Bone Chemical Composition Research Articles

New approach for deacidification and consolidation of bone artifacts

Acidic conditions affect the archaeological bone in the burial and in uncontrolled display and storage environment or due to improper restoration processes. Accordingly, bones become weak and fragile. This study aims to evaluate nano calcium propionate and nano styrene butyl acrylate (used for the first time in the treatment of bones) at different concentrations for deacidification and consolidation of fragile bones. New bone samples were prepared. Artificial accelerated aging (acid and heat) was applied to prepare aged untreated samples. Deacidification and consolidation processes using the materials mentioned above were applied. The analytical techniques used were transmission electron microscope (TEM) and thermal gravimetric analysis (TGA) were used for morphological and thermal stability investigation for the prepared nano styrene butyl acrylate copolymer and its calcium propionate nonocomposites, a digital microscope and scanning electron microscope (SEM) for investigation of the surface morphology, pH value measurement, change of color measurement, attenuated total reflection—Fourier transform infrared spectroscopy (ATR/FTIR), contact angle (wettability), and X-ray diffraction analysis for measurement of bone crystallinity. The results proved that acid-heat aging affected bone properties such as changes in surface morphology and color, decrease in pH value, and contact angle. Bone samples became more crystalline, and the chemical composition of bone was also affected. The treatment of aged untreated bone samples with the materials used in this study improved their properties, such as increasing the pH value and contact angle. The surface morphology, color change, and crystallinity of bone improved and became more stable.

Variation in Juvenile Long Bone Properties as a Function of Age: Mechanical and Compositional Characterization.

Bone is a heterogeneous, hierarchical biocomposite material made of an organic matrix filled with a mineral component, which plays an important role in bone strength. Although the effect of the mineral/matrix ratio on the mechanical properties of bone during aging has been intensively investigated, the relationship between the mechanical properties and the chemical composition of bone with age requires additional research in juvenile individuals. In this study, bone coupons from bovine and ovine animal species were machined from cortical areas of long bones to quantify whether the variation in mechanical properties at different stages of development is related to the change in the composition of bone tissue. An energy-dispersive X-ray detector (EDX) attached to a scanning electron microscope (SEM) was used to perform a compositional analysis of the tissue. In addition, nanoindentation analyses were carried out to address how the elastic modulus changed with age. Nonparametric statistical analyses found significant differences (p < 0.05) in Ca content and elastic modulus between species, but no differences were found within each species with development. A multiple linear regression model found that the elastic modulus was significantly related to the decrease in P and C in the samples, to the animal species (larger in bovine), and development, although not linearly. This model also found an interaction between Ca and development that could explain the lack of significance of the relationship between the elastic modulus and development in the univariate models.

Bond Strength and Adhesion Mechanisms of Novel Bone Adhesives.

Bone adhesives offer distinct advantages over the use of screws to attached internal fixation plates (IFPs). As the chemical composition of bone is similar to dentine, it is possible that the types of monomers used to make dentine adhesives could be utilised to affix IFPs to bone. The ability to attach a bio-resorbable IFP to porcine bone was assessed for the monomer 10-methacryloyloxydecyl dihydrogen phosphate (MDP), used either as a homopolymer or a copolymer with urethane dimethacrylate (MDP + U). Additionally, the addition of a priming step (MDP + U + P) was evaluated. The chemical interactions of the monomers with bone were assessed using XRD and imaged using TEM, revealing the formation of nano-layered structures with the MDP primer, something we believe has not been reported on bone. In a 6-week artificial aging study both MDP + U and MDP + U + P demonstrated adequate shear bond strength to affix bio-resorbable IFPs. The cytotoxicity profiles of the adhesive formulations were determined using indirect and direct contact with MC3T3 cells, with indirect conditions suggesting the MDP + U + P is as cytocompatible as the resorbable IFP. The findings of this study suggest our newly developed adhesive has the potential to be used as a bone adhesive to affix bioresorbable IFPs.

