutyric Acid↗

PubMed2003

Biodegradable plastics from renewable sources.

Plastic waste disposal is a huge ecotechnological problem and one of the approaches to solving this problem is the development of biodegradable plastics. This review summarizes data on their use, biodegradability, commercial reliability and production from renewable resources. Some commercially successful biodegradable plastics are based on chemical synthesis (i.e. polyglycolic acid, polylactic acid, polycaprolactone, and polyvinyl alcohol). Others are products of microbial fermentations (i.e. polyesters and neutral polysaccharides) or are prepared from chemically modified natural products (e.g., starch, cellulose, chitin or soy protein).

Bacteria↗

PubMed2000

[Reduction of colonization of new mattresses with bacteria, moulds and house dust mites by complete mattress covers].

BACKGROUND AND OBJECTIVE: We investigated if the colonisation of new mattresses with house dust mites, bacteria, and fungi could be reduced by using synthetic mattress covers as compared to common cotton covers. PATIENTS/METHODS: 84 healthy volunteers were assigned to two groups. Group A (n = 43) received the cotton covers, group B (n = 41) the synthetic covers which were made of a polyester microfaser with a polyurethane surface layer (Pro-Tex, Germed, Schwarzenbek, Germany). RESULTS: The mite antigen concentration after six months was significantly lower in group B. Three months after the start of the study counts of bacteria and moulds were significantly higher in group A compared to group B. CONCLUSIONS: It can be recommended that patients suffering from an allergy to mites or moulds may reduce their domestic allergen exposure by using the synthetic mattress covers tested in this study. Since cotton covers are very likely to become colonised by bacteria and moulds, they must be cleaned periodically (at least every 2nd-3d month).

Animals↗

PubMed2005

[Functional tendon repair in orthopedic tumor surgery].

Large defects of functional soft tissue structures, e.g., extensor mechanism, ligaments, muscles, and joint capsule, may occur in tumor surgery or revision surgery following conventional joint replacement. Reconstruction can be performed using biological grafts such as free or pedicled tendon-muscle flaps, allografts, or synthetic material. Prerequisites for synthetic material are good biologic tolerance with fibroblastic ingrowth, mechanical resistance to fatigue, and a maximum of tension force with a minimum of elongation. In this study we used a nonresorbable band of longitudinal polyester fibers with a minimal rupture level of 4000 N and an elongation rate less than 7% of its original length. The shape of the band was designed for universal use with 40 cm length and 6 cm width. Its primary indication was augmentation or complete reconstruction of the extensor mechanism of the knee joint after large extra-articular tumor resections in primary bone tumors. Furthermore, its use for hip joint capsule reconstruction in luxation, coverage of megaprostheses of the humerus, and augmentation after biological reconstruction of tendons achieved excellent results.

Bone Neoplasms↗

PubMed2006

Characterization of Melanocarpus albomyces steryl esterase produced in Trichoderma reesei and modification of fibre products with the enzyme.

Melanocarpus albomyces steryl esterase STE1 is considered to be an interesting tool for several industrial applications due to its broad substrate specificity. STE1 was produced in the filamentous fungus Trichoderma reesei in a laboratory bioreactor at an estimated production level of 280 mg l(-l). The properties of the purified recombinant enzyme (rSTE1), such as substrate specificity, molecular mass, pH optimum and stability and thermostability, were characterized and compared to the corresponding properties of the native enzyme. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed one band with a molecular weight of 60 kDa for rSTE1, whereas analytical gel filtration showed a dimeric structure with a molecular weight of 120 kDa. The rSTE1 was somewhat less stable under different conditions and had slightly lower activities on various substrates than the native STE1. The effects of rSTE1 on the properties of paper sheets and polyethylene terephthalate (PET) fabric were preliminarily evaluated. Due to the hydrolysis of triglycerides and steryl esters by the rSTE1 treatment, the tensile strength and hydrophilicity of the paper were increased. The rSTE1 treatment increased significantly the polarity of PET by hydrolysing the ester bonds in the polyester backbone. Dyeing of PET with methylene blue was also slightly improved after rSTE1 treatment.

