Biomaterials.info - Resources for Engineers

Record 241 to 260

[Permanent-wear lenses and biomaterials]
Cochet, P. (1984), Bull Soc Ophtalmol Fr 84(12): 1433-40.

[Pharmaceutical hydrophilic gels]
Chalupova, Z., R. Masteikova, et al. (2005), Ceska Slov Farm 54(2): 55-9.
Abstract: From the pharmacopoeial standpoint, gels, together with ointments, creams, pastes, cataplasmata, and medicated plasters, rank among the group of topical semisolid preparations applied to the skin. They are bicoherent systems composed of the internal phase made of a polymer producing a coherent three-dimensional net-like structure, which fixes the liquid vehicle as the external phase. Intermolecular forces bind the molecules of the solvent to a polymeric net, thus decreasing the mobility of these molecules and producing a structured system with increased viscosity. The physical and chemical bonds binding the particles of the internal phase provide a relatively stable structure, which can originate by swelling of solid polymers, or by decreasing the solubility of the polymer in a solution. An important group of gels used in pharmacy are hydrophylic gels, or hydrogels, usually made of hydrophyilc polymers, which under certain conditions and polymer concentration, jellify. Attention of pharmaceutical research now concentrates primarily on hydrophilic gels, as this dosage form seems to be prospective for the development of modern drugs based on systems with prolonged and controlled release of active ingredients.

[Plaster and plaster models, a biomaterial of choice]
Burdairon, G. (1982), Cah Prothese 10(40): 107-14.

[Polymer biomaterials (polyphosphazenes) in the repair of peripheral nervous system]
Nicoli Aldini, N., P. Caliceti, et al. (1996), Ann Ital Chir 67(6): 843-8.
Abstract: Biodegradable polymers gives interesting perspectives of use in making artificial conduits for peripheral nerve reconstruction. Poliphosphazenes are materials highly biocompatible and have a controllable reabsorption rate. According to the substitutes that are introduced in the molecule, they can also be used as a framework for drug release. Conduits obtained with poli [bis(etilalanate) phosphazene] were evaluated as guides for nerve regeneration in an experimental animal model. In six Wistar rats, under general anesthesia and with microsurgical technique, the ischiatic nerve was isolated. On the right side a segment of the nerve was removed in order to create a 10 mm gap. The defect was then repaired using the conduit. On the controlateral limb the nerve continuity was restored using as an autograft the segment removed from the right. Control were performed at 30, 90, 180 days and consisted in histological and electron microscopy investigations. They showed the gradual degradation of the conduit without signs of local and general toxicity. The regeneration of the nerve fibers in the lumen of the conduit was not significantly different from the one obtained with the autologous grafts. So poliphosphazene conduits may be considered effective as a guide for nerve regeneration, above all for the possibility of use the polymer as a carrier for neurite-promoting factors.

[Possible sources of aspergilla infection in a hematological hospital]
Petrova, N. A. and G. A. Kliasova (2005), Ter Arkh 77(7): 71-7.
Abstract: AIM: To investigate spread, species spectrum, quantity of aspergilla spores in the air of a hematological hospital. MATERIAL AND METHODS: Air samples (250 I/min, PU-1B device) were collected in hematological departments monthly. Isolation and identification of mycelial fungi were made on Chapek medium. In detection of Aspergillus spp. culture in the biomaterial, additional samples of the air and wash-out from the surfaces were collected. RESULTS: A 4-year mycological monitoring of the air has found that aspergilla constituted dominating micromycetes both by occurrence (45%) and amount (5.66%). The spectrum of Aspergillus spp. were represented by 17 species. Of them A. fumigatus, A. niger, A. flavus, A. terreus and A. nidulans comprised 31%. Aspergillus spp. concentrations in the wards with laminar ventilation was 1.8 CFU/m3, in plenum-air exhaustion ventilation--2.1 CFU/m3, exchange ventilation--12.2 CFU/m3. Increased amount (31%) and concentration (11.9 CFU/m3) of Aspergillus spp spores in the air occurred in autumn. A. fumigatus (44%), a. flavus (42%), A. niger (8%), A. versicolor (3%), Aspergillus spp (3%) were detected in 33 patients. The rate of detection of Aspergillus isolated from the patients was also the highest in autumn (34%). Aspergillus spores mean concentration in the wards of patients with invasive aspergillesis was 13.1 CFU/m3, in the nearby wards--12.4 CFU/m3. Morphologically identical strains Aspergillus spp. isolated from the patient and environment were obtained in 9 cases. CONCLUSION: Minimal concentration of aspergilla spores was in the wards with laminar air flow furnished with plenum-air exhaustion ventilation. Annual correlation (for 4 years) of seasonal dynamics of the incidence of Aspergillus spp. from patients with invasive aspergillesis and number of spores in the air support suggestion that air is one of the sources of infection in immunocompromised patients. In spite of wide prevalence of Aspergillus spp. in hospital air, morphologically identical strains from the patient and environment are encountered rarely. There may be additional sources of infection and mechanisms of invasive aspergillesis onset in immunocompromised patients. Genotyping of morphologically identical strains was not made.

