Sample records for calcium phosphates

  1. Osteoinduction by calcium phosphate biomaterials

    Microsoft Academic Search

    Huipin Yuan; Zongjian Yang; Yubao Li; Xingdong Zhang; J. D. De Bruijn; K. De Groot

    1998-01-01

    Different materials were implanted in muscles of dogs to study the osteoinduction of calcium phosphate biomaterials. Bone formation was only seen in calcium phosphate biomaterials with micropores, and could be found in hydroxyapatite (HA) ceramic, tricalcium phosphate\\/hydroxyapatite ceramic (BCP), ß-TCP ceramic and calcium phosphate cement. The osteoinductive potential was different in different materials. The results indicate that osteoinduction can be

  2. Calcium Phosphate Biomaterials: An Overview

    Microsoft Academic Search

    Huipin Yuan; KLAAS DE GROOT

    Calcium phosphates are used by our body to build bones and are being applied to produce biomaterials for bone repair. It is\\u000a well-known that calcium phosphate biomaterials guide new bone formation, form a tight bond with the newly formed bone, and\\u000a are therefore, by definition, osteoconductive. Besides their osteoconductive property, it was found that calcium phosphate\\u000a biomaterials, only with specific

  3. 21 CFR 182.8217 - Calcium phosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2009-04-01 true Calcium phosphate. 182.8217 Section 182.8217 Food...RECOGNIZED AS SAFE Nutrients § 182.8217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic)....

  4. 21 CFR 182.1217 - Calcium phosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Calcium phosphate. 182.1217 Section 182.1217 Food...Purpose GRAS Food Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic)....

  5. 21 CFR 182.8217 - Calcium phosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Calcium phosphate. 182.8217 Section 182.8217 Food...RECOGNIZED AS SAFE Nutrients § 182.8217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic)....

  6. 21 CFR 182.1217 - Calcium phosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Calcium phosphate. 182.1217 Section 182.1217 Food...Purpose GRAS Food Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic)....

  7. Thiosulfate Reduces Calcium Phosphate Nephrolithiasis

    PubMed Central

    Asplin, John R.; Donahue, Susan E.; Lindeman, Christina; Michalenka, Anne; Strutz, Kelly Laplante; Bushinsky, David A.

    2009-01-01

    An uncontrolled trial reported that sodium thiosulfate reduces formation of calcium kidney stones in humans, but this has not been established in a controlled human study or animal model. Using the genetic hypercalciuric rat, an animal model of calcium phosphate stone formation, we studied the effect of sodium thiosulfate on urine chemistries and stone formation. We fed genetic hypercalciuric rats normal food with or without sodium thiosulfate for 18 wk and measured urine chemistries, supersaturation, and the upper limit of metastability of urine. Eleven of 12 untreated rats formed stones compared with only three of 12 thiosulfate-treated rats (P < 0.002). Urine calcium and phosphorus were higher and urine citrate and volume were lower in the thiosulfate-treated rats, changes that would increase calcium phosphate supersaturation. Thiosulfate treatment lowered urine pH, which would lower calcium phosphate supersaturation. Overall, there were no statistically significant differences in calcium phosphate supersaturation or upper limit of metastability between thiosulfate-treated and control rats. In vitro, thiosulfate only minimally affected ionized calcium, suggesting a mechanism of action other than calcium chelation. In summary, sodium thiosulfate reduces calcium phosphate stone formation in the genetic hypercalciuric rat. Controlled trials testing the efficacy and safety of sodium thiosulfate for recurrent kidney stones in humans are needed. PMID:19369406

  8. Next generation calcium phosphate-based biomaterials

    PubMed Central

    LC, Chow

    2009-01-01

    It has been close to a century since calcium phosphate materials were first used as bone graft substitutes. Numerous studies conducted in the last two decades have produced a wealth of information on the chemistry, in vitro properties, and biological characteristics of granular calcium phosphates and calcium phosphate cement biomaterials. An in depth analysis of several key areas of calcium phosphate cement properties is presented with the aim of developing strategies that could lead to break-through improvements in the functional efficacies of these materials. PMID:19280963

  9. 21 CFR 182.6215 - Monobasic calcium phosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 false Monobasic calcium phosphate. 182.6215 Section 182.6215...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  10. 21 CFR 582.6215 - Monobasic calcium phosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 false Monobasic calcium phosphate. 582.6215 Section 582.6215...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  11. 21 CFR 582.6215 - Monobasic calcium phosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 false Monobasic calcium phosphate. 582.6215 Section 582.6215...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  12. 21 CFR 182.6215 - Monobasic calcium phosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 false Monobasic calcium phosphate. 182.6215 Section 182.6215...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  13. 21 CFR 182.6215 - Monobasic calcium phosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 false Monobasic calcium phosphate. 182.6215 Section 182.6215...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  14. 21 CFR 582.6215 - Monobasic calcium phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 2012-04-01 false Monobasic calcium phosphate. 582.6215 Section 582.6215...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  15. 21 CFR 582.6215 - Monobasic calcium phosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 false Monobasic calcium phosphate. 582.6215 Section 582.6215...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  16. 21 CFR 182.6215 - Monobasic calcium phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 2012-04-01 false Monobasic calcium phosphate. 182.6215 Section 182.6215...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use....

  17. Chloride- and alkali-containing calcium phosphates as basic materials to prepare calcium phosphate cements.

    PubMed

    Bermúdez, O; Boltong, M G; Driessens, F C; Ginebra, M P; Fernández, E; Planell, J A

    1994-10-01

    Combinations of an alkali-containing calcium phosphate-like rhenanite, sodium whitlockite or calcium potassium phosphate and a chloride-containing calcium phosphate-like spodiosite or chloroapatite with or without additions of other calcium phosphates like monocalcium phosphate monohydrate, dicalcium phosphate or dicalcium phosphate dihydrate were made and mixed with water into pastes. The setting time of these pastes was determined. After soaking for a day in Ringer's solution at 37 degrees C the compressive strength and the diametral tensile strength were determined. Two of the combinations tried in this study resulted in the formation of cements at room temperature. One cement was of the type dicalcium phosphate, whereas the other gave octocalcium phosphate as the solid reaction product. The byproducts formed were an aqueous solution of NaCl and one of K2HPO4, respectively. Applications for bone repair and augmentation are envisaged. PMID:7841290

  18. Frequency of renal phosphate leak among patients with calcium nephrolithiasis

    Microsoft Academic Search

    Dominique Prié; Vincent Ravery; Laurent Boccon-Gibod; Gérard Friedlander

    2001-01-01

    Frequency of renal phosphate leak among patients with calcium nephrolithiasis.BackgroundNephrolithiasis is a frequent disorder affecting 10 to 15% of the population in Europe and the United States. More than 80% of renal stones are made of calcium oxalate and calcium phosphate. The main identified risks for calcium renal stone formation are hypercalciuria and urinary saturation. A urine phosphate (Pi) loss

  19. Interaction between Plant Nutrients: IV. Interaction between Calcium and Phosphate

    Microsoft Academic Search

    Svend Tage Jakobsen

    1993-01-01

    The interaction between calcium and phosphate is complex because these ions both support and counteract each other. The supporting effect is due to a simultaneous uptake and translocation of calcium and phosphate. The counteracting effect is caused by precipitation of less soluble calcium phosphates at the vicinity of nutrient-absorbing roots.At high activity ratios between potassium and calcium the risk of

  20. Calcium metal to synthesize amorphous or cryptocrystalline calcium phosphates A. Cuneyt Tas

    E-print Network

    Tas, A. Cuneyt

    Calcium metal to synthesize amorphous or cryptocrystalline calcium phosphates A. Cuneyt Tas Metal Phosphate Synthesis Metallic calcium was never used before as the calcium source in synthesizing solutions. The formation of calcium phosphate (CaP) in synthesis solutions was immediately initiated

  1. Physiology of Calcium and Phosphate Metabolism: 1980 Refresher Course, Syllabus.

    ERIC Educational Resources Information Center

    Knox, Franklyn G., Ed.

    1980-01-01

    This syllabus reviews information concerning calcium and phosphate regulation. Topics of interest include the following: calcium metabolism, phosphorus metabolism, bone, parathyroid hormone, calcitonin, and vitamin D. (CS)

  2. Original article Acid gelation of colloidal calcium phosphate-

    E-print Network

    Paris-Sud XI, Université de

    Original article Acid gelation of colloidal calcium phosphate- depleted preheated milk Marie Abstract ­ This study aimed at understanding the role of colloidal calcium phosphate (CCP) in acid gelation of acid gels. colloidal calcium phosphate / CCP / acid milk gel / dialysis ­ 90 °C 10 min p

  3. Microwave-assisted synthesis of calcium phosphate nanowhiskers

    E-print Network

    Tas, A. Cuneyt

    Microwave-assisted synthesis of calcium phosphate nanowhiskers Sahil Jalota, A. Cuneyt Tas Carolina 29634 (Received 12 February 2004; accepted 29 March 2004) Calcium phosphate [single temperature for 1 h to obtain the nanowhiskers or powders of the desired calcium phosphate bioceramics. I

  4. Osseointegration of composite calcium phosphate bioceramics.

    PubMed

    Frayssinet, P; Mathon, D; Lerch, A; Autefage, A; Collard, P; Rouquet, N

    2000-05-01

    The resistance of macroporous calcium phosphate ceramics to compressive strength generally is low and depends on, among other factors, porosity percentage and pore size. A compromise always is adopted between high porosity, required for a good integration, and mechanical strength, which increases with material density. We improved the strength of macroporous calcium phosphate ceramics of interconnected porosity by filling the pores with a highly soluble, self-setting calcium phosphate cement made of TCP and DCPD. Cylinders of the resulting material were implanted in sheep condyles and subjected to histological analysis after 20, 60, and 120 days. Microradiographs were made of the histological sections. The control material consisted of ceramic that had not been loaded with cement. Progressive ingrowth of bone into the ceramic pores occurred as the cement was degraded during the first implantation period. Marked degradation of the cement was apparent after 2 months, with fragmentation of the cement in most of the pores and the presence of bone tissue between the fragments. All the cement had been replaced by bone after 4 months. Some fragments of cement still were embedded in the newly formed bone. There was no significant difference between the integration of loaded and nonloaded ceramics. Filling the macroporous ceramic pores with a calcium phosphate cement significantly improved the mechanical strength of these ceramics without modifying their integration in the healing bone. PMID:10679675

  5. Preparation of Calcium-Loaded Liposomes and Their Use in Calcium Phosphate Formation

    E-print Network

    Preparation of Calcium-Loaded Liposomes and Their Use in Calcium Phosphate Formation Phillip B within dipalmitoylphosphatidylcholine lipid vesicles, which were then used to form calcium phosphate as high as 85 mM. Addition of inorganic phosphate to the calcium-loaded liposomes resulted in liposome

  6. Hydroxyapatite formation from a hydrated calcium monohydrogen phosphate precursor

    Microsoft Academic Search

    Marion D. Francis; Ned C. Webb

    1970-01-01

    Hydrated calcium monohydrogen phosphate is proposed as the logical precursor in the formation of hydroxyapatite and a unifying theory for the formation of low calcium, or defect apatites, is presented. Structural relationships between calcium monohydrogen phosphate dihydrate and hydroxyapatite indicate that either material can provide the atomic arrangment for the epitaxial growth of one on the other. The formation of

  7. ili G d C l i h hFertilizer Grade Calcium Phosphate RecoveryFertilizerGrade Calcium Phosphate RecoveryFertilizer Grade Calcium Phosphate Recovery Phillip Barak, PhDAmanda Boyce, MSc Phillip Barak, PhDAmanda Boyce, MSc

    E-print Network

    Barak, Phillip

    ili G d C l i h hFertilizer Grade Calcium Phosphate RecoveryFertilizerGrade Calcium Phosphate RecoveryFertilizer Grade Calcium Phosphate Recovery Phillip Barak, PhDAmanda Boyce, MSc F W T Pl Phillip endeavored to improve on this recovery system by producing calcium phosphates from p p y fl idi d b d t i d

  8. Amorphous calcium phosphate and its application in dentistry

    Microsoft Academic Search

    Jie Zhao; Yu Liu; Wei-bin Sun; Hai Zhang

    2011-01-01

    Amorphous Calcium Phosphate (ACP) is an essential mineral phase formed in mineralized tissues and the first commercial product\\u000a as artificial hydroxyapatite. ACP is unique among all forms of calcium phosphates in that it lacks long-range, periodic atomic\\u000a scale order of crystalline calcium phosphates. The X-ray diffraction pattern is broad and diffuse with a maximum at 25 degree\\u000a 2 theta, and

  9. Nanostructured calcium phosphates for biomedical applications: novel synthesis and characterization

    Microsoft Academic Search

    Prashant N. Kumta; Charles Sfeir; Dong-Hyun Lee; Dana Olton; Daiwon Choi

    2005-01-01

    Materials play a key role in several biomedical applications, and it is imperative that both the materials and biological aspects are clearly understood for attaining a successful biological outcome. This paper illustrates our approach to implement calcium phosphates as gene delivery agents. Calcium phosphates (CaP) belong to the family of biocompatible apatites and there are several CaP phases, the most

  10. Nano-porous calcium phosphate balls.

    PubMed

    Kovach, Ildyko; Kosmella, Sabine; Prietzel, Claudia; Bagdahn, Christian; Koetz, Joachim

    2015-08-01

    By dropping a NaH2PO4·H2O precursor solution to a CaCl2 solution at 90°C under continuous stirring in presence of two biopolymers, i.e. gelatin (G) and chitosan (C), supramolecular calcium phosphate (CP) card house structures are formed. Light microscopic investigations in combination with scanning electron microscopy show that the GC-based flower-like structure is constructed from very thin CP platelets. Titration experiments indicate that H-bonding between both biopolymers is responsible for the synergistic effect in presence of both polymers. Gelatin-chitosan-water complexes play an important role with regard to supramolecular ordering. FTIR spectra in combination with powder X-ray diffraction show that after burning off all organic components (heating up >600°C) dicalcium and tricalcium phosphate crystallites are formed. From high resolution transmission electron microscopy (HR-TEM) it is obvious to conclude, that individual crystal platelets are dicalcium phosphates, which build up ball-like supramolecular structures. The results reveal that the GC guided crystal growth leads to nano-porous supramolecular structures, potentially attractive candidates for bone repair. PMID:26052107

  11. Biocompatibility and resorption of a brushite calcium phosphate cement

    Microsoft Academic Search

    Felix Theiss; Detlef Apelt; Bastian Brand; Annette Kutter; Katalin Zlinszky; Marc Bohner; Sandro Matter; Christian Frei; Joerg A. Auer; Brigitte von Rechenberg

    2005-01-01

    A hydraulic calcium phosphate cement with ?-tricalcium phosphate (TCP) granules embedded in a matrix of dicalcium phosphate dihydrate (DCPD) was implanted in experimentally created defects in sheep. One type of defect consisted of a drill hole in the medial femoral condyle. The other, partial metaphyseal defect was located in the proximal aspect of the tibia plateau and was stabilized using

  12. Phase transformation of calcium phenyl phosphate in calcium hydroxyapatite

    SciTech Connect

    Tanaka, Hidekazu [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan)]. E-mail: hidekazu@riko.shimane-u.ac.jp; Ibaraki, Koshiro [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Uemura, Masao [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Hino, Ryozi [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Kandori, Kazuhiko [School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582 (Japan); Ishikawa, Tatsuo [School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582 (Japan)

    2007-07-03

    Calcium phenyl phosphate (CaPP) was synthesized from a mixture of Ca(OH){sub 2} and phenyl phosphate (C{sub 6}H{sub 5}PO{sub 4}H{sub 2}) in an aqueous media. XRD pattern of CaPP exhibited five diffraction peaks at 2{theta} = 6.6, 13.3, 20.0, 26.8 and 33.7{sup o}. The d-spacing ratio of these peaks was ca. 1:1/2:1/3:1/4:1/5. The molar ratios of Ca/P and phenyl/P of CaPP were 1.0 and 0.92, respectively, and the chemical formula of the material was expressed as (C{sub 6}H{sub 5}PO{sub 4}){sub 0.92}(HPO{sub 4}){sub 0.08}Ca.1.3H{sub 2}O, similar to that of dicalcium phosphate dihydrate (CaHPO{sub 4}.2H{sub 2}O: DCPD). These results allowed us to infer that CaPP is composed of a multilayer alternating bilayer of phenyl groups of the phosphates and DCPD-like phase. The structure of the material was essentially not altered after aging at pH 9.0-11.0 and 85 deg. C in an aqueous media. While, after aging at pH {<=}8.0, the diffraction peaks of CaPP were suddenly weakened and disappeared at pH 7.0. Besides, new peaks due to calcium hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}: Hap) appeared and their intensity was strengthened with decreasing the solution pH. TEM observation revealed that the Hap particles formed at pH 6.0 are fibrous with ca. 1.5 {mu}m in length and ca. 0.2 {mu}m in width. From these results, it is presumed that the layered CaPP was dissolved, hydrolyzed and reprecipitated to fibrous Hap particles at pH {<=}8.0 and 85 deg. C in aqueous media. This phase transformation of CaPP in Hap resembled to the formation mechanism of Hap in animal organism.