Cloning, Molecular↗

PubMed2006

Mutation on N-terminus of polyhydroxybutyrate synthase of Ralstonia eutropha enhanced PHB accumulation.

Polyhydroxyalkanoate (PHA) synthase is the central enzyme involved in the biosynthesis of PHA, a family of bacterial biodegradable polyesters. Due to its high variability, the N-terminal fragment of this enzyme was previously considered as unnecessary for a functionally active enzyme. In this study, polyhydroxybutyrate synthase from Ralstonia eutropha (PhbC(Re)) with a deletion on N-terminal 88 amino acid residues showed a significant reduced activity, as reflected by only 1.5% PHB accumulation compared with the wild type which produced 58.4% PHB of the cell dry weight. Whilst several site-specific mutagenesis results revealed the amphiphilic alpha-helix assembled by the amino acid region, D70-E88 played an important role in both maintaining the PHB synthase activity and regulating molecular weight and polydispersity of accumulated PHB homopolymer.

Acyltransferases↗

PubMed1999

Quantification of bacterial polyhydroxyalkanoic acids by Nile red staining.

The fluorescence properties of one chemically and seven biologically produced polyhydroxyalkanoic acid were investigated as film castings and in living cells respectively after staining with Nile red. All these polyesters show a similar fluorescence behaviour, revealing a clear fluorescence maximum at an excitation wavelength between 540 nm and 560 nm and an emission wavelength between 570 nm and 605 nm. This could be shown by the use of two-dimensional fluorescence spectroscopy and flow cytometry. The examination of native poly(3-hydroxybutyric acid), poly(3HB), granules isolated from cells of Ralstonia eutropha H16 showed that the addition of 6.0 micrograms Nile red is necessary for total staining of 1.0 mg granules. The fluorescence intensity at an excitation wavelength of 550 nm and an emission wavelength of 600 nm showed high correlation to the poly(3HB) concentration of grana suspensions at different grana concentrations. These results and the staining of cell suspensions during cultivation experiments revealed that Nile red has a high potential for the quantitative determination of hydrophobic bacterial polyhydroxyalkanoic acids.

Bacteriological Techniques↗

PubMed2000

Exploitation of butyrate kinase and phosphotransbutyrylase from Clostridium acetobutylicum for the in vitro biosynthesis of poly(hydroxyalkanoic acid).

Active butyrate kinase (Buk) and phosphotransbutyrylase (Ptb) were purified in three steps: ammonium sulfate precipitation, hydrophobic chromatography on phenyl-Sepharose and affinity chromatography on Matrex Red A from recombinant Escherichia coli K2006 (pJC7). They were then successfully exploited for in vitro synthesis of 3-hydroxybutyryl-CoA (3HBCoA), 4-hydroxybutyryl-CoA (4HBCoA), 4-hydroxyvaleryl-CoA (4HVCoA) and poly(hydroxyalkanoic acid) (PHA). In addition, the ability of the PHA synthase of Chromatium vinosum, PhaEC(Cv), to use these CoA thioesters was evaluated. Combination of Buk and Ptb with PhaEC(Cv) established a new system for in vitro synthesis of poly(3-hydroxybutyric acid) [poly(3HB)]. In this system, 3-hydroxybutyric acid was converted to 3HBCoA by Buk and Ptb at the expense of ATP. Formation of 3HBCoA was further driven by the polymerization of 3HBCoA molecules to poly(3HB) by PHA synthase, and the released CoA was recycled by Ptb. This system therefore also ensured the regeneration of CoA. With ATP as the energy supply, which was hydrolyzed to ADP and phosphate, 2.6 mg poly(3HB) was obtained from a 1-ml reaction mixture containing 7.6 mg 3-hydroxybutyrate at the beginning. Studies showed that Ptb and PHA synthase were the rate-limiting steps in this system, and initial CoA concentrations ranging from 1 to 7 mM did not inhibit poly(3HB) synthesis. Synthesis of various polyesters of 3HB and 4HB with this system was also tested, and copolyesters containing 4HB of 1-46 mol % were obtained.

