|Articles about Biomaterials|
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| The use of hydroxyapatite cement and a pericranial/deep temporal fascia graft for cranioplastic reconstruction of translabyrinthine craniectomy defects
Hussain, A. and F. Ahsan (2005), Ear Nose Throat J 84(2): 86, 89-90, 92.
Abstract: Most translabyrinthine temporal bone defects are reconstructed with free abdominal fat grafts, with or without the use of hydroxyapatite cement. However, these procedures are associated with considerable morbidity at the graft donor site, with a 6 to 15% incidence of cerebrospinal fluid (CSF) leaks, and with postoperative headaches. We have developed a new technique for reconstructive cranioplasty that involves the use of hydroxyapatite cement and a pericranial/deep temporal fascia graft. This technique obviates the need for an abdominal fat graft and therefore circumvents the morbidity associated with it; it may also significantly reduce the incidence of CSF leaks and postoperative headaches. We describe the results of our use of this technique in a series of 10 patients. Based on our early findings, we believe that this technique holds great promise for reconstructive cranioplasty following translabyrinthine craniectomy.
| The use of Integra in an upper extremity avulsion injury
Wolter, T. P., E. M. Noah, et al. (2005), Br J Plast Surg 58(3): 416-8.
Abstract: We present the case of a 22-year-old man who suffered an avulsion injury of the left upper extremity including the elbow region in an industrial accident. After debridement of the skin flap, the defect was primarily closed with Integra. On day 22 split thickness skin graft was performed. Functional and aesthetic outcome and skin quality are excellent.
| The use of intraorally harvested autogenous block grafts for vertical alveolar ridge augmentation: a human study
Proussaefs, P. and J. Lozada (2005), Int J Periodontics Restorative Dent 25(4): 351-63.
Abstract: This study presents a clinical, radiographic, laboratory, and histologic/histomorphometric analysis of the use of mandibular block autografts for vertical alveolar ridge augmentation. Twelve patients were included in the study. The autogenous block autografts were fixated at the recipient sites with screws, and a mixture of autogenous bone marrow and inorganic bovine mineral (Bio-Oss) was used at the periphery. At re-entry surgery, all the grafts appeared well incorporated at the recipient sites. Radiographic measurements revealed an average of 5.75 +/- 1.29 mm vertical ridge augmentation at 1 month after surgery and 4.75 +/- 1.29 mm at 4 to 6 months after surgery. This indicated 17.4% resorption. Laboratory volumetric measurements revealed an average of 0.84 +/- 0.34 mL of alveolar ridge augmentation 1 month after surgery and 0.71 +/- 0.28 mL at 6 months postoperatively. The resorption rate according to the laboratory volumetric measurements was 15.5%. Linear laboratory measurements revealed 5.92 +/- 1.38 mm of vertical ridge augmentation 1 month postoperatively and 4.08 +/- 1.01 mm at 4 to 6 months after surgery. Histologic evaluation of the block autografts indicated signs of active remodeling activity in 10 of the 12 specimens. In one case the block graft became exposed and infected, and in another case the block autograft became dislodged during implant placement surgery. Histomorphometric analysis of the peripheral particulate bone indicated bone present at 33.99% +/- 8.82% of the graft surface, while 42.43% +/- 11.06% of the area was occupied by fibrous tissue and 23.89% +/- 9.12% was made up of residual Bio-Oss particles. Residual Bio-Oss particles were in tight contact with newly formed bone along 58.57% +/- 15.22% of their perimeter.
| The use of poly(ethylene oxide) for the efficient stabilization of entrapped alpha-chymotrypsin in silicone elastomers: a chemometric study
Ragheb, A. M., O. E. Hileman, et al. (2005), Biomaterials 26(34): 6973-83.