  13. Are we mismanaging calcium and phosphate metabolism in renal failure?

    Microsoft Academic Search

    Chen H. Hsu

    1997-01-01

    Secondary hyperparathyroidism and renal osteodystrophy are the consequences of abnormal calcium, phosphate, and calcitriol metabolism ensuing from renal failure. Evidence suggests that calcium balance tends to become negative as we grow older than 35 years of age; however, the current dialysis modalities provide patients regardless of age with excessive calcium during dialysis. Administration of calcitriol in the management of hyperparathyroidism

  14. 382 Mlle J. BRIGANDO ET MM. CHAMP ET CLOSSON. -LES PHOSPHATES LES PHOSPHATES DE CALCIUM DU LAIT

    E-print Network

    Paris-Sud XI, Université de

    382 Mlle J. BRIGANDO ET MM. CHAMP ET CLOSSON. -LES PHOSPHATES LES PHOSPHATES DE CALCIUM DU LAIT, est conditionnée par leur teneur en phosphates insolubles de calcium. En raison de l'importance au intéressant d'étudier les facteurs qui modifient les phosphates de calcium du lait et d'examiner les

  15. Chemistry misconceptions associated with understanding calcium and phosphate homeostasis

    NSDL National Science Digital Library

    William H. Cliff (Niagara University Biology)

    2009-12-01

    Successful learning of many aspects in physiology depends on a meaningful understanding of fundamental chemistry concepts. Two conceptual diagnostic questions measured student understanding of the chemical equilibrium underlying calcium and phosphate homeostasis. One question assessed the ability to predict the change in phosphate concentration when calcium ions were added to a saturated calcium phosphate solution. Fifty-two percent of the students correctly predicted that the phosphate concentration would decrease in accord with the common ion effect. Forty-two percent of the students predicted that the phosphate concentration would not change. Written explanations showed that most students failed to evoke the idea of competing chemical equilibria. A second question assessed the predicted change in calcium concentration after solid calcium phosphate was added to a saturated solution. Only 11% of the students correctly predicted no change in calcium concentration; 86% of the students predicted an increase, and many based their prediction on a mistaken application of Le Chatelier's principle to heterogeneous equilibria. These results indicate that many students possess misconceptions about chemical equilibrium that may hamper understanding of the processes of calcium and phosphate homeostasis. Instructors can help students gain greater understanding of these physiochemical phenomena by adopting strategies that enable students achieve more accurate conceptions of chemical equilibria.

  16. Calcium phosphate scaffold from biogenic calcium carbonate by fast ambient condition reactions

    NASA Astrophysics Data System (ADS)

    Dutta, Abhishek; Fermani, Simona; Arjun Tekalur, Srinivasan; Vanderberg, Abigail; Falini, Giuseppe

    2011-12-01

    Calcium phosphate biogenic materials are biocompatible and promote bioactivity and osteoconductivity, which implies their natural affinity and tendency to bond directly to bones subsequently replacing the host bone after implantation owing to its biodegradability. Calcium hydrogen phosphate dihydrate, CaHPO 4·2H 2O, is known to be a nucleation precursor, in aqueous solutions, for apatitic calcium phosphates and, hence, a potential starting material for bone substitutes. Numerous approaches, via hydrothermal and ambient synthetic routes, have been used to produce calcium phosphate from biogenic calcium carbonate, taking advantage of the peculiar architecture and composition of the latter. In this article, the lamellar region of the cuttlefish bone ( Sepia officinalis) was used as a framework for the organized deposition of calcium phosphate crystals, at ambient conditions via a fast procedure involving an amorphous calcium carbonate intermediate, and ending with a conversion to calcium phosphate and a fixation procedure, thereby resulting in direct conversion of biogenic calcium carbonate into calcium phosphates at ambient conditions from the scale of months to hours.

  17. Osteoclastic resorption of calcium phosphate ceramics with different hydroxyapatite\\/?-tricalcium phosphate ratios

    Microsoft Academic Search

    S. Yamada; D. Heymann; J.-M. Bouler; G. Daculsi

    1997-01-01

    To study the influence of calcium phosphate ceramic solubility on osteoclastic resorption, neonatal rabbit bone cells were cultured for 2 days on hydroxyapatite (HA), ?-tricalcium phosphate (?-TCP) and two types of biphasic calcium phosphate (BCP) with HA\\/?-TCP ratios of 2575 and 7525. Solubility was regulated by varying the ratio of less-soluble HA and more-soluble ?-TCP. After removal of stromal cells

  18. J Mater Sci Mater Med . Author manuscript The stability mechanisms of an injectable calcium phosphate ceramic

    E-print Network

    Paris-Sud XI, Université de

    calcium phosphate ceramic suspension Ahmed Fatimi 1 , Jean-Fran ois Tassinç 2 , Monique A. V. Axelos 3: Pierre Weiss Abstract Calcium phosphate ceramics are widely used as bone (hydroxypropylmethylcellulose: HPMC) as matrix and bioactive calcium phosphate ceramics (biphasic calcium phosphate: BCP

  19. Interaction of zinc with a synthetic calcium phosphate mineral.

    PubMed

    Davey, H P; Embery, G; Cummins, D

    1997-01-01

    As zinc has been included in several oral health products as an anticalculus and antiplaque agent, the interaction of zinc with a synthetic phosphate was investigated. The synthetic calcium phosphate used in this study was beta-tricalcium phosphate, or whitlockite, which is a major constituent of mature calculus. The aim of this work was to study the mechanism of uptake of zinc to this mineral. Zinc was readily taken up by the calcium phosphate to a maximum level of 13.9 mumol/m2. The interaction was reversible and followed a Langmuir adsorption isotherm. There was no concomitant release of calcium with zinc uptake. Inclusion of calcium in the exposure solution did however marginally depress the acquisition of zinc (12% max), but fluoride had no significant effect on uptake. PMID:9353583

  20. Calcium phosphate implants coatings as carriers for BMP2

    Microsoft Academic Search

    Y. Liu; J. F. He; E. B. Hunziker

    2009-01-01

    The osteoconductivity of dental implants can be improved by coating them with a layer of calcium phosphate (CaP), which can be rendered osteoinductive by functionalizing it with an osteogenic agent, such as bone morphogenetic protein 2 (BMP-2). In the present study, we wished to compare the osteoindcutive efficacies of three different types of BMP-2-bearing calcium-phosphate coating: one of hydroxyapatite (C-HA),

  1. Mechanical insertion properties of calcium-phosphate implant coatings

    Microsoft Academic Search

    T. T. Hägi; L. Enggist; D. Michel; S. J. Ferguson; Y. Liu; E. B. Hunziker

    2010-01-01

    Objectives: To investigate the influence of protein incorporation on the resistance of biomimetic calcium-phosphate coatings to the shear forces that are generated during implant insertion. Materials and Methods: Thirty-eight standard (5 × 13 mm) Osseotite® implants were coated biomimetically with a layer of calcium phosphate, which either lacked or bore a co-precipitated (incorporated) depot of the model protein bovine serum

  2. Factors affecting the precipitation of calcium phosphate in vitro

    Microsoft Academic Search

    W. G. Robertson

    1973-01-01

    The precipitation of calcium phosphatein vitro was studied in order to define the processes of homogeneous and heterogeneous nucleation and to study the effect of certain\\u000a inhibitors of crystallization on these processes. It was shown that the solubility-determining surface phase of the calcium\\u000a phosphate formed by homogeneous nucleation had a Ca\\/P molar ratio close to that of octacalcium phosphate (OCP)

  3. Transient amorphous calcium phosphate in forming enamel.

    PubMed

    Beniash, Elia; Metzler, Rebecca A; Lam, Raymond S K; Gilbert, P U P A

    2009-05-01

    Enamel, the hardest tissue in the body, begins as a three-dimensional network of nanometer size mineral particles, suspended in a protein gel. This mineral network serves as a template for mature enamel formation. To further understand the mechanisms of enamel formation we characterized the forming enamel mineral at an early secretory stage using X-ray absorption near-edge structure (XANES) spectromicroscopy, transmission electron microscopy (TEM), FTIR microspectroscopy and polarized light microscopy. We show that the newly formed enamel mineral is amorphous calcium phosphate (ACP), which eventually transforms into apatitic crystals. Interestingly, the size, shape and spatial organization of these amorphous mineral particles and older crystals are essentially the same, indicating that the mineral morphology and organization in enamel is determined prior to its crystallization. Mineralization via transient amorphous phases has been previously reported in chiton teeth, mollusk shells, echinoderm spicules and spines, and recent reports strongly suggest the presence of transient amorphous mineral in forming vertebrate bones. The present finding of transient ACP in murine tooth enamel suggests that this strategy might be universal. PMID:19217943

  4. TRANSIENT AMORPHOUS CALCIUM PHOSPHATE IN FORMING ENAMEL

    PubMed Central

    Beniash, Elia; Metzler, Rebecca A.; Lam, Raymond S.K.; Gilbert, P.U.P.A.

    2009-01-01

    Enamel, the hardest tissue in the body, begins as a three-dimensional network of nanometer size mineral particles, suspended in a protein gel. This mineral network serves as a template for mature enamel formation. To further understand the mechanisms of enamel formation we characterized the forming enamel mineral at an early secretory stage using x-ray absorption near-edge structure (XANES) spectromicroscopy, transmission electron microscopy (TEM), FTIR microspectroscopy and polarized light microscopy. We show that the newly formed enamel mineral is amorphous calcium phosphate (ACP), which eventually transforms into apatitic crystals. Interestingly, the size, shape and spatial organization of these amorphous mineral particles and older crystals are essentially the same, indicating that the mineral morphology and organization in enamel is determined prior to its crystallization. Mineralization via transient amorphous phases has been previously reported in chiton teeth, mollusk shells, echinoderm spicules and spines, and recent reports strongly suggest the presence transient amorphous mineral in forming vertebrate bones. The present finding of transient ACP in murine tooth enamel suggests that this strategy might be universal. PMID:19217943

  5. Chemistry Misconceptions Associated with Understanding Calcium and Phosphate Homeostasis

    ERIC Educational Resources Information Center

    Cliff, William H.

    2009-01-01

    Successful learning of many aspects in physiology depends on a meaningful understanding of fundamental chemistry concepts. Two conceptual diagnostic questions measured student understanding of the chemical equilibrium underlying calcium and phosphate homeostasis. One question assessed the ability to predict the change in phosphate concentration…

  6. Biologically controlled precipitation of calcium phosphate by Ramlibacter tataouinensis

    Microsoft Academic Search

    Karim Benzerara; Nicolas Menguysupasu; François Guyot; Feriel Skouri; Gilles de Luca; Mohamed Barakat; Thierry Heulin

    2004-01-01

    Ramlibacter tataouinensis, a ?-proteobacterium strain isolated from an arid environment, was cultured on a solid culture medium supplemented with calcium. Optical and transmission electron microscopies (TEM) showed that the precipitation of nanometer-sized calcium phosphate particles was mainly restricted to the cysts at the center of the colonies and occurred first in the periplasm of the bacteria then inside the cells.

  7. Calcium phosphate-based remineralization systems: scientific evidence?

    PubMed

    Reynolds, E C

    2008-09-01

    Dental caries remains a major public health problem in most communities even though the prevalence of disease has decreased since the introduction of fluorides. The focus in caries research has recently shifted to the development of methodologies for the detection of the early stages of caries lesions and the non-invasive treatment of these lesions. Topical fluoride ions, in the presence of calcium and phosphate ions, promote the formation of fluorapatite in tooth enamel by a process referred to as remineralization. The non-invasive treatment of early caries lesions by remineralization has the potential to be a major advance in the clinical management of the disease. However, for net remineralization to occur adequate levels of calcium and phosphate ions must be available and this process is normally calcium phosphate limited. In recent times three calcium phosphate-based remineralization systems have been developed and are now commercially available: a casein phosphopeptide stabilized amorphous calcium phosphate (Recaldent (CPP-ACP), CASRN691364-49-5), an unstabilized amorphous calcium phosphate (ACP or Enamelon) and a bioactive glass containing calcium sodium phosphosilicate (NovaMin). The purpose of this review was to determine the scientific evidence to support a role for these remineralization systems in the non-invasive treatment of early caries lesions. The review has revealed that there is evidence for an anticariogenic efficacy of the Enamelon technology for root caries and for the Recaldent technology in significantly slowing the progression of coronal caries and promoting the regression of lesions in randomized, controlled clinical trials. Hence the calcium phosphate-based remineralization technologies show promise as adjunctive treatments to fluoride therapy in the non-invasive management of early caries lesions. PMID:18782374

  8. Oral phosphate binders in CKD - is calcium the (only) answer?

    PubMed

    Goldsmith, David; Covic, Adrian

    2014-06-01

    All-cause mortality and cardiovascular- related mortality have both been linked to abnormal serum phosphate concentrations in chronic kidney disease (CKD). Aberrant serum phosphate concentration in patients with CKD has also been associated with adverse cardiac and renal outcomes. Early prevention or management of rising or high serum phosphate concentrations in patients with CKD is now considered to be an important intervention to prevent downstream complications resulting from the poor management of serum calcium and parathyroid hormone (PTH). It is widely considered that starting phosphate binder therapy early, with concurrent dietary management of serum phosphate, constitutes an effective course of interventions, although normalization of serum phosphate in dialysis patients remains atypical, unless specific dialytic measures are also undertaken. Calcium- based phosphate binders are often the first type of binders prescribed due to their low cost. Evidence shows that most phosphate binders are roughly equally effective in lowering serum phosphate concentrations in adults compared to placebo, with a small probability that sevelamer hydrochloride is better than calcium acetate or lanthanum carbonate. However, not all binders are created equal in regards to their safety profiles. The potential for accumulations and toxicities does exist with very long-term continuous exposure. We discuss these issues in the course of this review. PMID:25017668

  9. Le Lait (1983),63, 317-332 Migration du calcium et des phosphates

    E-print Network

    Paris-Sud XI, Université de

    1983-01-01

    Le Lait (1983),63, 317-332 Migration du calcium et des phosphates inorganiques dans les fromages à calcium et en phosphates des fromages ont permis de montrer que les phosphates sont le facteur limitant de pour l'obtenir; les teneurs en calcium et phosphate ainsi que le rapport de ces deux éléments

  10. Differences in gastrointestinal calcium absorption after the ingestion of calcium-free phosphate binders.

    PubMed

    Behets, Geert J; Dams, Geert; Damment, Stephen J; Martin, Patrick; De Broe, Marc E; D'Haese, Patrick C

    2014-01-01

    Both calcium-containing and noncalcium-containing phosphate binders can increase gastrointestinal calcium absorption. Previously, we observed that lanthanum carbonate administration to rats with renal failure is not associated with increased calciuria. Additionally, lanthanum carbonate treatment in dialysis patients has been associated with a less pronounced initial decrease in serum parathyroid hormone compared with other phosphate binders. For 8 days, male Wistar rats received a diet supplemented with 2% lanthanum carbonate, 2% sevelamer, 2% calcium carbonate, or 2% cellulose. Calciuria was found to be increased in animals with normal renal function treated with sevelamer or calcium carbonate but not with lanthanum carbonate. In animals with renal failure, cumulative calcium excretion showed similar results. In rats with normal renal function, serum ionized calcium levels were increased after 2 days of treatment with sevelamer, while calcium carbonate showed a smaller increase. Lanthanum carbonate did not induce differences. In animals with renal failure, no differences were found between sevelamer-treated, calcium carbonate-treated, and control groups. Lanthanum carbonate, however, induced lower ionized calcium levels within 2 days of treatment. These results were confirmed in normal human volunteers, who showed lower net calcium absorption after a single dose of lanthanum carbonate compared with sevelamer carbonate. In conclusion, these two noncalcium-containing phosphate-binding agents showed a differential effect on gastrointestinal calcium absorption. These findings may help to improve the management of calcium balance in patients with renal failure, including concomitant use of vitamin D. PMID:24197066

  11. The Nucleation and growth of Calcium Phosphate by Amelogenin

    SciTech Connect

    Tarasevich, Barbara J.; Howard, Christopher J.; Larson, Jenna L.; Snead, Malcolm L.; Simmer, Jim; Paine, Michael L.; Shaw, Wendy J.

