Effect of large doses of parenteral vitamin D on glycaemic control and calcium/phosphate metabolism in patients with stable type 2 diabetes mellitus: a randomised, placebo-controlled, prospective pilot study.

OBJECTIVE Vitamin D (D₃) status is reported to correlate negatively with insulin production and insulin sensitivity in patients with type 2 diabetes mellitus (T2DM). However, few placebo-controlled intervention data are available. We aimed to assess the effect of large doses of parenteral D3 on glycosylated haemoglobin (HbA(₁c)) and estimates of insulin action (homeostasis model assessment insulin resistance: HOMA-IR) in patients with stable T2DM. MATERIALS AND METHODS We performed a prospective, randomised, double-blind, placebo-controlled pilot study at a single university care setting in Switzerland. Fifty-five patients of both genders with T2DM of more than 10 years were enrolled and randomised to either 300,000 IU D₃ or placebo, intramuscularly. The primary endpoint was the intergroup difference in HbA(₁c) levels. Secondary endpoints were: changes in insulin sensitivity, albuminuria, calcium/phosphate metabolism, activity of the renin-aldosterone axis and changes in 24-hour ambulatory blood pressure values. RESULTS After 6 months of D₃ supply, there was a significant intergroup difference in the change in HbA(₁c) levels (relative change [mean ± standard deviation] +2.9% ± 1.5% in the D₃ group vs +6.9% ± 2.1% the in placebo group, p = 0.041) as HOMA-IR decreased by 12.8% ± 5.6% in the D₃ group and increased by 10% ± 5.4% in the placebo group (intergroup difference, p = 0.032). Twenty-four-hour urinary albumin excretion decreased in the D₃ group from 200 ± 41 to 126 ± 39, p = 0.021). There was no significant intergroup difference for the other secondary endpoints. CONCLUSIONS D₃ improved insulin sensitivity (based on HOMA-IR) and affected the course of HbA(₁c) positively compared with placebo in patients with T2DM.

Osteoclast-like cells on deproteinized bovine bone mineral and biphasic calcium phosphate: light and transmission electron microscopical observations.

OBJECTIVES The occurrence of multinucleated giant cells (MNGCs) on bone substitute materials has been recognized for a long time. However, there have been no studies linking material characteristics with morphology of the MNGCs. The aim was to analyze the qualitative differences of MNGCs on two commercially available calcium phosphate bone substitute materials retrieved from bone defects. MATERIAL AND METHODS Six defects were prepared bilaterally in the mandibular body of three mini pigs. The defects were randomly grafted with either deproteinized bovine bone mineral (DBBM) or biphasic calcium phosphate (BCP). After a healing period of four weeks, bone blocks were embedded in LR White resin. Three consecutive sections per defect were analyzed as follows: two with light microscopy using toluidine blue and tartrate-resistant acid phosphatase (TRAP) staining and one with transmission electron microscopy. RESULTS Multinucleated giant cells appeared on both biomaterials. On BCP, MNGCs had a flat morphology and were not observed in resorption lacunae. On DBBM, the MNGCs appeared more round and were often found in shallow concavities. MNGCs on both biomaterials demonstrated a varying degree of TRAP staining, with a tendency toward higher staining intensity of MNGCs on BCP. At the ultrastructural level, signs of superficial dissolution of BCP together with phagocytosis of minor fragments were observed. MNGCs on the surface of DBBM demonstrated sealing zones and ruffled borders, both features of mature osteoclasts. CONCLUSION MNGCs demonstrated distinctly different histological features depending on the bone substitute material used. Further research is warranted to understand the clinical implications of these morphological observations.

Bone healing around nanocrystalline hydroxyapatite, deproteinized bovine bone mineral, biphasic calcium phosphate, and autogenous bone in mandibular bone defects.