Age-related changes in cationic compositions of human cranial base bone apatite measured by X-ray energy dispersive spectroscopy (EDS) coupled with scanning electron microscope (SEM).

One of the most common scientific methods to study the chemical composition of bone matter is energy-dispersive X-ray spectroscopy (EDS). However, interpretation of the data obtained can be quite complicated and require a thorough understanding of bone structure. This is especially important when evaluating subtle changes of chemical composition, including the age-related ones. The aim of current study is to create a method of processing the obtained data that can be utilized in clinical medicine and use it to evaluate the age evolution of bone chemical composition. To achieve this goal, an elemental composition of 62 samples of cadaver compact bone, taken from the skull base (age: Me = 57.5; 21/91(min/max); Q1 = 39.5, Q3 = 73.75), was studied with EDS. We used the original method to estimate the amount of Mg2+ cations. We detected and confirmed an increase of Mg2+ cation formula amount in the bone apatite, which characterizes age-related resorption rate. Analysis of cation estimated ratio in a normative bone hydroxylapatite showed an increase of Mg2+ amount (R = 0.43, p = 0.0005). Also, Ca weight fraction was shown to decrease with age (R=-0.43, p = 0.0005), which in turn confirmed the age-dependent bone decalcification. In addition, electron probe microanalysis (EPMA) and X-ray diffraction analysis (XRD) were performed. EDS data confirmed the EPMA results (R = 0.76, p = 0.001). In conclusion, the proposed method can be used in forensic medicine and provide additional data to the known trends of decalcification and change of density and crystallinity of mineral bone matter.

Tamoxifen improves homeostasis in the peri-implant bone remodeling of osseointegrated titanium implants.

The purpose of this preclinical study was to evaluate the influence of tamoxifen (TAM) on the peri-implant bone remodeling of osseointegrated titanium implants in ovariectomized female rats. Seventy-two female rats underwent bilateral ovariectomy 20 weeks before implants placement. One titanium implant was inserted in each tibia of the animals. Six weeks following the implant surgery, animals were randomly divided into two experimental groups (n=36), which received either saline solution (SS) or tamoxifen citrate (TAM) via gavage until euthanasia. Euthanasia was performed at 30, 60, and 90 days after the first gavage. Assessments of bone to implant contact (BIC), bone ingrowth percentage (BIN), morphological description of cellular and tissue reactions, immunohistochemistry for the detection of bone morphogenetic protein 2/4 (BMP2/4), runt-related transcription factor 2 (RUNX-2), osteocalcin (OCN) and tartrate-resistant acid phosphatase (TRAP), and bone chemical composition through scanning electron microscopy with energy-dispersive x-ray spectroscopy were performed. Tamoxifen group presented higher BIC, higher BIN, higher RUNX-2 and OCN, lower TRAP-positive cells/mm2 , and no differences regarding BMP-2/4 positive cells/mm2 than SS group in all periods. TAM group also showed higher Ca/P rate than SS group. Tamoxifen enhanced the remodeling of the bone surrounding titanium implants in ovariectomized rats.

Photoacoustic characterization of bone physico-chemical information.

Osteoporosis usually alters the chemical composition and physical microstructure of bone. Currently, most clinical techniques for bone assessment are focused on the either bone microstructure or bone mineral density (BMD). In this study, a novel multi-wavelength photoacoustic time-frequency spectral analysis (MWPA-TFSA) method was introduced based on the optical absorption spectra and photoacoustic effects of biological macromolecules, which evaluates changes in bone chemical composition and microstructure. The results demonstrated that osteoporotic bones had decreased BMD, more lipids, and wider trabecular separation filled with larger marrow clusters, which were consistent with multiple gold-standard results, suggesting that the MWPA-TFSA method has the potential to provide a thorough bone physico-chemical information evaluation noninvasively and nonradiatively.

