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Polyglycolic Acid (polyglycolic + acid)
Selected AbstractsOld habits tie hard: an in vitro comparison of first-throw tension holding in Polyglycolic acid (Dexon S) and Polyglactin 910 (Coated Vicryl)CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 2 2006Thomas L Kersey MB BS Abstract Purpose:, To compare the first-throw tension holding property of two braided absorbable sutures commonly used in oculoplastic surgery. Methods:, The study was an in vitro experimental model. 6/0 Polyglycolic acid (Dexon S) and 6/0 Polyglactin 910 (Coated Vicryl) were compared using an experimental model to determine first-throw knot security. A polypropylene suture (Surgipro 2) was included as a benchmark to judge the apparatus by, ensuring that our experiment could be designed independently of the test suture materials. Increasing metric loads were applied to the first double throw of a surgical knot. Each suture was tested to the point of knot slipping and the critical tension recorded. All the sutures were kept wet during use. Three variations of the experiment were undertaken: experiment 1 , two metal loops brought together by the test suture; experiment 2 , two strips of tissue brought together by the test suture; and experiment 3 , a knot tied over a metal bar coated in tissue. The tissue used was processed cross-linked porcine dermal collagen (Permacol). Each experiment was repeated three times for each suture type and the mean value taken. Results:, Experiment 1: Dexon S 12.2 g (11, 12, 13.5), Coated Vicryl 2.5 g (2.5, 2.5, 2.5) and Surgipro 2 2.3 g (2, 2, 3); experiment 2: Dexon S 33.33 g (30, 35, 35), Coated Vicryl 25 g (25, 25, 25) and Surgipro 2 5 g (5, 5, 5); experiment 3: Dexon S 100 g (100, 100, 100), Coated Vicryl 56.667 g (60, 55, 55) and Surgipro 2 5 g (5, 5, 5). Conclusions:, Dexon S-braided absorbable suture has significantly better first-throw knot security when compared with Coated Vicryl. This is an important property when suturing tissues under tension as it minimizes slippage before the locking throw is tied. [source] Disc structure function and its potential for repairINTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 1 2002J. Melrose The intervertebral disc (IVD) is the largest predominantly avascular, aneural, alymphatic structure of the human body. It provides articulation between adjoining vertebral bodies and also acts as a weight-bearing cushion dissipating axially applied spinal loads. The IVD is composed of an outer collagen-rich annulus fibrosus (AF) and a central proteoglycan (PG)-rich nucleus pulposus (NP). Superior and inferior cartilaginous endplates (CEPs), thin layers of hyaline-like cartilage, cover the ends of the vertebral bodies. The AF is composed of concentric layers (lamellae) which contain variable proportions of type I and II collagen, this tissue has high tensile strength. The NP in contrast is a gelatinous PG-rich tissue which provides weight-bearing properties to the composite disc structure. With the onset of age, cells in the NP progressively die as this tissue becomes depleted of PGs, less hydrated and more fibrous as the disc undergoes an age-dependent fibrocartilaginous transformation. Such age-dependent cellular and matrix changes can decrease the discs' biomechanical competence and trauma can further lead to failure of structural components of the disc. Annular defects are fairly common and include vertebral rim-lesions, concentric (circumferential) annular tears (separation of adjacent annular lamellae) and radial annular tears (clefts which initiate within the NP). While vascular in-growth around annular tears has been noted, evidence from human post-mortem studies indicate they have a limited ability to undergo repair. Several experimental approaches are currently under evaluation for their ability to promote the repair of such annular lesions. These include growth of AF fibrochondrocytes on a resorbable polycaprolactone (PCL) bio-membrane.1 Sheets of fibrochondrocytes lay down type-I collagen and actin stress fibres on PCL. These matrix components are important for the spatial assembly of the collagenous lamella during annular development and correct phenotypic expression of cells in biomatrices.1 An alternative approach employs preparation of tissue engineered IVDs where AF and NP cells are separately cultured in polyglycolic