The individual healing profile of a given bone substitute with respect to osteogenic potential and substitution rate must be considered when selecting adjunctive grafting materials for bone regeneration procedures. In this study, standardized mandibular defects in minipigs were filled with nanocrystalline hydroxyapatite (HA-SiO), deproteinized bovine bone mineral (DBBM), biphasic calcium phosphate (BCP) with a 60/40% HA/β-TCP (BCP 60/40) ratio, or particulate autogenous bone (A) for histological and histomorphometric analysis. At 2 weeks, percent filler amongst the test groups (DBBM (35.65%), HA-SiO (34.47%), followed by BCP 60/40 (23.64%)) was significantly higher than the more rapidly substituted autogenous bone (17.1%). Autogenous bone yielded significantly more new bone (21.81%) over all test groups (4.91%-7.74%) and significantly more osteoid (5.53%) than BCP 60/40 (3%) and DBBM (2.25%). At 8 weeks, percent filler amongst the test groups (DBBM (31.6%), HA-SiO (31.23%), followed by BCP 60/40 (23.65%)) demonstrated a similar pattern and was again significantly higher as compared to autogenous bone (9.29%). Autogenous bone again exhibited statistically significantly greater new bone (55.13%) over HA-SiO (40.62%), BCP 60/40 (40.21%), and DBBM (36.35%). These results suggest that the osteogenic potential of HA-SiO and BCP is inferior when compared to autogenous bone. However, in instances where a low substitution rate is desired to maintain the volume stability of augmented sites, particularly in the esthetic zone, HA-SiO and DBBM may be favored. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 1478-1487, 2015.

An X-ray micro-fluorescence study to investigate the distribution of Al, Si, P and Ca ions in the surrounding soft tissue after implantation of a calcium phosphate-mullite ceramic composite in a rabbit animal model

Synthetic calcium phosphates, despite their bioactivity, are brittle. Calcium phosphate-mullite composites have been suggested as potential dental and bone replacement materials which exhibit increased toughness. Aluminium, present in mullite, has however been linked to bone demineralisation and neurotoxicity: it is therefore important to characterise the materials fully in order to understand their in vivo behaviour. The present work reports the compositional mapping of the interfacial region of a calcium phosphate-20 wt% mullite biocomposite/soft tissue interface, obtained from the samples implanted into the long bones of healthy rabbits according to standard protocols (ISO-10993) for up to 12 weeks. X-ray micro-fluorescence was used to map simultaneously the distribution of Al, P, Si and Ca across the ceramic-soft tissue interface. A well defined and sharp interface region was present between the ceramic and the surrounding soft tissue for each time period examined. The concentration of Al in the surrounding tissue was found to fall by two orders of magnitude, to the background level, within similar to 35 mu m of the implanted ceramic.

Aplicação de agentes remineralizantes sobre o esmalte clareado: eficácia contra o manchamento por café

The aim of this study was to evaluate the influence of remineralizing agents on the susceptibility of enamel cleared by the coffee pigmentation during office bleaching. Fifty bovine incisors were selected and randomly assigned into 5 groups (n = 10) on the basis of remineralizing agents: G1 gel hydrogen peroxide to 35% (control group); G2, hydrogen peroxide gel and a 35% gel 2% neutral fluorine; G3, hydrogen peroxide gel and a 35% nanostructured calcium phosphate gel, G4, hydrogen peroxide gel and a 35% casein fosfoptídia-phosphate and amorphous calcium folder; G5 hydrogen peroxide gel to 35% without mineralizing agent. All groups exception G1 (control group) were subjected to pigmentation soluble coffee according to the manufacturer's guidelines. The samples were immersed in coffee at temperature of 55° C, 1 time a day for 4 minutes. Color changes were performed by Easyshade spectrophotometer at CIE Lab method before and after 3 whitening sessions. Data were analyzed by analysis of variance ANOVA. The results showed statistically significant differences between the remineralizing substances for the parameters L *, a *, b * ΔE (p <0.0001). The L * values for the group G5, and the b * for G2 and G5 groups differed from the control group. After the 3rd whitening session, Fluor's group (G2) and that without mineralizing agent (G5) showed ΔE values less than the control group that did not undergo pigmentation. It was concluded that only the nanoclusters remineralizing agents Phosphopeptides Casein-Amorphous Calcium Phosphate and Calcium Amorphous phosphate were able to reduce the coffee interference whitening efficacy of hydrogen peroxide.