3-Hydroxybutyric Acid↗

PubMed2005

Relationship between tissue ingrowth and mesh contraction.

Contraction is a well-documented phenomenon occurring within two months of mesh implantation. Its etiology is unknown, but it is suggested to occur as a result of inadequate tissue ingrowth into the mesh and has been associated with hernia recurrence. In continuation of our previous studies, we compared tissue ingrowth characteristics of large patches of polyester (PE) and heavyweight polypropylene (PP) and their effect on mesh contraction. The materials used were eight PE and eight PP meshes measuring 10 x 10 cm2. After random assignment to the implantation sites, the meshes were fixed to the abdominal wall fascia of swine using interrupted polypropylene sutures. A necropsy was performed three months after surgery for evaluation of mesh contraction/shrinkage. Using a tensiometer, tissue ingrowth was assessed by measuring the force necessary to detach the mesh from the fascia. Histologic analysis included inflammatory and fibroblastic reactions, scored on a 0-4 point scale. One swine developed a severe wound infection that involved two PP meshes and was therefore excluded from the study. The mean area covered by the PE meshes (87 +/- 7 cm2) was significantly larger than the area covered by the PP meshes (67 +/- 14 cm2) (p = 0.006). Tissue ingrowth force of the PE meshes (194 +/- 37 N) had a trend toward being higher than that of the PP meshes (159 +/- 43 N), although it did not reach statistical significance. There was no difference in histologic inflammatory and fibroblastic reactions between mesh types. There was a significant correlation between tissue ingrowth force and mesh size (p = 0.03, 95% CI: 0.05-0.84). Our results confirm those from previous studies in that mesh materials undergo significant contraction after suture fixation to the fascia. PE resulted in less contraction than polypropylene. A strong integration of the mesh into the tissue helps prevent this phenomenon, which is evidenced by a significant correlation between tissue ingrowth force and mesh size.

Animals↗

PubMed2001

[Indications, technique and initial results of passive cardiomyoplasty].

The cardiac support device (CSD, Acorn Cardiovasc. Inc.), a knitted polyester tissue, is surgically placed over the ventricles to prevent further dilatation of the heart. The aim of this study was to evaluate the feasibility and safety of CSD implantation in patients with advanced heart failure from cardiomyopathy of either idiopathic or ischemic origin. From April 1999, 23 patients received the CSD. In 8 patients the CSD implantation was the only surgical measure; in 12 patients a concomitant mitral valve repair was performed. In three more patients, the CSD implantation was combined with other surgical procedures. The CSD was placed while on bypass with the heart beating, attached to the AV groove and tailored anteriorly to snugly fit the ventricles. There were no intraoperative deaths or complications. Two patients died early postoperatively (4 d, 21 d); 1 late death occurred (44 d postop). The deaths were not considered to be device related. There were no CSD-related adverse events. Six months postoperatively all patients improved by at least one NYHA class. Echocardiography at 6 months revealed an increase in LVEF; the LVEDD decreased accordingly. Mitral valve regurgitation improved in all patients. These findings indicate that the CSD is safe, and improves heart failure symptoms and left ventricular function. Additional studies have to confirm these results.

Adult↗

PubMed2004

Soft palate implants: a new option for treating habitual snoring.

One hundred six patients with proven habitual snoring were each treated with three implants consisting of a cylindrical-shaped segment of braided polyester filaments (18 mm in length with an outer diameter of 1.5 mm) in the soft palate. The implants, pre-loaded in a single-use delivery tool, were inserted into the soft palate under local anesthesia. Along with the initial examination, follow-up exams were done after the treatment to test the safety and efficacy of the procedure. Snoring post treatment was reported as "no snoring" or "slight/occasional" in the majority of the cases after treatment. The results indicate there were no serious adverse events reported. The most frequent minor adverse events were partial extrusions in which the patient often presented a minor foreign body sensation along with mild transient pain. This data has demonstrated the procedure as a minimally invasive, relatively painless, simple procedure that has been shown to be safe and effective.

