Biomaterials.info - Resources for Engineers

Record 341 to 360

[Treatment using Polish collagen biomaterials]
Grzybowski, J. (1997), Polim Med 27(3-4): 11-8.
Abstract: The article presents the review of all published and not published results of clinical investigations of new polish collagen biomaterials that have been registered in Poland recently. Two main medical applications of the biomaterials--used as hemostatic tampons and/or as biological dressings for wound care have been described here. The collagen sponges proved to be useful in chronic wound care and for hemostasis of bleeding wounds. The collagen membranes are effective in extensive superficial wounds care (burns, skin donor places or wounds after dermabrasion).

[Trends in orthodontic biomaterials: metals and ceramics]
Matasa, C. G. (2000), Orthod Fr 71(4): 335-41.
Abstract: While the beginning of orthodontics was marked by an acute scarcity in materials, the modern clinician has to face a large array of devices made of metals, plastics, ceramics and combinations thereof. Each of these materials have been developed for other purposes than orthodontics, and then transplanted "as is" in a field which has its own demands. During the years, theses devices, as well as the materials these are made of, have been modified most of time to the benefit of both the patient and the clinician, and some time to that of the manufacturer who has tried to save, or bypass limiting patients. Among the latter are the harder, but less corrosion resistant steels, the efficient but corrosion prone brazing, the inexpensive but weaker molded attachments, the aesthetic but fragile ceramics. Understanding the trends and basics of materials science should help the clinician to avoid being sued iatrogenic inflicted affections.

[Tricalcium phosphate, vector of antibiotics: gentamycin and vancomycin. In vitro physicochemical characterization, study of biomaterial porosity and gentamycin and vancomycin elution]
Brouard, S., J. Lelan, et al. (1997), Chirurgie 122(7): 397-403.
Abstract: We have investigated a Vancomycin and Gentamycin loaded macroporous tri-calcium phosphate-type beta-ceramic, Calciresorbr. Elution kinetics of Vancomycin and Gentamycin from spheric implants was studied by varying porosity and initial concentrations; then, the other following parameters, that can be modulated and are likely to be involved in this elution process, were analysed: Antibiotic charge: quantitative analysis (titration). qualitative analysis by scanning electron microscopy. Material's porosity: qualitative analysis: optical and scanning electron microscopy. quantitative analysis by stereology and treatment. This physicochemical characterization would favour correct manufacturing of new macroporous synthetic bioceramics in order to achieve satisfactory elution kinetics and homogenous materials.

[Usage of Cerasorbe in complex treatment of chronic generalized periodontitis (clinical-experimental study)]
Motsonelidze, N. R., T. V. Okropiridze, et al. (2005), Georgian Med News(118): 17-20.
Abstract: The effectiveness of the bioactive osteoplastic composition--Cerasorbe--at a surgical stage of combined treatment of chronic generalized periodontitis was examined. The results obtained in the study and the control groups prove, that Cerasorbe allows reduction of the treatment duration and achieves remission of the disease. From 127 patients with chronic generalized periodontitis 65 were operated by microplasmatic scalpel-irradiator as a part of a complex treatment. The treatment course comprised of 3-5 procedures. The quantity of manipulations was determined by the severity of the pathological process. Before and after the treatment the radiographical investigation was carried out in both groups. At the 18th month after the surgical intervention bone regeneration, confirmed by radiography, was shown in 87,8% cases in the study group and in 60,1% in the control group. The work presents experimental and morphological studies of regeneration of damaged areas of maxillo-facial bones. Time course of healing of defects in the lower jaw bone filled with Cerasorb was studied in experiment on rabbits. On days 7, 14, 21 and 28 four rabbits from each group were killed and the defects were investigation by X-ray and histological methods. We have stained the micropreparations by hematoxilin-eosine. In experiments with Cerasorb, bone regenerations replaced up to one half of the defect area by the day 28. We have shown high efficiency of Cerasorb in experiment and during complex treatment. Cerasorb stimulated reparative osteogenesis and can be recommended for using in the clinical practice.

[Use of an alternative for whole animal experiments: determining embryotoxicity of dental biomaterials by differentiation of ES cells]
Imai, K. and M. Nakamura (2005), Nippon Yakurigaku Zasshi 125(6): 335-42.

