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A quick screening test of biomaterials by means of chick embryo techniques
Hulbert, S. F., J. J. Klawitter, et al. (1974), J Biomed Mater Res 8(2): 137-53.

A rapid quantitative method based on motility of bull sperm cells for in vitro toxicity testing of biomaterials
Petzoldt, R., H. Wolf, et al. (1985), Biomaterials 6(2): 105-9.
Abstract: A quantitative method for in vitro toxicity testing of biomaterials, based on measurements of time-dependent changes of bull sperm motility, is described. In comparison to the haemolytic and toxic effects of biomaterials such as polyurethanes, poly(vinyl chloride) tubes and bioglass ceramics on erythrocytes and the proliferation rate of human embryonic lung fibroblasts, this method is shown to be more sensitive. The simplicity, rapidity and reproducibility of the test under application of genetically identical cells are advantages that make it suitable for screening large numbers of samples. The quantification of test results allows inter-laboratory comparison.

A REDOR NMR study of a phosphorylated statherin fragment bound to hydroxyapatite crystals
Gibson, J. M., V. Raghunathan, et al. (2005), J Am Chem Soc 127(26): 9350-1.

A reflection scanning acoustic microscope for bone and bone-biomaterials interface studies
Meunier, A., J. L. Katz, et al. (1988), J Orthop Res 6(5): 770-5.
Abstract: A relatively simple scanning acoustic microscope (SAM) that operates in the reflection mode has been constructed. The system uses a 20 MHz spherically focused transducer, acting both as transmitter and as detector, to obtain acoustic impedance information on a thin surface layer at a maximum resolution of approximately 100 micron. The specimen is mounted on an X-Y driving system (precision, 5 micron) under computer control in order to scan a grid of 256 x 256 points across areas ranging from 6.5 to 1300 mm2. An algorithm is used to reference the data against standards; specially developed software provides for pseudo-color mapping, three-dimensional images, zooming to 16 x magnification, contouring, and single line profiles of the data. The system has been used to determine inhomogeneities in surface acoustic properties of mineralized tissues and implant materials, in many cases as a complement to using ultrasonic wave propagation techniques to measure the bulk anisotropic properties.

A relation between hysteresis and other visco elastic properties of some biomaterials
Apter, J. T. and E. Marquez (1968), Biorheology 5(4): 285-301.

A resorbable biomaterial shaped as a tubular chamber and containing stem cells: a pilot study on artificial bone regeneration
Giardino, R., N. Nicoli Aldini, et al. (2000), Int J Artif Organs 23(5): 331-7.
Abstract: In a previous study, we showed how healing of non-union defects in rabbit radii can be achieved by means of a tubular resorbable chamber, in comparison with untreated defects. In the present study, we placed bone marrow stem cells inside the chamber. Bone marrow was obtained by percutaneous aspiration from the iliac crest in 9 adult New Zealand rabbits. Stem cells were separated by the centrifugation technique. In the same animals, a defect of 10 mm was created in both radii. On the left side, the defect was treated with the poly-DL-Lactide chamber, in which a suspension of autologous cells was injected; on the right side, only autologous cells were used. Radiological and histomorphometric data were compared within this study as well as with the results of our previous study. At 3, 6 and 9 months, there was no healing on the right side.On the left side, progressive bone formation with reunion of the stumps was observed in the chamber. We conclude that stem cells can accelerate bone healing when contained in the tubular chamber.