Abstract: The enzyme alpha-chymotrypsin, a model for catalytic proteins, was entrapped in different silicone elastomers that were formed via the condensation-cure room temperature vulcanization (CC-RTV) of silanol terminated poly(dimethylsiloxane) with tetraethyl orthosilicate as a crosslinker, in the presence of different poly(ethylene oxide) oligomers that were functionalized with triethoxysilyl groups. The effects of various chemical factors on both the activity and entrapping efficiency of proteins (leaching) were studied using a 2-level fractional factorial design--a chemometrics approach. The factors studied include the concentration and chain length of poly(ethylene oxide), enzyme content, and crosslinker (TEOS) concentration. The study indicated that poly(ethylene oxide) can stabilize the entrapped alpha-chymotrypsin in silicone rubber: the specific activity can be maximized by incorporating a relatively high content of short chain, functional PEO. Increased enzyme concentration was found to adversely affect the specific activity. The effect of TEOS was found to be insignificant when PEO was present in the elastomer, however, it does affect the activity positively in the case of simple elastomers.
| The use of porcine small intestinal submucosa as a biomaterial for perineal herniorrhaphy in the dog
Stoll, M. R., J. L. Cook, et al. (2002), Vet Surg 31(4): 379-90.
Abstract: OBJECTIVES: To develop an in vivo perineal hernia model, to develop a technique for using small intestinal submucosa (SIS) in perineal hernia repair, to further elucidate the biological behavior of SIS, and to compare SIS herniorrhaphy with the internal obturator muscle transposition (IOT) technique. STUDY DESIGN: Prospective evaluation comparing SIS herniorrhaphy with IOT. ANIMALS: Twelve adult castrated male, large-breed dogs. METHODS: All dogs had bilateral pelvic diaphragm defects created by complete excision of the levator ani muscle. Each dog had one side repaired using SIS and the other by IOT. Pain and inflammation were subjectively scored. Dogs were killed 2 weeks (n = 4), 12 weeks (n = 4), or 16 weeks (n = 4) after surgery. Each pelvic diaphragm was biomechanically tested to failure. The pelvic diaphragms from 2 normal dogs (n = 4 sides) were also biomechanically tested. Failure site, maximum pressure, displacement at failure, and initial linear stiffness values were determined. Histologic assessment was performed. Statistical analysis was performed with significance set at P <.05 RESULTS: No significant postoperative complications were noted. There were no significant differences in maximum pressure to failure, displacement, or stiffness when comparing normal, SIS, and IOT at any time point. The SIS group had significantly less displacement (P =.004) at 2 weeks than at weeks 12 or 16. For all herniorrhaphy techniques, the failure site was central (n = 22) or at the suture line (n = 2). At 2 weeks, histologic evaluation of tissues from the IOT group showed inflammation, mineralization, and necrosis, which were not present in tissues from the SIS group. Histologic examination at 12 and 16 weeks showed no microscopic differences in cell population or tissue characteristics between the IOT and SIS groups. CONCLUSIONS: SIS herniorrhaphy was successfully performed in this in vivo model of perineal hernia in the dog. CLINICAL RELEVANCE: This study suggests that SIS can be used as a primary means of repair, as augmentation when the internal obturator muscle is thin and friable, or as a salvage procedure in cases of recurrence in dogs with perineal hernia.
| The use of rhodamine 6G and fluorescence microscopy in the evaluation of phospholipid-based polymeric biomaterials
Wang, J. H., J. D. Bartlett, et al. (2005), J Microsc 217(Pt 3): 216-24.
Abstract: A technique is described that allows the staining and subsequent visualization of polymers that contain the phosphorylcholine (PC) group. These materials are useful as bulk materials or coatings for the fabrication of medical devices. The staining method employs rhodamine 6G, which can be simply and rapidly applied to the polymer coating and imaged using fluorescence microscopy. The specificity of the staining for the PC polymers makes this technique suitable for the evaluation of a wide range of substrates and provides qualitative information on coating uniformity, coverage and morphology. It can be used to examine the durability of, and defects in, the coating. Statistical analysis of the fluorescent intensity by measuring the pixel value during imaging can allow for the method to be used as a quality control tool.
| The use of silicone as a biomaterial
Lee, G. M. (1995), Med Device Technol 6(3): 20-5.
Abstract: The availability of silicone biomaterials has severely declined. This has been caused by the departure of many suppliers because of product liability concerns and the increase in litigation, particularly in the United States. This article discusses the current and future problems facing the health care industry.
| The use of Surgi Wrap in delayed adjustable strabismus surgery
Choung, H. K. and J. M. Hwang (2005), Am J Ophthalmol 140(3): 433-6.
