PubMed · 5448663
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R C Lindeman. 1970. Middle ear fluid.. https://pubmed.ncbi.nlm.nih.gov/5448663/
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Carbonate-containing hydroxyapatite (HA) films were prepared by low-temperature hydrothermal annealing from carbonate-containing calcium phosphate amorphous coatings on titanium substrates. The biocompatibility of the carbonate-containing HA layers was estimated by in vitro tests using simulated body fluid (SBF). Precursory amorphous coatings were deposited with rf-magnetron sputtering apparatus, using calcium phosphate glass target in Ar/CO2 atmosphere. The carbonate-containing HA coatings were successfully formed by the annealing at above 130 degrees C for 20 h. On the basis of SEM observation, about 2-microm thickness films coated rigidly were durable enough for the hydrothermal treatment. The coating layer was revealed to consist of single phase of PO4(-) and OH- partially carbonated HA by XRD and IR analyses. Overgrowing of bone-like apatite layers on the carbonate-containing HA surfaces in the SBF implied that the obtained films acquired a sufficient osteoconductivity, while it was still unclear that activity was enhanced, compared to pure HA coatings. The low-temperature hydrothermal annealing method was effective for preparation of rigid HA coatings on titanium as well as modification of their chemical compositions.
The paper by Lykissa and Maharaj (Lykissa, E. D.; Maharaj, S. V. M Anal. Chem. 2006, 78, 2925-2933) purports to provide evidence that the urine of women with silicone breast implants contain 60 to over 1700 times more platinum in their urine that the urine of people with no known exposure to platinum. Further, they purport to show evidence that the platinum used in the manufacture of breast implants (Pt0) is converted by a unknown process to yield highly oxidized platinum species, stable in biological matrixes, up to and including Pt6+. This correspondence poses three questions associated with the work and directs the reader's attention to the data, which clearly show that the blood and urine platinum levels in implanted women and their healthy control group were not significantly different from one another.
The paper by Lykissa and Maharaj (Lykissa, E. D.; Maharaj, S. V. M. Anal. Chem. 2006, 78, 2925-2933) comes to two main conclusions: platinum is found at elevated levels in women who have received breast implants, and the platinum is present in unusual oxidation states. The authors make clear their view that these are very surprising and disturbing results, both because of the quantity of platinum found and the association between higher oxidation states of platinum and toxicity of various types (sensitization-contact dermatitis, carcinogencity, among others). However, the conclusions arrived at by the authors are unsupported by the Experimental Section of the paper and the data that are reported there, and contravene the well-established chemistry of platinum.