A review on the design and reporting of studies on drug-gene interaction
Smits, K. M., J. S. Schouten, et al. (2005), J Clin Epidemiol 58(7): 651-4.
Abstract: OBJECTIVE: Methodological standards for clinical pharmacogenetic studies should be developed to improve reporting of studies and facilitate their inclusion in systematic reviews. The essence of these studies lies within the concept of effect modification. STUDY DESIGN AND SETTING: A narrative review discussing methodological issues in the design and reporting of pharmacogenetic studies. RESULTS: Studying effect modification within a trial leads to the comparison of subgroups based on genotype. Differences in effect based on genotype should preferably be expressed in absolute terms (risk differences) to facilitate clinical decisions on treatment. Information on the distribution of potential effect modifiers or prognostic factors should be available to prevent a biased comparison of differences in effect between genotypes. The distribution of genotypes should also be presented and compared to Hardy-Weinberg equilibrium to check for selection bias. Additional points of interest include the possibility of selective nonavailability of biomaterial and the choice of a statistical model to study effect modification. CONCLUSION: Additional methodological issues should be taken into account when designing and reporting pharmacogenetic studies, to ensure high study quality. We present several important issues for future studies investigating drug-gene interactions that can serve as a basis for further discussion on methodology in pharmacogenetics.

A review: secondary ion mass spectrometry (SIMS) of polymeric biomaterials
Davies, M. C. and R. A. Lynn (1990), Clin Mater 5(2-4): 97-114.
Abstract: This paper comprises a short review of the application of secondary ion mass spectrometry (SIMS) to the surface chemical analysis of biomaterials, with the main emphasis on biomedical polymers. By the use of appropriate examples, the technique is shown to provide detailed information on the surface chemical structure of the top 1-2 nm of a range of biodegradable polymers, copolymers, surface modified materials and drug delivery systems. Semi-quantitative information on the surface composition of copolymeric materials can also be obtained. The molecular specificity of the technique can be exploited to identify the presence of additives (eg. drugs, peptides) or contaminants in the surfaces of biomaterials. This approach can be extended to situations where biomolecules of interest are covalently immobilised on biomaterial surfaces. Finally, SIMS imaging analysis is shown to provide a means of determining the lateral distribution of additive molecules in surfaces.

A sanguine future for biomaterials
Maugh, T. H., 2nd (1982), Science 217(4565): 1129-30.

A scanning electron microscopical study of the two sides of polypropylene mesh (Marlex) and PTFE (Gore Tex) mesh 2 years after complete abdominal wall reconstruction. A study of 15 cases
Danino, A. M., G. Malka, et al. (2005), Br J Plast Surg 58(3): 384-8.
Abstract: The use of biomaterials for the repair of abdominal wall defect is becoming common and safe. It has been 20 years since the senior author developed a method to reconstruct the very large transfixing abdominal wall defect with a combination of two biomaterials (Gore Tex) PTFE as a neo peritoneum and polypropylene superficial to this in order to give rigidity to the abdominal wall) and a superficial flap. An observation at the electron microscopy level of the two sides of the implants' surfaces was performed. At the time of a late abdominal wall surgical revision on 15 patients, the prosthesis fragments have been analyzed at the electron microscopy level. The aim of our study was to analyze the late evolution of the different sides of these prostheses. Our results showed, for the first time in vivo, that there is an impressive stability of the deep side of PTFE ultra structure after implantation, a significant difference of the two sides of PTFE at the ultrastructural level and the creation of an intermediate tissue between the two meshes. In contrast, the polypropylene invariably gave rise to adhesions and colonisation by the surrounding tissues. Findings confirmed that the structure and porosity of a biomaterial play a key role in the appearance of adhesions and their consistency.

A secreted form of ADAM9 promotes carcinoma invasion through tumor-stromal interactions
Mazzocca, A., R. Coppari, et al. (2005), Cancer Res 65(11): 4728-38.
Abstract: Tumor cell invasion is a process regulated by integrins, matrix-degrading enzymes, and interactions with host tissue stromal cells. The ADAM family of proteins plays an important role in modulating various cellular responses. Here, we show that an alternatively spliced variant of ADAM9 is secreted by hepatic stellate cells and promotes carcinoma invasion. ADAM9-S induced a highly invasive phenotype in several human tumor cell lines in Matrigel assays, and the protease activity of ADAM9-S was required for invasion. ADAM9-S binds directly to alpha6beta4 and alpha2beta1 integrins on the surface of colon carcinoma cells through the disintegrin domain. ADAM9-S was also able to cleave laminin and promote invasion. Analysis of human liver metastases revealed that ADAM9 is expressed by stromal liver myofibroblasts, particularly those that are localized within the tumor stroma at the invasive front. These results emphasize the importance of tumor-stromal interactions in invasion and suggest that ADAM9-S can be an important determinant in the ability of cancer cells to invade and colonize the liver.

