Search Results (8)

The management of hyperparathyroidism (intact parathyroid hormone (iPTH) serum levels > 585 pg/mL), frequently focuses on the appropriate control of mineral and bone markers, with the decrease in serum and dietary phosphorus as two of the targets. We aimed to investigate the association between iPTH, serum phosphorus levels and dietary intake. This was a cross-sectional, multicenter, observational study with 561 patients on hemodialysis treatment. Clinical parameters, body composition and dietary intake were assessed. For the analysis, patients were divided into three groups: (a) iPTH < 130, (b) iPTH between 130 and 585 and (c) iPTH > 585 pg/mL. The association between PTH, serum phosphorus and dietary intake was analyzed using linear regression models. In the whole sample, 23.2% of patients presented an iPTH > 585 pg/mL. Patients with higher iPTH levels were those with longer HD vintage and lower ages, higher serum phosphorus, serum calcium, Ca/P product, albumin and caffeine intake, and a lower dietary intake of phosphorus, fiber, riboflavin and folate. Higher serum phosphorus predicted higher iPTH levels, even in the adjusted model. However, lower dietary phosphorus and fiber intake were predictors of higher iPTH levels, including in the adjusted model. Our results bring new data to the relationship between dietary intake and iPTH values. Despite higher serum phosphorus being observed in patients with HPTH, an opposite association was noted regarding dietary phosphate and fiber. Full article

This study examined the effectiveness of coating demineralized bone matrix (DBM) with amorphous calcium phosphate (DBM + CaP), as well as a composite of DBM, calcium phosphate, and serum albumin (DBM + CaP + BSA). The intact structure of DBM promotes the transformation of amorphous calcium phosphate (CaP) into dicalcium phosphate dihydrate (DCPD) with a characteristic plate shape and particle size of 5–35 µm. The inclusion of BSA in the coating resulted in a better and more uniform distribution of CaP on the surface of DBM trabeculae. MG63 cells showed that both the obtained forms of CaP and its complex with BSA did not exhibit cytotoxicity up to a concentration of 10 mg/mL in vitro. Ectopic (subcutaneous) implantation in rats revealed pronounced biocompatibility, as well as strong osteoconductive, osteoinductive, and osteogenic effects for both DBM + CaP and DBM + CaP + BSA, but more pronounced effects for DBM + CaP + BSA. In addition, for the DBM + CaP + BSA samples, there was a pronounced full physiological intrafibrillar biomineralization and proangiogenic effect with the formation of bone-morrow-like niches, accompanied by pronounced processes of intramedullary hematopoiesis, indicating a powerful osteogenic effect of this composite. Full article

Calcium phosphates (CaP) composites with biomacromolecules and/or nanomaterials have recently emerged as a potential solution to improve the poor mechanical properties and biological response of CaP. Among the methods available for preparation of such composites, precipitation at low temperatures attracts special interest as it allows preservation of the activity of biomacromolecules. However, precipitation of CaP in the presence of two additives is a complex process that needs to be studied in detail to rationalize composite preparation. This study aimed to investigate co-precipitation of CaP on different TiO₂ nanomaterials (TiNMs), including nanoparticles (TiNPs), nanoplates (TiNPls), nanotubes (TiNTs), and nanowires (TiNWs), in the presence of bovine serum albumin (BSA) and chitosan (Chi). The obtained results have shown that both BSA and Chi inhibited transformation of amorphous to crystalline CaP, even in the presence of TiNMs at concentrations that promoted transformation. Chi proved to be a stronger inhibitor due to its more flexible structure. The presence of BSA and Chi did not influence the composition of the CaP formed as calcium-deficient hydroxyapatite (CaDHA) was formed in all the systems. However, both macromolecules influenced the morphology of the formed CaDHA in different ways depending on the type of TiNM used. BSA and Chi adsorbed on all the TiNMs, as confirmed by zeta potential measurements, but this adsorption reduced the amount of CaP formed on TiNMs only in the case of TiNWs. The obtained results contribute to the understanding of the influence of BSA and Chi on CaP precipitation in the presence of nanomaterials and thus to the rational design of CaP-based multi-composite materials. Full article

Calcium phosphate has attracted enormous attention as a bone regenerative material in biomedical fields. In this study, we investigated the effect of microwave treatment on calcium phosphate deposited TiO₂ nanoflower to improve protein adsorption. Hierarchical rutile TiO₂ nanoflowers (TiNF) fabricated by a hydrothermal method were soaked in modified simulated body fluid for 3 days to induce calcium phosphate (CAP) formation, followed by exposure to microwave radiation (MW). Coating the dental implants with CAP/TiNF provides a means of improving the biological properties, as the structure, morphology, and thickness of the composites can be controlled. The composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), field emission transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR), respectively. The composites were identified to be composed of aggregated nano-sized particles with sphere-like shapes, and the calcium phosphate demonstrated low crystallinity. The ability of bovine serum albumin (BSA) to adsorb on MW-treated CAP/TiNF composites was studied as a function of BSA concentration. The Sips isotherm was used to analyze the BSA adsorption on MW-treated CAP/TiNF composites. The MW-treated samples showed high protein adsorption capacity, thereby indicating their potential in various biomedical applications. Full article