    2007-06-15

    The nucleation processes involved in calcium phosphate formation in tooth enamel are not well understood but are believed to involve proteins in the extracellular matrix. The ability of one enamel protein, amelogenin, to promote the nucleation and growth of calcium phosphate was studied in an in vitro system involving metastable supersaturated solutions. It was found that recombinant amelogenin (rM179 and rp(H)M180) promoted the nucleation of calcium phosphate compared to solutions without protein. The amount of calcium phosphate increased with increasing supersaturation of the solutions and increasing protein concentrations up to 6.5 µg/ml. At higher protein concentrations, the amount of calcium phosphate decreased. The kinetics of nucleation were studied in situ and in real time using a quartz crystal microbalance (QCM) and showed that the protein reduced the induction time for nucleation compared to solutions without protein. This work shows a nucleation role for amelogenin in vitro which may be promoted by the association of amelogenin into nanosphere templates, exposing charged functionality at the surface. This research was performed at Pacific Northwest National Laboratory, operated by Battelle for the US-DOE. A portion of the research was performed in the EMSL, a national scientific user facility sponsored by the DOE-OBER at PNNL.

  12. Bacterial biosynthesis of a calcium phosphate bone-substitute material.

    PubMed

    Thackray, Aniac C; Sammons, Rachel L; Macaskie, Lynne E; Yong, Ping; Lugg, Harriet; Marquis, Peter M

    2004-04-01

    A species of Serratia bacteria produces nano-crystalline hydroxyapatite (HA) crystals by use of a cell-bound phosphatase enzyme, located both periplasmically and within extracellular polymeric materials. The enzyme functions in resting cells by cleaving glycerol-2-phosphate (G-2-P) to liberate free phosphate ions which combine with calcium in solution to produce a cell-bound calcium phosphate material. Bacteria grown as a biofilm on polyurethane reticulated foam cubes were challenged with calcium and G-2-P in a bioreactor to produce a 3-D porous bone-substitute material. The scaffold has 1 mm macropores and 1 microm micropores. XRD showed the crystallites to be 25-28 nm in size, resembling HA before sintering and beta-tricalcium phosphate (beta-TCP, whitlockite) after. When biofilm was grown on titanium discs and challenged with calcium and G-2-P, a calcium phosphate layer formed on the discs. Biomineralisation is therefore a potential route to production of precursor nanophase HA, which has the potential to improve strength. The scaffold material produced by this method could be used as a bone-filler or as an alternative method for coating implants with a layer of HA. PMID:15332607

  13. A Review Paper on Biomimetic Calcium Phosphate Coatings

    PubMed Central

    Lin, X.; de Groot, K.; Wang, D.; Hu, Q.; Wismeijer, D.; Liu, Y.

    2015-01-01

    Biomimetic calcium phosphate coatings have been developed for bone regeneration and repair because of their biocompatibility, osteoconductivity, and easy preparation. They can be rendered osteoinductive by incorporating an osteogenic agent, such as bone morphogenetic protein 2 (BMP-2), into the crystalline lattice work in physiological situations. The biomimetic calcium phosphate coating enables a controlled, slow and local release of BMP-2 when it undergoes cell mediated coating degradation induced by multinuclear cells, such as osteoclasts and foreign body giant cells, which mimics a physiologically similar release mode, to achieve sustained ectopic or orthotopic bone formation. Therefore, biomimetic calcium phosphate coatings are considered to be a promising delivery vehicle for osteogenic agents. In this review, we present an overview of biomimetic calcium phosphate coatings including their preparation techniques, physico-chemical properties, potential as drug carrier, and their pre-clinical application both in ectopic and orthotopic animal models. We briefly review some features of hydroxyapatite coatings and their clinical applications to gain insight into the clinical applications of biomimetic calcium phosphate coatings in the near future. PMID:25893016

  14. Renal Control of Calcium, Phosphate, and Magnesium Homeostasis.

    PubMed

    Blaine, Judith; Chonchol, Michel; Levi, Moshe

    2015-07-01

    Calcium, phosphate, and magnesium are multivalent cations that are important for many biologic and cellular functions. The kidneys play a central role in the homeostasis of these ions. Gastrointestinal absorption is balanced by renal excretion. When body stores of these ions decline significantly, gastrointestinal absorption, bone resorption, and renal tubular reabsorption increase to normalize their levels. Renal regulation of these ions occurs through glomerular filtration and tubular reabsorption and/or secretion and is therefore an important determinant of plasma ion concentration. Under physiologic conditions, the whole body balance of calcium, phosphate, and magnesium is maintained by fine adjustments of urinary excretion to equal the net intake. This review discusses how calcium, phosphate, and magnesium are handled by the kidneys. PMID:25287933

  15. Alternative technique for calcium phosphate coating on titanium alloy implants.

    PubMed

    Le, Van Quang; Pourroy, Geneviève; Cochis, Andrea; Rimondini, Lia; Abdel-Fattah, Wafa I; Mohammed, Hadeer I; Carradò, Adele

    2014-01-01

    As an alternative technique for calcium phosphate coating on titanium alloys, we propose to functionalize the metal surface with anionic bath containing chlorides of palladium or silver as activators. This new deposition route has several advantages such as controlled conditions, applicability to complex shapes, no adverse effect of heating, and cost effectiveness. A mixture of hydroxyapatite and calcium phosphate hydrate is deposited on the surface of Ti-6Al-4V. Calcium phosphate coating is built faster compared with the one by Simulated Body Fluid. Cell morphology and density are comparable to the control one; and the results prove no toxic compound is released into the medium during the previous seven days of immersion. Moreover, the cell viability is comparable with cells cultivated with the virgin medium. These experimental treatments allowed producing cytocompatible materials potentially applicable to manufacture implantable devices for orthopedic and oral surgeries. PMID:24646569

  16. Gelatin powders accelerate the resorption of calcium phosphate cement and improve healing in the alveolar ridge.

    PubMed

    Matsumoto, Goichi; Sugita, Yoshihiko; Kubo, Katsutoshi; Yoshida, Waka; Ikada, Yoshito; Sobajima, Satoshi; Neo, Masashi; Maeda, Hatsuhiko; Kinoshita, Yukihiko

    2014-05-01

    The aim of this study was to show the effectiveness of combining calcium phosphate cement and gelatin powders to promote bone regeneration in the canine mandible. We mixed gelatin powders with calcium phosphate cement to create a macroporous composite. In four beagle dogs, two saddle-type bone defects were created on each side of the mandible, and calcium phosphate cement alone or calcium phosphate cement containing composite gelatin powders was implanted in each of the defects. After a healing period of six months, mandibles were removed for µCT and histological analyses. The µCT and histological analyses showed that at experimental sites at which calcium phosphate cement alone had been placed new bone had formed only around the periphery of the residual calcium phosphate cement and that there had been little or no ingrowth into the calcium phosphate cement. On the other hand, at experimental sites at which calcium phosphate cement containing composite gelatin powders had been placed, we observed regenerated new bone in the interior of the residual calcium phosphate cement as well as around its periphery. The amount of resorption of calcium phosphate cement and bone regeneration depended on the mixing ratio of gelatin powders to calcium phosphate cement. New bone replacement was significantly better in the sites treated with calcium phosphate cement containing composite gelatin powders than in those treated with calcium phosphate cement alone. PMID:24105428

  17. Solubilization of inorganic calcium phosphates—Solubilization mechanisms

    Microsoft Academic Search

    P. Illmer; F. Schinner

    1995-01-01

    Two species [Penicillium aurantiogriseum and Pseudomonas sp. (PI1889)] having high abilities in solubilizing inorganic phosphates (hydroxylapatite and brushite) were used to examine solubilization mechanisms. No direct contact between microorganisms and calcium phosphates (Ca-Ps) were necessary for effective solubilization. The P-concentration in solution did not increase according to a sigmoid curve type. Therefore, sampling time is of particular importance for estimating

  18. Optimization of calcium phosphate fine ceramic powders preparation

    NASA Astrophysics Data System (ADS)

    Sezanova, K.; Tepavitcharova, S.; Rabadjieva, D.; Gergulova, R.; Ilieva, R.

    2013-12-01

    The effect of biomimetic synthesis method, reaction medium and further precursor treatments on the chemical and phase composition, crystal size and morphology of calcium phosphates was examined. Nanosized calcium phosphate precursors were biomimetically precipitated by the method of continuous precipitation in three types of reaction media at pH 8: (i) SBF as an inorganic electrolyte system; (ii) organic (glycerine) modified SBF (volume ratio of 1:1); (iii) polymer (10 g/l xanthan gum or 10 g/l guar gum) modified SBF (volume ratio of 1:1). After maturation (24 h) the samples were lyophilized, calcinated at 300°C for 3 hours, and washed with water, followed by new gelation, lyophilization and step-wise (200, 400, 600, 800, and 1000°C, each for 3 hours) sintering. The reaction medium influenced the chemical composition and particle size but not the morphology of the calcium phosphate powders. In all studied cases bi-phase calcium phosphate fine powders with well-shaped spherical grains, consisting of ?-tricalcium phosphate (?-TCP) and hydroxyapatite (HA) with a Ca/P ratio of 1.3 - 1.6 were obtained. The SBF modifiers decreased the particle size of the product in the sequence guar gum ˜ xanthan gum < glycerin < SBF medium.

  19. [Regulation and disorders of calcium and phosphate metabolism].

    PubMed

    Michigami, Toshimi

    2014-02-01

    Calcium and phosphate are the constituents of biomineral, and their levels in circulation are regulated by various hormones. Disorders in calcium/phosphate metabolism are often associated with skeletal demineralization and pathological calcification. Some of the hypophosphatemic rickets/osteomalacia are caused by the increased bioactivity of FGF23, and classified into FGF23-mediated hypophosphatemic rickets/osteomalacia. In the adult patients with FGF23-mediated hypophosphatemic rickets/osteomalacia, mineralizing enthesopathy is an often observed complication. In addition, mutations of the same genes can be responsible for both rickets/osteomalacia and ectopic calcification. PMID:24473349

  20. Phosphate-bonded calcium aluminate cements

    DOEpatents

    Sugama, T.

    1993-09-21

    A method is described for making a rapid-setting phosphate-bonded cementitious material. A powdered aluminous cement is mixed with an aqueous solution of ammonium phosphate. The mixture is allowed to set to form an amorphous cementitious material which also may be hydrothermally treated at a temperature of from about 120 C to about 300 C to form a crystal-containing phosphate-bonded material. Also described are the cementitious products of this method and the cement composition which includes aluminous cement and ammonium polyphosphate. 10 figures.

  1. Molecular mechanisms of crystallization impacting calcium phosphate cements

    PubMed Central

    Giocondi, Jennifer L.; El-Dasher, Bassem S.; Nancollas, George H.; Orme, Christine A.

    2010-01-01

    The biomineral calcium hydrogen phosphate dihydrate (CaHPO4·2H2O), known as brushite, is a malleable material that both grows and dissolves faster than most other calcium minerals, including other calcium phosphate phases, calcium carbonates and calcium oxalates. Within the body, this ready formation and dissolution can play a role in certain diseases, such as kidney stone and plaque formation. However, these same properties, along with brushite’s excellent biocompatibility, can be used to great benefit in making resorbable biomedical cements. To optimize cements, additives are commonly used to control crystallization kinetics and phase transformation. This paper describes the use of in situ scanning probe microscopy to investigate the role of several solution parameters and additives in brushite atomic step motion. Surprisingly, this work demonstrates that the activation barrier for phosphate (rather than calcium) incorporation limits growth kinetics and that additives such as magnesium, citrate and bisphosphonates each influence step motion in distinctly different ways. Our findings provide details of how, and where, molecules inhibit or accelerate kinetics. These insights have the potential to aid in designing molecules to target specific steps and to guide synergistic combinations of additives. PMID:20308110

  2. Formation of Calcium Phosphate Whiskers in Hydrogen Peroxide (H2O2) Solutions at 901C

    E-print Network

    Tas, A. Cuneyt

    Formation of Calcium Phosphate Whiskers in Hydrogen Peroxide (H2O2) Solutions at 901C A. Cuneyt Tas of synthesizing calcium phosphate whiskers was developed. Commercially available b-tricalcium phosphate (b-Ca3(PO4 phosphate (OCP: Ca8H2(PO4)6 . 5H2O) and carbonated apatitic (apatite-like) calcium phosphate (Ap-CaP). As

  3. Comparison study of biomimetic strontium-doped calcium phosphate coatings by electrochemical deposition and air plasma

    E-print Network

    Meng, Yizhi

    Comparison study of biomimetic strontium-doped calcium phosphate coatings by electrochemical of the strontium-doped calcium phosphate coatings were evaluated using bone cell culture using MC3T3-E1 osteoblast of strontium incorporation in calcium phosphate coatings. The morphology and composition of deposited coatings

  4. Casein precipitation equilibria in the presence of calcium ions and phosphates

    E-print Network

    Velev, Orlin D.

    Casein precipitation equilibria in the presence of calcium ions and phosphates C. Guo a , B, which can be explained by a mechanism involving the formation of calcium phosphate microcrystals and formation of sturdy aggregates of co-precipitated calcium phosphate and casein. The crystallite formation

  5. Effect of milk solids concentration on the pH, soluble calcium and soluble phosphate levels

    E-print Network

    Boyer, Edmond

    Note Effect of milk solids concentration on the pH, soluble calcium and soluble phosphate levels and equilibrium states of calcium and inorganic phosphate, are considered to be important in the stabilityH and the concentrations of soluble calcium (Casol) and soluble inorganic phosphate (Psol). At any given temperature

  6. Parameters influencing calcium phosphate precipitation in granular sludge sequencing batch reactor

    E-print Network

    Mailhes, Corinne

    Parameters influencing calcium phosphate precipitation in granular sludge sequencing batch reactor BP 84234, F-31432 Toulouse Cedex 4, France a b s t r a c t Calcium phosphate precipitation inside to accumulate in the granule, the main calcium phosphate precursors that form prior to HAP are here investigated

  7. In vitro testing of calcium phosphate (HA, TCP, and biphasic HA-TCP) whiskers

    E-print Network

    Tas, A. Cuneyt

    In vitro testing of calcium phosphate (HA, TCP, and biphasic HA-TCP) whiskers Sahil Jalota, Sarit B: Calcium phosphate [single-phase hydroxyapa- tite (HA, Ca10(PO4)6(OH)2), single-phase tricalcium phos for 1 h to obtain the whiskers of the desired calcium phosphate (CaP) bioceramics. These whis- kers were

  8. Self-Assembly of Filamentous Amelogenin Requires Calcium and Phosphate: From Dimers via Nanoribbons to Fibrils

    E-print Network

    Sali, Andrej

    Self-Assembly of Filamentous Amelogenin Requires Calcium and Phosphate: From Dimers via Nanoribbons calcium, phosphate, and pH 4.0-6.0. The pH range suggests that the formation of ion bridges through the importance of calcium and phosphate in self-assembly. X-ray scattering characterized amelo- genin dimers

  9. Synthesis of Calcium HydroxyapatiteTricalcium Phosphate (HATCP) Composite Bioceramic Powders and Their Sintering Behavior

    E-print Network

    Tas, A. Cuneyt

    Synthesis of Calcium Hydroxyapatite­Tricalcium Phosphate (HA­TCP) Composite Bioceramic Powders (HA)) and tri- calcium phosphate (Ca3(PO4)2 (TCP))--were prepared as submicrometer-sized, chemically. Starting materials of calcium ni- trate tetrahydrate and diammonium hydrogen phosphate salts that were

  10. In vitro dissolution of calcium phosphate-mullite composite in simulated body fluid

    E-print Network

    Srivastava, Kumar Vaibhav

    In vitro dissolution of calcium phosphate-mullite composite in simulated body fluid Ashok Priya, calcium, magnesium, phosphate, sulphate etc. [3]. Additionally, the human body environment osseointegration [1, 4]. Additionally, the calcium phosphate (CaP) based ceramics, like HAp has beneficial

  11. Mapping calcium phosphate activated gene networks as a strategy for targeted osteoinduction of human progenitors

    E-print Network

    Chen, Christopher S.