[Use of biomaterials for preventive and restorative purposes]
Szabo, G. (1992), Fogorv Sz 85(3): 65-9.
Abstract: At the Dept. of Maxillofacial Surgery, Semmelweis University of Medicine many biomaterials have been used in the last 10 year. Author deals with only three materials, such as solid aluminiumoxyde ceramics, titanium screws and HTR Polymers. The Al2O3 ceramics can be used for the reconstruction of the lower jaws, the condyle and the coronoid process of the mandible as well as for dental implants and for the improvement of the facial contour. This material proved to be the most suitable for the reconstruction of the mandible and TM joint. The titanium screw implant (Flexi-root system) has been used in many hundreds of patients with some 90% success rate. The HTR Polymer has been used in the periodontal surgery, in small and medium size cyst operations and sinus lift procedures. The technique of sinus lift has also been discussed.

[Use of biomaterials in dental implantology]
Commissionat, Y. (1995), Bull Acad Natl Med 179(3): 569-82; discussion 583.

[Vascular biomaterials: from biomedical engineering to tissue engineering]
Meddahi-Pelle, A., I. Bataille, et al. (2004), Med Sci (Paris) 20(6-7): 679-84.
Abstract: Biomaterials are already widely used in medical sciences. The field of biomaterials began to shift to produce materials able to stimulate specific cellular responses at the molecular level. The combined efforts of cell biologists, engineers, materials scientists, mathematicians, geneticists, and clinicians are now used in tissue engineering to restore, maintain, or improve tissue functions or organs. This rapidly expanding approach combines the fields of material sciences and cell biology for the molecular design of polymeric scaffolds with appropriate 3D configuration and biological responses. Future developments for new blood vessels will require improvements in technology of materials and biotechnology together with the increased knowledge of the interactions between materials, blood, and living tissues. Biomaterials represent a crucial mainstay for all these studies.

[Venous catheter associated infection: possible prevention are often still not utilized]
Panknin, H. T. (2005), Pflege Z 58(2): 88-93.

[Vertebral body replacement with Synex in combined posteroanterior surgery for treatment of thoracolumbar injuries]
Knop, C., U. Lange, et al. (2005), Oper Orthop Traumatol 17(3): 249-80.
Abstract: OBJECTIVE: Reduction and stabilization of unstable spinal injuries with reconstruction of the anterior column resulting in a permanent restitution of the physiologic spinal alignment, stability and load-bearing capacity. INDICATIONS: Unstable injuries and lesions of the spine from T4 to L5 resulting in a reduced load-bearing capacity of the anterior spinal column caused by vertebral fractures and injury of the intervertebral disks, posttraumatic kyphotic deformities, pathologic fractures, tumors. Relative indications: younger patients with monosegmental injuries; patients with severe osteoporosis. CONTRAINDICATIONS: Concomitant serious thoracic injuries or preexisting cardiopulmonary disease precluding anterior intervention. SURGICAL TECHNIQUE: Combined posteroanterior treatment with (1) posterior reduction and stabilization with an internal fixator and interlaminar fusion with autogenous bone grafts; (2) thoracoscopic anterior approach with reconstruction of the anterior column with a distractible titanium implant for vertebral body replacement (Synex), interbody fusion with autogenous bone grafts and/or beta-tricalciumphosphate. RESULTS: 50 consecutive patients (29 men, 21 women) with an average age of 43 years (20-77 years) were treated with Synex. The most frequent indication was acute injury (n = 36). A bisegmental reconstruction was performed in 30 patients, a monosegmental in 20. Mean follow-up 19.5 months (14-31 months) in 41 patients. 18/33 patients returned to their previous occupation, and 32/41 resumed their recreational activities. At follow-up, 32/41 were free of symptoms or complained of only occasional pain, eight reported marked pain and one severe pain. A VAS spine score (0-100 points, visual analog scale, 19 items) was used for assessment; the preoperative score amounted to 83.1 +/- 20.2 (21-100), the postoperative score to 63.8 +/- 19.5 (25-99). The mean decrease in VAS spine score was 19.3 +/- 22.3. The average degree of correction measured radiologically for patients with fresh injuries or posttraumatic malalignment was 18.6 degrees +/- 10 degrees and the loss of correction 2.1 degrees +/- 2.9 degrees. No implant-related complications were observed.

[Vroman effect of plasma protein adsorption to biomaterials surfaces]
Huang, J., Y. Yue, et al. (1999), Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 16(3): 371-6.
Abstract: Fibrinogen adsorption from plasma to biomaterials surfaces passes through a maximum when studied as a function of adsorption time, plasma concentration, or column height in narrow spaces and these are called Vroman effect. Studies have demonstrated that Vroman effect is a general phenomenon of plasma proteins and reflects the competitive adsorption of plasma proteins for a limited number of surface sites. In this paper, the factors affecting Vroman effect, the relationship between contact activation and fibrinogen displacement, and the significance of the Vroman effect with respect to blood-material interactions are reviewed.