acid and sodium alginate biomatrices, either separately or within a manifold designed to reproduce the required IVD dimensions for its use as a prospective implant device.2 AF and NP cells have also been grown on tissue culture inserts after their recovery from alginate bead culture to form plugs of tissue engineered cartilage.3 A key component in this latter strategy was the stimulation of the high density disc cell cultures with osteogenic protein-1 (OP-1) 200 ng/mL.3 This resulted in the production of tissue engineered AF and NP plugs with compositions, histochemical characteristics and biomechanical properties approaching those of the native disc tissues.2,3 Such materials hold reat promise in future applications as disc or annular implants. The introduction of appropriate genes into disc cells by gene transduction methodology using adenoviral vectors or ,gene-gun' delivery systems also holds considerable promise for the promotion of disc repair processes.4 Such an approach with the OP-1 gene is particularly appealing.5 The anchoring of discal implants to vertebral bodies has also been evaluated by several approaches. A 3D fabric based polyethylene biocomposite holds much promise as one such anchorage device6 while biological glues used to seal fibrocartilaginous structures such as the AF and meniscus8 following surgical intervention, also hold promise in this area. Several very promising new experimental approaches and strategies are therefore currently under evaluation for the improvement of discal repair. The aforementioned IVD defects are a common cause of disc failure and sites of increased nerve in-growth in symptomatic IVDs in man and are thus often sources of sciatic-type pain. Annular defects such as those described above have formerly been considered incapable of undergoing spontaneous repair thus a clear need exists for interventions which might improve on their repair. Based on the rapid rate of progress and the examples outlined above one may optimistically suggest that a successful remedy to this troublesome clinical entity will be developed in the not so distant future. References 1JohnsonWEBet al. (2001) Directed cytoskeletal orientation and intervertebral disc cell growth: towards the development of annular repair techniques. Trans Orthop Res Soc26, 894. 2MizunoHet al. (2001) Tissue engineering of a composite intervertebral disc. Trans Orthop Res Soc26, 78. 3MatsumotoTet al. (2001) Formation of transplantable disc shaped tissues by nucleus pulposus and annulus fibrosus cells: biochemical and biomechanical properties. Trans Orthop Res Soc26, 897. 4NishidaKet al. (2000) Potential applications of gene therapy to the treatment of intervertebral disc disorders. Clin Orthop Rel Res379 (Suppl), S234,S241. 5MatsumotoTet al. (2001) Transfer of osteogenic protein-1 gene by gene gun system promotes matrix synthesis in bovine intervertebral disc and articular cartilage cells. Trans Orthop Res Soc26, 30. 6ShikinamiY , Kawarada (1998) Potential application of a triaxial three-dimensional fabric (3-DF) as an implant. Biomaterials19, 617,35. [source] Regeneration of canine peroneal nerve with the use of a polyglycolic acid,collagen tube filled with laminin-soaked collagen sponge: a comparative study of collagen sponge and collagen fibers as filling materials for nerve conduitsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 6 2001Toshinari Toba Abstract A novel artificial nerve conduit was developed and its efficiency was evaluated on the basis of promotion of peripheral nerve regeneration across an 80-mm gap in dogs. The nerve conduit was made of a polyglycolic acid,collagen tube filled with laminin-soaked collagen sponge. Conduits filled with either sponge- or fiber-form collagen were implanted into an 80-mm gap of the peroneal nerve (five dogs for each form). Twelve months postoperatively nerve regeneration was superior in the sponge group both morphometrically (percentage of neural tissue: fiber: 39.7 ± 5.2, sponge: 43.0 ± 4.5, n=3) and electrophysiologically (fiber: CMAP 1.06 ± 0.077, SEP 1.32 ± 0.127 sponge: CMAP 1.04 ± 0.106, SEP 1.24 ± 0.197, n=5), although these differences were not statistically significant. The observed regeneration was complementary to successful results reported previously in the same model, in which collagen fibers exclusively were used. The results indicate a possible superiority of collagen sponge over collagen fibers as filling materials. In addition, the mass-producibility, superior scaffolding potential, and capacity for gradual release of soluble factors of the sponge provide make it an attractive alternative to fine fibers, which are both technologically difficult and costly to produce. This newly developed nerve conduit has the potential to enhance peripheral nerve regeneration across longer gaps commonly encountered in clinical settings. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 622,630, 2001 [source] Enhanced cartilage tissue engineering by sequential exposure of chondrocytes to FGF-2 during 2D expansion and BMP-2 during 3D cultivationJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2001Ivan Martin Abstract Bovine calf articular chondrocytes, either primary or expanded in monolayers (2D) with or without 5 ng/ml fibroblast growth factor-2 (FGF-2), were cultured on three-dimensional (3D) biodegradable polyglycolic acid (PGA) scaffolds with or without 10 ng/ml bone morphogenetic protein-2 (BMP-2). Chondrocytes expanded without FGF-2 exhibited high intensity immunostaining for smooth muscle ,-actin (SMA) and collagen type I and induced shrinkage of the PGA scaffold, thus resembling contractile fibroblasts. Chondrocytes expanded in the presence of FGF-2 and cultured 6 weeks on PGA scaffolds yielded engineered cartilage with 3.7-fold higher cell number, 4.2-fold higher wet weight, and 2.8-fold higher wet weight glycosaminoglycan (GAG) fraction than chondrocytes expanded without FGF-2. Chondrocytes expanded with FGF-2 and cultured on PGA scaffolds in the presence of BMP-2 for 6 weeks yielded engineered cartilage with similar cellularity and size, 1.5-fold higher wet weight GAG fraction, and more homogenous GAG distribution than the corresponding engineered cartilage cultured without BMP-2. The presence of BMP-2 during 3D culture had no apparent effect on primary chondrocytes or those expanded without FGF-2. In summary, the presence of FGF-2 during 2D expansion reduced chondrocyte expression of fibroblastic molecules and induced responsiveness to BMP-2 during 3D cultivation on PGA scaffolds. © 2001 Wiley-Liss, Inc. [source] Failure of xenoimplantation using porcine synovium-derived stem cell-based cartilage tissue constructs for the repair of rabbit osteochondral defectsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 8 2010Ming Pei Abstract The use of xenogeneic tissues offers many advantages with respect to availability, quality control, and timing of tissue harvest. Our previous study indicated that implantation of premature tissue constructs from allogeneic synovium-derived stem cells (SDSCs) facilitated cartilage tissue regeneration. The present study investigated the feasibility of xenoimplantation of SDSC-based premature tissue constructs for the repair of osteochondral defects. Porcine SDSCs were mixed with fibrin gel, seeded in polyglycolic acid (PGA) scaffolds, and cultured in a rotating bioreactor system supplemented for 1 month with growth factor cocktails. The engineered porcine premature tissues were implanted to repair surgically induced osteochondral defects in the medial femoral condyles of 12 rabbits. Three weeks after surgery, the xenoimplantation group exhibited a smooth, whitish surface while the untreated control remained empty. Surprisingly, 6 months after surgery, the xenoimplantation group displayed some tissue loss while the untreated control group was overgrown with fibrocartilage tissue. In the xenoimplantation group, chronic inflammation was observed in synovial tissue where porcine major histocompatibility complex (MHC) class II antigen positively stained in the engulfed foreign bodies. In addition, porcine source cells also migrated from the implantation site and may have been responsible for the observed loss of glycosaminoglycans (GAGs) underneath surrounding articular cartilage. The histological score was much worse in the xenoimplanted group than in the untreated control. Our study suggested that SDSC-based xenogeneic tissue constructs might cause delayed immune rejection. Xenotransplantation may not be an appropriate approach to repair osteochondral defects. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1064,1070, 2010 [source] Design and assessment of a tissue-engineered model of human phalanges and a small jointORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 4 2005WJ Landis Structured Abstract Authors ,, Landis WJ, Jacquet R, Hillyer J, Lowder E, Yanke A, Siperko L, Asamura S, Kusuhara H, Enjo M, Chubinskaya S, Potter K, Isogai N. Objectives ,, To develop models of human phalanges and small joints by suturing different cell-polymer constructs that are then implanted in athymic (nude) mice. Design ,, Models consisted of bovine periosteum, cartilage, and/or tendon cells seeded onto biodegradable polymer scaffolds of either polyglycolic acid (PGA) or copolymers of PGA and poly-L-lactic acid (PLLA) or poly- , -caprolactone (PCL) and PLLA. Constructs were fabricated to produce a distal phalanx, middle phalanx, or distal interphalangeal joint. Setting and Sample Population ,, Studies of more than 250 harvested implants were conducted at the Northeastern Ohio Universities College of Medicine. Experimental Variable ,, Polymer scaffold, cell type, and implantation time were examined. Outcome Measure ,, Tissue-engineered specimens were characterized by histology, transmission electron microscopy, in situ hybridization, laser capture microdissection and qualitative and quantitative polymerase chain reaction analysis, magnetic resonance microscopy, and X-ray microtomography. Results ,, Over periods to 60 weeks of implantation, constructs developed through vascularity from host mice; formed new cartilage, bone, and/or tendon; expressed characteristic genes of bovine origin, including type I, II and X collagen, osteopontin, aggrecan, biglycan, and bone sialoprotein; secreted corresponding proteins; responded to applied mechanical stimuli; and maintained shapes of human phalanges with small joints. Conclusion ,, Results give insight into construct processes of tissue regeneration and development and suggest more complete tissue-engineered cartilage, bone, and tendon models. These should have significant future scientific and clinical applications in medicine, including their use in plastic surgery, orthopaedics, craniofacial reconstruction, and teratology. [source] Repair of the trigeminal nerve: a reviewAUSTRALIAN DENTAL JOURNAL, Issue 2 2010RHB Jones Abstract Nerve surgery in the maxillofacial region is confined to the trigeminal and facial nerves and their branches. The trigeminal nerve can be damaged as a result of trauma, local anaesthesia, tumour removal and implant placement but the most common cause relates to the removal of teeth, particularly the inferior alveolar and lingual nerves following third molar surgery. The timing of nerve repair is controversial but it is generally accepted that primary repair at the time of injury is the best time to repair the nerve but it is often a closed injury and the operator does not know the nerve is injured until after the operation. Early secondary repair at about three months after injury is the most accepted time frame for repair. However, it is also thought that a reasonable result can be obtained at a later time. It is also generally accepted that the best results will be obtained with a direct anastamosis of the two ends of the nerve to be repaired. However, if there is a gap between the two ends, a nerve graft will be required to bridge the gap as the two ends of the nerve will not be approximated without tension and a passive repair is important for the regenerating axons to grow down the appropriate perineural tubes. Various materials have been used for grafting and include autologous grafts, such as the sural and greater auricular nerves, vein grafts, which act as a conduit for the axons to grow down, and allografts such as Neurotube, which is made of polyglycolic acid (PGA) and will resorb over a period of time. [source] Extent of cell differentiation and capacity for cartilage synthesis in human adult adipose-derived stem cells: Comparison with fetal chondrocytesBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2010Nastaran Mahmoudifar Abstract This study evaluated the extent of differentiation and cartilage biosynthetic capacity of human adult adipose-derived stem cells relative to human fetal chondrocytes. Both types of cell were seeded into nonwoven-mesh polyglycolic acid (PGA) scaffolds and cultured under dynamic conditions with and without addition of TGF-,1 and insulin. Gene expression for aggrecan and collagen type II was upregulated in the stem cells in the presence of growth factors, and key components of articular