The relative influence of the topography and chemistry of TiAl6V4 surfaces on osteoblastic cell behaviour.

Proliferation and adhesion of mouse (MC3T3-E1) osteoblastic cells and primary human osteoblastic cells were carried out on Ti6Al4V titanium alloy samples with varied surface roughnesses. Mechanically or manually polished surfaces were prepared to produce respectively non-oriented or oriented residual polishing grooves. Sand-blasted surfaces were prepared using 500 microm or 3 mm alumina particles. Surface roughness parameters showed a negative correlation in comparison to proliferation and adhesion parameters. X-ray microprobe chemical surface microanalysis showed complete disturbance of the surface element composition of the Ti6Al4V alloy following sand-blasting treatment. An AlOx-enriched layer was observed on sample surfaces. This may lead to the suspicion that the concomittant effect of surface roughness amplitude and AlOx surface concentration has an effect on osteoblastic cell proliferation and adhesion. These findings show the significance of chemical surface analysis after any surface treatment of titanium-based implants before any biological use.

Corrosion of surgical implants.

Corrosion on orthopaedic implants has been studied. Twelve intramedullary nails and twelve osteosynthesis plates were implanted up to eight and thirteen years, respectively. Analysis of biological fluids from all patients was carried out and revealed high concentrations of nickel and chromium that correlated to the implantation time. All implants were corroded by both crevice and intergranular corrosion. Intergranular corrosion is related to mechanical and heating treatments. Crevice-like corrosion is probably enhanced by sulphur present in amino-acids. Electronic probe analysis shows the reaction study between both sulphur and nickel and sulphur and chromium. These results are compared to the metal distribution in body fluids. After a certain incubation time the corrosion accelerates as is characteristic for crevice-like corrosion processes. Studies of the distribution rate of two Ni-Fe-Cr dental alloys in a cell culture system give similar results: metal-ion release increases with the exposure time.

[Silicone inclusions in the spleen in a patient under chronic hemodialysis]. / Inclusions de silicone dans la rate chez une hémodialysée chronique.

A 67-year-old woman with chronic renal failure, in periodic hemodialysis, presented an hemolytic anemia in relation to splenic sequestration. Light Microscopic examination of the spleen revealed multiple granulomatous reaction. Numerous macrophages contained inclusions which were non-birefringent and non-staining with routine stains. Electron microscopy, scanning electron microscopy and energy dispersive X-Ray analysis were performed and revealed silicone. Its origin was silicone tubing of the hemodialysis equipment. Pathogenic effects of silicone are discussed.

[Acute renal failure caused by acute oxalosis after massive ingestion of pyridoxilate]. / Insuffisance rénale aiguë par oxalose aiguë après ingestion massive de piridoxilate.

The authors report a case of acute renal failure with hyperoxaluria and intratubular deposits of oxalate crystals, following a massive ingestion of piridoxilate. Cases of calciumoxalate urolithiasis have also been reported after chronic administration of piridoxilate.