Formation Of Calcium Hydroxyapatite Research Articles

Heritability of crystal related arthropathies

The most common types of crystal arthropathies are gout and calcium pyrophosphate deposition (CPPD) disease. Serum urate levels are influenced by a combination of genetic factors and the environment. There are studies estimating the heritability of urate ranging from 45% to 73%. Approximately 3% of the variance in serum urate level is explained by the locus SLC2A9. Among the Caucasian population, 10% of all gout cases may be largely attributable to locus ABCG2. Loss or reduction function of ABCG2 halves the kidney’s ability to secrete uric acid. Gain-of-function mutations in ENPP1 gene may be involved in the development of CPPD disease. Loss-of-function mutations in ANKH leads to excess calcium hydroxyapatite formation. Conclusions: There is reason to believe that studying susceptibility genes for the crystal arthropathies will contribute to our understanding of the complexity of inheritance of these disorders. At present many other genes involved in crystal arthropathies are being investigated, and we hope that soon, novel therapeutic targets will be found.

Formation of 2D calcium hydroxyapatite on stainless steel modified with a TiN sublayer

The thin films of calcium hydroxyapatite were deposited on a stainless steel substrate modified with titanium nitride (TiN) using an aqueous sol–gel method and characterized by X-ray diffraction analysis. It was demonstrated for the first time that the formation of calcium hydroxyapatite during heat treatment inhibited the formation of Fe2O3 and promoted the formation of TiO2 on the surface.

Formation of calcium hydroxyapatite with high concentration of homogeneously distributed silver

Abstract In this study for the synthesis of silver-doped calcium hydroxyapatite (Ca10(PO4)6(OH)2:Ag; CHAp:Ag) an environmentally friendly aqueous sol-gel processing has been suggested. The sinterability and morphological properties of silver-activated calcium hydroxyapatite were investigated in the present study. The calcium hydroxyapatite doped with high concentration of silver (up to 10 wt %) has been prepared. This simple synthetic approach offers a feasible way to obtain highly homogeneous silver-doped CHAp bioceramics with possible application in medicine. The synthesis products were characterized using X-ray powder diffraction (XRD) analysis, infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The content of Ca, P and Ag in the synthesis products was determined by SEM (EDX).

Effect of modified 5% sodium fluoride on the surface roughness and hardness of the enamel of primary incisors: An in vitro study

Background: There has been interest over the past decade in the principle that additives that promote the formation of calcium hydroxyapatite can increase the efficacy of sodium fluoride varnishes (NaF). Aim: This study aimed to compare in vitro; the protective effect of a commercially available 5% NaF varnish with the protective effects of 5% NaF varnishes enhanced with functional tricalcium phosphate (fTCP) and amorphous calcium phosphate (ACP). Methodology: A total of 120 primary incisors were divided into four groups of 30 teeth. Group 1 comprised a control group that received no fluoride varnish, Group 2, teeth treated with 5% NaF varnish, Group 3, treated with 5% NaF enhanced with fTCP and Group 4, teeth treated with 5% NaF enhanced with ACP. Surface roughness before and after pH cycling was measured using a profilometer, whereas surface microhardness was measured after pH cycling. Results: Teeth in Group 4 (ACP) and Group 3 (fTCP) showed significantly higher surface microhardness values than the other groups, but there existed a large variation in the range of values obtained. No Significant differences were observed in the change in surface roughness among all groups. Conclusion: The large variation seen in the microhardness values suggest that the effects of the addition of ACP or FTCP to 5% NaF varnish may not be predictable in primary teeth.

Preparation and Characterization of Hydroxyapatite Impregnated Semi‐interpenetrating Polymer Networks (IPNs) of Polyvinyl Alcohol and Poly(Acrylamide‐co‐acrylic Acid)

A semi‐interpenetrating polymer network (IPN) of poly(vinyl alcohol) and poly(acrylamide‐co‐acrylic acid) was prepared, and the formation of calcium hydroxyapatite (HAP) on/in the polymeric network was studied by a novel alternate soaking process. The prepared HAP–IPN matrix was characterized by IR, x‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron micrograph (SEM) analyses, and structural parameters of the IPN such as average molecular weight between crosslinks (M c), crosslink density (q), and number of elastically effective chains (V e) were calculated from water uptake measurements. The swelling of the IPN in phosphate and calcium solutions and the amount of HAP formed were investigated as a function of the chemical architecture of the polymeric matrix. The influence of number of reaction cycles and temperature of the swelling medium on the amount of HAP formed within the IPN were also studied.