Nutritional reconstruction in an early modern population: Searching for a relationship between dental microwear and bone element composition

BackgroundObserving the microwear patterns of the dental crowns enamel surface can provide information on the ingredients and structure of the food consumed, but also on eating habits and lifestyle. Major role in reconstructing the diet and lifestyle of past populations is played by the analysis of alkaline earth metals, such as strontium, barium, zinc and calcium. Ba and Sr are indicators of the consumption of vegetables, plants (cereals and legumes) and marine organisms. This study aims to assess dietary diversity and identify its components based on microscopic techniques and chemical analyses of material from early modern archaeological sites in Wrocław, Poland. MethodsThe material consisted of 36 permanent molars and the intrasternal parts of 122 first ribs, collected from 6 Wroclaw early modern cemeteries. Tooth microwear was evaluated on Scanning electron microscopy images, with Microwear 4.02 software. Bone chemical composition (Ca, P, Ba, Sr content) was evaluated with mass spectrometry. ResultsMost lines were present on the teeth from St. Mary Magdalene Cemetery, with the lowest average number of lines observed on the teeth from St. Barbara Cemetery. The Ca/P ratios calculated for different sites formed two clusters that allows to distinguish two groups of archaeological sites with different bone preservation status. Number of differences in Ba/Sr, Sr/Ca, Ba/Ca ratios was found between disctinct archaeological sites. A number of correlations were found between the concentration of the chemical elements, but no statistically significant correlation was found between the microwear characteristics and the proportion of the elements studied. Some strong correlations were found between microwear features and the Ca/P ratio. Conclusionsthe different values of Sr/Ca, Ba/Ca and Ba/Sr ratios indicate different diets in the different communities. The data obtained indicate a mixed diet, with a relatively high proportion of animal products throughout Wrocław. Conclusions should be treated with caution due to secondary diagenesis. The lack of interdependence between microwear and chemical composition characteristics suggests that the two methods should be considered complementary and not overlapping, as they provide different insights into the diets of past populations. The comparison of microwear between different sites should always take into account secondary diagenesis and the burial environment, as these influence the characteristics of microwear.

Chronic Lead Exposure Alters Mineral Properties in Alveolar Bone

The objective of the present study was to investigate the effects of chronic lead exposure on the mineral properties of alveolar bone. For this purpose, female Wistar rats (n = 8) were exposed to 1000 ppm lead acetate in drinking water for 90 days, while the control group (n = 5) was treated with sodium acetate. The alveolar bone structure and chemical composition of the dissected mandibles were examined using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), inductively coupled plasma optical emission spectrometry (ICP-OES), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD) techniques to determine possible alterations in alveolar bone due to lead exposure. In addition, changes in bone mechanical properties were analysed using a three-point bending test. Exposure to lead induced notable changes in bone mineralization and properties, specifically a reduction of the trabecular thickness and bone mineral density. Furthermore, there was a reduction in carbonate content and an increase in bone mineral crystallinity. These changes in bone mineralization could be explained by an alteration in bone turnover due to lead exposure. Three-point bending showed a trend of decreased displacement at failure in the mandibles of lead-exposed rats, which could compromise the mechanical stability and normal development of the dentition.

