Mineralization behaviour of some new phema-based copolymers with potential uses in tissue engineering

This paper reports the mineralization ability of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloylamido glutamic acid (MAGA) based copolymers incubated in synthetic fluids. MAGA monomer was obtained by organic synthesis and next p(HEMA-co-MAGA) copolymers with different compositions were prepared by bulk radical polymerization using benzoyle peroxide as initiator and ethyleneglycol dimethacrylate as cross-linking agent. The monomer and polymers were further characterized by FTIR-ATR spectroscopy to confirm their structure. Finally, polymers ability to initiate the formation and growth of HA crystals onto their surface in synthetic fluids was proven. SEM analysis showed the formation of apatite-like crystals (calcospherites), fact confirmed also by EDX analysis

Polymerization of 2-(hydroxyethyl)methacrylate by two different initiator/accelerator systems: a Raman spectroscopic monitoring

The control of monomer polymerization is important when preparing biocompatible devices. The compound 2-(hydroxyethyl)methacrylate can be polymerized by redox systems using benzoyl peroxide (BPO) (as accelerator) and a substituted amine (as initiator). However, this system is associated with a highly exothermic polymerization, and end-products with inflammatory properties are produced. We have used ascorbic acid (AA) to induce BPO fragmentation and have compared the kinetics of the reaction, by Raman microscopy, with that obtained with a substituted amine. The breaking of the C= bond (Raman stretching vibration at 1641 cm−1) could be monitored in both cases and reflected the incorporation of new monomer molecules into the chain. The AA-induced polymerization was slower than with the substituted amine and was accompanied by the appearance of a new band at 1603 cm−1, assigned to the stretching vibrations of -COOH species incorporated into the chains. Raman microscopy appears to be a powerful tool in the study of polymeric biomaterial preparation

Bone Quality Changes In 3 Cases Of Hypophosphatasia: A Ftiri Study

International audienc

Osteomalacia in a patient with Paget's bone disease treated with long-term etidronate

SummaryA 93 year-old woman with Paget\u27s disease of bone had been treated with etidronate without interruption during 20 years. The daily dose was usual (5 mg/kg/day) but this prescription had never been stopped by her physicians. Two fractures had already occurred in pagetic (right tibia) and non pagetic bones (right fibula) within the last 2 years, and she presented rib fractures, another right tibia fracture and right femur fracture during hospitalization time. X-rays films showed major osteolysis of left ulna and right tibia. Blood samples and technetium bone scan brought no evidence for sarcoma or lytic evolution of the disease. A transiliac bone biopsy on non pagetic bone site confirmed the diagnosis of osteomalacia (increased osteoid parameters), with secondary hyperparathyroidism (hook resorption). In Paget\u27s disease of bone, continuous treatment by etidronate may induce generalized osteomalacia, and increase the risk of fracture in both pagetic and non-pagetic bones. Whereas physicians and pharmaceutical industry try to improve the observance of those drugs, this striking observation also points out that a prescription always needs to be updated

Metaplastic woven bone in bone metastases: A Fourier-transform infrared analysis and imaging of bone quality (FTIR)

Most osteolytic tumors are in fact mixed and contain an osteoblastic component associated with the predominant osteolytic areas. This metaplastic woven bone is always evidenced by histological analysis even in the absence of radiological expression. Metaplastic bone formation reflects the activation of new osteoblasts coming from the stimulation of the dormant lining cells. Twelve patients with secondary metastases of the iliac crest evidenced by hot spots on a Tc-MBP san were diagnosed by histomorphometry on bone biopsies. Fourier Transformed InfraRed analysis and Imaging (FTIRI) was used on 4μm thick sections of undecalcified bone. The mineralization degree, carbonate substitution, crystallinity and the cross-links ratio of collagen (1660/1690cm bands) were determined. The matrix characteristics were analyzed and imaged in the pre-existing residual bone and in the metaplastic woven bone in the vicinity of the tumor cells. FTIRI provided images of the phosphate, amide and combination of peak ratio after having selected the peaks of interest. In addition, the matrix properties can be measured and compared between the old and newly-formed bones. Woven bone appeared poorly calcified with a low phosphate/amide ratio (P=0.03) crystallinity (P<0.0001) and carbonate substitution (P=0.003). Collagen was less mature as evidenced by lower cross-links (P=0.01). Woven bone associated with bone metastasis appears poorly mineralized and rapidly elaborated by osteoblasts. The collagenous phase of the bone matrix has a low level of reticulation. FTIRI is a powerful tool to measure and visualize the various components of the bone matrix in human diseases

Estimation of skeletal age at death in adults using the acetabulum and the auricular surface – An application on the Terry Collection

