Biomedical subjects

J L Aurelle

Publications and source records attributed to J L Aurelle.

4 recordsLinked to original sources

PubMed2000

Practice of a testing bench to study the effects of cyclic stretching on osteoblast-orthopaedic ceramic interactions.

A new experimental method has been used to study the behaviour of human osteoblasts cultured on bioceramics subjected to mechanical strains. The ceramics were alumina, hydroxyapatite (HA) and a duplex system composed of hydroxyapatite-covered alumina. The system applied 400 microdeformations for a 6-h period with a cycle frequency of 0.5 Hz to osteoblasts growing on ceramic-covered disks. The effects of strains on short-term cell viability, cell growth, alkaline phosphatase (ALP) activity, and collagen biosynthesis were assessed. When possible, the parameters (lactate dehydrogenase) were studied along the experiment in samples of the culture medium, in the other cases by comparison of stretched and unstretched cultures on the same ceramics with the same cell line. In relationship with the coating, mechanical strains resulted in a decrease in DNA corresponding to cell number, an LDH release during straining, an unchanged (alumina) or decreased (HA and duplex) ALP activity, a decrease (HA and duplex) of collagen and total protein synthesis or an increase of it (alumina). The stress-producing device and its associated protocol are shown to be suitable for investigating the behaviour of cells, cultured on biomaterials subjected to mechanical strain.

Alkaline Phosphatase↗

PubMed1999

Interaction of a plasma-sprayed hydroxyapatite coating in contact with human osteoblasts and culture medium.

The loss of calcium from plasma-sprayed calcium phosphate ceramics (CPCs) on bioinert metal substrate (Ti-6Al-4V) immersed in cell culture medium with or without human osteoblast culture was measured. The ceramics were a CPC and a duplex system composed of a CPC layer on an alumina coating. The dissolution of calcium compounds was monitored by measuring the calcium leaked from the coatings into the culture medium in 15 days. Calcium was measured by flame photometry. The surfaces of the ceramics exposed to the culture medium and in contact with osteoblasts were analysed by X-ray diffraction (XRD). The dissolution process occurred in the first 6 days of contact, but the calcium released into the culture medium was only a small fraction of the calcium content of the coatings. The presence or absence of osteoblasts on the surface of the ceramics did not make significant difference for the calcium release. The XRD spectra of the ceramics before and after immersion and in contact with cells did not show a significant change in the compounds of the coatings.

Aerosols↗

PubMed1996

A pilot study comparing screw-shaped implants. Surface analysis and histologic evaluation of bone healing.

The purpose of this study was to compare surface treatment and bone formation adjacent to 2 screw shaped implants of similar design manufactured by two different companies. The test implants were manufactured by SERF (Decines, France), while the controls were manufactured by Nobelpharma (Goteborg, Sweden). The surface of 3 standard 3.75 mm test and 3 standard 3.75 mm control implants were investigated by means of scanning electron microscopy (SEM), X-ray micro-analysis, electron spectroscopy for chemical analysis (ESCA) and surface topography analysis. There was a microscopic difference on the thread design (SEM). Test threads were flat at the edge, while controls appeared rounded at the edge of the threads. Tests and controls were made of commercially pure titanium, with a regular topography. Results of ESCA indicated that the carbon peak for SERF implants was slightly higher than for the Brånemark implants. 5 test and 5 control implants were installed into the epiphyseal head of the femur of 2 ewes using a standardized surgical technique. In order to stain the bone for histologic analysis, oxytetracycline injections were given 17 and 8 days before the animals were sacrificed. The animals were sacrificed 12 weeks after implant placement. Histomorphometric analysis indicated that there was an average bone to implant contact orf 68% for the test implants and 61% for the controls. There were no statistical differences between tests and controls. The preliminary results of this pilot study indicated that early bone healing for the 2 screw shaped implants investigated were similar.

Animals↗

PubMed1996

[Wear characteristics of different metal-polyethylene beating surfaces. An experimental study of a new model of knee prosthesis].

PURPOSE OF THE STUDY: Wear of artificial components joint is the most important factor in long term durability. Only few studies have analysed in laboratory experimentation the quality of different alloys on the same type of prosthesis. MATERIAL: During the development of a new knee prosthesis, we studied the friction mechanisms of the metal/polyethylene (UHMWPE) couple and particularly the value of titanium alloy (Ti-6AI-4V) treatment using an ionic nitrogen implantation process (IMPLATEC). Two friction surfaces were studied in vitro: one in flexion-extension between femoral component and tibial plateau, the other in rotation between tibial plateau and "metal-back". METHODS: The implanted Ti-6AI-4V was compared with 316L stainless steel, cobalt chromium molybdenium alloy and with Ti-6AI-4V using a prosthesis of each configuration. The samples were tested on a TRIBOCUP friction machine during 3 x 10(6) cycles in Ringer 's solution. The friction couples were controlled every 200,000 cycles and the loss of polyethylene mass every 500,000 cycles. We have also evaluated the roughness and the rubbing surface macroscopically. RESULTS: The results analysis shows that friction couples such as Cobalt Chromium and implanted Ti-6AI-4V are weakest but implanted Ti-6AI-4V over time, tends to match the strength of Ti-6AI-4V without treatment. With implanted Ti-6AI-4V and with Cobalt Chromium alloy, the loss of polyethylene is slight comparatively to the stainless steel and non implanted Ti-6AI-4V. Surface analysis showed good protection of titanium alloy by ionic implantation especially in the femoral component where roughness is close (0.04 micron) to that of Cobalt Chromium alloy (0.07 micron). DISCUSSION: Our study confirms the results with pin-on-disk and cup-on-ball with results for the Ti-6AI-4V implanted and Cobalt Chromium alloys with protection of the metal surface and decrease of polyethylene wear comparatively to stainless steel and non implanted Ti-6AI-4V. CONCLUSION: Our conclusion is for this type of experimental device that the surface condition is satisfactory for such friction couples as implanted Ti-6AI-4V/polyethylene and Cobalt-chromium/polyethylene, with very similar results. However, the long-term durability of the nitrogen implanted on Titanium Alloy remains unknown.

Biodegradation, Environmental↗