[What is thought of the various surface treatments of biomaterials used in dental and maxillofacial implantology?]
Muster, D., B. Demri, et al. (1998), Rev Stomatol Chir Maxillofac 99 Suppl 1: 89-93.
Abstract: The surface treatments for biomaterials have the following goals: to increase the biocompatibility and the tissue acceptation, to prevent infection to reduce the abrupt interfaces; to favour the biological integration and the long term in service behaviour. Advantages and inconveniences of these methods are analysed for the main biomaterials categories: metals, synthetic polymers, ceramics, materials of biological origin. In addition to appropriate physico-chemical and mechanical properties, the existence of biologically functional interfaces with the living cells is more and more wished. In the next 20 years, it appears likely that the design of prostheses or implants in actual clinical use will have to be totally or partly reconsidered.

[X-ray powder diffraction (XRD) in the study of biomaterials used in dentistry. 3]
Valdre, G., R. Mongiorgi, et al. (1995), Minerva Stomatol 44(1-2): 21-32.
Abstract: This study considers X-ray power diffraction (XRD) applied to the study of mineral-based biomaterials used in odontostomatology. By means of this method the following materials were analysed: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable fine Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2, Osprogel, Bio-oss, Biostite, Osprovit, Merck Hydroxyapatite. These analysis allow the identification of the crystalline phases, the study of the crystallinity and the crystal chemistry of the samples prepared as powder mixtures. This method permits the determination of the physical chemical and crystalline characteristics of these mineral based biomaterials formed by powders or transformable in powders. All of this information is indispensable for the evaluation of the functional biocompatibility of a biomaterial when its reaction in a biological environment is already known. This method has a great number of advantages against the traditional methods, marking with solid phases, it does not destroy the sample, it does not modify the physical or chemical characteristics and gives more information.

15(S)-hydroxyeicosatetraenoic acid induces angiogenesis via activation of PI3K-Akt-mTOR-S6K1 signaling
Zhang, B., H. Cao, et al. (2005), Cancer Res 65(16): 7283-91.
Abstract: To determine whether the lipoxygenase metabolites of arachidonic acid, 5(S)-, 12(S)-, and 15(S)-hydroxyeicosatetraenoic acids [5(S)-HETE, 12(S)-HETE, and 15(S)-HETE, respectively] are angiogenic, we have studied their effects on human dermal microvascular endothelial cell (HDMVEC) tube formation and migration. All three HETEs stimulated HDMVEC tube formation and migration. Because 15(S)-HETE was found to be more potent than 5(S)-HETE and 12(S)-HETE in HDMVEC tube formation, we next focused on elucidation of the signaling mechanisms underlying its angiogenic activity. 15(S)-HETE stimulated Akt and S6K1 phosphorylation in HDMVEC in a time-dependent manner. Wortmannin and LY294002, two specific inhibitors of phosphatidylinositol 3-kinase (PI3K), blocked both Akt and S6K1 phosphorylation, whereas rapamycin, a specific inhibitor of Akt downstream effector, mammalian target of rapamycin (mTOR), suppressed only S6K1 phosphorylation induced by 15(S)-HETE suggesting that this eicosanoid activates the PI3K-Akt-mTOR-S6K1 signaling in HDMVEC. Wortmannin, LY294002, and rapamycin also inhibited 15(S)-HETE-induced HDMVEC tube formation and migration. In addition, all three HETEs stimulated angiogenesis as measured by in vivo Matrigel plug assay with 15(S)-HETE being more potent. Pharmacologic inhibition of PI3K-Akt-mTOR-S6K1 signaling completely suppressed 15(S)-HETE-induced in vivo angiogenesis. Consistent with these observations, adenoviral-mediated expression of dominant-negative Akt also blocked 15(S)-HETE-induced HDMVEC tube formation and migration and in vivo angiogenesis. Together, these results show for the first time that 15(S)-HETE stimulates angiogenesis via activation of PI3K-Akt-mTOR-S6K1 signaling.

17-beta-estradiol eluting stent versus phosphorylcholine-coated stent for the treatment of native coronary artery disease
Airoldi, F., C. Di Mario, et al. (2005), Am J Cardiol 96(5): 664-7.
Abstract: In this study we randomly compared the estradiol eluting stent (17-beta-E) with phosphorylcholine (PC)-coated stents in native coronary arteries. The incidence of angiographic restenosis was 23% in the 17-beta-E group and 31% in the PC group (p = 0.34). The major adverse cardiovascular event rates were also similar in the 2 groups (17% in the 17-beta-E group vs 22% in the PC group, p = 0.47). The mid-term clinical and angiographic outcomes did not indicate superiority of the 17-beta-E eluting stent over the control PC stent.

