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Biomedical subjects

D Muster

Publications and source records attributed to D Muster.

At least 19 recordsLinked to original sources

Fluoride controlled release tablets for intrabuccal use.

We have developed a fluoride controlled release delivering system for intrabuccal use, permitting to reach high enough local concentrations for desirable therapeutic effect with minimal side effects. We have formulated tablets of 160-200mg intended to be fixed on a tooth. The tablets have a granular matrix composed of pure hydroxyapatite, Eudragit((R)) and/or ethylcellulose. NaF is added either by a mechanical mixing or an impregnation method. Profiles of continuous in vitro drug release in saline phosphate buffered solution were recorded by means of a fluoride selective electrode. Linear profiles are observed when ethylcellulose is used. The most reproducible results are obtained when the impregnation method is used. Eudragit((R)) increases the dissolution efficiencies while ethylcellulose decreases it.

Administration, Buccal↗

Tissues and bone adhesives--historical aspects.

Glues and adhesives attach to a surface principally involving molecular attraction, whereas cements mostly work through mechanical interlocking. The adhesive and its degradation products must be biocompatible: chemical, clinical, legal, physical aspects are considered; the toxicity of even minor components must be extremely reduced. The idea of bone bonding using biological materials has been proposed by Gluck, in Berlin, more than a century ago. Cements and adhesives have been used for the fixation of fractures, the repair of defects and the fixation of prostheses. The cements are initially liquid or plastic and conform with the irregularities in the substratum, producing better bonding on rough surfaces. Developed during the early 1950s, cyanocrylate adhesives attracted the medical community by their bonding strength and ability to bond in wet environments but reports of displacement of the fracture ends were followed by reports of high infection rates, nonunion, and severe local reactions. Polymethylmethacrylate does not form a chemical bond with bone but a mechanical bond, a weak bone-polymer joint. Charnley used self-curing acrylic cement to bond a femoral head prosthesis into a femur. When adhesives are used to bond tissues, the polymer acts as a barrier between the growing edges and delay healing; the adhesive tends to be rapidly isolated from the bone by a fibrotic, non-adhesive capsule. No proof exists concerning the osteogenic potential of fibrin sealing (FS); its beneficial effect on bone formation has been questioned even if there is some evidence that FS should influence the early phases of bone repair and may help to solve the problem of reattachment of small osteocartilagenous fragments following joint trauma.

Animals↗

Casted titanium for dental applications: an XPS and SEM study.

Casted titanium for dental crowns has been investigated by means of X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The samples were prepared according to the Ohara process. XRD analysis revealed that the investment consisted essentially of SiO2, Mg2P2O7, SiO2 x H2O and Mg2SiO4. SEM experiments combined with EDX analysis revealed the following atomic concentrations Si (62.6%), Mg (19.7%), P (17.1%), and Ca (0.6%). After casting, the titanium samples exhibit a rough and irregular surface, and XRD analysis indicated that titanium contains essentially the alpha phase and traces of the beta phase. After demoulding titanium samples, the investment side which was in contact with titanium was black colored, proving the reaction between titanium and the investment. XPS analysis performed on this side of the investment indicated that the Si 2p peak presents a shoulder on the low binding energy side and thus suggest that SiO2 has been transformed into metallic Si.

Chemical Phenomena↗

Elaboration and evaluation of an intraoral controlled release delivering system.

In order to improve the administration of drugs for all pathology of the oral cavity, we have developed an intraoral controlled release delivering system, permitting to reach high enough local concentrations for desirable therapeutic effect with minimal side effects. We have formulated tablets of 200 mg intended to be fixed on a tooth. These tablets resist food and drink attacks. The tablets we elaborated have a granular matrix composed of hydroxyapatite, ethyl cellulose and Eudragit. Zinc sulfate is used as the first model of an active drug, it has a therapeutic effect on buccal mucous. Profiles of continuous in-vitro drug release in distilled water at 37 degrees C show that zinc sulfate release by the matrix structure for the different tablet formulations is regulated by the proportions of the different components.

Acrylic Resins↗

[What is thought of the various surface treatments of biomaterials used in dental and maxillofacial implantology?].

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.

Aluminum Oxide↗

[Development and evaluation of an active substance controlled-release device for use in the oral cavity].

In order to improve drug administration for diseases of the oral cavity, we have developed an intraoral controlled release delivery system enabling local concentrations high enough for desirable therapeutic effect with minimal side effects. We have formulated 200 mg tablets to be fixed on a tooth. These tablets resist attacks by food and beverages. The tablets have a granular matrix composed of hydroxyapatite, ethyl cellulose and Eudragit. Zinc sulfate, which has a therapeutic effect on the buccal mucosa was used as the first model of an active drug. Profiles of continuous in vitro drug release in distilled water at 37 degrees C show that zinc sulfate release by the matrix structure for the different tablet formulations is regulated by the proportions of the different components.

Acrylic Resins↗

Surface characterization of C/Ti-6Al-4V coating treated with ion beam.