A comparative study of physicochemical properties of AH Plus, Epiphany, and Epiphany SE root canal sealers

P>Aim To assess the physicochemical properties and the surface morphology of AH Plus, Epiphany, and Epiphany SE root canal sealers. Methodology Five samples of each material were employed for each test according to ANSI/ADA specification 57. The samples were assigned to four groups: (i) AH Plus; (ii) Epiphany; (iii) Epiphany + Thinning Resin; (iv) Epiphany SE. The distilled water used during the solubility test was submitted to spectrometry to verify the release of calcium ions. The morphologies of the external surface and the cross-section of the samples were analysed by means of a scanning electron microscope (SEM). Statistical analysis was performed by using One-Way anova and post hoc Tukey-Kramer tests with the null hypothesis set as 5%. Results Setting time, flow and radiopacity results were in accordance with ANSI/ADA requirements whereas the dimensional change of all sealers and solubility of Epiphany did not fulfil ANSI/ADA protocols. AH Plus and Epiphany SE were similar in terms of flow, radiopacity, solubility and dimensional change. The spectrometry test revealed significant calcium ion release from Epiphany with and without the thinning resin. SEM analysis revealed essentially a homogeneous surface with compact layer and some rough areas. Conclusions Setting time, flow, and radiopacity tests conformed to ANSI/ADA standardization. The dimensional change in all groups and the solubility of Epiphany were greater than values considered acceptable, with higher amounts of calcium ion release. Epiphany SE revealed more organized, compacted, and homogeneous polymers in a reduced resin matrix when compared with the other groups.

Application of quantitative analytical electron microscopy to the mineral content of insect cuticle

Quantification of calcium in the cuticle of the fly larva Exeretonevra angustifrons was undertaken at the micron scale using wavelength dispersive X-ray microanalysis, analytical standards, and a full matrix correction. Calcium and phosphorus were found to be present in the exoskeleton in a ratio that indicates amorphous calcium phosphate. This was confirmed through electron diffraction of the calcium-containing tissue. Due to the pragmatic difficulties of measuring light elements, it is not uncommon in the field of entomology to neglect the use of matrix corrections when performing microanalysis of bulk insect specimens. To determine, firstly, whether such a strategy affects the outcome and secondly, which matrix correction is preferable, phi-rho (z) and ZAF matrix corrections were contrasted with each other and without matrix correction. The best estimate of the mineral phase was found to be given by using the phi-rho (z) correction. When no correction was made, the ratio of Ca to P fell outside the range for amorphous calcium phosphate, possibly leading to flawed interpretation of the mineral form when used on its own.

Estudo da influência dos íons K+, Mg2+, SO4(2-) e CO3(2-) na cristalização biomimética de fosfato de cálcio amorfo (ACP) e conversão a fosfato octacálcico (OCP)

The crystallization of hydroxyapatite (HA) in aqueous solution can be described by the mechanism ACP -> OCP -> HA. In this work, it was studied the influence of K+, Mg2+, SO4(2-) and CO3(2-) ions in the formation of ACP and in its conversion to OCP, using biomimetic coatings on metallic substrates of commercially pure titanium (Ti c.p.). The results showed that Mg2+ and CO3(2-) ions favored both the formation of ACP and its conversion to OCP. Differently, K+ and SO4(2-) ions did not influence the formation of ACP and, consequently, interfered in the conversion to OCP.

Fosfatos de cálcio de interesse biológico: importância como biomateriais, propriedades e métodos de obtenção de recobrimentos

For decades the Hydroxyapatite (HA) was only bioceramic of calcium phosphate system used for bone replacement and regeneration, due to its similarity to the mineral phase of bones and teeth. Because its slow degradation, other calcium phosphate classified as biodegradable started to awaken interest, such as: amorphous calcium phosphate (ACP), octacalcium phosphate (OCP) and tricalcium phosphate (TCP). This work presents the evolution of the use of other calcium phosphates due to their better solubility than the HA, comparing their main physical-chemical and biological properties. Are also presented the main methods used to obtain bioceramic coatings on metal and polymer surfaces.