    Mapping calcium phosphate activated gene networks as a strategy for targeted osteoinduction: Received 8 January 2013 Accepted 5 March 2013 Available online 26 March 2013 Keywords: Calcium phosphate endogenous mechanisms of in vivo calcium phosphate-driven, ectopic bone formation could be identified

  12. CRYSTALLIZATION OF CALCIUM PHOSPHATE ORIENTED BY SELF-ASSEMBLING DIBLOCK COPOLYMERS,

    E-print Network

    Amrhein, Valentin

    CRYSTALLIZATION OF CALCIUM PHOSPHATE ORIENTED BY SELF-ASSEMBLING DIBLOCK COPOLYMERS, IN SOLUTION. MINERALIZATION OF CALCIUM PHOSPHATE IN PRESENCE OF DHBC 28 B. AMPHIPHILIC POLY(ETHYLENE OXIDE)-BLOCK-POLY(VALEROLACTONE) DIBLOCK COPOLYMERS AS TEMPLATE FOR CALCIUM PHOSPHATE MINERALIZATION 30 1. SELF-ASSEMBLY IN AQUEOUS

  13. Author's personal copy Submicron spheres of amorphous calcium phosphate forming in a stirred

    E-print Network

    Tas, A. Cuneyt

    Author's personal copy Submicron spheres of amorphous calcium phosphate forming in a stirred SBF in revised form 25 April 2014 Available online 20 May 2014 Keywords: Amorphous; Calcium phosphate; Submicron; Spheres; Synthesis X-ray-amorphous calcium phosphate (ACP) spheres were synthesized in a simulated

  14. Sedimentation Study of Biphasic Calcium Phosphate Particles A. Fatimi1,a

    E-print Network

    Paris-Sud XI, Université de

    Sedimentation Study of Biphasic Calcium Phosphate Particles A. Fatimi1,a , J. F. Tassin2,b , M. A pierre.weiss@univ-nantes.fr Keywords: biphasic calcium phosphate, cellulose ether derivatives, sedimentation, viscosity. Abstract. Injectable calcium phosphate (CaP) biomaterial is considered

  15. Osteoblast proliferation on neat and apatite-like calcium phosphate-coated titanium foam scaffolds

    E-print Network

    Tas, A. Cuneyt

    Osteoblast proliferation on neat and apatite-like calcium phosphate-coated titanium foam scaffolds of loosely-attached calcium phosphates on titanium implants further improved their in vivo bone by the osteoclasts. Supersaturated calcium phosphate (CaP) solutions, such as synthetic body fluids (SBF

  16. Interaction between hydroxypropyl methylcellulose and biphasic calcium phosphate after steam sterilisation

    E-print Network

    Boyer, Edmond

    1 Interaction between hydroxypropyl methylcellulose and biphasic calcium phosphate after steam in deionised water containing biphasic calcium phosphate (BCP) granules (60% hydroxyapatite/40% -tricalcium, and a dialytic method was then use to extract calcium phosphate salts from HPMC. The percentage of HPMC extracted

  17. Calcium Gluconate in Phosphate Buffered Saline Increases Gene Delivery with Adenovirus Type 5

    E-print Network

    Hemminki, Akseli

    Calcium Gluconate in Phosphate Buffered Saline Increases Gene Delivery with Adenovirus Type 5 Marko the calcium and phosphate present in the serum mix to precipitate, and this was responsible for enhanced gene calcium and phosphate are present in many solutions. To translate this into an approach potentially

  18. Sintering, Phase Stability, and Properties of Calcium Phosphate-Mullite Shekhar Nath,z

    E-print Network

    Srivastava, Kumar Vaibhav

    Sintering, Phase Stability, and Properties of Calcium Phosphate-Mullite Composites Shekhar Nath, and microstructure development in calcium phosphate (CaP)-mullite composites. The experimen- tal results reveal of HAp due to dehydro- xylation (removal of OHÀ ion) resulting in biphasic calcium phosphate (BCP

  19. Short-term implantation effects of a DCPD-based calcium phosphate cement

    Microsoft Academic Search

    Patrick Frayssinet; Laurent Gineste; Philippe Conte; Jacques Fages; Nicole Rouquet

    1998-01-01

    Calcium phosphate cements can be handled in paste form and set in a wet medium after precipitation of calcium phosphate crystals in the implantation site. Depending on the products entering into the chemical reaction leading to the precipitation of calcium phosphates, different phases can be obtained with different mechanical properties, setting times and injectability. We tested a cement composed of

  20. Antibacterial Nanocomposite with Calcium Phosphate and Quaternary Ammonium

    Microsoft Academic Search

    L. Cheng; M. D. Weir; K. Zhang; S. M. Xu; Q. Chen; X. Zhou; H. H. K. Xu

    2012-01-01

    Secondary caries is a frequent reason for restoration failure, resulting from acidogenic bacteria and their biofilms. The objectives of this study were to: (1) develop a novel nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and quaternary ammonium dimethacrylate (QADM); and (2) investigate its mechanical and antibacterial durability. A spray-drying technique yielded NACP with particle size of 116 nm. The

  1. The bactericidal and biocompatible characteristics of reinforced calcium phosphate cements

    Microsoft Academic Search

    Tianyi Wu; Xiaolin Hua; Zhiwei He; Xinfu Wang; Xiaowei Yu; Weiping Ren

    2012-01-01

    Infection remains a serious medical problem in orthopaedic surgery. Antibiotic administration can be available either systemically via the blood stream or locally, directly into the infected bone. One of the main limitations of antibiotic administration is the development of multi-antibiotic-resistant bacterial strains. In this study, we developed bactericidal calcium phosphate cements (CPC) by incorporation of different molecular weight chitosan and

  2. Low temperature method for the production of calcium phosphate fillers

    Microsoft Academic Search

    Anna Rita Calafiori; Marcello Marotta; Alfonso Nastro; Guglielmo Martino

    2004-01-01

    BACKGROUND: Calcium phosphate manufactured samples, prepared with hydroxyapatite, are used as either spacers or fillers in orthopedic surgery, but these implants have never been used under conditions of mechanical stress. Similar conditions also apply with cements. Many authors have postulated that cements are a useful substitute material when implanted in vivo. The aim of this research is to develop a

  3. Synthesis and characterization of magnesium doped biphasic calcium phosphate.

    PubMed

    Toibah, A R; Sopyan, I; Mel, M

    2008-07-01

    The incorporation of magnesium ions into the calcium phosphate structure is of great interest for the development of artificial bone implants. This paper investigates the preparation of magnesium-doped biphasic calcium phosphate (Mg-BCP) via sol gel method at various concentrations of added Mg. The effect of calcinations temperature (ranging from 500 degrees C to 900 degrees C) and concentrations of Mg incorporated into BCP has been studied by the aid of XRD, TGA and infrared spectroscopy (IR) in transmittance mode analysis. The study indicated that the powder was pure BCP and Mg-BCP with 100% purity and high crystallinity. The results also indicated that beta-tricalcium phosphate (beta-TCP) phase can be observed when the powder was calcined at 800 degrees C and above. PMID:19024995

  4. Mechanical properties of calcium phosphate scaffolds fabricated by robocasting.

    PubMed

    Miranda, Pedro; Pajares, Antonia; Saiz, Eduardo; Tomsia, Antoni P; Guiberteau, Fernando

    2008-04-01

    The mechanical behavior under compressive stresses of beta-tricalcium phosphate (beta-TCP) and hydroxyapatite (HA) scaffolds fabricated by direct-write assembly (robocasting) technique is analyzed. Concentrated colloidal inks prepared from beta-TCP and HA commercial powders were used to fabricate porous structures consisting of a 3-D tetragonal mesh of interpenetrating ceramic rods. The compressive strength and elastic modulus of these model scaffolds were determined by uniaxial testing to compare the relative performance of the selected materials. The effect of a 3-week immersion in simulated body fluid (SBF) on the strength of the scaffolds was also analyzed. The results are compared with those reported in the literature for calcium phosphate scaffolds and human bone. The robocast calcium phosphate scaffolds were found to exhibit excellent mechanical performances in terms of strength, especially the HA structures after SBF immersion, indicating a great potential of this type of scaffolds for use in load-bearing bone tissue engineering applications. PMID:17688280

  5. Involvement of intracellular calcium in the phosphate efflux from mammalian nonmyelinated nerve fibers

    Microsoft Academic Search

    P. Jirounek; J. Vitus; G. J. Jones; W. F. Pralong; R. W. Straub

    1984-01-01

    Summary Phosphate efflux was measured as the fractional rate of loss of radioactivity from desheathed rabbit vagus nerves after loading with radiophosphate. The effects of strategies designed to increase intracellular calcium were investigated. At the same time, the exchangeable calcium content was measured using45Ca. Application of calcium ionophore A23187 increased phosphate efflux in the presence of external calcium in parallel

  6. Diagnosis and clinical manifestations of calcium pyrophosphate and basic calcium phosphate crystal deposition diseases.

    PubMed

    Ea, Hang-Korng; Lioté, Frédéric

    2014-05-01

    Basic calcium phosphate and pyrophosphate calcium crystals are the 2 main calcium-containing crystals that can deposit in all skeletal tissues. These calcium crystals give rise to numerous manifestations, including acute inflammatory attacks that can mimic alarming and threatening differential diagnoses, osteoarthritis-like lesions, destructive arthropathies, and calcific tendinitis. Awareness of uncommon localizations and manifestations such as intraspinal deposition (eg, crowned dens syndrome, tendinitis of longus colli muscle, massive cervical myelopathy compression) prevents inappropriate procedures and cares. Coupling plain radiography, ultrasonography, computed tomography, and synovial fluid analysis allow accurate diagnosis by directly or indirectly identifying the GRAAL of microcrystal-related symptoms. PMID:24703344

  7. Setting reaction and hardening of an apatitic calcium phosphate cement.

    PubMed

    Ginebra, M P; Fernández, E; De Maeyer, E A; Verbeeck, R M; Boltong, M G; Ginebra, J; Driessens, F C; Planell, J A

    1997-04-01

    The combination of self-setting and biocompatibility makes calcium phosphate cements potentially useful materials for a variety of dental applications. The objective of this study was to investigate the setting and hardening mechanisms of a cement-type reaction leading to the formation of calcium-deficient hydroxyapatite at low temperature. Reactants used were alpha-tricalcium phosphate containing 17 wt% beta-tricalcium phosphate, and 2 wt% of precipitated hydroxyapatite as solid phase and an aqueous solution 2.5 wt% of disodium hydrogen phosphate as liquid phase. The transformation of the mixture was stopped at selected times by a freeze-drying techniques, so that the cement properties at various stages could be studied by means of x-ray diffraction, infrared spectroscopy, and scanning electron microscopy. Also, the compressive strength of the cement was measured as a function of time. The results showed that: (1) the cement setting was the result of the alpha-tricalcium phosphate hydrolysis, giving as a product calcium-deficient hydroxyapatite, while beta-tricalcium phosphate did not participate in the reaction; (2) the extent of conversion of alpha-TCP was nearly 80% after 24 hr; (3) both the extent of conversion and the compressive strength increased initially linearly with time, subsequently reaching a saturation level, with a strong correlation observed between them, indicating that the microstructural changes taking place as the setting reaction proceeded were responsible for the mechanical behavior of the cement; and (4) the microstructure of the set cement consisted of clusters of big plates with radial or parallel orientations in a matrix of small plate-like crystals. PMID:9126187

  8. JOURNAL OF MATERIALS SCIENCE: MATERIALS IN MEDICINE 16 (2005) 167 174 Formation of apatitic calcium phosphates

    E-print Network

    Tas, A. Cuneyt

    2005-01-01

    calcium phosphates in a Na-K-phosphate solution of pH 7.4 A. C. TAS1,, F. ALDINGER2 1 School of Materials crystalline, apatitic calcium phosphate powders have been synthesized by slowly adding a Na- and K-containing reference phosphate solution with a pH value of 7.4 to an aqueous calcium nitrate solution at 37 C. Nano

  9. Comparative chemistry of amorphous and apatitic calcium phosphate preparations

    Microsoft Academic Search

    J. D. Termine; E. D. Eanes

    1972-01-01

    Unwashed samples of amorphous calcium phosphate (ACP) contain an irreplaceable labile fraction, rich in acid phosphate and low in Ca\\/P ratio, which is irreversibly lost during the washing process. Native ACP precipitated in the pH range 6.6–10.6 varied in Ca\\/P molar ratio from 1.18 to 1.50 and in HPO42?\\/total P from 33.0% to 10.1%. At pH 7.40, native ACP had

  10. Sphingosine 1Phosphate Mobilizes Sequestered Calcium, Activates Calcium Entry, and Stimulates Deoxyribonucleic Acid Synthesis in Thyroid FRTL-5 Cells

    Microsoft Academic Search

    KID TORNQUIST; PIA SAARINEN; MINNA VAINIO; MIKAEL AHLSTROM

    1997-01-01

    Sphingosine 1-phosphate (SPP) potently mobilizes sequestered cal- cium and is a mitogen in several cell types. In the present investi- gation, we have evaluated the effect of SPP on intracellular free calcium concentration ((Ca21)i) and synthesis of DNA in thyroid FRTL-5 cells. SPP rapidly and transiently mobilized sequestered calcium and stimulated entry of extracellular calcium. The entry of calcium, but

  11. A safer disposal of hazardous phosphate coating sludge by formation of an amorphous calcium phosphate matrix.

    PubMed

    Navarro-Blasco, I; Duran, A; Pérez-Nicolás, M; Fernández, J M; Sirera, R; Alvarez, J I

    2015-08-15

    Phosphate coating hazardous wastes originated from the automotive industry were efficiently encapsulated by an acid-base reaction between phosphates present in the sludge and calcium aluminate cement, yielding very inert and stable monolithic blocks of amorphous calcium phosphate (ACP). Two different compositions of industrial sludge were characterized and loaded in ratios ranging from 10 to 50 wt.%. Setting times and compressive strengths were recorded to establish the feasibility of this method to achieve a good handling and a safe landfilling of these samples. Short solidification periods were found and leaching tests showed an excellent retention for toxic metals (Zn, Ni, Cu, Cr and Mn) and for organic matter. Retentions over 99.9% for Zn and Mn were observed even for loadings as high as 50 wt.% of the wastes. The formation of ACP phase of low porosity and high stability accounted for the effective immobilization of the hazardous components of the wastes. PMID:26024992

  12. Synthesis of amorphous calcium phosphate using various types of cyclodextrins

    SciTech Connect

    Li Yanbao [Singapore-MIT Alliance, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Wiliana, Tjandra [Singapore-MIT Alliance, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Tam, Kam C. [Singapore-MIT Alliance, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)]. E-mail: mkctam@ntu.edu.sg

    2007-05-03

    Amorphous calcium phosphate (ACP) was synthesised in aqueous solution at room temperature using cyclodextrins. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and thermal analysis (DTA/TGA) were performed on the calcium phosphate precipitates obtained from solutions. We observed that only {beta}-CD could stabilise the amorphous phase in the mother solution because of the lower solubility of {beta}-CD in water and the ACP remained stable in aqueous solution for more than 24 h at room temperature. The ACP particle has an initial particle size of less than 40 nm, Ca/P molar ratio of 1.67 and {beta}-CD absorbed on its surface. The mechanism for the stabilisation of ACP is proposed.

  13. The influence of Sr content in calcium phosphate coatings.

    PubMed

    Lindahl, Carl; Pujari-Palmer, Shiuli; Hoess, Andreas; Ott, Marjam; Engqvist, Håkan; Xia, Wei

    2015-08-01

    In this study calcium phosphate coatings with different amounts of strontium (Sr) were prepared using a biomineralization method. The incorporation of Sr changed the composition and morphology of coatings from plate-like to sphere-like morphology. Dissolution testing indicated that the solubility of the coatings increased with increased Sr concentration. Evaluation of extracts (with Sr concentrations ranging from 0 to 2.37?g/mL) from the HA, 0.06Sr, 0.6Sr, and 1.2Sr coatings during in vitro cell cultures showed that Sr incorporation into coatings significantly enhanced the ALP activity in comparison to cells treated with control and HA eluted media. These findings show that calcium phosphate coatings could promote osteogenic differentiation even in a low amount of strontium. PMID:26042720

  14. Calcium phosphate-based composites as injectable bone substitute materials.

    PubMed

    Low, Kah Ling; Tan, Soon Huat; Zein, Sharif Hussein Sharif; Roether, Judith A; Mouriño, Viviana; Boccaccini, Aldo R

    2010-07-01

    A major weakness of current orthopedic implant materials, for instance sintered hydroxyapatite (HA), is that they exist as a hardened form, requiring the surgeon to fit the surgical site around an implant to the desired shape. This can cause an increase in bone loss, trauma to the surrounding tissue, and longer surgical time. A convenient alternative to harden bone filling materials are injectable bone substitutes (IBS). In this article, recent progress in the development and application of calcium phosphate (CP)-based composites use as IBS is reviewed. CP materials have been used widely for bone replacement because of their similarity to the mineral component of bone. The main limitation of bulk CP materials is their brittle nature and poor mechanical properties. There is significant effort to reinforce or improve the mechanical properties and injectability of calcium phosphate cement (CPC) and this review resumes different alternatives presented in this specialized literature. PMID:20336722

  15. The effect of calcium phosphate implant coating on osteoconduction

    Microsoft Academic Search

    Cheng Yang

    2001-01-01

    Objective: The purpose of this study was to determine whether a calcium phosphate (CaP) coating would have a significant impact on osteoconduction. Study Design: In this investigation, porous-surfaced titanium alloy (Ti-6Al-4V) implants were prepared with or without the addition of a thin surface layer of CaP applied by means of sol-gel coating and implanted into the tibiae of 16 rabbits.

