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Biomedical subjects

D Muster

Publications and source records attributed to D Muster.

36 records · Page 2Linked to original sources
PubMed1983

Effect of acclimation temperature on oxygen transport in the blood of the carp, Cyprinus carpio.

The temperature dependence of the O2 equilibrium in whole blood was measured in carp acclimated for more than 3 weeks at 10 degrees C or 20 degrees C water temperature. O2 combining curves were obtained for the same samples at 10 degrees C or 20 degrees C using blood from the 10 degrees C or 20 degrees C acclimated fish (group A) or only at the acclimation temperature (group B). Whereas in group B the P50 was about the same at both temperatures, in group A P50 was higher at 20 degrees C than at 10 degrees C, yielding an apparent heat of oxygenation delta H = -9.9 kcal/mol at pH = 8.0. The CO2 Bohr effect in group A was delta log P50/delta pH = -0.93 at 20 degrees C and -1.17 at 10 degrees C, whereas in group B no temperature effect was seen (-0.98 and -0.97). The acclimation temperature had no effect on the electrophoretic Hb pattern. As expected, the in vivo pH changed inversely with temperature from 8.06 at 10 degrees C to 7.73 at 20 degrees C, enhancing the temperature-induced shift in P50. Acclimation reverses partly the changes in O2 affinity, thereby improving the uptake of oxygen in the gills.

Acclimatization↗
PubMed1983

[Study of the corrosion of metallic biomaterials by surface physical methods].

The authors investigated the corrosion mechanism of metallic implants inserted into the human body in contact with bone. It was shown that a significant degree of corrosion occurred after several months. The dissolution seems to be non-selective but can be different for each individual. The corrosion mechanism is complex, starting with an inter-granular process, but pitting also occurred . The oxidation of Fe2+ to Fe3+ favours the elimination of iron oxides and is followed by the destruction of the local alloy structure. An estimation of the quantity of each type of element released in the organism was also realized.

Biocompatible Materials↗
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↗