Anatomical Variation of Human Bone Bioapatite Crystallography

This systematic investigation of bioapatite, the mineral component of human bone, aims to characterize its crystallographic state, including lattice parameters and average crystallite size, and correlate these values with respect to anatomical position (bone function), physicality, and bone chemical composition. In sample sets of buried bone from three different human adult skeletons, anatomical variation of crystallographic parameters and correlation to chemical composition were indeed observed. In general, the observed bioapatite a unit-cell edge-length among all analyzed human bones in this study was larger by 0.1–0.2% compared to that of stoichiometric hydroxylapatite (HAp), and substantially larger than that of fluorapatite (FAp). Across all analyzed samples, the a (=b) lattice parameter (unit cell edge-length) varies more than does the c lattice parameter. Average crystallite size (average coherent diffracting domain size) in the c-direction was equal to approximately 25 nm, ranging among the analyzed 18 bone samples from about 20–32 nm, and varying more than crystallite size in the a,b-direction (~8–10 nm). Neither lattice parameters nor average bioapatite crystallite sizes appeared to be correlated with bone mechanical function. The relative chemical composition of the bone material, however, was shown to correlate with the a (=b) lattice parameter. To our knowledge, this research provides, for the first time, the systematic study of the crystallographic parameters of human bone bioapatite in the context of anatomical position, physical constitution, and bone chemical composition using X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FTIR).

Bone chemical composition changes in bird bones from laboratory exposure to saline lake conditions

The abundance of bird bones in archeological contexts of high salt is potentially impacted by salinization, which can affect bone preservation. We exposed wing elements (humeri, ulnae, and radii) of domestic chicken (Gallus gallus domesticus) to laboratory conditions simulating a saline lake substrate with overlaying saltwater for up to 32 weeks. Our analyses based on bone ashing and elemental concentration using ICP-OES are reported. The data provide useful taphonomic information regarding changes in bone mineral content, element concentrations, and element to phosphorus ratios of bird bones exposed to saline environments. Results showed that all exposed wing bones increased significantly in bone mineral content, which indicated that wing bones most likely became stronger. Overall, ionic concentrations of Ca2+, K+, Mg2+, Na+, P5+, Sr2+, and Si4+, except Fe3+, changed significantly among all wing bones with saline exposure. These changes in ion concentration took place in as little as 4 weeks. Element to phosphorus ratios provided insight into potential ionic substitutions between the bone and the saline substrate and solution exposure. The results from our study provide direct evidence that the chemical composition of bird bones deposited along saline lake shorelines quickly become altered.

Fatigue-caused damage in trabecular bone from clinical, morphological and mechanical perspectives

Bone quantity and quality are considered the main predictors of bone mechanical properties (i.e., strength and fracture resistance). These factors deal with the morphology and chemical composition of bone and can be assessed by non-invasive techniques such as dual-energy x-ray absorptiometry (DXA), providing the bone mineral density (BMD) and the trabecular bone score (TBS). These parameters, and in particular BMD, are currently used as clinical predictors of fracture risk but do not provide information regarding the fatigue life. Bone is continuously subjected to fatigue loading and fatigue-induced damage can be crucial in fragility fractures. To probe the effect of fatigue-induced damage on bone microarchitecture and elucidate the effect of such damage on the bone clinical parameters, we combined fatigue testing on ex-vivo porcine trabecular bone samples with DXA measurements and μCT imaging. In addition, we performed interrupted cyclic tests at different load levels and measured fatigue-induced damage accumulation in the form of stiffness degradation. We also highlighted the change of clinical and microstructural parameters during the accumulation of fatigue-induced damage in interrupted fatigue tests. Our results suggest that the parameters obtained from the current non-invasive diagnostic protocols (i.e. μCT and DXA) are not able to assess the amount of fatigue-induced damage. This can be due to the fact that such techniques provide global parameters, whereas fatigue-induced damage is a local phenomenon, closely connected to the microarchitecture.

Aggregation of Nanosized Hydroxyapatite Particles and Inhibition of Cell Adhesion on this Bio-Active Material as Key Factors that Limit its Biointegration