A self-ordered, crystalline glass, mesoporous nanocomposite with high proton conductivity of 2 x 10(-2) S cm-1 at intermediate temperature
Yamada, M., D. Li, et al. (2005), J Am Chem Soc 127(38): 13092-3.

A silanized hydroxypropyl methylcellulose hydrogel for the three-dimensional culture of chondrocytes
Vinatier, C., D. Magne, et al. (2005), Biomaterials 26(33): 6643-51.
Abstract: Articular cartilage has limited intrinsic repair capacity. In order to promote cartilage repair, the amplification and transfer of autologous chondrocytes using three-dimensional scaffolds have been proposed. We have developed an injectable and self-setting hydrogel consisting of hydroxypropyl methylcellulose grafted with silanol groups (Si-HPMC). The aim of the present work is to assess both the in vitro cytocompatibility of this hydrogel and its ability to maintain a chondrocyte-specific phenotype. Primary chondrocytes isolated from rabbit articular cartilage (RAC) and two human chondrocytic cell lines (SW1353 and C28/I2) were cultured into the hydrogel. Methyl tetrazolium salt (MTS) assay and cell counting indicated that Si-HPMC hydrogel did not affect respectively chondrocyte viability and proliferation. Fluorescent microscopic observations of RAC and C28/I2 chondrocytes double-labeled with cell tracker green and ethidium homodimer-1 revealed that chondrocytes proliferated within Si-HPMC. Phenotypic analysis (RT-PCR and Alcian blue staining) indicates that chondrocytes, when three-dimensionnally cultured within Si-HPMC, expressed transcripts encoding type II collagen and aggrecan and produced sulfated glycosaminoglycans. These results show that Si-HPMC allows the growth of differentiated chondrocytes. Si-HPMC therefore appears as a potential scaffold for three-dimensional amplification and transfer of chondrocytes in cartilage tissue engineering.

A simple method for ex vivo evaluation of biomaterial interaction with blood platelets
Mantovani, F., W. Marconi, et al. (1980), Int J Artif Organs 3(5): 305-10.
Abstract: The process of thrombus formation, as a consequence of the interaction of artificial surfaces with blood, is related to the activation of blood platelets. A simple ex vivo method, which is suitable for the evaluation of the platelet-surface interaction is described. This method has been used to compare the haemocompatibility of several artificial materials, including nylon-6, Silastic and pyrolytic carbon.

A simple non invasive computerized method for the assessment of bone repair within osteoconductive porous bioceramic grafts
Beltrame, F., R. Cancedda, et al. (2005), Biotechnol Bioeng 92(2): 189-98.
Abstract: Single energy X-ray imaging, due to its low cost and flexibility, is one of the most used and common technique to assess bone state and bone remodeling over time. Standardized X-ray images are needed to compare sets of radiographs for semi-quantitative analyses of tissue remodeling. However, useful mathematical modeling for the analysis of high level radiographic images are not easily available. In order to propose a useful evaluation tool to a wide clinical scenario, we present an innovative calibration algorithm for a semi-quantitative analysis of non-standardized digitized X-ray images. For calibration on a unique standardization scale, three time invariant regions (ROI) of radiographs were selected and analyzed. The accuracy of the normalization method for X-ray films was successfully validated by using an aluminum step wedge for routine X-ray exposures as tool to standardize serial radiographs (Pearson correlation test: R(2) = 0.96). This method was applied to investigate the progression of the new bone deposition within ceramic scaffolds used as osteoconductive substitute in large bone defects taking advantage of a large animal model. This innovative image-processing algorithm allowed the identification and semi-quantification of the bone matrix deposited within the implant. The osteo-integration at the bone-implant interface was also investigated. A progressively increasing bone tissue deposition within the porous bioceramic implant and a progressive osteo-integration was observed during the 12 months of the trial.