Increasing attention is focused on developing biomaterials as temporary scaffolds that provide a specific environment and microstructure for bone tissue regeneration. The aim of the present work was to synthesize silicon-doped biomimetic multi-phase composite scaffolds based on bioactive inorganic phases and biocompatible polymers (poly(ε-caprolactone), PCL) using simple and inexpensive methods. Porous multi-phase composite scaffolds from cuttlefish bone were synthesized using a hydrothermal method and were further impregnated with (3-aminopropyl)triethoxysilane 1–4 times, heat-treated (1000 °C) and coated with PCL. The effect of silicon doping and the PCL coating on the microstructure and mechanical and biological properties of the scaffolds has been investigated. Multi-phase scaffolds based on calcium phosphate (hydroxyapatite, α-tricalcium phosphate, β-tricalcium phosphate) and calcium silicate (wollastonite, larnite, dicalcium silicate) phases were obtained. Elemental mapping revealed homogeneously dispersed silicon throughout the scaffolds, whereas silicon doping increased bovine serum albumin protein adsorption. The highly porous structure of cuttlefish bone was preserved with a composite scaffold porosity of ~78%. A compressive strength of ~1.4 MPa makes the obtained composite scaffolds appropriate for non-load-bearing applications. Cytocompatibility assessment by an MTT assay of human mesenchymal stem cells revealed the non-cytotoxicity of the obtained scaffolds. Full article

This study compared the apatite-forming ability (AFA) levels of flowable and putty formulations of Nishika Canal Sealer BG Multi (F-NBG and P-NBG, respectively) and attempted to clarify the cause of differences in the AFA levels of F-NBG and P-NBG. NBG samples were aged in simulated body fluid (SBF) or 1-, 5-, or 10-g/L bovine serum albumin-containing SBF (BSA-SBF) and analyzed in terms of their ultrastructures, elemental compositions, and Raman spectra to identify apatite formation. The phosphate ion consumption rates of NBG samples in the media were evaluated as an indicator of apatite growth. The original elemental composition, calcium ion release, and alkalizing ability levels of F-NBG and P-NBG were also evaluated. Apparent apatite formation was detected on all NBG samples except F-NBG aged in 10-g/L BSA-SBF. P-NBG consumed phosphate ions faster than F-NBG. As-prepared P-NBG showed more silicon elements on its surface than as-prepared F-NBG. P-NBG released more calcium ions than F-NBG, although their alkalizing ability levels did not differ statistically. In conclusion, the AFA of P-NBG was greater than that of F-NBG, probably because of the greater ability of P-NBG to expose silanol groups on the surface and release calcium ions. Full article

Protein–peptide–calcium phosphate composites were developed for achieving sustainable and controlled protein release. Bovine serum albumin (BSA) as a model acidic protein was efficiently encapsulated with basic polypeptides such as polylysine and polyarginine during the precipitation of calcium phosphate (CaP). The prepared composites were fully characterized in terms of their morphologies, crystallinities, and the porosity of their structures, and from these analyses, it was observed that there are no significant differences between the composites. Scanning transmission electron microscopy and energy dispersive X-ray spectroscopy analysis indicated a homogeneous distribution of nitrogen and sulfur, confirming the uniform distribution of BSA and polypeptide in the CaP composite. In vitro release studies demonstrated that the composite prepared with the peptides α-polylysine and polyarginine were suitable for the gradual release of the protein BSA, while those containing ε-polylysine and no peptide were unsuitable for protein release. Additionally, these composites showed high hemocompatibility for mouse red blood cells, and the osteoblast-like cell proliferation and spread in media with the composites prepared using BSA and α-polylysine showed similar tendencies to medium with no composite. From these results, protein–peptide–CaP composites are expected to be useful as highly biocompatible protein delivery agents. Full article

Bioinert ceramics have been commonly used in the field of orthopedic and dentistry due to their excellent mechanical properties, esthetic look, good biocompatibility and chemical inertness. However, an activation of its bioinert surface could bring additional advantages for better implant-integration in vivo. Therefore, we introduce an innovative biomimetic co-precipitation technique by using modified simulated body fluid (SBF) to obtain a composite coating made of organic/non-organic components. The zirconia samples were soaked in SBF containing different concentrations of protein (0.01, 0.1, 1, 10 and 100 g/l). Bovine serum albumin (BSA) was applied as a standard protein. During the soaking time, a precipitation of calcium phosphate took place on the substrate surfaces. The proteins were incorporated into the coating during precipitation. Morphology changes of precipitated hydroxyapatite (HAp) due to the presence of proteins were observed on SEM-images. The presence of proteins within the coating was proven by using SEM/energy dispersive X-ray spectroscopy (EDX) and immunohistochemical analysis. We conclude that it is possible to co-precipitate the organic/non-organic composite on inert ceramic by using the wet-chemistry method. In future studies, BSA could be replaced by targeted proteins appropriate to the application area. This method could create new biomaterials, the surfaces of which could be tailored according to the desires and requirements of their use. Full article