  16. Epidemiology of calcium pyrophosphate crystal arthritis and basic calcium phosphate crystal arthropathy.

    PubMed

    Abhishek, Abhishek; Doherty, Michael

    2014-05-01

    Calcium pyrophosphate crystal deposition (CPPD) is common and mainly associates with increasing age and osteoarthritis (OA). Recent studies suggest that CPPD occurs as the result of a generalized articular predisposition and may also associate with low cortical bone mineral density. The epidemiology of basic calcium phosphate (BCP) crystal deposition is poorly understood. Although periarticular BCP crystal deposits occurs at all ages and in both sexes, intra-articular BCP crystal deposition tends to associate with increasing age and OA. Calcium pyrophosphate and BCP crystals frequently coexist in joints with OA. PMID:24703342

  17. Injectable biphasic calcium phosphate cements as a potential bone substitute.

    PubMed

    Sariibrahimoglu, Kemal; Wolke, Joop G C; Leeuwenburgh, Sander C G; Yubao, Li; Jansen, John A

    2014-04-01

    Apatitic calcium phosphate cements (CPCs) have been widely used as bone grafts due to their excellent osteoconductive properties, but the degradation properties are insufficient to stimulate bone healing in large bone defects. A novel approach to overcome the lack of degradability of apatitic CPC involves the development of biphasic CPCs (BCPC) based on tricalcium phosphate (TCP) in both ?- and ?-polymorphs. The aim of the current study was to prepare and analyze the physicochemical properties of BCPCs based on dual phase ?/?-TCP as obtained by heat treatment of pure ?-TCP. The handling and mechanical characteristics of the samples as well as the degradation behavior under in vitro condition were investigated and compared with a standard monophasic ?-TCP-based CPC. The results showed that different heat treatments of commercially available ?-TCP allowed the formation of biphasic calcium phosphate powder with a variety of ?/?-TCP ratios. The use of biphasic powder particles as a reactant for CPCs resulted into increased setting and injectability times of the final BCPCs. During hardening of the cements, the amount of apatite formation decreased with increasing ?-TCP content in the biphasic precursor powders. The morphology of the monophasic CPC consisted of plate-like crystals, whereas needle-like crystals were observed for BCPCs. In vitro degradation tests demonstrated that dissolution rate and corresponding calcium release from the set cements increased considerably with increasing ?-TCP content, suggesting that apatitic CPCs can be rendered degradable by using biphasic ?/?-TCP as powder precursor phase. PMID:24106108

  18. Mechanical properties of zinc and calcium phosphates: Structural insights and relevance to anti-wear functionality

    E-print Network

    Mueser, Martin

    Mechanical properties of zinc and calcium phosphates: Structural insights and relevance to anti of an experimental nature, on the response of zinc and calcium phosphates to large stresses. This overview, University of Western Ontario, Canada 3 ArcelorMittal-Dofasco R&D, Hamilton, ON, Canada Metal phosphates have

  19. Simulations of Inositol Phosphate Metabolism and Its Interaction with InsP3-Mediated Calcium Release

    E-print Network

    Bhalla, Upinder S.

    Simulations of Inositol Phosphate Metabolism and Its Interaction with InsP3-Mediated Calcium(1,4,5)P3-mediated calcium release. We find temporal dynamics of most inositol phosphates 560065, India ABSTRACT Inositol phosphates function as second messengers for a variety of extracellular

  20. Formation of Biomimetic Porous Calcium Phosphate Coatings on Surfaces of Polyethylene/Zinc Stearate Blends

    E-print Network

    Drelich, Jaroslaw W.

    Formation of Biomimetic Porous Calcium Phosphate Coatings on Surfaces of Polyethylene/Zinc Stearate the need for the metallic containment devices. Calcium phosphate (CaP) coatings on either metallic Technological University Houghton, MI 49931, USA Keywords: biomaterials, biomimetic deposition, calcium

  1. Response to "Chemistry misconceptions associated with understanding calcium and phosphate homeostasis"

    NSDL National Science Digital Library

    David S. Goldfarb (St. Vincent's Hospital, and New York University School of Medicine)

    2010-03-01

    I enjoyed Dr. Cliff's "conceptual diagnostic test" regarding calcium phosphate equilibrium and was relieved that I chose the correct answers (1). Question 2 was the more difficult one, and I hesitated before almost answering it incorrectly. Dr. Cliff asks what would happen if more calcium phosphate is added to a beaker containing calcium, phosphate, and calcium phosphate "at equilibrium." His answer states the question differently: "Only 11% of the students correctly answered the conceptual diagnostic question about the addition of solid calcium phosphate to a saturated [emphasis added] solution of calcium phosphate." The question did not specify that the solution was saturated but that it was "at equilibrium." It is not simply a question about understanding "mass action." One also needs to realize that the solvent is saturated if a solid in the solvent is at equilibrium. That is an additional concept itself and, when not made explicit, might explain why only 11% of the students answered it correctly.

  2. Remineralization of Enamel Subsurface Lesions by Casein Phosphopeptide-stabilized Calcium Phosphate Solutions

    Microsoft Academic Search

    E. C. Reynolds

    1997-01-01

    Casein phosphopeptides (CPP) stabilize amorphous calcium phosphate (ACP), localize ACP in dental plaque, and are anticariogenic in animal and in situ human caries models. In this in vitro study, CPP-stabilized calcium phosphate solutions were shown to remineralize subsurface lesions in human third-molar enamel. Solutions were used to examine the effect of CPP-calcium phosphate concentration on remineralization. Other solutions were used

  3. Europium-doped amorphous calcium phosphate porous nanospheres: preparation and application as luminescent drug carriers

    Microsoft Academic Search

    Feng Chen; Ying-Jie Zhu; Kui-Hua Zhang; Jin Wu; Ke-Wei Wang; Qi-Li Tang; Xiu-Mei Mo

    2011-01-01

    Calcium phosphate is the most important inorganic constituent of biological tissues, and synthetic calcium phosphate has been widely used as biomaterials. In this study, a facile method has been developed for the fabrication of amorphous calcium phosphate (ACP)\\/polylactide-block-monomethoxy(polyethyleneglycol) hybrid nanoparticles and ACP porous nanospheres. Europium-doping is performed to enable photoluminescence (PL) function of ACP porous nanospheres. A high specific surface

  4. Oral calcium phosphate: A new therapy for Crigler-Najjar disease?

    Microsoft Academic Search

    CN Van der Veere; P. L. M. Jansen; M. Sinaasappel; R Van der Meer; Sijs van der I. H; J. A. Rammeloo; P. Goyens; CM Van Nieuwkerk; R. P. J. Oude Elferink

    1997-01-01

    BACKGROUND & AIMS: Calcium phosphate binds unconjugated bilirubin in vitro, and dietary calcium phosphate supplementation reduces the serum bilirubin level in rats with hereditary unconjugated hyperbilirubinemia (Gunn rats). The aim of this study was to evaluate the effect of oral calcium phosphate supplementation on plasma bilirubin levels in patients with Crigler-Najjar disease.METHODS: A placebo-controlled, double-blind, crossover design was used. Eleven

  5. Effect of strontium ions substitution on gene delivery related properties of calcium phosphate nanoparticles

    Microsoft Academic Search

    A. HanifiM; M. H. Fathi; H. Mir Mohammad Sadeghi

    2010-01-01

    Gene therapy has been considered a strategy for delivery of therapeutic nucleic acids to a specific site. Calcium phosphates\\u000a are one gene delivery vector group of interest. However, low transfection efficiency has limited the use of calcium phosphate\\u000a in gene delivery applications. Present work aims at studying the fabrication of strontium substituted calcium phosphate nanoparticles\\u000a with improved gene delivery related

  6. Method of coating a substrate with a calcium phosphate compound

    SciTech Connect

    Gao, Yufei (Kennewick, WA); Campbell, Allison A. (Kennewick, WA)

    2000-01-01

    The present invention is a method of coating a substrate with a calcium phosphate compound using plasma enhanced MOCVD. The substrate is a solid material that may be porous or non-porous, including but not limited to metal, ceramic, glass and combinations thereof. The coated substrate is preferably used as an implant, including but not limited to orthopaedic, dental and combinations thereof. Calcium phosphate compound includes but is not limited to tricalcium phosphate (TCP), hydroxyapatite (HA) and combinations thereof. TCP is preferred on a titanium implant when implant resorbability is desired. HA is preferred when the bone bonding of new bone tissue into the structure of the implant is desired. Either or both of TCP and/or HA coated implants may be placed into a solution with an agent selected from the group of protein, antibiotic, antimicrobial, growth factor and combinations thereof that can be adsorbed into the coating before implantation. Once implanted, the release of TCP will also release the agent to improve growth of new bone tissues and/or to prevent infection.

  7. Calcium phosphate bone cements for local vancomycin delivery.

    PubMed

    Loca, Dagnija; Sokolova, Marina; Locs, Janis; Smirnova, Anastasija; Irbe, Zilgma

    2015-04-01

    Among calcium phosphate biomaterials, calcium phosphate bone cements (CPCs) have attracted increased attention because of their ability of self-setting in vivo and injectability, opening the new opportunities for minimally invasive surgical procedures. However, any surgical procedure carries potential inflammation and bone infection risks, which could be prevented combining CPC with anti-inflammatory drugs, thus overcoming the disadvantages of systemic antibiotic therapy and controlling the initial burst and total release of active ingredient. Within the current study ?-tricalcium phosphate based CPCs were prepared and it was found that decreasing the solid to liquid phase ratio from 1.89g/ml to 1.23g/ml, initial burst release of vancomycin within the first 24h increased from 40.0±2.1% up to 57.8±1.2% and intrinsic properties of CPC were changed. CPC modification with vancomycin loaded poly(lactic acid) (PLA) microcapsules decreased the initial burst release of drug down to 7.7±0.6%, while only 30.4±1.3% of drug was transferred into the dissolution medium within 43days, compared to pure vancomycin loaded CPC, where 100% drug release was observed already after 12days. During the current research a new approach was found in order to increase the drug bioavailability. Modification of CPC with novel PLA/vancomycin microcapsules loaded and coated with nanosized hydroxyapatite resulted in 85.3±3.1% of vancomycin release within 43days. PMID:25686933

  8. Calcium phosphate microcrystal deposition in the human intervertebral disc.

    PubMed

    Lee, Robert S; Kayser, Mike V; Ali, S Yousuf

    2006-01-01

    A variety of crystals have been identified in both normal and pathological connective tissues. Calcium phosphate 'cuboidal' microcrystal deposition has been found, using transmission electron microscopy (TEM), in femoral articular cartilage, where they are distributed as a band 5-50 microm beneath the articular surface. These cuboid microcrystals have been identified as magnesium whitlockite. Our objective was to investigate their presence in the human intervertebral disc. In this study, two degenerate and 15 scoliotic discs were examined using light microscopy and TEM techniques to determine the presence of calcium phosphate crystals. Calcium pyrophosphate dihydrate (CPPD) deposition was identified in one degenerate disc specimen. Using TEM and electron probe analysis, cuboid microcrystals were identified in the annulus fibrosus and nucleus pulposus of both degenerate specimens, but not in the discs from young scoliotic patients. Cuboid microcrystal deposition was found predominantly around cells, which were mainly necrotic, with some association with extracellular lipidic/membranous debris. This is the first TEM report of whitlockite in the intervertebral disc. In one specimen coexistence of cuboid and CPPD crystal deposition was found. PMID:16420375

  9. Calcium phosphate microcrystal deposition in the human intervertebral disc

    PubMed Central

    Lee, Robert S; Kayser, Mike V; Yousuf Ali, S

    2006-01-01

    A variety of crystals have been identified in both normal and pathological connective tissues. Calcium phosphate ‘cuboidal’ microcrystal deposition has been found, using transmission electron microscopy (TEM), in femoral articular cartilage, where they are distributed as a band 5–50 µm beneath the articular surface. These cuboid microcrystals have been identified as magnesium whitlockite. Our objective was to investigate their presence in the human intervertebral disc. In this study, two degenerate and 15 scoliotic discs were examined using light microscopy and TEM techniques to determine the presence of calcium phosphate crystals. Calcium pyrophosphate dihydrate (CPPD) deposition was identified in one degenerate disc specimen. Using TEM and electron probe analysis, cuboid microcrystals were identified in the annulus fibrosus and nucleus pulposus of both degenerate specimens, but not in the discs from young scoliotic patients. Cuboid microcrystal deposition was found predominantly around cells, which were mainly necrotic, with some association with extracellular lipidic/membranous debris. This is the first TEM report of whitlockite in the intervertebral disc. In one specimen coexistence of cuboid and CPPD crystal deposition was found. PMID:16420375

  10. Biomaterials 26 (2005) 63236334 Compositional effects on the formation of a calcium phosphate layer

    E-print Network

    Lu, Helen H.

    2005-01-01

    Biomaterials 26 (2005) 6323­6334 Compositional effects on the formation of a calcium phosphate. Solution phosphorous and calcium concentrations will also be measured. The second objective of the study

  11. Abstract No Hung0356 A P-XANES Study of Phosphate Sorption to Gibbsite and Calcium Carbonate

    E-print Network

    Sparks, Donald L.

    Abstract No Hung0356 A P-XANES Study of Phosphate Sorption to Gibbsite and Calcium Carbonate S to investigate phosphate sorption reactions to gibbsite (Al(OH)3) in the presence of calcium and to calcium solution and freeze-dried. Samples of phosphate sorbed to calcium carbonate were prepared in a similar

  12. Can. J. Fish. Aquat. Sci. (2013) Prepublication Draft Page 1 Modeling the Calcium and Phosphate Mineralization

    E-print Network

    Kunkel, Joseph G.

    2013-01-01

    Can. J. Fish. Aquat. Sci. (2013) Prepublication Draft Page 1 Modeling the Calcium and Phosphate, model building, biomineralization, ab initio, carbonate apatite, calcite, amorphous calcium carbonate content, fig 1 (Kunkel et al. 2012; Kunkel and Jercinovic 2013). Calcium carbonate is the dominant calcium

  13. Premixed injectable calcium phosphate cement with excellent suspension stability.

    PubMed

    Chen, Fangping; Mao, Yuhao; Liu, Changsheng

    2013-07-01

    Premixed injectable calcium phosphate cement (p-ICPC) pastes have advantages over aqueous injectable calcium phosphate cement (a-ICPC) because p-ICPC remain stable during storage and harden only after placement into the defect. This paper focused on the suspension stability of p-ICPC paste by using fumed silica as a stabilizing agent and propylene glycol (PEG) as a continuous phase. Multiple light scanning techniques were first applied to evaluate the suspension stability. The results indicated that fumed silica effectively enhanced the suspension stability of p-ICPC pastes. The stabilizing effect of fumed silica results from the network structure formed in PEG because of its thixotropy. The p-ICPC could be eventually hydrated to form hydroxyapatite under aqueous circumstances by the unique replacement between water and PEG. p-ICPC (1) not only possesses proper thixotropy and compressive strength but has good injectability as well. p-ICPC (1) was cytocompatible and had no adverse effect on the attachment and proliferation of MG-63 cells in vitro. These observations may have applicability to the development of other nonaqueous injectable biomaterials for non-immediate filling and long-term storage. PMID:23563980

  14. Nucleation, growth and evolution of calcium phosphate films on calcite.

    PubMed

    Naidu, Sonia; Scherer, George W

    2014-12-01

    Marble, a stone composed of the mineral calcite, is subject to chemically induced weathering in nature due to its relatively high dissolution rate in acid rain. To protect monuments and sculpture from corrosion, we are investigating the application of thin layers of hydroxyapatite (HAP) onto marble. The motivation for using HAP is its low dissolution rate and crystal and lattice compatibility with calcite. A mild, wet chemical synthesis route, in which diammonium hydrogen phosphate salt was reacted with marble, alone and with cationic and anionic precursors under different reaction conditions, was used to produce inorganic HAP layers on marble. Nucleation and growth on the calcite substrate was studied, as well as metastable phase evolution, using scanning electron microscopy, grazing incidence X-ray diffraction, and atomic force microscopy. Film nucleation was enhanced by surface roughness. The rate of nucleation and the growth rate of the film increased with cationic (calcium) and anionic (carbonate) precursor additions. Calcium additions also influenced phase formation, introducing a metastable phase (octacalcium phosphate) and a different phase evolution sequence. PMID:25233226

  15. The flame photometric determination of calcium in phosphate, carbonate, and silicate rocks

    USGS Publications Warehouse

    Kramer, H.