A specific quantitative assay for collagen synthesis by cells seeded in collagen-based biomaterials using sirius red F3B precipitation
Lee, D. A., E. Assoku, et al. (1998), J Mater Sci Mater Med 9(1): 47-51.
Abstract: The measurement of collagen synthesis by seeded cells in vitro is a prerequisite for the assessment of biocompatibility of many biomaterials. Existing methods are either complicated or not applicable to systems utilizing collagen-based materials, and the development of a rapid and simple technique would be an advantage. In the current paper, a method is described which relies on the radiolabelling of newly synthesized protein with [3H]-proline followed by specific precipitation of collagen using 1% sirius red dissolved in water. The results indicate that collagen binding to sirius red is unaffected by using water rather than picric acid as a solvent and the dye binds in a similar fashion to collagen type I, II and III. Cycloheximide treatment of the gels indicated that precipitated [3H]-proline was restricted to macromolecular protein. Collagenase treatment eradicated labelled precipitation formation when using 1% sirius red in water, indicating a high degree of specificity for collagen whilst specificity was poor when using 1% sirius red in picric acid. The method described is both simple and rapid and shows a high degree of specificity and sensitivity. For these reasons it is highly suited for the assessment of collagen synthesis by cells in collagen-based materials.

A stainless steel bracket for orthodontic application
Oh, K. T., S. U. Choo, et al. (2005), Eur J Orthod 27(3): 237-44.
Abstract: Aesthetics has become an essential element when choosing orthodontic fixed appliances. Most metallic brackets used in orthodontic therapy are made from stainless steel (SS) with the appropriate physical properties and good corrosion resistance, and are available as types 304, 316 and 17-4 PH SS. However, localized corrosion of these materials can frequently occur in the oral environment. This study was undertaken to evaluate the accuracy of sizing, microstructure, hardness, corrosion resistance, frictional resistance and cytotoxicity of commercially available Mini-diamond (S17400), Archist (S30403) and experimentally manufactured SR-50A (S32050) brackets.The size accuracy of Mini-diamond was the highest at all locations except for the external horizontal width of the tie wing (P < 0.05). Micrographs of the Mini-diamond and Archist showed precipitates in the grains and around their boundaries. SR-50A showed the only austenitic phase and the highest polarization resistance of the tested samples. SR-50A also had the highest corrosion resistance [SR-50A, Mini-diamond and Archist were 0.9 x 10(-3), 3.7 x 10(-3), and 7.4 x 10(-3) mm per year (mpy), respectively], in the artificial saliva. The frictional force of SR-50A decreased over time, but that of Mini-diamond and Archist increased. Therefore, SR-50A is believed to have better frictional properties to orthodontic wire than Mini-diamond and Archist. Cytotoxic results showed that the response index of SR-50A was 0/1 (mild), Mini-diamond 1/1 (mild+), and Archist 1/2 (mild+). SR-50A showed greater biocompatibility than either Mini-diamond or Archist.It is concluded that the SR-50A bracket has good frictional property, corrosion resistance and biocompatibility with a lower probability of allergic reaction, compared with conventionally used SS brackets.