cartilage such as glycosaminoglycan (GAG) and collagen type II were synthesized in cultured tissue constructs. However, on a per cell basis and in the presence of growth factors, accumulation of GAG and collagen type II were, respectively, 3.4- and 6.1-fold lower in the stem cell cultures than in the chondrocyte cultures. Although the stem cells synthesized significantly higher levels of total collagen than the chondrocytes, only about 2.4% of this collagen was collagen type II. Relative to cultures without added growth factors, treatment of the stem cells with TGF-,1 and insulin resulted in a 59% increase in GAG synthesis, but there was no significant change in collagen production even though collagen type II gene expression was upregulated 530-fold. In contrast, in the chondrocyte cultures, synthesis of collagen type II and levels of collagen type II as a percentage of total collagen more than doubled after growth factors were applied. Although considerable progress has been achieved to develop differentiation strategies and scaffold-based culture techniques for adult mesenchymal stem cells, the extent of differentiation of human adipose-derived stem cells in this study and their capacity for cartilage synthesis fell considerably short of those of fetal chondrocytes. Biotechnol. Bioeng. 2010;107: 393,401. © 2010 Wiley Periodicals, Inc. [source] SELECTED COCHRANE SYSTEMATIC REVIEWS Absorbable Synthetic Versus Catgut Suture Material for Perineal RepairBIRTH, Issue 2 2000C. Kettle A substantive amendment to this systematic review was last made on 19 May 1999. Cochrane reviews are regularly checked and updated if necessary. ABSTRACT Background and objectives: Approximately 70% of women will experience some degree of perineal trauma following vaginal delivery and will require stitches. This may result in perineal pain and superficial dyspareunia. The objective of this review was to assess the effects of absorbable synthetic suture material as compared with catgut on the amount of short- and long-term pain experienced by mothers following perineal repair. Search strategy: We searched the Cochrane Pregnancy and Childbirth Group trials register. Selection criteria: Randomised trials comparing absorbable synthetic (polyglycolic acid and polyglactin) with plain or chromic catgut suture for perineal repair in mothers after vaginal delivery. Data collection and analysis: Trial quality was assessed independently by two reviewers. Data were extracted by one reviewer and checked by the second reviewer. Main results: Eight trials were included. Compared with catgut, the polyglycolic acid and polyglactin groups were associated with less pain in first three days (odds ratio 0.62, 95% confidence interval 0.54,0.71). There was also less need for analgesia (odds ratio 0,63, 95% confidence interval 0.52,0.77) and less suture dehiscence (odds ratio 0.45, 95% confidence interval 0.29,0.70). There was no significant difference in long-term pain (odds ratio 0.81, 95% confidence interval 0.61,1.08). Removal of suture material was significantly more common in the polyglycolic acid and polyglactin groups (odds ratio 2.01, 95% confidence interval 1.56,2.58). There was no difference in the amount of dyspareunia experienced by women. Reviewers' conclusions: Absorbable synthetic suture material (in the form of polyglycolic acid and polyglactin sutures) for perineal repair following childbirth appears to decrease women's experience of short-term pain. The length of time taken for the synthetic material to be absorbed is of concern. A trial addressing the use of polyglactin has recently been completed and this has been included in this updated review. Citation: Kettle C, Johanson RB. Absorbable synthetic versus catgut suture material for perineal repair (Cochrane Review). In: The Cochrane Library, Issue 4, 1999, Oxford: Update Software. ,,, The preceding report is an abstract of regularly updated, systematic reviews prepared and maintained by the Cochrane Collaboration. The full texts of the reviews are available in The Cochrane Library (ISSN 1464-780X). Seehttp://www.update-software.com/cochrane.htmor contact Update Software,info@update.co.uk, for information on subscribing to The Cochrane Library in your area. Update Software Ltd, Summertown Pavilion, Middle Way, Oxford OX2 7LG, United Kingdom (Tel.: +44 1865 513902; Fax: +44 1865 516918). [source] | |||||||||||||