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Biomedical subjects

D Muster

Publications and source records attributed to D Muster.

15 recordsLinked to original sources
PubMed1992

[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↗
PubMed1990

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↗
PubMed1989

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↗
PubMed1979

Bone bonding through bioadhesives: present status.

Until recently use of adhesives was confined to cases in which glued areas could be pre-treated or at least cleaned. Thus, grease or oil contaminated surfaces could not be joined together by glueing. More recently, some adhesives have been developed which allow previous treatment of greasy surfaces to be avoided. Among these we find epoxy resins, acrylics and polyurethances. These adhesives have been used until now in various industries. We have begun a research program with these products and in aiming to design an adhesive which would enable immediate and strong bone bonding and avoid problems of metallic fixation, this study is a continuation of our previous research. Thus we tested - currently available surgical and dental adhesives - original mixtures developed in our laboratory. Mechanical assays were performed on bone samples from human femurs in different conditions : dried, cleaned, fresh, or after immersion in physiological solution. They consist essentially of tensile tests on Lhomargy and Zwick's machine wherein the stress is directed perpendicular to the interface. Variations of tensile strength (in h bar) are related to hardening time and to mixture composition. The specimens are joined together either in monolayers or in multilayers. The use of adequate catalysts ensures setting at room temperature. Torsion tests and fatigue tests are carried out concomitantly. Standardized bevel fermoral osteotomies were performed on mice with a dental saw after I.P. Nembutal anesthesia in order to test biological tolerance : - for the control group we study the evolution of bone repair after circumferential wiring - for the animals under test, bones are glued together with one of the proposed adhesives. Radiological and histological studies (using classical Azantrichrome staining after demineralization) are carried out at regular time intervals. In the control animals particular attention is paid to the time course of the formation, constitution and evolution of callus. In the test animals, we can observe callus formation, bone growth into the adhesive material and glue resorption, and look for specific antigenic phenomena. Despite expected improvements, bone glueing remains a challenge and only restricted clinical applications can be proposed.

Adhesives↗
PubMed1979

Fatigue - corrosion of endoprosthesis titanium alloys.

Commercial total hip prostheses often show certain metallurgical faults (porosities, coarse grains, growth dendrites, carbide networks). In order to investigate more accurately the role played by these different parameters in prostheses failure we performed a large number of systematic corrosion, fatigue and fatigue - corrosion tests on these materials and on commercial total hip prostheses. Ultimate strengthes seem to be reached for cast cobalt alloys, whereas titanium alloys, such as Ta 6 V, present very high fatigue limit under corrosion. Thus, rotative bending fatigue - corrosion tests in biological environment provide values about 50 DaN/mm2. This value, is nevertheless appreciably higher than those obtained with stellites and stainless steel. Titanium alloys, because of their mechanical performances, their weak Young's modulus (11000 DaN/mm2) and their relative lightness (4.5. g/cm3), which are associated with a good biocompatibility, seem very promising for permanent implants realisation.

Alloys↗
PubMed1978

Mandibular osteosynthesis by miniature screwed plates via a buccal approach.

The modified Michelet's (1973) technique of mandibular osteosynthesis, which consists of monocortical juxta-alveolar and sub-apical osteosynthesis, without compression and without inter-maxillary fixation, is described. This technique can be used in many types of mandibular fracture, single or multiple, associated or isolated, except in the case of a fracture of the condylar neck and in the presence of pre-existing infection. Infected fractures are treated by orthopaedic methods. Materials used (plates and screws) and particulars of the method have been tested by multi-disciplinary experimentation, particularly by anatomical verification and biomechanical studies. The ideal line of osteosynthesis is described. For the author, this technique is a routine treatment of any type of mandibular fracture.

Bone Plates↗
PubMed1976

[Effect of insulin on the development of the tooth germ in mice].

After recalling the interactions affecting dental differentiation, the authors analyze the effects of various concentrations in insulin on dental rudiments cultivated in vitro. They found: an oedema causing histological lesions, no anticipation of cell differentiation or stimulation of collagen secretion, a decrease in mitotic activity but stimulation of thymidine 3H incorporation after short contact times.

Animals↗
PubMed1975

[Various effects of insulin on in vitro dental differenciation].

The authors have studied the effects of insulin at various concentrations on in vitro cultivated dental rudiments. They observed histologic lesions generated by edema, neither anticipated cellular differentiation nor stimulation of collagen secretion, decrease of mitotic activity, but stimulation of thymidine 3H incorporation after short contact times.

Animals↗
PubMedDate not supplied

[How and when to prescribe systemic antibiotics?].

The use and prescription of antibiotics is getting everyday more and more complex for the general practitioner. Nowadays, due to the increasing number of antibiotics, it is necessary to know the patient's medical history, as well as be knowledgeable in bacteriology, pharmacology and toxicology, immunology and infectiology. It is important to determine the administration mode, the dosage and length of the antibiotic treatment, to get maximum effectiveness, while being aware of the possible drug interactions.

Anti-Bacterial Agents↗