Surface of titanium alloy (Ti-6AI-4V) has been modified by ion beam mixing of thin C film. X-ray photoelectron spectroscopy analysis showed that after mixing, the surface film consists essentially of a Ti compound containing (Ti, O and C), TiO2, Ti and C contamination. The composition of the surface modified film determined by Rutherford backscattering spectrometry is approximately Ti0.5O0.3C0.2 and its thickness is about 200 nm. After three months immersion in a simulated body fluid, the growth of calcium phosphate species containing both HPO4- and H2PO4- (probably CaHPO4 and Ca(HPO4)2) have been observed. Titanium is found to be essentially composed of the Ti compound after immersion suggesting that both metallic Ti and TiO2 have dissolved.

Alloys↗

[Biomaterials and public health: avoid the drift].

The difficulties found in the maturation of the Science of Biomaterials are analysed at the different levels: research, education, industry, reglementary and legislative environment, needs of hospitals and private practices. Proposals are made for a better response to the needs of an area which should have a growth at least as important as that of drugs.

Biocompatible Materials↗

[Rutherford back-scattering spectrometry and photoelectron spectroscopy of the calcium/titanium interface].

Evaporation of calcium on commercially pure titanium was performed. Heatings under vacuum or oxygen flow improved calcium diffusion in the titanium substrate. X-Ray Photoelectron Spectroscopy did not revealed any superficial segregation of titanium but revealed the formation of CaCO3. The film formed on titanium was characterized using X-ray photoelectron spectroscopy with argon-ion sputtering. The results indicated that: the surface layer consisted of CaCO3; the interface contained CaCP3, CaO et TiO2; only CaO was present in the bulk titanium.

Argon↗

Late complication of a Greenfield filter associating caudal migration and perforation of the abdominal aorta by a ruptured strut.

We report the case of a 67-year-old woman who was admitted for surgical removal of a Greenfield filter that had been inserted 7 years before because of recurrent deep vein thrombosis associated with pulmonary embolism. This complication appeared on a plain abdominal radiogram that showed a 7 cm distal migration of the filter, a 30-degree angulation, and rupture of a strut at the level of the hub. Computed tomography, aortography, and ascending cavography demonstrated that the inferior vena cava was perforated by the struts and that the ruptured strut had penetrated the infrarenal aorta. As demonstrated by scanning electron microscopy, the fracture was due to a structural defect of the strut at its insertion point within the hub, with no sign of corrosion. Energy-dispersive radiography analysis failed to demonstrate impurity in the metal composition.

Aged↗

[Biomaterials and infection in dental and maxillofacial surgery].

Based on metals, polymers, ceramics, carbons or natural products, biomaterials represent an essential contribution to the repair or reconstruction of the hard or soft tissues of the dental and maxillofacial area. In order to avoid unsuccessful results these materials should realize a satisfactory tissue integration without bacterial colonization able to compromise the tissue-biomaterial finalized cooperation. The evolution of the science and technology of biomaterials should allow to get tissue toxicity-free materials which also inhibit microorganisms adherence, the infectability becoming a criteria as important as the biocompatibility itself.

Biocompatible Materials↗

Surface physics methods and in vitro bone-biomaterial interface control.

After a brief review of the main characteristics of some spectroscopic and microscopic methods for surface and interface analysis, preliminary and prospective studies of biocompatible materials (hydroxyapatite, alumina) for implant coating purposes are presented. The results show that the use of complementary techniques allows information on the physical and chemical properties of the coatings both on a microscopic and on an atomic scale to be obtained.

Aluminum Oxide↗

Lack of stereoselectivity in the inotropic and phosphodiesterase inhibitory effects of saterinone enantiomers.

The enantiomers of the positive inotropic and a1-adrenoceptor blocking agent saterinone (+/-)-1,2-dihydro-5-[4-[2-hydroxy-3- [4-(2-methoxyphenyl)-1-piperazinyl]propoxy] phenyl]-6-methyl-2-oxo-3-pyridine-carbonitrile, BDF 8634) have been investigated with in vitro and in vivo models in laboratory animals. In the guinea pig papillary muscle, saterinone enantiomers had equipotent inotropic activity and were also as potent as racemic saterinone; the (R)-enantiomer, however, exhibited a greater efficacy than the related compounds. Saterinone and its enantiomers were equipotent in the inhibition of phosphodiesterase PDE III activity in the guinea pig myocardium. The equipotent inotropic effects were also observed after parenteral and enteral administration in cats. In receptor binding studies, (S)-saterinone was 10-fold more potent than (R)-saterinone by inhibiting [3H]-prazosin binding to specific alpha 1-adrenoceptor sites in rat brain cortex membranes. However, in the isolated thoracic aorta of the rabbit, (S)-saterinone was only 3-fold more potent than (R)-saterinone at preventing the pressor effects of phenylephrine. When the enantiomers were tested in vivo against the pressor effects of phenylephrine in the pithed rat, (S)-saterinone was only 2-fold more potent than (R)-saterinone in its alpha 1-adrenoceptor blocking potency. Thus the enantiomers of saterinone do not display enantio-selectivity in their inotropic and PDE III inhibitory effects in vitro, nor in their cardiotonic effects in vivo. There is a slight enantio-selectivity at alpha 1-adrenoceptors in receptor binding studies, but this is reduced to biologically irrelevant magnitude in functional studies in vitro and in vivo.

3',5'-Cyclic-AMP Phosphodiesterases↗