Abstract—Different synthetic calcium phosphate compounds are used as osteoplastic materials for filling of bone defects during surgical reconstruction of bone. Synthetic nanosized hydroxyapatite is of particular interest because of its similarity to the chemical composition of bone and its osteoinductive potential. However, it is also known that nanosized hydroxyapatite can inhibit the processes of biointegration of biomaterials, although we have no clear understanding of the mechanisms that are responsible for this effect. In our in vitro studies suppression of cell adhesion on nanosized hydroxyapatite that may lead to anoikis was shown. Studies in which rat subcutaneous heterotopic implantation methods were used showed that nanosized hydroxyapatite in vivo formed a slightly resorbable agglomerate that blocks cell migration into the material, as well as neocollagenesis processes in it, including the processes of encapsulation of the material. In this case, the processes of neocollagenesis along the periphery of the sample were observed only over a dense layer of dead cells (cellular debris) surrounding the agglomerated nanosized hydroxyapatite. Addition of demineralized bone collagen matrix to nanosized hydroxyapatite as a conductive component contributed to colonization of the material by the cells, resorption of nanosized hydroxyapatite, and active construction of the neocollagen matrix. These results show that modification of nanosized hydroxyapatite with a conductive component is required in order to prevent its agglomeration and thus increase its biointegration and osteoinductive potential in the body.

Investigation of changes in bone density and chemical composition associated with bone marrow oedema-type appearances in magnetic resonance images of the equine forelimb

BackgroundThe aetiology of bone marrow oedema-like abnormalities (BMOA) seen on magnetic resonance imaging (MRI) is as yet not fully understood. The current study aimed to investigate the potential of projection radiography and Raman microspectroscopy to provide information regarding the underlying physiological changes associated with BMOA in equine bone samples.MethodsMRI was used to assess 65 limbs from 43 horses. A subset of 13 limbs provided 25 samples, 8 with BMOA present and 17 as controls; these were examined with projection radiography to assess bone mineral density and Raman spectroscopy to assess bone composition. Statistical analysis was conducted using SPSS, the relationship between BMOA and age was tested using binary logistic regression, other outcome measures via unpaired t-tests.ResultsOverall BMOA was found to be associated with locally increased bone density (p = 0.011), suggesting increased bone formation; however, no measurable changes relating to bone remodelling were found, and there were no detectable changes in the chemical composition of bone.ConclusionsBMOA is associated with locally increased bone density, without an associated change in the chemical composition of bone, suggesting this is not linked to BMOA. The presence of increased bone density associated with BMOA does appear to suggest that an increased amount of bone formation is occurring in these regions, but as Raman microspectroscopy data do not demonstrate any significant changes in bone chemical composition associated with BMOA, it would appear that the increased bone volume is due to a greater amount of bone being formed rather than an imbalance in relation to bone remodelling.The study provides a proof of principle for the use of Raman microspectroscopy and projection radiography in in vitro studies of BMOA.

Mimicking Bone Chemical Composition Using Economical Materials for X-Ray Imaging Quality Assurance and Educational Purposes

Imaging different bone sites for medical education requires the formation of bone-equivalent materials that mimic bone density. We investigated an economic imaging composition that characterizes bone density in imaging for quality assurance and educational purposes. Four different compositions were tested to reveal the best composition in simulating bone density in X-ray imaging. Hydrated lime was discovered to be the most suitable because it is durable (stiff and does not crumble), easy to source and process, and attenuates imaging X-rays enough to resemble real bone. Hydrated lime provides a significantly better phantom than the other combinations used.

Uremic Toxicity and Bone in CKD.

Patients with chronic kidney disease (CKD), especially those on dialysis treatment, are at high risk of bone fracture. In CKD-mineral and bone disorder (CKD-MBD), secondary hyperparathyroidism in patients with advanced CKD induces bone abnormalities, and skeletal resistance to parathyroid hormone (PTH) starts in the early stages of kidney disease. Uremic toxins such as indoxyl sulfate and p-cresyl sulfate reduce the expression of PTH receptor as well as PTH-induced cyclic adenosine 3',5' monophosphate production in osteoblasts. CKD also impairs bone strength, especially quality. In a rat model, kidney damage reduces the bone-storage modulus and changes the cortical bone chemical composition with or without hyperparathyroidism. The oral charcoal adsorbent AST-120 improves CKD-induced bone abnormalities as blood levels of indoxyl sulfate decrease. Uremic osteoporosis, a new concept of CKD-related bone fragility, is a main cause of CKD-induced bone abnormalities, particularly impaired bone quality. There is limited information about the effect and safety of anti-osteoporotic drugs for patients with CKD, especially those on dialysis, but the use of AST-120 and renin-angiotensin system inhibitors may modulate bone quality and decrease the incidence of fracture. Thus, the management of CKD-MBD plus use of other therapeutic interventions for uremic osteoporosis is necessary to prevent bone fragility in patients with CKD.