Abstract: PURPOSE: To determine the effect of Surgi Wrap (MacroPore Biosurgery, Inc, San Diego, California, USA) in delayed adjustable strabismus surgery. DESIGN: An animal study. METHODS: A prospective, masked-observer, controlled study was performed in rabbits. Forty-eight eyes of 24 rabbits were divided into two groups. After recession of the superior rectus muscle (SRM), Surgi Wrap was applied beneath and over the SRM in the Surgi Wrap group, and no barrier was applied in the control group. Delayed adjustment was performed once on each superior rectus muscle at 1, 2, and 3 weeks after surgery by a masked observer. The possible length to adjust, the force required for the adjustment, and the degree of any adhesions were also evaluated. RESULTS: In the control group, adjustment was impossible in all of the five eyes at 1, 2, and 3 postoperative weeks, respectively. In the Surgi Wrap group, adjustment was possible in four of 10 eyes at 1 week after surgery, in two of 10 eyes at 2 weeks after surgery, and in none of the 10 eyes at 3 weeks after surgery. CONCLUSION: The use of Surgi Wrap could delay adjustment in some of the eyes up to 1 or 2 weeks after surgery. Surgi Wrap could be helpful for short-term delayed adjustment in rabbit eyes.
| The use of xenogeneic small intestinal submucosa as a biomaterial for Achilles tendon repair in a dog model
Badylak, S. F., R. Tullius, et al. (1995), J Biomed Mater Res 29(8): 977-85.
Abstract: A study was conducted to evaluate the tissue response to a xenogeneic biomaterial when this material was used to repair an experimentally induced Achilles tendon defect in the dog. Twenty dogs had a 1.5 cm segmental defect of the Achilles tendon created surgically which was then repaired with acellular connective tissue derived from porcine small intestinal submucosa (SIS). The animals were sacrificed at 1, 2, 4, 8, 12, 16, 24, and 48 weeks and the neotendons examined for uniaxial longitudinal tensile strength, morphologic appearance, hydroxyproline (collagen) content, and disappearance of the originally implanted SIS material over time. The contralateral normal Achilles tendons served as controls as did four additional dogs that had a 1.5 cm segmental Achilles tendon defect created surgically without subsequent surgical repair with SIS. Results showed the SIS remodeled neotendons to be stronger than the musculotendinous origin or the boney insertion (> 1000 N) by 12 weeks after surgery and to consist of organized collagen-rich connective tissue similar to the contralateral normal tendons. The four dogs in which no SIS was implanted showed inferior strength at the comparable time points of 4, 8, 12, and 16 weeks. Immunohistochemical studies suggest that the SIS biomaterial becomes degraded within the first eight weeks and serves as a temporary scaffold around which the body deposits appropriate and organized connective tissue. SIS is a promising biomaterial worthy of further investigation for orthopedic soft tissue applications.
| The viability and function of primary rat hepatocytes cultured on polymeric membranes developed for hybrid artificial liver devices
Grant, M. H., C. Morgan, et al. (2005), J Biomed Mater Res A 73(3): 367-75.
Abstract: Bioartificial liver devices require membranes to support the function and viability of hepatocytes because they are anchorage-dependent cells. This study investigated the ability of several polymeric membranes to support the functions of primary hepatocyte cultures. Tailor-made membranes were sought by synthesizing acrylonitrile copolymers with different comonomers resulting in ionic, hydrophilic, or reactive functional groups on the polymer surface. Hepatocyte morphology and viability were assessed by confocal microscopy, and function by the content and activities of cytochrome P450, and the expression of glutathione S-transferases. Hydrophilic membranes (polyacrylonitrile and acrylonitrile copolymerized with 2-acrylamino-2-methyl-propane sulfonic acid) were more biocompatible than hydrophobic membranes such as polysulfone. The chemistry of the hydrophilic group was important; amine groups had a deleterious effect on maintenance of the primary hepatocytes. The biocompatibility of hydrophobic membranes was improved by collagen coating. Improving the chemistry of membranes for artificial liver devices will enhance the phenotypic stability of the cells, enabling us to prolong treatment times for patients.
| The vistas and horizons of bony reconstruction--commentary
Van Damme, P. A. (2005), J Craniomaxillofac Surg 33(2): 75-8.
| The XIIth International Symposium on Recent Advances in Drug Delivery Systems
Vives, E. (2005), Expert Opin Drug Deliv 2(3): 597-601.