[Preliminary research on preparation of porcine bladder acellular matrix graft for tissue engineering applications.]
Zhang, Y. S., H. Z. Li, et al. (2005), Zhonghua Yi Xue Za Zhi 85(38): 2724-7.
Abstract: OBJECTIVE: To investigate the preparation method of porcine bladder acellular matrix graft (BAMG) and evaluate the feasibility of using BAMG as biomaterial scaffold to construct tissue engineering bladder. METHODS: Bladders were harvested from adult pigs at a slaughterhouse and were decellularized by the method of enzyme digestion or eradicator washing. The BAMG was then examined by optic microscope and electron microscope to confirm no cell elements remained. The structure of the BAMG was always observed through the Scanning Microscope. The skeletal muscle stem cells of New Zealand white rabbits were implanted in 96-hole-plank and cultured by BAMG extract liquid or normal culture medium. The cytotoxcity of BAMG was tested through MTT assay. New Zealand white rabbits were underwent bladder triangle area spared cystectomy and reconstructed by the heterogeneity BAMG. The animal bladders were obtained after six weeks and the tissue regeneration was examined. RESULTS: Good outcome were obtained with either of the two methods. There were no cell elements remained under the examination of optical microscope and electron microscope. The interstice could observed on BAMG through the Scanning Microscope. The relative growth rate (RGR) was 81%, 88%, 93% and 96% separately on the 2nd, the 4th, the 6th and the 8th day (t = 3.7419, P < 0.025). The cytotoxcity score was I, whick indicated that BAMG had a good cytocompatibility. All rabbits were alive except one which died from diarrhea. The reconstructed bladder resumed the construction and function of the bladder. The transitional cells and muscle cells growth could be seen in the scaffold of the repaired bladder after six weeks. CONCLUSION: The porcine BAMG has good biocompatibility and can be used as ideal biomaterial scaffold of bladder tissue engineering.

[Preparation methods of nanocavity biomaterials with recognition specificity via template imprinting of proteins]
Lu, S. L., G. X. Cheng, et al. (2003), Zhongguo Yi Xue Ke Xue Yuan Xue Bao 25(5): 640-4.
Abstract: Nanocavity biomaterials with recognition specificity imprinted by using proteins as templates may successful serve as substitutes for antibodies, enzymes, and other native biological structures as well as cell bracket materials. It has numerous applications in biotechnology, medicine and so on. In this paper, the principle of template imprinting is introduced briefly, the specialty of template imprinting of proteins is analyzed, and the methods of template imprinting of proteins including protein entrapment, microbead surface imprinting, flat surface imprinting as well as the epitope are reviewed in details.

[Probe into the platelets adhesion to carbonaceous biomaterials]
Li, B., J. Na, et al. (2004), Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 21(1): 12-5.
Abstract: In order to clarify the mechanism of blood coagulation for carbonaceous biomaterials, the plasma rich in platelet was obtaining through the centrifugation of fresh human blood containing anticoagulant. Adhesive tests of platelets to surfaces of DLC, diamond film(DF) and graphite was carried out at 37 degrees C. Then, morphology observation, counting and deformation index calculation of the platelets adhering to surfaces of the three kinds of materials were analyzed by SEM. It has been shown that there is no any platelet on the surface of DLC, but on DF and graphite, a lot of platelets are observed with serious deformation of type III-V. The adhesive amounts of platelet on the surface of graphite are more than those on DF, but deformation index of platelets on the surface of DF is more than that on graphite. Three major conclusions have been obtained through comparative analyses with our previous researches and related literatures: (1) Adhesion, deformation and collection of platelets occoured in succession on material surfaces resulting from protein adsorption are the major mechanism of blood coagulation of carbonaceous materials; (2) Deformation degree of platelets is more important hemocompatibility index than consumption ratio of platelets for carbonaceous materials; (3) The purer the DLC, the better is the hemocompatibility. These conclusions possess important directive function for improving and designing carbonaceous materials used in artificial mechanical heart valves.

[Problem of bone-biomaterial interface]
Muster, D. and M. Champy (1978), Actual Odontostomatol (Paris)(121): 109-24.

[Progress in the studies on the evaluation of biocompatibility of biomaterials]
Yang, X. and T. Xi (2001), Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 18(1): 123-8.
Abstract: Biocompatibility remains the central theme for biomaterials applications in medicine. It generally refers to the compatibility between the biomaterials and the receptor, including tissue-compatibility and blood-compatibility. The definition of the biocompatibility has been greatly changed in recent years; it is now accepted as involving two principle areas, one is the principle of 'biosafety', the second is the principle of 'biofunctionality'.

[Properties of biomaterials (7). Optical properties]
Kanai, H. (1977), Iyodenshi To Seitai Kogaku 15(1): 48-56.

[Properties of biomaterials. (3) Thermal properties]
Togawa, T. (1975), Iyodenshi To Seitai Kogaku 13(6): 370-4.

[Properties of biomaterials. (6) Application to biological systems]
Nakabayashi, N. (1976), Iyodenshi To Seitai Kogaku 14(4): 321-7.