A structural approach in the study of bones: fossil and burnt bones at nanosize scale

We review the different factors affecting significantly mineral structure and composition of bones. Particularly, it is assessed that micro-nanostructural and chemical properties of skeleton bones change drastically during burning; the micro- and nanostructural changes attending those phases manifest themselves, amongst others, in observable alterations to the bones colour, morphology, microstructure, mechanical strength and crystallinity. Intense changes involving the structure and chemical composition of bones also occur during the fossilization process. Bioapatite material is contaminated by an heavy fluorination process which, on a long-time scale reduces sensibly the volume of the original unit cell, mainly the a-axis of the hexagonal P63/m space group. Moreover, the bioapatite suffers to a varying degree of extent by phase contamination from the nearby environment, to the point that rarely a fluorapatite single phase may be found in fossil bones here examined. TEM images supply precise and localized information, on apatite crystal shape and dimension, and on different processes that occur during thermal processes or fossilization of ancient bone, complementary to that given by X-ray diffraction and Attenuated Total Reflection Infrared spectroscopy. We are presenting a synthesis of XRD, ATR-IR and TEM results on the nanostructure of various modern, burned and palaeontological bones.

Bone mineral properties in growing Col1a2+/G610C mice, an animal model of osteogenesis imperfecta

The Col1a2+/G610C knock-in mouse, models osteogenesis imperfecta in a large old order Amish family (OOA) with type IV OI, caused by a G-to-T transversion at nucleotide 2098, which alters the gly-610 codon in the triple-helical domain of the α2(I) chain of type I collagen. Mineral and matrix properties of the long bones and vertebrae of male Col1a2+/G610C and their wild-type controls (Col1a2+/+), were characterized to gain insight into the role of α2-chain collagen mutations in mineralization. Additionally, we examined the rescuability of the composition by sclerostin inhibition initiated by crossing Col1a2+/G610C with an LRP+/A214V high bone mass allele. At age 10-days, vertebrae and tibia showed few alterations by micro-CT or Fourier transform infrared imaging (FTIRI). At 2-months-of-age, Col1a2+/G610C tibias had 13% fewer secondary trabeculae than Col1a2+/+, these were thinner (11%) and more widely spaced (20%) than those of Col1a2+/+ mice. Vertebrae of Col1a2+/G610C mice at 2-months also had lower bone volume fraction (38%), trabecular number (13%), thickness (13%) and connectivity density (32%) compared to Col1a2+/+. The cortical bone of Col1a2+/G610C tibias at 2-months had 3% higher tissue mineral density compared to Col1a2+/+; Col1a2+/G610C vertebrae had lower cortical thickness (29%), bone area (37%) and polar moment of inertia (38%) relative to Col1a2+/+. FTIRI analysis, which provides information on bone chemical composition at ~7μm-spatial resolution, showed tibias at 10-days did not differ between genotypes. Comparing identical bone types in Col1a2+/G610C to Col1a2+/+ at 2-months-of-age, tibias showed higher mineral-to-matrix ratio in trabeculae (17%) and cortices (31%). and in vertebral cortices (28%). Collagen maturity was 42% higher at 10-days-of-age in Col1a2+/G610C vertebral trabeculae and in 2-month tibial cortices (12%), vertebral trabeculae (42%) and vertebral cortices (12%). Higher acid-phosphate substitution was noted in 10-day-old trabecular bone in vertebrae (31%) and in 2-month old trabecular bone in both tibia (31%) and vertebrae (4%). There was also a 16% lower carbonate-to-phosphate ratio in vertebral trabeculae and a correspondingly higher (22%) carbonate-to-phosphate ratio in 2month-old vertebral cortices. At age 3-months-of-age, male femurs with both a Col1a2+/G610C allele and a Lrp5 high bone mass allele (Lrp5+/A214V) showed an improvement in bone composition, presenting higher trabecular carbonate-to-phosphate ratio (18%) and lower trabecular and cortical acid-phosphate substitutions (8% and 18%, respectively). Together, these results indicate that mutant collagen α2(I) chain affects both bone quantity and composition, and the usefulness of this model for studies of potential OI therapies such as anti-sclerostin treatments.