188Rhenium(V)-dimercaptosuccinic acid loaded poly(lactic-co-glycolic)acid microspheres for targeted radiotherapy: production and effectivity
Shukla, J., G. P. Bandopadhyaya, et al. (2005), Pharmazie 60(8): 583-7.
Abstract: Poly(lactic-co glycolic)acid (75:25) (PLGA) microspheres for the delivery of a radiation dose to tumors were synthesized after loading the 188Re(V) labeled DMSA. The 188ReO4- in place of 99mTcO4- was replaced to label DMSA, because of their structural and chemical similarities and to make the molecule site specific for radiotherapy. The radiolabeling efficiency of DMSA was more than 97% as confirmed by ITLC. A solvent evaporation technique was used to encapsulate DMSA in PLGA microspheres. Electron microscopy demonstrated the microspheres size ranged between 0.4-1.8 microm. As demonstrated by DSC, DMSA was encapsulated (20-30%) within the microspheres in solid solution, metastable molecular dispersion or crystallization forms. In vitro release studies confirmed the stability of DMSA.

19th European conference on biomaterials
Joyce, T. J. (2005), Expert Rev Med Devices 2(6): 655-6.

25 breakout companies--biotech: Sirtris Pharmaceuticals, Bacterin, XDX
Stipp, D., M. Boyle, et al. (2005), Fortune 151(10): 169.

3D microenvironment as essential element for osteoinduction by biomaterials
Habibovic, P., H. Yuan, et al. (2005), Biomaterials 26(17): 3565-75.
Abstract: In order to unravel the mechanism of osteoinduction by biomaterials, in this study we investigated the influence of the specific surface area on osteoinductive properties of two types of calcium phosphate ceramics. Different surface areas of the ceramics were obtained by varying their sintering temperatures. Hydroxyapatite (HA) ceramic was sintered at 1150 and 1250 degrees C. Biphasic calcium phosphate (BCP) ceramic, consisting of HA and beta-tricalcium phosphate (beta-TCP), was sintered at 1100, 1150 and 1200 degrees C. Changes in sintering temperature did not influence the chemistry of the ceramics; HA remained pure after sintering at different temperatures and the weight ratio of HA and beta-TCP in the BCP was independent of the temperature as well. Similarly, macroporosity of the ceramics was unaffected by the changes of the sintering temperature. However, microporosity (pore diameter <10 microm) significantly decreased with increasing sintering temperature. In addition to the decrease of the microporosity, the crystal size increased with increasing sintering temperature. These two effects resulted in a significant decrease of the specific surface area of the ceramics with increasing sintering temperatures. Samples of HA1150, HA1250, BCP1100, BCP1150 and BCP1200 were implanted in the back muscles of Dutch milk goats and harvested at 6 and 12 weeks post implantation. After explantation, histomorphometrical analysis was performed on all implants. All implanted materials except HA1250 induced bone. However, large variations in the amounts of induced bone were observed between different materials and between individual animals. Histomorphometrical results showed that the presence of micropores within macropore walls is necessary to make a material osteoinductive. We postulate that introduction of microporosity within macropores, and consequent increase of the specific surface area, affects the interface dynamics of the ceramic in such a way that relevant cells are triggered to differentiate into the osteogenic lineage.

3D morphology of cell cultures: a quantitative approach using micrometer synchrotron light tomography
Thurner, P., R. Muller, et al. (2005), Microsc Res Tech 66(6): 289-98.
Abstract: Current issues in both tissue engineering and cell biology deal with cell behavior extensively in 3D. Here, we explore synchrotron radiation micro-computed tomography as a tool for morphological characterization of such 3D cellular constructs, providing micrometer resolution in soft and hard tissues. Novel image processing techniques allowed quantification of local and global cell distributions, cell density, adhesive cell culture surface, and scaffold geometry. For proof of concept, we applied this technique to characterize the morphology of two cell cultures of different phenotypes, namely human dermal fibroblasts and mouse calvarial osteoblast-like cells, both seeded on a polymer multifilament yarn. From 3D visualizations in these case studies, we saw that the fibroblasts spanned between the yarn filaments and in this way encapsulated the yarn, whereas the osteoblast-like cells lined the filament surfaces and did not span between them. Differences found in cell distribution as a function of distance to the median yarn axis and the closest filament surface, respectively, quantified these qualitative impressions gained from 3D visualizations. Moreover, the volume-normalized adhesive surface differed by one order of magnitude between the two phenotypes. Our approach allows quantitative correlation of local scaffold geometry and cell morphology. It can be used to investigate the influence of cell phenotype as well as various biochemical agents on tissue engineering constructs and the behavior of cells in culture.

First Page

Last Page