Influence of chromium(III) on the formation of calcium hydroxyapatite

Colloidal Ca 10(PO 4) 6(OH) 2(HA) particles doped with Cr 3+ ions in different mole ratios (Cr/(Ca + Cr) = X Cr) by a coprecipitation method were characterized by ICP, XRD, N 2 adsorption, TEM, EPMA, TG, XPS and FTIR. Ca 2+ ions of HA were substituted by Cr 3+ ions in one to one at X Cr ⩽ 0.13. The particle size increased with an increase in X Cr. When doped at X Cr ⩾ 0.13 irregular particles were formed besides long rectangular particles containing Cr 3+ ions less than ca 0.03 in X Cr. The compositions of these two kinds of particles showed that the long rectangular particles were HA and the irregular particles were hydrated calcium chromium phosphate hydroxide. The growth of HA crystals was strongly promoted by doping Cr 3+ ions.

Resolution of Ion Translocating Proteolipid Subclasses Active in Bacterial Calcification

Formation of calcium hydroxyapatite occurs on membrane surfaces via interaction of calcium, inorganic phosphate, phospholipids, calcifiable proteolipids, and ion flux to and from the nucleating site. Recently, this laboratory reported that proteolipids from the calcifying bacterium, Bacterionema matruchotti, act as an ionophore when reconstituted into bacteriorhodopsin-proteoliposomes. This ionophoric activity is blocked by [14C]dicyclohexylcarbodiimide ([14C]DCCD). SDS-PAGE shows that [14C]DCCD binds to a single band of Mr 8500. To determine whether proteins other than the [14C]DCCD-binding protein are involved, we examined the function of proteolipid species extracted by solvents of differing polarity. Proteolipids were isolated independently from chloroform:methanol (2:1) and chloroform:methanol:HCl (200:100:1) extracts of the bacteria by Sephadex LH-20 chromatography and were electrophoresed on 12.5% acrylamide gels. The chloroform:methanol extract contained a major hand at Mr 10,000 that was not present in gels of proteolipid isolated by acidified solvent. Proteolipids extracted in chloroform:methanol:HCl included a broad band at Mr 8500, which co-migrated with the [14C] DCCD-binding protein. The rate and extent of proton translocation were not altered when either proteolipid extract was added individually to bacteriorhodopsin proteoliposomes. However, when proteolipids isolated from the chloroform:methanol and chloroform:methanol:HCl extracts were combined, the rate and extent of translocation were increased. These data demonstrate that at least two proteolipid proteins are necessary for ionophoric activity, the Mr 10,000 protein isolated by chloroform:methanol 2:1 and the [14C]DCCD-binding protein requiring acidified solvent for extraction.

Ion-translocating Properties of Calcifiable Proteolipids

De novo formation of calcium hydroxyapatite in biological systems occurs on membrane surfaces through specific interactions of Ca, Pi, phospholipids, calcifiable proteolipids, and ion flux to and from the nucleating site. This paper reports an in vitro model demonstrating an ion transport function for calcifiable proteolipid. Bacterionema matruchotii proteolipid was incubated with a radiolabeled H+-channel inhibitor, 14C-dicyclohexyl-carbodiimide, and binding characterized by displacement studies with DCCD or ethyldimethylaminopropylcarbodiimide. A carboxyl binding site was suggested by displacement of DCCD by the nucleophile, glycine ethyl ester. The displacement studies indicated that proteolipid bound DCCD via carboxyl group interaction in a hydrophobic region of the protein. SDS-polyacrylamide gel electrophoresis showed that all label was associated with a single band of 8500 Mr. No non-specific binding of 14C-DCCD to phospholipids occurred, since all bound label was associated with protein following Sephadex LH-20 chromatography of crude proteolipid. Phospholipid liposomes were prepared containing bacteriorhodopsin and proteolipid or proteolipid-14C-DCCD, via cholate dialysis. Transmembrane pH changes established by the bacteriorhodopsin H+ pump were measured in the presence and absence of added proteolipid. Proteolipid had an effect similar to those of uncouplers such as tetraphenylboron. Both the rate and extent of proton translocation increased following addition of proteolipid to BR-liposomes. 14C-DCCD abolished the proteolipid-augmented ion transport. When tetraphenylboron was used to abolish the transmembrane electrical potential, calcifiable proteolipid did not augment proton transport.(ABSTRACT TRUNCATED AT 250 WORDS)