    1957-01-01

    A flame photometric method of determining calcium in phosphate, carbonate, and silicate locks has been developed Aluminum and phosphate interference was overcome by the addition of a large excess of magnesium. The method is rapid and suitable for routine analysis Results obtained are within ?? 2% of the calcium oxide content. ?? 1957.

  16. Biphasic calcium phosphate concept applied to artificial bone, implant coating and injectable bone substitute

    Microsoft Academic Search

    G. Daculsi

    1998-01-01

    The development of calcium phosphate ceramics and other related biomaterials for bone graft involved a better control of the process of biomaterials resorption and bone substitution. The bioactive concept was developed for biphasic calcium phosphate ceramics (BCP). An optimum balance of the more stable phase of HA and more soluble TCP was obtained for controlling gradual dissolution in the body,

  17. [Exploration of the parathyroid gland function by intake or oral calcium and phosphate (only oral intake and sequential treatment with calcium-phosphate)].

    PubMed

    Guillemant, J; Oberlin, F; Horlait, S; Guillemant, S

    1991-10-01

    The parathyroid hormone response to the oral intake of either calcium or phosphate was explored in 10 young adults (23-28 years). First, the subjects were investigated during free running diet. They ingested a single oral dose of 500 mg of calcium (as a bag of Sandocal) and 10 days later a single oral dose of phosphate (750 mg of phosphorus as a tablet of Phosphore Sandoz Forte). Samples of blood and urine were collected before and during the 4 hours following the ingestion of either calcium or phosphate. After intake of calcium an acute response was obtained with a 58% decrease in PTH 1-84 at 1 hr (p less than 0.001) and a 33% decrease in nephrogenous cAMP (p less than 0.001). After ingestion of phosphate the response was delayed and less constant with a 25% increase in PTH 1-84 at 3 hr (p less than 0.01) and a 27% increase in nephrogenous cAMP (p less than 0.001). Then, the effects of a calcium therapy (3 daily doses of 500 mg each for 20 days) and of a subsequent phosphate therapy (2 daily doses of 750 mg each for 10 days) on the parathyroid hormone response to the administration of a single dose of phosphate were studied. On days 10, 21 and 31 baseline blood and urine samples were obtained prior to calcium and phosphate administration for measuring PTH 1-84 and nephrogenous cAMP. No significant variation was found. On days 21 (after calcium therapy) and 31 (after phosphate therapy) an oral load of phosphate was administered according to the procedure described above.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1663656

  18. [Chondrocalcinosis. Clinical impact of intra-articular calcium phosphate crystals].

    PubMed

    Fuerst, M

    2014-06-01

    Calcium pyrophosphate dihydrate (CPPD) crystals are known to cause acute attacks of pseudogout in joints but crystal deposition has also been reported to be associated with osteoarthritis (OA). Aside from CPPD crystals, basic calcium phosphates (BCPs), consisting of carbonate-substituted hydroxyapatite (HA), tricalcium phosphate and octacalcium phosphate, have been found in synovial fluid, synovium and cartilage of patients with OA. Although CPPD crystals have been found to be associated with OA and are an important factor in joint disease, this has also recently been associated with a genetic defect. However, according to the most recent findings, the association of BCP crystals, such as apatite with OA is much stronger, as their presence significantly correlates with the severity of cartilage degeneration. Identification of BCP crystals in OA joints remains problematic due to a lack of simple and reliable methods of detection. The clinical and pathological relevance of cartilage mineralization in patients with OA is not completely understood. It is well established that mineralization of articular cartilage is often found close to hypertrophic chondrocytes. A significant correlation between the expression of type X collagen, a marker for chondrocyte hypertrophy and cartilage mineralization was observed. In the process of endochondral ossification, the link between hypertrophy and matrix mineralization is particularly well described. Hypertrophic chondrocytes in OA cartilage and at the growth line share certain features, not only hypertrophy but also a capability to mineralize the matrix. Recent data indicate that chondrocyte hypertrophy is a key factor in articular cartilage mineralization strongly linked to OA and does not characterize a specific subset of OA patients, which has important consequences for therapeutic strategies for OA. PMID:24924727

  19. Biocompatibility and resorption of a brushite calcium phosphate cement.

    PubMed

    Theiss, Felix; Apelt, Detlef; Brand, Bastian; Kutter, Annette; Zlinszky, Katalin; Bohner, Marc; Matter, Sandro; Frei, Christian; Auer, Joerg A; von Rechenberg, Brigitte

    2005-07-01

    A hydraulic calcium phosphate cement with beta-tricalcium phosphate (TCP) granules embedded in a matrix of dicalcium phosphate dihydrate (DCPD) was implanted in experimentally created defects in sheep. One type of defect consisted of a drill hole in the medial femoral condyle. The other, partial metaphyseal defect was located in the proximal aspect of the tibia plateau and was stabilized using a 3.5 mm T-plate. The bone samples of 2 animals each per group were harvested after 2, 4, 6 and 8 weeks. Samples were evaluated for cement resorption and signs of immediate reaction, such as inflammation, caused by the cement setting in situ. Differences regarding these aspects were assessed for both types of defects using macroscopical, radiological, histological and histomorphometrical evaluations. In both defects the brushite matrix was resorbed faster than the beta-TCP granules. The resorption front was followed directly by a front of new bone formation, in which residual beta-TCP granules were embedded. Cement resorption occurred through (i) extracellular liquid dissolution with cement disintegration and particle formation, and (ii) phagocytosis of the cement particles through macrophages. Signs of inflammation or immunologic response leading to delayed new bone formation were not noticed at any time. Cement degradation and new bone formation occurred slightly faster in the femur defects. PMID:15701367

  20. Preparation of macroporous calcium phosphate cement tissue engineering scaffold.

    PubMed

    Barralet, J E; Grover, L; Gaunt, T; Wright, A J; Gibson, I R

    2002-08-01

    Unlike sintered hydroxyapatite there is evidence to suggest that calcium phosphate cement (CPC) is actively remodelled in vivo and because CPC is formed by a low-temperature process, thermally unstable compounds such as proteins may be incorporated into the matrix of the cement which can then be released after implantation. The efficacy of a macroporous CPC as a bone tissue engineering scaffold has been reported; however, there have been few previous studies on the effect of macroporosity on the mechanical properties of the CPC. This study reports a novel method for the formation of macroporous CPC scaffolds, which has two main advantages over the previously reported manufacturing route: the cement matrix is considerably denser than CPC formed from slurry systems and the scaffold is formed at temperatures below room temperature. A mixture of frozen sodium phosphate solution particles and CPC powder were compacted at 106 MPa and the sodium phosphate was allowed to melt and simultaneously set the cement. The effect of the amount of porogen used during processing on the porosity, pore size distribution and compressive strength of the scaffold was investigated. It was found that macroporous CPC could reliably be fabricated using cement:ice ratios as low as 5:2. PMID:12102177

  1. Bone Origin of the Serum Complex of Calcium, Phosphate, Fetuin, and Matrix Gla Protein: Biochemical Evidence for

    E-print Network

    Price, Paul A.

    Bone Origin of the Serum Complex of Calcium, Phosphate, Fetuin, and Matrix Gla Protein: Biochemical-remodeling compartment (BRC), a cancellous bone compartment in which the concentrations of calcium and phosphate will cause a sharp rise in the concentrations of calcium and phosphate in the aqueous solution of the BRC

  2. Structural characterization of Sol-Gel derived Sr-substituted calcium phosphates with anti-osteoporotic and

    E-print Network

    Paris-Sud XI, Université de

    1 Structural characterization of Sol-Gel derived Sr- substituted calcium phosphates with anti to prepare un-doped and Sr-doped calcium phosphate ceramics exhibiting a porous structure. The samples) and Tri Calcium Phosphate (-TCP). Doping with Sr2+ ions has a clear effect on the proportions

  3. Physico-chemical and in vitro biological properties of novel doped amorphous calcium phosphate-based cements.

    E-print Network

    Paris-Sud XI, Université de

    1 Physico-chemical and in vitro biological properties of novel doped amorphous calcium phosphate Abstract Calcium phosphate cements (CPC) are successfully used as bone substitutes in dentistry of a settable matrix and biphasic calcium phosphates (BCP) granules. X-ray diffraction data of the cement

  4. Rapid coating of Ti6Al4V at room temperature with a calcium phosphate solution similar to 10 simulated

    E-print Network

    Tas, A. Cuneyt

    Rapid coating of Ti6Al4V at room temperature with a calcium phosphate solution similar to 10, we report the utilization of high ionic strength (>1100 mM) calcium phosphate solutions in depositing 20­65- m-thick, bonelike apatitic calcium phosphate on Ti6Al4V within 2­6 h, at room temperature

  5. Calcium Phosphate Nanoparticles Synthesis Make sure the hood is clean and free of all chemicals other than the ones required.

    E-print Network

    Burgess, Kevin

    Calcium Phosphate Nanoparticles Synthesis Procedure: · Make sure the hood is clean and free of all to dissolve calcium chloride completely). · Likewise prepare 6 x 10-3 M disodium phosphate solution from the above degassed water. · Disodium phosphate is less soluble in water than calcium chloride; please stir

  6. The Inhibition of Calcium Phosphate Precipitation by Fetuin Is Accompanied by the Formation of a Fetuin-Mineral Complex*

    E-print Network

    Price, Paul A.

    The Inhibition of Calcium Phosphate Precipitation by Fetuin Is Accompanied by the Formation- apatite from supersaturated solutions of calcium and phosphate in vitro is accompanied by the formation of the fetuin-mineral complex, a high molecular mass com- plex of calcium phosphate mineral and the proteins fe

  7. Solid-Liquid Adsorption of Calcium Phosphate on TiO2 C. C. Chusuei and D. W. Goodman*

    E-print Network

    Goodman, Wayne

    Solid-Liquid Adsorption of Calcium Phosphate on TiO2 C. C. Chusuei and D. W. Goodman* Department of Chemistry, Texas A&M University, College Station, Texas 77843-3144 Received April 27, 1999 Calcium phosphate evidence for 3-dimensional (3D) phosphate islands forming on top of the calcium. ToF-SIMS analysis of CP

  8. A new approach in biomimetic synthesis of calcium phosphate coatings using lactic acidNa lactate buffered body fluid solution

    E-print Network

    Tas, A. Cuneyt

    A new approach in biomimetic synthesis of calcium phosphate coatings using lactic acid­Na lactate phosphate Coating Biomimetic a b s t r a c t The main objective of this study was to investigate calcium,3]. More recently, calcium phosphate (CaP) coatings, such as hydroxyapatite (Ca10(PO4)6(OH)2), have been

  9. 45S5 Bioactive glass surface charge variations and the formation of a surface calcium phosphate layer in a

    E-print Network

    Lu, Helen H.

    45S5 Bioactive glass surface charge variations and the formation of a surface calcium phosphate: bioactivity; surface charge; fibronectin; protein adsorption; calcium phosphate layer INTRODUCTION By forming a surface calcium phosphate layer in vivo, bioactive materials, such as 45S5 bioactive glass (BG), are able

  10. Porous, Biphasic CaCO3-Calcium Phosphate Biomedical Cement Scaffolds from Calcite (CaCO3) Powder

    E-print Network

    Tas, A. Cuneyt

    Porous, Biphasic CaCO3-Calcium Phosphate Biomedical Cement Scaffolds from Calcite (CaCO3) Powder AH 3.2 by adding NaOH, to form biphasic, micro-, and macroporous calcite-apatitic calcium phosphate (Ap-stoichiometric, apatitic calcium phosphate (Ap-CaP) with a large and reactive surface area of 100­ 200 m2 /g.23 Bone

  11. Patterns of radiographic abnormalities associated with basic calcium phosphate and calcium pyrophosphate dihydrate crystal deposition in the knee

    Microsoft Academic Search

    P B Halverson; D J McCarty

    1986-01-01

    Radiographs and synovial fluids from 66 knees representing 59 patients with symptomatic osteoarthritis were evaluated to determine the pattern of radiographic abnormalities associated with basic calcium phosphate (BCP), calcium pyrophosphate dihydrate (CPPD), or both crystals together. Crystals were found in 71% of fluids. In general, CPPD crystals correlated with patient age, while BCP crystals correlated with joint degeneration. Synovial fluid

  12. Novel dental adhesive containing antibacterial agents and calcium phosphate nanoparticles.

    PubMed

    Melo, Mary Anne S; Cheng, Lei; Weir, Michael D; Hsia, Ru-Ching; Rodrigues, Lidiany K A; Xu, Hockin H K

    2013-05-01

    Secondary caries remains the main reason for dental restoration failure. Replacement of failed restorations accounts for 50%-70% of all restorations performed. Antibacterial adhesives could inhibit biofilm acids at tooth-restoration margins, and calcium phosphate (CaP) ions could remineralize tooth lesions. The objectives of this study were to: (1) incorporate nanoparticles of silver (NAg), quaternary ammonium dimethacrylate (QADM), and nanoparticles of amorphous calcium phosphate (NACP) into bonding agent; and (2) investigate their effects on dentin bonding and microcosm biofilms. An experimental primer was made with pyromellitic glycerol dimethacrylate (PMGDM) and 2-hydroxyethyl methacrylate (HEMA). An adhesive was made with bisphenol-A-glycerolate dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA). NAg was incorporated into primer at 0.1 wt %. The adhesive contained 0.1% NAg and 10% QADM, and 0%-40% NACP. Incorporating NAg into primer and NAg-QADM-NACP into adhesive did not adversely affect dentin bond strength (p > 0.1). Scanning electron microscopy showed numerous resin tags, and transmission electron microscopy revealed NAg and NACP in dentinal tubules. Viability of human saliva microcosm biofilms on primer/adhesive/composite disks was substantially reduced via NAg and QADM. Metabolic activity, lactic acid, and colony-forming units of biofilms were much lower on the new bonding agents than control (p < 0.05). In conclusion, novel dental bonding agents containing NAg, QADM, and NACP were developed with the potential to kill residual bacteria in the tooth cavity and inhibit the invading bacteria along tooth-restoration margins, with NACP to remineralize tooth lesions. The novel method of combining antibacterial agents (NAg and QADM) with remineralizing agent (NACP) may have wide applicability to other adhesives for caries inhibition. PMID:23281264

  13. Calcium phosphate nanoparticles functionalized with a dimethacrylate monomer.

    PubMed

    Rodrigues, Marcela Charantola; Hewer, Thiago Lewis Reis; Brito, Giancarlo Espósito de Souza; Arana-Chavez, Victor Elias; Braga, Roberto Ruggiero

    2014-12-01

    The synthesis of calcium phosphate nanoparticles may include modifying agents to tailor particle size, reduce agglomeration and add specific functionalities. This study describes the synthesis of dicalcium phosphate dihydrate (DCPD) nanoparticles functionalized with triethylene glycol dimethacrylate (TEGDMA), added to one of the reacting solutions, with the purpose of reducing agglomeration and improving the compatibility with vinyl-based resin matrices. The nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), elemental analysis, thermogravimetric analysis (TGA), transmission electronic microscopy (TEM), dynamic light scattering (DLS), and surface area (BET). As controls, proprietary DCPD nanoparticles and nanoparticles synthesized without the addition of TEGDMA ("bare") were subjected to the same analytical methods. XRD revealed a similar crystalline structure of the synthesized materials in comparison to the proprietary nanoparticles. The presence of a TEGDMA layer was confirmed by elemental analysis and TGA, corresponding to a mass fraction of 8.5%. FTIR analysis of the functionalized nanoparticles revealed the suppression of some absorbance bands found in the neat TEGDMA. A chemisorption mechanism between TEGDMA and the surface of primary particles by ion-dipole interaction involving TEGDMA oxyethylene, and also an interaction mechanism between the particle surface and terminal-CH3 groups are proposed. Functionalized nanoparticles showed 3 to 11 times higher surface area than the controls, in agreement with DLS data, indicating lower agglomeration. PMID:25491810

  14. Injectable calcium-phosphate-based composites for skeletal bone treatments.

    PubMed

    Ambrosio, L; Guarino, V; Sanginario, V; Torricelli, P; Fini, M; Ginebra, M P; Planell, J A; Giardino, R

    2012-04-01

    Alpha-tricalcium-phosphate-based bone cements hydrolyze and set, producing calcium-deficient hydroxyapatite. They can result in an effective solution for bone defect reconstruction due to their biocompatibility, bioactivity and adaptation to shape and bone defect sizes, together with an excellent contact between bone and graft. Moreover, the integration of hydrogel phase based on poly(vinyl alcohol) (PVA) to H-cem-composed of ?-tricalcium phosphate (98% wt) and hydroxyapatite (2% wt)-allows improving the mechanical and biological properties of the cement. The aim of this work was to evaluate the influence of the PVA on relevant properties for the final use of the injectable bone substitute, such as setting, hardening, injectability and in vivo behaviour. It was shown that by using PVA it is possible to modulate the setting and hardening properties: large increase in injectability time (1 h) in relation with the plain cement (few minutes) was achieved. Moreover, in vivo tests confirmed the ability of the composite to enhance bone healing in trabecular tissue. Histological results from critical size defects produced in rabbit distal femoral condyles showed after 12 weeks implantation a greater deposition of new tissue on bone-composite interfaces in comparison to bone-cement interfaces. The quality of bone growth was confirmed through histomorphometric and microhardness analysis. Bone formation in the composite implantation sites was significantly higher than in H-cem implants at both times of evaluation. PMID:22456083

  15. Sustained release of simvastatin from premixed injectable calcium phosphate cement.

    PubMed

    Montazerolghaem, Maryam; Engqvist, Håkan; Karlsson Ott, Marjam

    2014-02-01

    Locally applied simvastatin is known to promote bone regeneration; however, the lack of suitable delivery systems has restricted its clinical use. In this study we demonstrate for the first time the use of premixed acidic calcium phosphate cement (CPC) as a delivery system for water-solubilized simvastatin. Freeze-dried simvastatin ?-hydroxy acid (SVA) was added to the premixed cement paste in four different doses (1, 0.5, 0.25, and 0 mg SVA/g cement). The addition of the drug did not alter the cement setting time (38 min), compression strength (5.54 MPa), or diametral tensile strength (2.62 MPa). In a release study conducted in phosphate buffered saline at 37°C, a diffusion-controlled release was observed for over a week. Furthermore, the osteogenic effect of the released SVA was demonstrated in vitro. Cell proliferation, alkaline phosphatase activity, and mineralization were assayed after incubation with cement extracts. The lower doses of SVA (0.5 and 0.25 mg SVA/g cement) showed an approximately fourfold increase in mineralization as compared to the control. In conclusion, our findings suggest that premixed acidic CPC is a good option for local delivery of SVA, due to its ability of slowly releasing the drug, leading to a prolonged stimulation of osteogenesis. PMID:23533004

  16. The initial phases of calcium and magnesium phosphates precipitated from solutions of high to medium concentrations

    NASA Astrophysics Data System (ADS)

    Abbona, F.; Madsen, H. E. Lundager; Boistelle, R.