[Properties of biomaterials. 4. Mechanical properties]
Nakayama, K. (1976), Iyodenshi To Seitai Kogaku 14(1): 58-63.

[Raman spectrometry applied to calcified tissue and calcium-phosphorus biomaterials]
Penel, G., G. Leroy, et al. (2000), Bull Group Int Rech Sci Stomatol Odontol 42(2-3): 55-63.
Abstract: The rigid part of the human body consists essentially of carbonated apatite (calcium phosphate). Biologists don't have any tools to study this "mineral" phase, though its origin is organic. A new approach of some compounds like enamel or bone is obtained with the Raman micro-characterisation by a very fine analysis of chemical bonds in a micrometric scale. This method allows the characterisation, the analysis and the dosage of ions, like carbonate, acid phosphates, proteins and fatty acids. The identification of other organic or mineral compounds (e.g. calcium carbonate, calcium oxide, substitutant ions.) is also possible. The Raman microspectrometry can also be used to study the chemical and physical properties of biomaterials and their evolution after implantation in a dental or bone site. On synthetical calcium phosphate, beta-TCP, brushite and hydroxyapatite can be distinguished and the impurities found in plasma spray deposits can be measured. The detection of alpha-, beta-, or gamma-pyrophosphates could be obtained in some commercial beta-TCP. The Raman microspectrometry is the only non-destructive method which allows the identification of the chemical bonds in a micrometric scale and gives the "fingerprint" of the studied component.

[Recent trends in developmental research of biomaterials and their outcome]
Ikada, Y. (1988), Nippon Rinsho 46(7): 1623-9.

[Recent trends in drug delivery systems using biomaterials]
Kurisawa, M. and N. Yui (1996), Nippon Rinsho 54(7): 2004-11.
Abstract: Since the concept of sustained release of biologically active agents was established in 1970's, the sustained release has been examined by controlling the diffusion of drugs through polymeric matrices and/or the degradation of these polymers. Recently, drug release in proportion to internal or external stimuli has been getting important, which can be achieved by using stimuli-responsive polymeric materials. Majority of these polymers have been designed as to achieve their functions by changes in temperature, pH, glucose concentration, and the release of ribosomal enzymes. Especially, among those materials, biodegradable polymers have much potential for applications as implantable carriers for drug delivery system (DDS). In an auto feed-back drug delivery, several physiological changes in a living body can be utilized as the signal inducing polymer degradation and subsequent drug release. A hydrogel composed of hydrophilic biomaterials has been focused because of their high responsibility to the stimulus. In this paper, currently investigated DDS using hydrogels are reviewed with their strategies.

[Regeneration of the axotomised sciatic nerve in dogs using the tubulisation technique with Chitosan biomaterial preloaded with progesterone]
Rosales-Cortes, M., J. Peregrina-Sandoval, et al. (2003), Rev Neurol 36(12): 1137-41.
Abstract: INTRODUCTION: Injuries to peripheral nerves can have different causes and may lead to disorders affecting mobility, sensitivity and loss of motor function as they progress. Weiss, in 1944, introduced tubulisation to promote the regeneration of a sectioned nerve. In this study the biomaterial Chitosan was used to induce and stimulate the regeneration of the sciatic nerve in dogs. At the same time, we took advantage of the characteristics offered by Chitosan to include the neurosteroid progesterone in its matrix, as a promoter of axonal growth. AIMS. The aim of our study was to determine the degree of regeneration of the sciatic nerve in dogs when axotomised tubulised with a Chitosan prosthesis steeped in the neurosteroid progesterone. MATERIALS AND METHODS: Young adult female dogs were used to evaluate the regeneration of the sciatic nerve induced at a standard of 15 mm; regeneration was determined by means of an axonal growth chamber. Nerve growth was studied through histological analysis and by electron microscope. RESULTS: The statistical analysis showed that there were no significant differences in the number of myelinated fibres between the experimental groups. The electron microscope images of the transmission in the regenerated nerves in the groups that were tubulised with Chitosan, with and without neurosteroid preloading, revealed an advanced regenerative process. This was evidenced by the fact that collagen fibres, elastin, Schwann cells and both myelinated and non myelinated fibres were observed in all cases. CONCLUSIONS: The regeneration of axotomised, tubulised nerves was achieved regardless of the treatment that was applied. The distal nerve segment that was analysed revealed a similar structure to that of a normal nerve.

[Registration of hardness measurements of biomaterials in the nanometer area with scanning force microscopy studies]
Kopp, B., C. Ropke, et al. (1998), Biomed Tech (Berl) 43 Suppl: 424-5.

[Rehabilitation of the hollow cavities using bone reconstruction and biomaterials]
Gersdorff, M. C. and T. A. Robillard (1988), Acta Otorhinolaryngol Belg 42(1): 35-9.
Abstract: The joint use of biocompatible ceramic granules coated with a thin layer of bone dust and temporalis fascia would appear to the authors to offer a solution in the rehabilitation of the radical mastoidectomy cavity. The practical simplicity and the plasticity of the system, as well as the excellent biocompatibility and bioactivity of the materials used, combine to make this a highly satisfactory procedure.

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