Adult↗

PubMed2005

Comparative investigation of alloplastic materials for hernia repair with improved methodology.

BACKGROUND: A variety of alloplastic materials are used for hernia repair. We discuss the long-term stability and possible shrinkage of these materials. In the past, measurement of pore sizes was used to study the physical properties of alloplastic meshes. The aim of this study was to evaluate the measurement of pore sizes with regard to its correlation to possible mesh alteration. METHODS: The water absorption of different polypropylene (PP) and polyester (PE) mesh materials under defined conditions was studied. For shrinkage studies, meshes were stored in formaldehyde, distilled water, saline solution, trypsin solution, urea solution, and hydrogen peroxide. The measurement of the relation between material and pore was evaluated to investigate the potential shrinking and enlargement processes. This material-pore index (MPI) before as well as 1, 7, and 14 days after incubation was measured. RESULTS: In comparison to measuring single pore sizes, MPI determination is the more efficient method to evaluate the possible shrinking or enlargement processes of alloplastic materials. With this technique, incorrect determination of pore sizes due to the dynamic textile structure of meshes and to shrinkage or enlargement, is excluded. All tested alloplastic materials showed an insignificant increase in water absorption under the condition of rehydration up to 0.4%. We did not observe variances in the material in shrinking or enlargement. CONCLUSIONS: MPI was found to be more reliable than measuring single pores to investigate possible external influences on polymer materials. Biomaterials such as PP and PE proved to be absolutely inert under various in vitro conditions.

Hernia, Abdominal↗

PubMed2005

A comparative study of adhesion formation and abdominal wall ingrowth after laparoscopic ventral hernia repair in a porcine model using multiple types of mesh.

BACKGROUND: The ideal mesh for laparoscopic ventral hernia repair is not yet identified. METHODS: We laparoscopically placed polypropylene (PPM), expanded polytetrafluoroethylene (ePTFE), and polyester with antiadhesive collagen layer (PCO) in eight pigs using sutures and tacks for fixation. After 28-day survival, we compared adhesion formation, fibrous ingrowth, and shrinkage among the types of mesh. RESULTS: Mean area of adhesions to PCO (8.25%) was less than that to ePTFE (57.14%, p < 0.001) or PPM (79.38%, p < 0.001). Adhesions peel strength was less for PCO (2.3 N) than for PPM (16.1 N, p < 0.001) or ePTFE (8.8 N, p = 0.02). Peel strength of mesh from the abdominal wall was less for ePTFE (1.3 N/cm of mesh width) than for PCO (2.8 N/cm, p = 0.001) or PPM (2.1 N/cm, p = 0.05). ePTFE area (94.4 cm(2)) was less than that for PCO (118.6 cm(2), p < 0.001) or PPM (140.7 cm(2), p < 0.02). CONCLUSION: PCO had fewer and less severe adhesions than ePTFE or PPM while facilitating excellent ingrowth of the adjacent parietal tissue.

Abdominal Wall↗

PubMed2004

Radiolucent cage for cervical vertebral reconstruction: a prospective study of 17 cases with 2-year minimum follow-up.