Formation of hybrid materials based on calcium phosphate deposit on carbon fiber scaffold

Event Abstract Back to Event Formation of hybrid materials based on calcium phosphate deposit on carbon fiber scaffold Quentin Picard1, Lise Guichaoua1, Sandrine Delpeux-Ouldriane1, Nathalie Rochet2, Jérôme Chancolon1, Franck Fayon3, Fabienne Warmont1 and Sylvie Bonnamy1 1 CNRS / University of Orleans, ICMN, France 2 INSERM/BIPOA, IBV, France 3 CNRS, CEMHTI, France Introduction: Due to their breathability, specific mechanical properties and biocompatibility, activated carbon clothes (ACC) have previously been considered for hard and soft tissue implanting. However, their poor biological activity restricts their extensive use in medical applications and therefore needs to be enhanced[1]-[3]. Carbon fiber-reinforced calcium phosphate (CaP) composites, combining the highly biocompatible, osteoconductive and bioactive CaP matrix with the properties of carbon fibers, are promising bioceramic material, which could be particularly useful in the reconstruction of bone defects[3]. Experimental Methods: CaP coated ACC are obtained by sono-electrodeposition process using cathodic polarization. Ca(NO3)2, 4H2O and NH4H2PO4 are used as electrolyte. The influence of electrochemical parameters is connected to the amount, microtexture, structure and chemical composition of CaP phases. The materials biocompatibility was determined by culturing primary human osteoblast-cells (HOST) in contact with CaP/ACC hybrid materials. Results and Discussion: The mass uptake tends to a limit corresponding to the decrease of nucleation sites. The current density gouverns the CaP characteristics: amount, morphology and chemical composition. Indeed, the quantity of deposit is proportional to the applied current density (thickness ranging from 10 nm to 1 µm). During CaP deposition, water electrolysis regime gouverns the pH decrease at the carbon electrode surface and consequently leads to CaP precipitation. This process gives biomimetic and uniform CaP coated fibers. Their CaP chemical compositions can be modulated to get similar ones to natural bones. SEM, HRTEM and FTIR characterizations show that the coating consists in a mixture of octacalcium phosphate and plate-like carbonated HA phases at low current densities and needle-like carbonated HA with calcium carbonate phases at high current densities. 1H and 31P MAS NMR of deposits confirm the presence of carbonated HA with a minority of disordered CaP phase. First biological results through in vitro osteoblast culture have evidenced the cell viability on hybrid materials (Fig. 1). Figure 1: SEM image of human osteoblasts cultured at 7 days in the presence of CaP/ACC hybrid material obtained at low current density. Conclusion: The sono-electrodeposition process allows to tailor the thickness, morphology (platelets or needles), chemical composition and to get biomimetic CaP coatings consisting mainly in carbonated HA with minor disordered CaP phases. Close to natural bone chemical composition, the CaP/ACC hybrid materials show a good interaction with primary HOST and therefore could be used as bioactive scaffold for bone regeneration. European Program PF7_IRSES « ABREM »; Region Centre Val-de-Loire project: Hybrid bio-actives materials for bone reconstruction

Osteopathology and selenium deficiency co-occurring in a population of endangered Patagonian huemul (Hippocamelus bisulcus).

