Apatite formation on nanomaterial calcium phosphate/poly-DL-lactide-co-glycolide in simulated body fluid.

UNLABELLED: Simulated body fluid (SBF) is an artificial fluid which has ionic composition and ionic concentration similar to human blood plasma. PURPOSE: This paper compares the interaction between the nanomaterial containing calcium phosphate/poly-dl-lactide-co-glycolide (N-CP/PLGA) and SBF, in order to investigate whether and to what extent inorganic ionic composition of human blood plasma leads to the aforementioned changes in the material. METHODS: N-CP/PLGA was incubated for 1, 2, 3, and 5 weeks in SBF. The surface of the material was analyzed on SEM-EDS and FTIR spectrometer, while SBF was subjected to pH and electrical conductivity measurement. RESULTS: Our results indicate that dissolution of the polymer component of the material N-CP/PLGA and precipitation of the material similar to hydroxyapatite on its surface are based on the morphologic changes seen in this material. CONCLUSIONS: The mechanism of the apatite formation on the bioceramic surface was intensively studied and was considered crucial in designing the new biomaterials. The results obtained in this work indicate that N-CP/PLGA may be a good candidate for application to bone regeneration.

Real-time monitoring of the mechanism of poorly crystalline apatite cement conversion in the presence of chitosan, simulated body fluid and human blood.

In this study, the real-time monitoring of structural changes, occurring upon poorly crystalline apatite bone cement hardening in the presence of chitosan, simulated body fluid and human blood, was performed. Strong experimental evidence of octacalcium phosphate intermediate phase is provided. The energy dispersive X-ray diffraction was applied in situ to monitor the structural changes upon the transformation process, while the Fourier transform infrared spectroscopy and the scanning electron microscopy supplied information on the vibrational and morphological properties of the system. The cooperative action of chitosan and simulated body fluid induces the formation of a preferentially oriented hydroxyapatite phase, this process being similar to the oriented self-assembling process in collagen-apatite matrix in human plasma, occurring upon in vivo biomineralization. Conversely, the presence of blood does not induce any significant change in hardening kinetics and the final structure of the investigated cement.

Characterization of granulations of calcium and apatite in serum as pleomorphic mineralo-protein complexes and as precursors of putative nanobacteria.

Calcium and apatite granulations are demonstrated here to form in both human and fetal bovine serum in response to the simple addition of either calcium or phosphate, or a combination of both. These granulations are shown to represent precipitating complexes of protein and hydroxyapatite (HAP) that display marked pleomorphism, appearing as round, laminated particles, spindles, and films. These same complexes can be found in normal untreated serum, albeit at much lower amounts, and appear to result from the progressive binding of serum proteins with apatite until reaching saturation, upon which the mineralo-protein complexes precipitate. Chemically and morphologically, these complexes are virtually identical to the so-called nanobacteria (NB) implicated in numerous diseases and considered unusual for their small size, pleomorphism, and the presence of HAP. Like NB, serum granulations can seed particles upon transfer to serum-free medium, and their main protein constituents include albumin, complement components 3 and 4A, fetuin-A, and apolipoproteins A1 and B100, as well as other calcium and apatite binding proteins found in the serum. However, these serum mineralo-protein complexes are formed from the direct chemical binding of inorganic and organic phases, bypassing the need for any biological processes, including the long cultivation in cell culture conditions deemed necessary for the demonstration of NB. Thus, these serum granulations may result from physiologically inherent processes that become amplified with calcium phosphate loading or when subjected to culturing in medium. They may be viewed as simple mineralo-protein complexes formed from the deployment of calcification-inhibitory pathways used by the body to cope with excess calcium phosphate so as to prevent unwarranted calcification. Rather than representing novel pathophysiological mechanisms or exotic lifeforms, these results indicate that the entities described earlier as NB most likely originate from calcium and apatite binding factors in the serum, presumably calcification inhibitors, that upon saturation, form seeds for HAP deposition and growth. These calcium granulations are similar to those found in organisms throughout nature and may represent the products of more general calcium regulation pathways involved in the control of calcium storage, retrieval, tissue deposition, and disposal.

Tumoral calcinosis due to GALNT3 C.516-2A >T mutation in a black African family.

Familial Tumoral Calcinosis (FTC) is a rare autosomal recessive disorder of the phosphocalcic metabolism caused by mutations in the FGF23 or GALNT3 genes. We have identified a Beninese family in which two brothers present FTC caused by a homozygous A>T transversion at the acceptor splice site in intron 1 of GALNT3 gene. We report on the clinical, biochemical, histopathological and molecular spectrum of the disorder in this family. The particularly severe phenotype, the amelogenesis imperfecta, and the carbapatite deposit observed in these patients, seem to be characteristic of our observations.

Bioactive tantalum metal prepared by NaOH treatment.

Untreated tantalum metal formed an apatite on its surface in simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma. However, it took an induction period as long as 4 weeks for apatite formation. The tantalum metal formed the apatite within 1 week when it was previously soaked in a 0.2 or 0.5M NaOH aqueous solution at 60 degrees C for 24 h to form a sodium tantalate hydrogel layer on its surface. The decrease in the induction period of apatite formation was attributed to the catalytic effect of the Ta-OH groups on the surface of the tantalum metal for apatite nucleation and acceleration of the apatite nucleation by an increased ionic activity product of the apatite in the fluid due to the release of Na(+) ions. The NaOH-treated tantalum metal can form apatite in a short period even in the living body and bond to the bone through this apatite layer. This indicates that a highly bioactive tantalum metal can be obtained by a simple chemical treatment.

Calcium metabolism in a fatal case of sodium fluoride poisoning.

A patient was admitted to a district general hospital within an hour of ingesting a fatal dose of sodium fluoride. The results of laboratory investigations, together with some in vitro findings, support the hypothesis that the hypocalcaemia of fluoride poisoning is the result of fluorapatite formation and not calcium fluoride precipitation, and that its persistence reflects the severity of the calcium deficit and not an inhibitoin of normal homeostatic mechanisms. It is suggested that the role of renal clearance of fluoride may be more important than had been realised hitherto.