A structural basis for depolymerization of alginate by polysaccharide lyase family-7
Yamasaki, M., K. Ogura, et al. (2005), J Mol Biol 352(1): 11-21.
Abstract: Alginate lyases depolymerize alginate, a heteropolysaccharide consisting of alpha-L-guluronate and beta-D-mannuronate, through a beta-elimination reaction. Their structure/function relationships are expected to provide information valuable to future industrial alginate processing and drug design for Pseudomonas aeruginosa alginate biofilm-dependent infection, but much remains unknown. Here, we present the crystal structure at 1.0 A resolution and the results of mutational analysis of Sphingomonas sp. A1 alginate lyase A1-II', which is grouped into the polysaccharide lyase (PL) family-7. The overall structure of A1-II' uses a beta-sandwich fold, and it has a large active cleft covered by two short flexible loops. Comparison with other family PL-7 structures indicated that loop opening is necessary for substrate binding when the catalytic reaction is initiated. In contrast to the disorder in many side-chains on the protein surface, the three adjacent beta-strands at the center of the active cleft are well ordered. This results from hydrogen bond networks and stacking-like associations identical with those in other family PL-7 structures. Disruption of these interactions by site-directed mutagenesis (R146A, E148A, R150A, Q189A, and K280A) makes the protein insoluble or greatly decreases its activity. The A1-II' structure includes two sulfate ions in the active cleft. Ammonium sulfate was a potent inhibitor with a Ki of 2.5 mM, indicating that our structure represents a model of the inhibitory state. Results of mutational analysis and continuous hydrogen bond networks suggest that Arg146, Gln189, His191, and Tyr284 form an active center. Tyr284OH appears particularly crucial to the catalytic reaction, which is supported by sulfate ion binding and the proximity to the C5 and O4 atoms of subsite +1 in the model obtained by energy minimization calculations using tri-mannuronate. The structural basis shown by this study is similar in many respects to that of the family PL-5 enzymes.

A study of biologically active peptide sequences (P-15) on the surface of an ABM scaffold (PepGen P-15) using AFM and FTIR
Hole, B. B., J. A. Schwarz, et al. (2005), J Biomed Mater Res A 74(4): 712-21.
Abstract: Cellular response to any biomaterial surface is governed by a number of factors including topography, surface chemistry, surface charge, structural heterogeneity, and physiological conditions. Understanding these factors at the nanoscale level is crucial to develop improved biomaterials. Any changes in these properties due to surface modifications need to be addressed properly, as they could have significant impact on the cellular interaction with biomaterials. In this study, the topography and surface chemistry of commercially available tissue engineered xenograft, PepGen P-15 [comprised of a synthetic peptide P-15 irreversibly attached to anorganic bovine bone mineral (OsteoGraf/-N)] was studied using Atomic Force Microscopy (AFM), and Fourier Transform Infrared Spectroscopy (FTIR). FTIR confirmed the presence of the peptide on the surface of PepGen P-15. Changes in the peptide conformation, which includes a decrease in the beta-strand accompanied by an increase in unordered structures/random coil structures after attachment on OsteoGraf/-N is observed. Specific functional groups, which are involved in the binding mechanism, are identified. The results suggest that the attachment of the peptide on OsteoGraf/-N occurs via a specific surface docking ionic interaction involving the C-terminal carboxylic group on the peptide with positive domains generated by hydroxyl vacancies on the apatite surface.

A study of structure and degradation of nonpolymeric biomaterials implanted in bone using reflected and transmitted light microscopy
Frayssinet, P., F. Tourenne, et al. (1993), Biotech Histochem 68(6): 333-41.
Abstract: Orthopedic biomaterials currently are made of metal alloy coated with one or more thin layers of dense or porous ceramic or metal. Sections of these materials implanted in human bone were made without altering the implant or bone-implant interfaces. Bone containing an implant was fixed and then embedded in polymethylmethacrylate. Thick sections were made using a cooled, low speed diamond saw, then ground and polished. Some were stained by fuchsin-toluidine staining solution, others were acid etched to reveal the structure of the metal contained in the prosthesis. Observation by reflected and transmitted light microscopy revealed microstructure of the implant material as well as features of the surrounding tissues.

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Last Modified: 8 February 2006