BackgroundAbout 1,000 endangered Patagonian huemul deer (Hippocamelus bisulcus) remain in Chile and 350–500 in Argentina. Most groups (>100) are not recovering, and prevalence of osteopathology in Argentina was at least 57%. Here I describe relevant cases of osteopathology from a Chilean population which, however, recently also provided data on trace mineral status, supporting the initial hypothesis that nutrition may be a primary etiologic factor. Additionally, recent data on bone chemical composition of Argentine cases and soil analyses are discussed.ResultsFluoride levels in Argentine cases with osteopathology were low and fluorosis was discarded as an etiological factor. Selenium deficiency occurred in 73% of huemul from the Chilean population which exhibited several cases with osteopathology. The pathophysiognomy included extensive erosion; tooth loss; porosification; perforations of palate, maxillar and mandibular bone with frequent exposure of tooth roots; and fractured mandibula. Areas currently used by remaining huemul have mainly acidic volcanic soils, which reduces selenium bioavailability: mean soil selenium levels from areas typically used by extant huemul were very deficient (0.19 ppm), corroborating documented overt selenium deficiency in local livestock and plants. The area of extant huemul is known to result in primary iodine deficiency in livestock which is aggravated by selenium deficiency.ConclusionsCurrently the most parsimonious explanation for frequent osteopathology and lack of numerical recovery are the combined effects of selenium and iodine deficiencies based on: osteopathology in a population of selenium deficient huemul; selenium deficient livestock, plants and soils; acidic soils; and regional primary iodine deficiency. The nexus between mineral nutrition and population dynamics of huemul may be due to constraints on their movements to fertile lowlands, including the elimination of historic migratory traditions, and concomitant elimination of source populations.

Using growth and body composition to determine weight at maturity in Nellore cattle

The aim of the present study was to estimate the relationships among water, crude protein (CP), ether extract (EE) and ash in the empty bodyweight (EBW), and the soft tissue and bone and, moreover, to determine an objective method to define weight at maturity in Nellore cattle. A dataset containing carcass and body compositions of 249 animals from 11 experiments was developed. There were 63 bulls, 105 steers, and 81 heifers where all animals were purebred Nellore, aged between zero and 24 months. The contents of water, CP and ash in the EBW were predicted by non-linear regressions, whereas an exponential model was used to predict EE. In addition, the content of CP was predicted on a fat-free dry matter (FFDM) basis, and maturity was defined as the point when no significant accretion of CP in the FFDM was observed. The soft tissue water (STW) was regressed on logistic Gompertz functions, and segmented regression models, whereas the analysis of bone chemical composition in the EBW was conducted using an exponential model. The gender effect was not significant (P &gt; 0.05) for EBW and EE; therefore, this effect was not included in the analysis of FFDM. The exponential model suggests that Nellore cattle reached maturity at ~445 kg and the segmented regression model suggested that maturity was reached at 429 kg. A significant relationship between the concentration of STW and soft tissue EE (STEE) was observed (STEE = 0.920 – 1.147 × STW; r2 = 0.96, mean square error = 1.01), but the soft tissue was not a good predictor of maturity, because it is dependent on the diet. Analysis of bone chemical composition showed that EE, water and ash become constant between 400 and 500 kg of EBW, and that CP in bones was constant at 19.1% of EBW. These data also suggested that bone composition could be a good predictor of maturity; however, with the high variability in our dataset, it was not possible to determine an EBW at which these components became constant with a reliable precision. We concluded that Nellore cattle reach maturity at ~437 kg of EBW and that CP in the FFDM and CP, water and ash in bones are good predictors of maturity, whereas soft tissue composition is not a useful predictor of maturity.