Rougé-Maillart et al. proposed a technique to determine the age of a subject using the acetabular surface and the auricular surface of the coxal bone. This technique has been described as promising, particularly in subjects under 50 years of age. The initial aim of this study was to test the technique on a new population with two observers, one of whom had no prior experience of the technique. A second aim was to confirm the utility of using the technique on elderly subjects. Material and method We worked on 210 bones (108 male and 102 female) from the Terry Collection. Two observers studied the bones (one was a beginner, one an advanced user of the technique). Age estimation of the skeletons was based on analysis of the auricular surface and the acetabulum as described in the method by Rougé-Maillart et al. Intra- and inter-observer correlations were performed to monitor the reliability and reproducibility of this technique in the overall population, before moving on to subjects aged over 50. Results For both observers, the data highlighted a good average correlation between score and real age (overall scores of 0.648 and 0.773) in the overall population. The similarity between the observers’ results increases as total scores are used. However, the inter-observer correlation is lower than for the previous study, as some criteria are more difficult to classify for the novice observer. As regards subjects over 50, the results are less reliable than expected, with a higher inter-observer variation than in the overall population. Conclusion This study confirms the reproducibility and effectiveness of the method. However, some criteria must be redefined, while others must be weighed. Likewise, a modification to the Bayesian approach with a change to the intervals should be considered

β-TCP granules mixed with reticulated hyaluronic acid induce an increase in bone apposition

International audienceβ beta-tricalcium phosphate (β-TCP) granules are suitable for repair of bone defects. They have an osteoconductive effect shortly after implantation. However, dry granules are difficult to handle in the surgical room because of low weight and lack of cohesion. Incorporation of granules in a hydrogel could be a satisfactory solution. We have investigated the use of hyaluronic acid (HyA) as an aqueous binder of the granules. β-TCP granules were prepared by the polyurethane foam technology. Commercially available linear (LHya) and reticulated hyaluronic acid (RHyA) in aqueous solution were used to prepare a pasty mixture that can be handled more easily than granules alone. Thirteen New Zealand White rabbits (3.5–3.75 kg) were used; a 4 mm hole was drilled in each femoral condyle. After flushing, holes were filled with either LHyA, RHyA, dry β-TCP granules alone, β-TCP granules + LHyA and β-TCP granules + RHyA. Rabbits were allowed to heal for one month, sacrificed and femurs were harvested and analysed by microCT and histomorphometry. The net amount of newly formed bone was derived from measurements done after thresholding the microCT images for the material and for the material+bone. LHyA and RHyA did not result in healing of the grafted area. LHyA was rapidly eluted from the grafted zone but allowed deposition of more granules, although the amount of formed bone was not significantly higher than with β-TCP granules alone. RHyA permitted the deposition of more granules which induced significantly more bone trabeculae without inducing an inflammatory reaction. RHyA appears to be a good vehicle to implant granules of β-TCP, since HyA does not interfere with bone remodeling

Les effets extra-osseux de la vitamine D : faits, questions et controverses

La vitamine D a été longtemps considérée comme une hormone utile pour réguler le métabolisme phosphocalcique et la minéralisation osseuse. Depuis dix ans, la progression des connaissances fondamentales et cliniques sur son influence pluritissulaire est vertigineuse. Les auteurs passent en revue les effets biologique et clinique de la vitamine D en particulier sur le système immunitaire, les maladies auto-immunes, les infections, le cancer, le syndrome métabolique, le risque de chute, les fonctions cognitives et le fonctionnement musculaire

In vitro calcification of chemically functionalized carbon nanotubes

Bone is composed of two phases. The organic phase is made of collagen fibrils assembled in broad fibers acting as a template for mineralization. The mineral phase comprises hydroxyapatite (HAP) crystals grown between and inside the collagen fibers. We have developed a biomimetic material using functionalized carbon nanotubes as scaffold to initiate in vitro mineralization. Biomimetic formation of HAP was performed on single-walled carbon nanotubes (SWCNTs) which have been grafted with carboxylic groups. Two types of nanotubes, HiPco(R) and Carbon Solutions(R), were oxidized via various acidic processes, leading to five different groups of carboxylated nanotubes, fully characterized by physical methods (thermogravimetric analysis, attenuated total reflectance infrared spectroscopy and X-ray photoelectron spectroscopy). All samples were dispersed in ultra-pure water and incubated for 2weeks in a synthetic body fluid, in order to induce the calcification of the SWCNTs. Scanning electron microscopy (SEM) and energy-dispersive X-ray analysis studies showed that Ca(2+) and PO(4)(3-) ions were deposited as round-shaped nodules (calcospherites) on the carboxylated SWCNTs. Fourier transform infrared and Raman spectroscopic studies confirmed the HAP formation, and image analysis made on SEM pictures showed that calcospherites and carboxylated SWCNTs were packed together. The size of calcospherites thus obtained in vitro from the HiPco(R) series was close to that issued from calcospherites observed in vivo. Functionalization of SWCNTs with carboxylic groups confers the capacity to induce calcification similar to woven bone

Extraskeletal effects of vitamin D: Facts, uncertainties, and controversies

Vitamin D was long viewed as a hormone acting chiefly to regulate calcium-phosphate metabolism and bone mineralization. Over the last decade, however, basic science and clinical researchers have produced a bewildering amount of information on the extraskeletal effects of vitamin D. This article is a review of the clinical and biological actions of vitamin D including effects on the immune system, auto-immune diseases, infections, cancer, metabolic syndrome, fall risk, cognitive function, and muscle function