Search results for "Apatite"
showing 10 items of 155 documents
Diagenetic stability of non-traditional stable isotope systems (Ca, Sr, Mg, Zn) in teeth – An in-vitro alteration experiment of biogenic apatite in i…
2021
Stable isotope ratios and trace element concentrations of fossil bones and teeth are important geochemical proxies for the reconstruction of diet and past environment in archaeology and palaeontology. However, since diagenesis can significantly alter primary diet-related isotope signatures and elemental compositions, it is important to understand and quantify alteration processes. Here, we present the results of in-vitro alteration experiments of dental tissues from a modern African elephant molar reacted in aqueous solutions at 30 °C and 90 °C for 4 to 63 days. Dental cubes with ≈ 3 mm edge length, comprising both enamel and dentin, were placed into 2 mL of acidic aqueous sol…
Changements environnementaux survenant à la limite Oligocène/Miocène du bassin des Limagnes (Massif central, France).
2018
16 pages; International audience; Continental environments are very sensitive to climatic variations. A unique opportunity to study the climate changes around the Oligocene/Miocene boundary is offered by the Limagne graben Basin (France) where this stage boundary is well constrained by fossils. Indeed, some localities of the Limagne Graben Basin are so rich in mammal remains that they have become a European reference for mammal biostratigraphy. The dominant sedimentary facies of the lacustrine deposits in the northern part of the Limagne Graben Basin are composed of poorly cemented marls and calcarenites containing various plants and animals remains (e.g. algae, fish bones and teeth, gastro…
Intra-skeletal variability in trace elemental content of Precolumbian Chupicuaro human bones: the record of post-mortem alteration and a tool for pal…
2011
14 pages; International audience; This study applies an intra-skeletal sampling strategy to examine post-mortem alteration of archaeological human bone from west Mexico, and to reconstruct ancient diet. Human bone from the Chupicuaro culture (Mexico, Preclassic period) constitutes an ideal material with which to examine subsistence strategies because the specific hydrothermal environment in which the population lived would have provided certain food components (hydrothermal waters and carbonates) with distinct signature in Ca, Mg, F, Li, Sr, Mn, V and U values. Four to ten samples were taken from the long bones of six skeletons. Bone trace element content (Ca, P, F, Mn, Mg, Na, Li, V, Zn, R…
Bone diagenesis in arid environments; An intra-skeletal approach
2014
Bone trace element content and isotopic composition are closely related to human nutrition. The investigation of archaeological bone geochemistry can help us to better understand the relationship between past populations and their environment alongside cultural practices as inferred from dietary reconstruction. However, dietary in- formation may be altered post-mortem by diagenetic processes in soil. In this study, bone mineralogy (Ca/P, sec- ondary minerals, organic matter content and bone apatite crystallinity), histology, element content (Mg, Na, F, Sr, Ba, Mn, Fe, La, Ce and U) and stable isotope composition (δ13Candδ18O carbonate) were investigated at the intra- individual scale in ord…
Revised phosphate-water fractionation equation reassessing paleotemperatures derived from biogenic apatite.
2010
8 pages; International audience; Oxygen isotopes of biogenic apatite have been widely used to reassess anomalous temperatures inferred from oxygen isotope ratios of ancient biogenic calcite, more prone to diagenetic alteration. However, recent studies have highlighted that oxygen isotope ratios of biogenic apatite differ dependent on used analytical techniques. This questions the applicability of the phosphate–water fractionation equations established over 25 years ago using earlier analytical techniques to more recently acquired data. In this work we present a new phosphate–water oxygen isotope fractionation equation based on oxygen isotopes determined on fish raised in aquariums at contro…
Improvement of osteogenic differentiation of human mesenchymal stem cells on composite poly l-lactic acid/nano-hydroxyapatite scaffolds for bone defe…
2020
Tissue engineering offers new approaches to repair bone defects, which cannot be repaired physiologically, developing scaffolds that mimic bone tissue architecture. Furthermore, biomechanical stimulation induced by bioreactor, provides biomechanical cues that regulate a wide range of cellular events especially required for cellular differentiation and function. The improvement of human mesenchymal stem cells (hMSCs) colonization in poly-L-lactic-acid (PLLA)/nano- hydroxyapatite (nHA) composite scaffold was evaluated in terms of cell proliferation (dsDNA content), bone differen- tiation (gene expression and protein synthesis) and ultrastructural analysis by comparing static (s3D) and dynamic…
Comments on "Dental lessons from past to present: Ultrastructure and composition of teeth from plesiosaurs, dinosaurs, extinct and recent sharks" by …
2016
The paper mentioned in the title suggests that several groups of extinct vertebrates used fluoroapatite as a tooth mineral in dentine and enamel when alive; its authors posit that this tooth mineralization drastically changed in all these lineages at some point during their evolution, leading to the use of hydroxyapatite as an alternative primary tooth mineral, because of hitherto unconsidered environmental changes. These conclusions are based on their finding high fluoride levels (i.e. fluoroapatite) in the dentine of fossilised shark teeth as well as in both the dentine and enamel of plesiosaurs, mosasaurs, and dinosaurs, which is in sharp contrast to recent teeth (which contain almost no…
In vitro evaluation of a biomaterial-based anticancer drug delivery system as an alternative to conventional post-surgery bone cancer treatment
2018
Patients diagnosed with osteosarcoma are currently treated with intravenous injections of anticancer agents after tumor resection. However, due to remaining neoplastic cells at the site of tumor removal, cancer recurrence often occurs. Successful bone regeneration combined with the control of residual cancer cells presents a challenge for tissue engineering. Cyclodextrins loaded with chemotherapeutic drugs reversibly release the drugs over time. Hydroxyapatite bone biomaterials coated with doxorubicin-loaded cyclodextrin should release the drug with time after implantation directly at the original tumor site and may be a way to eliminate residual neoplastic cells. In the present study, we h…
Amorphous polyphosphate–hydroxyapatite: A morphogenetically active substrate for bone-related SaOS-2 cells in vitro
2015
There is increasing evidence that inorganic calcium-polyphosphates (polyP) are involved in human bone hydroxyapatite (HA) formation. Here we investigated the morphology of the particles, containing calcium phosphate (CaP) with different concentrations of various Na-polyP concentrations, as well as their effects in cell culture. We used both SaOS-2 cells and human mesenchymal stem cells. The polymeric phosphate readily binds calcium ions under formation of insoluble precipitates. We found that addition of low concentrations of polyP (10wt.%, referred to the CaP deposits) results in an increased size of the HA crystals. Surprisingly, at higher polyP concentrations (10wt.%) the formation of cr…
The morphogenetically active polymer, inorganic polyphosphate complexed with GdCl 3 , as an inducer of hydroxyapatite formation in vitro
2015
Inorganic polyphosphate (polyP) is a physiological polymer composed of tens to hundreds of phosphate units linked together via phosphoanhydride bonds. Here we compared the biological activity of polyP (chain length of 40 phosphate units), complexed with Gd(3+) (polyP·Gd), with the one caused by polyP (as calcium salt) and by GdCl3 alone, regarding their potencies to induce hydroxyapatite (HA) formation in SaOS-2 cells in vitro. The three compounds, GdCl3, polyP and polyP·Gd were found to be non-toxic at concentrations up to at least 30μM. Selecting a low, 5μM, concentration it was found that polyP·Gd significantly induced HA formation, as determined by Alizarin Red S staining and by quantit…