Abstract: The XIIth International Symposium on Recent Advances in Drug Delivery Systems was held from 21-24 February 2005 in Salt Lake City, UT, USA. Approximately 250 people attended this symposium dedicated to a broad variety of topics, ranging from recent advances in drug delivery systems to biomaterials and novel concepts in macromolecular therapeutics. A total of 33 people, all recognised specialists in the aforementioned fields, presented 30-min up-to-date reviews of these topics, as well as discussing recent results. In addition, the symposium included a poster session with approximately 100 displays highlighting various interesting data.
| Themistocles Gluck, Berlin 1890: a pioneer of multidisciplinary applied research into biomaterials for endoprostheses
Muster, D. (1990), Bull Hist Dent 38(1): 3-6.
Abstract: In recent years, fascinating results have been obtained in reconstructive surgery through use of high tech biomaterials and sophisticated surgical techniques reinforced by pharmacology, anesthesiology and intensive care.
| Theory, measurement, and application of thermal properties of biomaterials
Bowman, H. F., E. G. Cravalho, et al. (1975), Annu Rev Biophys Bioeng 4(00): 43-80.
| Therapeutic embolization of a thoracoacromial artery perforated by placement of a deep venous catheter
Vandaele, P., S. Heye, et al. (2005), Jbr-Btr 88(2): 75-7.
Abstract: An 82-year-old man presented with massive external bleeding from the puncture site after placement of a deep venous catheter in the right subclavian vein. Emergent angiography revealed contrast extravasation along the central venous catheter tract due to perforation of the right thoracoacromial artery. Superselective catheterization of the bleeding artery followed by microparticle embolization definitively stopped the hemorrhage. During follow-up no recurrence of external bleeding was noted. Percutaneous embolization using microparticles is an effective tool to definitively treat iatrogenic arterial hemorrhage as a complication of deep venous catheter placement.
| Therapeutic potential of nanoparticulate systems for macrophage targeting
Chellat, F., Y. Merhi, et al. (2005), Biomaterials 26(35): 7260-75.
Abstract: The use of non-viral nanoparticulate systems for the delivery of therapeutic agents is receiving considerable attention for medical and pharmaceutical applications. This increasing interest results from the fact that these systems can be designed to meet specific physicochemical requirements, and they display low toxic and immunogenic effects. Among potential cellular targets by drug-loaded nanoparticles, macrophages are considered because they play a central role in inflammation and they act as reservoirs for microorganisms that are involved with deadly infectious diseases. The most common and potent drugs used in macrophage-mediated diseases treatment often induce unwanted side effects, when applied as a free form, due to the necessity of high doses to induce a satisfactory effect. This could result in their systemic spreading, a lack of bioavailability at the desired sites, and a short half-life. Therefore, the use of drug-loaded nanoparticles represents a good alternative to avoid, or at least decrease, side effects and increase efficacy. In this manuscript, we present an overview of the usefulness of nanoparticles for macrophage-mediated therapies in particular. We discuss, though not exhaustively, the potential of therapeutic agent-loaded nanoparticles for some macrophage-mediated diseases. We also underline the most important parameters that affect the interaction mechanisms of the macrophages and the physicochemical aspects of the particulate systems that may influence their performance in macrophage-targeted therapies.
| Thermal Characterizations of silver-containing bioactive glass-coated Sutures
Blaker, J. J., A. R. Boccaccini, et al. (2005), J Biomater Appl 20(1): 81-98.