    1986-04-01

    The precipitation of calcium and magnesium phosphates is performed at 25°C by mixing solutions of ammonium phosphate and solutions of calcium and magnesium chlorides under the condition [ P] = [ Ca] + [ Mg] in large pH intervals. Before any nucleation the phosphate concentration ranges from 0.50M to 0.01M. The phases first precipitated are CaHPO 4·2H 2O (brushite), CaHPO 4 (monetite), Ca 3(PO 4) 2· xH 2O (amorphous calcium phosphate), MgNH 4PO 4·6H 2O (struvite), and MgHPO 4·3H 2O (newberyite). The precipitation fields of each phase are determined and discussed as a function of pH, composition and supersaturation. The solutions are even supersaturated with respect to several other calcium phosphates but they never occur first even if their supersaturation is the highest.

  17. Polymeric additives to enhance the functional properties of calcium phosphate cements

    PubMed Central

    Perez, Roman A; Kim, Hae-Won

    2012-01-01

    The vast majority of materials used in bone tissue engineering and regenerative medicine are based on calcium phosphates due to their similarity with the mineral phase of natural bone. Among them, calcium phosphate cements, which are composed of a powder and a liquid that are mixed to obtain a moldable paste, are widely used. These calcium phosphate cement pastes can be injected using minimally invasive surgery and adapt to the shape of the defect, resulting in an entangled network of calcium phosphate crystals. Adding an organic phase to the calcium phosphate cement formulation is a very powerful strategy to enhance some of the properties of these materials. Adding some water-soluble biocompatible polymers in the calcium phosphate cement liquid or powder phase improves physicochemical and mechanical properties, such as injectability, cohesion, and toughness. Moreover, adding specific polymers can enhance the biological response and the resorption rate of the material. The goal of this study is to overview the most relevant advances in this field, focusing on the different types of polymers that have been used to enhance specific calcium phosphate cement properties. PMID:22511991

  18. Calcium phosphate granulation in anaerobic treatment of black water: a new approach to phosphorus recovery.

    PubMed

    Tervahauta, Taina; van der Weijden, Renata D; Flemming, Roberta L; Hernández Leal, Lucía; Zeeman, Grietje; Buisman, Cees J N

    2014-01-01

    Recovery of phosphorus from wastewater as calcium phosphate could diminish the need for mining of scarce phosphate rock resources. This study introduces a novel approach to phosphorus recovery by precipitation of calcium phosphate granules in anaerobic treatment of black water. The granules formed in the Upflow Anaerobic Sludge Blanket (UASB) reactor at lab- and demonstration-scale were analyzed for chemical composition and mineralogy by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Electron microprobe (EMP), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and micro X-ray Diffraction (XRD). The granules had a diameter of 1-2 mm, organic content of 33 wt%, and phosphorus content of 11-13 wt%. Three calcium phosphate phases were identified in the granules: hydroxyapatite, calcium phosphate hydrate and carbonated hydroxyapatite. Without any addition of chemicals, 7 gP/person/year can be recovered with the calcium phosphate granules, representing 2% of the incoming phosphorus in the UASB reactor. As the heavy metal content was lower compared to other phosphorus recovery products, phosphate rock and phosphorus fertilizer, the calcium phosphate granules could be considered as a new phosphorus product. PMID:24183558

  19. Precipitation of calcium carbonate and calcium phosphate under diffusion controlled mixing

    SciTech Connect

    Tsigabu Gebrehiwet; James R. Henriksen; Luanjing Guo; Don T. Fox; Hai Huang; Lee Tu; Yoshiko Fujita; Robert W. Smith; George Redden

    2014-07-01

    Multi-component mineral precipitation in porous, subsurface environments is challenging to simulate or engineer when in situ reactant mixing is controlled by diffusion. In contrast to well-mixed systems, the conditions that favor mineral precipitation in porous media are distributed along chemical gradients, which evolve spatially due to concurrent mineral precipitation and modification of solute transport in the media. The resulting physical and chemical characteristics of a mixing/precipitation zone are a consequence of coupling between transport and chemical processes, and the distinctive properties of individual chemical systems. We examined the spatial distribution of precipitates formed in “double diffusion” columns for two chemical systems, calcium carbonate and calcium phosphate. Polyacrylamide hydrogel was used as a low permeability, high porosity medium to maximize diffusive mixing and minimize pressure- and density-driven flow between reactant solutions. In the calcium phosphate system, multiple, visually dense and narrow bands of precipitates were observed that were reminiscent of previously reported Liesegang patterns. In the calcium carbonate system, wider precipitation zones characterized by more sparse distributions of precipitates and a more open channel structure were observed. In both cases, formation of precipitates inhibited, but did not necessarily eliminate, continued transport and mixing of the reactants. A reactive transport model with fully implicit coupling between diffusion, chemical speciation and precipitation kinetics, but where explicit details of nucleation processes were neglected, was able to qualitatively simulate properties of the precipitation zones. The results help to illustrate how changes in the physical properties of a precipitation zone depend on coupling between diffusion-controlled reactant mixing and chemistry-specific details of precipitation kinetics.

  20. Low temperature solution deposition of calcium phosphate coatings for orthopedic implants

    SciTech Connect

    Campbell, A.A.; Graff, G.L.

    1994-04-01

    Calcium phosphate coatings were grown from aqueous solution onto a derivatized self-assmebled monolayer (SAM) which was covalently bound to a titanium metal substrate. The SAM molecules provided an idea connection between the metal surface and the calcium phosphate coating. The trichlorosilane terminus of the SAM molecule insured covalent attachment to the surface, while the functionalized ``tail`` induced heterogeneous nucleation of the calcium phosphate coating from supersaturated solutions. This low temperature process allowed for uniform coatings to be produced onto complex-shaped and/or microporous surfaces and provided better control of phase purity.

  1. Structure, properties and animal study of a calcium phosphate/calcium sulfate composite cement.

    PubMed

    Chen, Wei-Luen; Chen, Chang-Keng; Lee, Jing-Wei; Lee, Yu-Ling; Ju, Chien-Ping; Lin, Jiin-Huey Chern

    2014-04-01

    In-vitro and in-vivo studies have been conducted on an in-house-developed tetracalcium phosphate (TTCP)/dicalcium phosphate anhydrous (DCPA)/calcium sulfate hemihydrate (CSH)-derived composite cement. Unlike most commercial calcium-based cement pastes, the investigated cement paste can be directly injected into water and harden without dispersion. The viability value of cells incubated with a conditioned medium of cement extraction is >90% that of Al2O3 control and >80% that of blank medium. Histological examination reveals excellent bonding between host bone and cement without interposition of fibrous tissues. At 12 weeks-post implantation, significant remodeling activities are found and a new bone network is developed within the femoral defect. The 26-week samples show that the newly formed bone becomes more mature, while the interface between residual cement and the new bone appears less identifiable. Image analysis indicates that the resorption rate of the present cement is much higher than that of TTCP or TTCP/DCPA-derived cement under similar implantation conditions. PMID:24582223

  2. Biogenic Calcium Phosphate Transformation in Soils over Millennium Time Scales

    SciTech Connect

    Sato, S.; Neves, E; Solomon, D; Liang, B; Lehmann, J

    2009-01-01

    Changes in bioavailability of phosphorus (P) during pedogenesis and ecosystem development have been shown for geogenic calcium phosphate (Ca-P). However, very little is known about long-term changes of biogenic Ca-P in soil. Long-term transformation characteristics of biogenic Ca-P were examined using anthropogenic soils along a chronosequence from centennial to millennial time scales. Phosphorus fractionation of Anthrosols resulted in overall consistency with the Walker and Syers model of geogenic Ca-P transformation during pedogenesis. The biogenic Ca-P (e.g., animal and fish bones) disappeared to 3% of total P within the first ca. 2,000 years of soil development. This change concurred with increases in P adsorbed on metal-oxides surfaces, organic P, and occluded P at different pedogenic time. Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy revealed that the crystalline and therefore thermodynamically most stable biogenic Ca-P was transformed into more soluble forms of Ca-P over time. While crystalline hydroxyapatite (34% of total P) dominated Ca-P species after about 600-1,000 years, {Beta}-tricalcium phosphate increased to 16% of total P after 900-1,100 years, after which both Ca-P species disappeared. Iron-associated P was observable concurrently with Ca-P disappearance. Soluble P and organic P determined by XANES maintained relatively constant (58-65%) across the time scale studied. Conclusions - Disappearance of crystalline biogenic Ca-P on a time scale of a few thousand years appears to be ten times faster than that of geogenic Ca-P.

  3. Calcium phosphate substrate-directed osteogenic differentiation of mesenchymal stem cells 

    E-print Network

    Cameron, Katherine Rachel

    2013-07-06

    of bone. Given the significant roles of silicon in bone growth and development there has been great interest in introducing silicon into synthetic bone grafts to enhance their bioactivity. Calcium phosphate based silicate containing grafts have...

  4. Effect of phosphate, calcium, and pH on the dissolution of a phosphate rock in soil

    Microsoft Academic Search

    AD Mackay; JK Syers

    1986-01-01

    The effect of phosphate (P), calcium (Ca), and pH on the dissolution of Sechura phosphate rock (SPR) in a Typic Dystrochrept was investigated in an incubation study over 90 days. Increasing the P status of the soil had little effect on either the rate or extent of dissolution of SPR, as measured by a single extraction with 0.5M NaOH, or

  5. TEM studies of calcium phosphates for the understanding of biomineralization

    NASA Astrophysics Data System (ADS)

    Xin, Renlong

    Calcium phosphate (Ca-P) formation and bone minerals have been the focus of research for several decades because achievements in these areas could provide valuable insights into the understanding of biomineralization. In this thesis work, Ca-P formation, octacalcium phosphate (OCP) to hydroxyapatite (HA) transformation and bone minerals were systematically studied by transmission electron microscopy (TEM) techniques. Ca-P formations on various bioceramics in simulated body fluid and in rabbit muscle sites were investigated. The bioceramics included sintered bioglass RTM, A-W glass-ceramics, HA, alpha-tricalcium phosphate (TCP), beta-TCP and HA-TCP. The comparative studies showed that OCP formation occurred on all types of bioceramic surfaces in vitro and in vivo, except on beta-TCP; however HA formation did not occur on every type of bioceramics; it less likely occurred on the surfaces of HA and alpha-TCP. These findings were contradicted to the common statements in literatures. OCP to HA transformations in vitro and in vivo were observed by high-resolution TEM (HRTEM). The in vitro transformation was induced by electron beam irradiations of in situ TEM on synthetic OCP crystals. The in vivo transformation was revealed on rod-like HA precipitates formed in dog muscle sites. Based on HRTEM examinations and image simulations, OCP/HA crystallographic orientations were determined to be OCP (010) // HA (01¯0) and OCP (001) // HA (001¯), which differed from a well known model proposed by Brown et al. The minerals of cortical bone were extracted from human tibiae and rat femurs using 10% neutral ethylenediamine tetraacetic acid (EDTA) solution. TEM examinations showed that the dominance of bone minerals was plate-like and a few were needle-like. The length of most plate-like minerals ranged from 50 to 150 nm but could be up to 200 nm. To the author's knowledge, OCP structure was for the first time, identified in a number of plate-like bone minerals by selected area electron diffraction (SAED) and HRTEM.

  6. Transfecting mammalian cells: optimization of critical parameters affecting calcium-phosphate precipitate formation

    Microsoft Academic Search

    Martin Jordan; Annette Schallhorn; Florian M. Wurm

    1996-01-01

    DNA-calcium phosphate co-precipitates arise spontaneously in supersaturated solutions. Highly effective precipitates for transfection purposes, however, can be generated only in a very narrow range of physico-chemical conditions that control the initiation and growth of precipitate complexes. The concentrations of calcium and phosphate are the main factors influencing characteristics of the precipitate complex, but other parameters, such as temperature, DNA concentration

  7. Effect of feeding high calcium levels and soft phosphate in the diet of laying hens 

    E-print Network

    Durham, James Ivey

    1961-01-01

    EFFECT OF FEEDING HIGH CALCIUM LEVELS AND SOFT PHOSPHATE IN THE DIET OF LAYING HENS A Thesis by James Ivey Durham Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in partial fulfillment of the requirements... Bone and the csi rum and Inorganic: Phosphate Cont ent. af. Blood Serum. . . . . . . . , . . . , Table 12 Analysis of Variance of Ashr Calcium and Pircsp, Content ar Eggshells snd the phosphorus Conte. u . I' Earrr Ash. 35 Table 13 Simple...

  8. X-ray diffraction radial distribution function studies on bone mineral and synthetic calcium phosphates

    Microsoft Academic Search

    M. D. Grynpas; L. C. Bonar; Melvin J. Glimcher

    1984-01-01

    An investigation of the molecular structure of bone mineral and synthetic calcium phosphates was carried out using radial distribution function (RDF) techniques. The X-ray data were collected using CuKa and MoKa radiation to insure the validity of the RDFs. Synthetic preparations of hydroxyapatite (HA) varying in their crystal size and crystallinity, and amorphous calcium phosphate (ACP), were studied, as well

  9. A comparison of the calcium-free phosphate binder sevelamer hydrochloride with calcium acetate in the treatment of hyperphosphatemia in hemodialysis patients

    Microsoft Academic Search

    Anthony J. Bleyer; Steven K. Burke; Maureen Dillon; Bruce Garrett; K. Shashi Kant; David Lynch; S. Noor Rahman; Patricia Schoenfeld; Isaac Teitelbaum; Steven Zeig; Eduardo Slatopolsky

    1999-01-01

    Current phosphate binders used in hemodialysis patients include calcium-based binders that result in frequent hypercalcemia and aluminum-based binders that result in total body aluminum accumulation over time. This investigation describes the use of a calcium- and aluminum-free phosphate-binding polymer in hemodialysis patients and compares it with a standard calcium-based phosphate binder. An open-label, randomized, crossover study was performed to evaluate

  10. RBS and XPS analyses of the composite calcium phosphate coatings for biomedical applications

    NASA Astrophysics Data System (ADS)

    Ide-Ektessabi, Ari; Yamaguchi, Tetsuro; Tanaka, Yoshikazu

    2005-12-01

    The calcium phosphate coatings on metallic implants are widely used for biomedical applications. The calcium phosphate coatings require mechanical strength, strong adhesion to the metallic implants, chemical stability and low dissolution into the human body fluid for stable functioning in the corrosive environment of the human body. In this study, a novel approach for improving the calcium phosphate coatings is utilized by adding trace metallic element into the coatings. We focused on teeth enamel, which is the hardest calcium phosphate tissue in the human body. Zn concentration increases exponentially from the interior to the surface of the enamel. As the Zn concentration increases, so the local hardness increases. Our previous studies suggest that Zn has influence on the hardness and other properties of enamel, calcium phosphate tissue. Calcium phosphate coatings doped with Zn was fabricated and characterized. The atomic composition and chemical state were investigated by using Rutherford backscattering spectroscopy (RBS) and X-ray photoelectron spectrometer (XPS), respectively. Scratch test was also carried out for measuring the adhesion of the coatings.