In cervical spondylotic myelopathy, extended anterior spinal cord decompression necessitates subsequent stable vertebral reconstruction. Reconstruction with an iliac crest graft and screw-plate fixation gives satisfactory clinical and radiological results, but they are often compromised by morbidity involving the bone harvest. The purpose of this study was to evaluate the contribution to cervical reconstruction of a biocompatible, radiolucent cage combined with screw-plate fixation, making use of bone harvested in situ. This prospective study was performed between July 2000 and March 2001 in eight women and nine men (mean age, 55 years) operated for cervical spondylotic myelopathy. Situated between levels C3 and C6, the cage was inserted after one corporectomy in ten patients, two corporectomies in five patients, and three corporectomies in two patients. The cage consisted of a polyester mesh impregnated with poly-L-lactic acid (PLLA) conferring temporary rigidity to the cage during bony fusion. Clinical and radiological follow-up (plain films, computed tomographic reconstruction in three cases) was performed at 2 months, 6 months, 12 months, 24 months and 36 months, postoperatively, with a mean follow-up of 30 months. Functional results were evaluated according to the Japanese Orthopaedic Association's scoring system. An independent surgeon assessed the radiological evidence of anterior cervical fusion using the grades proposed by Bridwell [6]. Every patient experienced neurological recovery. At last follow-up, radiological findings were consistent with grade I (complete fusion) in five cases, grade II (probable fusion) in ten cases, grade III (radiolucent halo in favor of non fusion) in one case, and grade IV (graft lysis) in one case with persistent neck pain. In three cases there was screw breakage (two grade II, one grade IV). None of these cases required surgical revision at latest follow-up. In extensive spinal cord decompression through an anterior approach, cervical reconstruction using the present type of cage can achieve clinical results comparable to conventional techniques. The rigidity of the cage meets biomechanical imperatives. Its radiolucency permits one to monitor the course of consolidation, contrary to metal cages. The cases of probable non-fusion and screw breakage were not accompanied by signs of instability on the flexion extension films. This cage meets the biologic and biomechanical imperatives of cervical reconstruction. It obviates complications involving bone harvest.

Adult↗

PubMed2005

Bioresorbable polymers: heading for a new generation of spinal cages.

The use of polymer-based bioresorbable materials is now expanding to the realm of spinal interbody fusion. Bioresorbable polymers have important advantages over metals, because they are temporary, much less stiff, and radiolucent. Most promising is a group of alpha-polyesters, in particular polylactide acids (PLAs). Their biocompatibility is excellent, and they have sufficient stiffness and strength to provide initial and intermediate-term stability required for bone healing. However, polylactides have characteristics that make them vulnerable to complications if not properly controlled. Degradation rate strongly depends on polymer type, impurities, manufacturing process, sterilization, device size, and the local environment. The fact that larger implants degrade faster is contra-intuitive, and should be considered in the design process. Also optimal surgical techniques, such as careful bone bed preparation, are required for a successful application of these materials. The purpose of this paper is to highlight the specific properties of these bioresorbable polymers and to discuss their potential and limitations. This is illustrated with early preclinical and clinical data.Bioresorbable cage technology is just emerging: their time-engineered degradation characteristics allow controlled dynamization in interbody applications, facilitating spinal fusion. Their radiolucency improves image assessment of fusion healing. Acceptance and use of bioresorbable implants may increase as further research and clinical studies report on their safety, efficacy, and proper usage.

Absorbable Implants↗

PubMed2000

Abrasion of artificial ligaments: a simulative study.

Abrasion failure of artificial ligaments possibly occurs in the early postoperative stages prior to the lining of bone tunnels with protective tissue. The effect of abrasion on the strength and stiffness of a polyester ligament was studied by implanting it in cadaveric knees, which were cyclically flexed through a physiologically relevant range, while subjecting the implant to tension of 300 N. The test was performed using ten cadaveric knees: (a) applying 49 000 load cycles to simulate the postoperative period after which the protective tissue fills the bony tunnel; (b) with the mouth of the bone tunnel radiused or left as after drilling the tunnel, and (c) for each of the two above conditions, with and without a protective sleeve surrounding the implant where it emerges from the tunnel. Following the tests, the implant strength was reduced by 33% when the mouth of the tunnel was not radiused, and by 28% when it was radiused, by 14% when the implant was protected without radiusing the tunnel exit, and by 13% when the tunnel was radiused. The stiffness was reduced by between 39% and 47% for the four conditions tested. It appears that the effect of abrasion is ameliorated by using a protective sleeve and by radiusing the mouth of the bone tunnels through which the implant is placed. The effect of the protective sleeve appears to be greater than that of just radiusing the tunnels, but it is appropriate to benefit from the combined effect of both measures.

Anterior Cruciate Ligament↗