Abstract: This study utilized and compared a number of thermal analysis methods to characterize the thermal properties of commercial sutures with and without antimicrobial coatings of silver-doped bioactive glass (AgBG) interlocking particulates. The effect of a slurry dipping technique used to coat resorbable Vicryl (polyglactin 910) and non-resorbable Mersilk surgical sutures with AgBG was investigated using conventional differential scanning calorimetry (DSC), high speed calorimetry (or HYPERDSC), and modulated temperature DSC (MTDSC). These methods were compared in terms of their ability to resolve the thermal transitions of the types of suture materials. Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were used to verify the thermal degradation temperatures of these materials and to quantify the AgBG coatings on the sutures.The use of complementary thermal analysis techniques enabled the understanding of the effect of the AgBG coating technique on the morphological properties of the sutures. The slurry dipping technique had no significant effect on the thermal transitions of both types of materials. The use of high speed calorimetry through DSC offered better resolution for the transitions that appeared to be weak through conventional heating regimes, and was able to separate broad double transitions. Furthermore, it was shown not to compromise either the melting temperature or the enthalpy of melting. Therefore this method allows for the accurate determination of thermal transitions through much shorter experimental times thus allowing for an increased sample throughput. The combined DTA and TGA indicated that a greater AgBG coating was obtained in the case of the Mersilk sutures.
| Thermal diffusion and chemical kinetics in laminar biomaterial due to heating by a free-electron laser
Hutson, M. S., S. A. Hauger, et al. (2002), Phys Rev E Stat Nonlin Soft Matter Phys 65(6 Pt 1): 061906.
Abstract: We have theoretically investigated the role of thermal diffusion and chemical kinetics as a possible dynamic explanation for the preferential ablative properties of infrared radiation from a free-electron laser (FEL). The model is based on a laminar system composed of alternating layers of protein and saline. We have compared exposure to 3 microm where water is the main absorber and 6.45 microm where both water and protein absorb. The picosecond pulses of the superpulse are treated as a train of impulses. We find that the heating rates are sufficient to superheat the outer saline layers on the nanosecond time scale, leading to explosive vaporization. We also find that competition between the layer-specific heating rates and thermal diffusion results in a wavelength-dependent separation in layer temperatures. We consider the onset of both chemical bond breaking and the helix-coil transition of protein prior to vaporization in terms of the thermal, chemical, and structural properties of the system as well as laser wavelength and pulse structure. There is no evidence for thermal bond breaking on these time scales. At 6.45 microm, but not 3 microm, there is evidence for a significant helix-coil transition. While the native protein is ductile, the denatured protein exhibits brittle fracture. This model provides a dynamic mechanism to account for the preferential ablative properties observed with FEL radiation tuned near 6.45 microm.
| Thermal stresses from large volumetric expansion during freezing of biomaterials
Shi, X., A. K. Datta, et al. (1998), J Biomech Eng 120(6): 720-6.
Abstract: Thermal stresses were studied in freezing of biomaterials containing significant amounts of water. An apparent specific heat formulation of the energy equation and a viscoelastic model for the mechanics problem were used to analyze the transient axi-symmetric freezing of a long cylinder. Viscoelastic properties were measured in an Instron machine. Results show that, before phase change occurs at any location, both radial and circumferential stresses are tensile and keep increasing until phase change begins. The maximum principal tensile stress during phase change increases with a decrease in boundary temperature (faster cooling). This is consistent with experimentally observed fractures at a lower boundary temperature. Large volumetric expansion during water to ice transformation was shown to be the primary contributor to large stress development. For very rapid freezing, relaxation may not be significant, and an elastic model may be sufficient.
| Thermoelectroelastic solutions for surface bone remodeling under axial and transverse loads
Qin, Q. H., C. Qu, et al. (2005), Biomaterials 26(33): 6798-810.
Abstract: Theoretical prediction of surface bone remodeling in the diaphysis of the long bone under various external loads are made within the framework of adaptive elastic theory. These loads include external lateral pressure, electric and thermal loads. Two solutions are presented for analyzing thermoelectroelastic problems of surface bone remodeling. The analytical solution that gives explicit formulation is capable of modeling homogeneous bone materials, while the semi-analytical solution is suitable for analyzing inhomogeneous cases. Numerical results are presented to verify the proposed formulation and to show the effects of mechanical, thermal and electric loads on surface bone remodeling process.
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