  11. Antibacterial nanocomposite with calcium phosphate and quaternary ammonium.

    PubMed

    Cheng, L; Weir, M D; Zhang, K; Xu, S M; Chen, Q; Zhou, X; Xu, H H K

    2012-05-01

    Secondary caries is a frequent reason for restoration failure, resulting from acidogenic bacteria and their biofilms. The objectives of this study were to: (1) develop a novel nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and quaternary ammonium dimethacrylate (QADM); and (2) investigate its mechanical and antibacterial durability. A spray-drying technique yielded NACP with particle size of 116 nm. The nanocomposite contained NACP and reinforcement glass fillers, with QADM in the resin. Two commercial composites were tested as controls. Composites were inoculated with Streptococcus mutans. After 180-day water-aging, NACP+QADM nanocomposite had flexural strength and elastic modulus matching those of commercial controls (p > 0.1). NACP+QADM nanocomposite reduced the biofilm colony-forming units (CFU) by 3-fold, compared with commercial composites (p < 0.05). Metabolic activity and lactic acid production of biofilms on NACP+QADM were much less than those on commercial composites (p < 0.05). The antibacterial properties of NACP+QADM were maintained after water-aging for 30, 90, and 180 d (p > 0.05). In conclusion, the novel NACP-QADM nanocomposite greatly decreased biofilm metabolic activity, CFU, and lactic acid, while matching the load-bearing capability of commercial composites without antibacterial properties. The NACP-QADM nanocomposite with strong and durable antibacterial properties, together with its previously reported Ca-PO(4) release capability, may render it useful for caries-inhibiting restorations. PMID:22403412

  12. Calcium Phosphate: A potential host for halide contaminated plutonium wastes.

    SciTech Connect

    Metcalfe, Brian L.; Donald, Ian W.; Fong, Shirley K.; Gerrard, Lee A.; Strachan, Denis M.; Scheele, Randall D.

    2009-07-06

    The presence of significant quantities of fluoride and chloride in four types of legacy wastes from plutonium pyrochemical reprocessing required the development of a new wasteform which could adequately immobilize the halides in addition to the Pu and Am. Using a simulant chloride-based waste (Type I waste) and Sm as the surrogate for the Pu3+ and Am3+ present in the waste, AWE developed a process which utilised Ca3(PO4)2 as the host material. The waste was successfully incorporated into two crystalline phases, chlorapatite, [Ca5(PO4)3Cl], and spodiosite, [Ca2(PO4)Cl]. Radioactive studies performed at PNNL with 239Pu and 241Am confirmed the process. A slightly modified version of the process in which CaHPO4 was used as the host was successful in immobilizing a more complex multi-cation oxide–based waste (Type II) which contained significant concentrations of Cl and F in addition to 239Pu and 241Am. This waste resulted in the formation of cation-doped whitlockite, Ca3-xMgx(PO4)2, ?-calcium phosphate, ?-Ca2P2O7 and chlor-fluorapatite rather than the chlorapatite and spodiosite formed with Type I waste.

  13. Antibacterial Nanocomposite with Calcium Phosphate and Quaternary Ammonium

    PubMed Central

    Cheng, L.; Weir, M.D.; Zhang, K.; Xu, S.M.; Chen, Q.; Zhou, X.; Xu, H.H.K.

    2012-01-01

    Secondary caries is a frequent reason for restoration failure, resulting from acidogenic bacteria and their biofilms. The objectives of this study were to: (1) develop a novel nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and quaternary ammonium dimethacrylate (QADM); and (2) investigate its mechanical and antibacterial durability. A spray-drying technique yielded NACP with particle size of 116 nm. The nanocomposite contained NACP and reinforcement glass fillers, with QADM in the resin. Two commercial composites were tested as controls. Composites were inoculated with Streptococcus mutans. After 180-day water-aging, NACP+QADM nanocomposite had flexural strength and elastic modulus matching those of commercial controls (p > 0.1). NACP+QADM nanocomposite reduced the biofilm colony-forming units (CFU) by 3-fold, compared with commercial composites (p < 0.05). Metabolic activity and lactic acid production of biofilms on NACP+QADM were much less than those on commercial composites (p < 0.05). The antibacterial properties of NACP+QADM were maintained after water-aging for 30, 90, and 180 d (p > 0.05). In conclusion, the novel NACP-QADM nanocomposite greatly decreased biofilm metabolic activity, CFU, and lactic acid, while matching the load-bearing capability of commercial composites without antibacterial properties. The NACP-QADM nanocomposite with strong and durable antibacterial properties, together with its previously reported Ca-PO4 release capability, may render it useful for caries-inhibiting restorations. PMID:22403412

  14. The bactericidal and biocompatible characteristics of reinforced calcium phosphate cements.

    PubMed

    Wu, Tianyi; Hua, Xiaolin; He, Zhiwei; Wang, Xinfu; Yu, Xiaowei; Ren, Weiping

    2012-08-01

    Infection remains a serious medical problem in orthopaedic surgery. Antibiotic administration can be available either systemically via the blood stream or locally, directly into the infected bone. One of the main limitations of antibiotic administration is the development of multi-antibiotic-resistant bacterial strains. In this study, we developed bactericidal calcium phosphate cements (CPC) by incorporation of different molecular weight chitosan and hydroxypropyltrimethyl ammonium chloride chitosan (HACC). Two standard strains, S. epidermidis (ATCC35984) and S. aureus (ATCC25923), and one clinical isolate, methicillin-resistant S. epidermidis (MRSE), were selected to evaluate the antibacterial activity of these bone cements. Our data showed that the CPC loaded with low molecular weight chitosan and HACC significantly inhibited the bacterial adhesion and biofilm formation. In addition, HACC-containing CPC has no cytotoxic effects on both mouse pluripotent C3H10T1/2cell line and a murine L929 fibroblast cell line. We propose that HACC-containing CPC represents a promising polymer-based bactericidal bone scaffold in controlling orthopaedic surgery-related infection. PMID:22556166

  15. Low temperature preparation of calcium phosphate structure via phosphorization of 3D-printed calcium sulfate hemihydrate based material

    Microsoft Academic Search

    J. Suwanprateeb; W. Suvannapruk; K. Wasoontararat

    2010-01-01

    The conversion of newly developed three dimensionally printed calcium sulfate hemihydrate (70–90% wt\\/wt CaSO4·0.5·H2O) based materials to calcium phosphate bioceramics by phosphorization in di-sodium hydrogen phosphate solution at 80°C for\\u000a 4, 8, 16 and 24 h was studied. It was found that transformation rate, phase composition and mechanical properties were influenced\\u000a by porosity in the fabricated samples and by the duration of

  16. Combustion synthesis of calcium phosphate bioceramic powders A. Cu neyt Tas *,1

    E-print Network

    Tas, A. Cuneyt

    Combustion synthesis of calcium phosphate bioceramic powders A. CuÈ neyt Tas *,1 Department)2; Combustion synthesis; Hydroxyapatite 1. Introduction Calcium hydroxyapatite (HA: Ca10(PO4)6(OH)2), the major), instead of water, as the precipitation medium. Self-propagating combustion synthesis (SPCS

  17. Retardation of Phosphate Release from Freshwater Benthic Sediments by Application of Ocher Pellets with Calcium Nitrate

    Microsoft Academic Search

    Yu-Mee Na; Seok S. Park

    2004-01-01

    This article presents an in situ treatment method for retardation of phosphate release from freshwater benthic sediments. The method is based on the addition of ocher pellets into benthic sediments. The pellets consist of ocher and calcium nitrate (OCN pellet). The OCN pellet slowly releases calcium and nitrate, together with ocher, into the sediment–water interface, where all three components play

  18. Technology for recovery of phosphorus from animal wastewater through calcium phosphate precipitation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A wastewater treatment process was developed for removal of phosphorus from livestock wastewater. The phosphorus is recovered as calcium phosphate with addition of only small quantities of liquid lime. The process is based on the distinct chemical equilibrium between phosphorus and calcium ions when...

  19. Phosphate and carbonate salts of calcium support robust bone building in osteoporosis123

    PubMed Central

    Recker, Robert R; Watson, Patrice; Lappe, Joan M

    2010-01-01

    Background: Calcium is an essential cotherapy in osteoporosis treatment. The relative effectiveness of various calcium salts for this purpose is uncertain. Many older women with osteoporosis have phosphorus intakes of <70% of the Recommended Dietary Allowance. Objective: Our objective was to test the hypothesis that calcium phosphate would better support anabolic bone building than would calcium carbonate. Design: This study was a 12-mo, randomized, positive-comparator, 2-arm, single-blind clinical trial in 211 patients treated with teriparatide who consumed <1000 mg phosphorus/d. Participants were randomly assigned to receive, in addition to teriparatide and 1000 IU cholecalciferol, 1800 mg calcium/d as either tricalcium phosphate or calcium carbonate. The primary endpoints were changes in lumbar spine and total hip bone mineral densities (BMDs); secondary endpoints were changes in bone resorption biomarkers and serum and urine calcium and phosphorus concentrations. Results: In the combined group, the lumbar spine BMD increased by 7.2%, and total hip BMD increased by 2.1% (P < 0.01 for both). However, there was no significant difference between calcium-treatment groups, and there were no significant between-group differences in serum calcium and phosphorus concentrations or in urine calcium concentrations. Bone resorption biomarkers increased in both groups, as expected with teriparatide, but the increases in the 2 calcium groups did not differ significantly. Conclusions: Tricalcium phosphate and calcium carbonate appear to be approximately equally effective in supporting bone building with a potent anabolic agent; phosphate salt may be preferable in patients with restricted phosphorus intakes. This trial was registered at clinicaltrials.gov as NCT00074711. PMID:20484446

  20. Stem Cells and Calcium Phosphate Cement Scaffolds for Bone Regeneration

    PubMed Central

    Wang, P.; Zhao, L.; Chen, W.; Liu, X.; Weir, M.D.; Xu, H.H.K.

    2014-01-01

    Calcium phosphate cements (CPCs) have excellent biocompatibility and osteoconductivity for dental, craniofacial, and orthopedic applications. This article reviews recent developments in stem cell delivery via CPC for bone regeneration. This includes: (1) biofunctionalization of the CPC scaffold, (2) co-culturing of osteoblasts/endothelial cells and prevascularization of CPC, (3) seeding of CPC with different stem cell species, (4) human umbilical cord mesenchymal stem cell (hUCMSC) and bone marrow MSC (hBMSC) seeding on CPC for bone regeneration, and (5) human embryonic stem cell (hESC) and induced pluripotent stem cell (hiPSC) seeding with CPC for bone regeneration. Cells exhibited good attachment/proliferation in CPC scaffolds. Stem-cell-CPC constructs generated more new bone and blood vessels in vivo than did the CPC control without cells. hUCMSCs, hESC-MSCs, and hiPSC-MSCs in CPC generated new bone and blood vessels similar to those of hBMSCs; hence, they were viable cell sources for bone engineering. CPC with hESC-MSCs and hiPSC-MSCs generated new bone two- to three-fold that of the CPC control. Therefore, this article demonstrates that: (1) CPC scaffolds are suitable for delivering cells; (2) hUCMSCs, hESCs, and hiPSCs are promising alternatives to hBMSCs, which require invasive procedures to harvest with limited cell quantity; and (3) stem-cell-CPC constructs are highly promising for bone regeneration in dental, craniofacial, and orthopedic applications. PMID:24799422

  1. Cephalexin-loaded injectable macroporous calcium phosphate bone cement.

    PubMed

    Hesaraki, Saeed; Nemati, Roghayeh

    2009-05-01

    Different types of calcium phosphate cements (CPCs) have been studied as potential matrices for incorporating different types of antibiotics. All of these matrices were morphologically microporous whereas macroporosity is essential for rapid cement resorption and bone replacement. In this study, liberation of cephalexin monohydrate (CMH) from a macroporous CPC was investigated over 0.5-300 h in simulated body fluid and some mathematical models were fitted to the release profiles. Macroporosity was introduced into the cement matrix by using sodium dodecyl sulfate molecules as air-entraining agents and the effect of both surfactant and CMH on basic properties of the CPC was studied. Incorporation of CMH into the CPC composition increased the setting time, decreased the crystallinity of the formed apatite phase, and improved the injectability of the paste. The use of both CMH and sodium dodecyl sulfate did not affect the rate of conversion of the reactants into apatite phase while soaking the cements in simulated body fluid. Results showed that the liberation rate of the drug from porous CPC was higher than that of the nonporous CPC but same release patterns were experienced in both types of cements, that is, like to nonporous CPC, a time-dependent controlled release of the incorporated drug was obtained from macroporous CPC. The Weibull model was the best fitting-equation for release profiles of all cements. The liberated CMH was as active as fresh cephalexin. It is concluded that this macroporous CPC can be successfully used as drug carrier with controlled release profile for the treatment of bone infections. PMID:18823021

  2. Low temperature method for the production of calcium phosphate fillers

    PubMed Central

    Calafiori, Anna Rita; Marotta, Marcello; Nastro, Alfonso; Martino, Guglielmo

    2004-01-01

    Background Calcium phosphate manufactured samples, prepared with hydroxyapatite, are used as either spacers or fillers in orthopedic surgery, but these implants have never been used under conditions of mechanical stress. Similar conditions also apply with cements. Many authors have postulated that cements are a useful substitute material when implanted in vivo. The aim of this research is to develop a low cristalline material similar to bone in porosity and cristallinity. Methods Commercial hydroxyapatite (HAp) and monetite (M) powders are mixed with water and compacted to produce cylindrical samples. The material is processed at a temperature of 37–120 degrees C in saturated steam to obtain samples that are osteoconductive. The samples are studied by X-ray powder diffraction (XRD), Vickers hardness test (HV), scanning electron microscopy (SEM), and porosity evaluation. Results The X-ray diffractions of powders from the samples show patterns typical of HAp and M powders. After thermal treatment, no new crystal phase is formed and no increase of the relative intensity of the peaks is obtained. Vicker hardness data do not show any relationship with treatment temperature. The total porosity decreases by 50–60% according to the specific thermal treatment. Scanning electron microscopy of the surfaces of the samples with either HAp 80%-M 20% (c) or Hap 50%-M 50% (f), show cohesion of the powder grains. Conclusions The dissolution-reprecipitation process is more intesive in manufactured samples (c) and (f), according to Vickers hardness data. The process occurs in a steam saturated environment between 37 degrees and 120 degrees C. (c) (f) manufactured samples show pore dimension distributions useful to cellular repopulation in living tissues. PMID:15035671

  3. Formation of hydroxyapatite in soils using calcium citrate and sodium phosphate for control of strontium migration.

    SciTech Connect

    Moore, Robert Charles; Hasan, Ahmed Ali Mohamed; Sanchez, Charles Anthony (University of Arizona, Yuma, AZ); Zhao, Hongting; Salas, Fred Manuel; Hasan, Mahmoud A. (Egyptian Atomic Energy Authority, Cairo, Egypt); Holt, Kathleen Caroline

    2003-08-01

    {sup 90}Sr contamination is a major problem at several U.S. sites. At some sites, {sup 90}Sr has migrated deep underground making site remediation difficult. In this paper, we describe a novel method for precipitation of hydroxyapatite, a strong sorbent for {sup 90}Sr, in soil. The method is based on mixing a solution of calcium citrate and sodium phosphate in soil. As the indigenous soil microorganisms mineralize the citrate, the calcium is released and forms hydroxyapatite. Soil, taken from the Albuquerque desert, was treated with a sodium phosphate solution or a sodium phosphate/calcium citrate solution. TEM and EDS were used to identify hydroxyapatite with CO{sub 3}{sup 2-} substitutions, with a formula of (Ca{sub 4.8}Na{sub 0.2})[(PO{sub 4}){sub 2.8}(CO{sub 3}){sub 0.2}](OH), in the soil treated with the sodium phosphate/calcium citrate solution. Untreated and treated soils were used in batch sorption experiments for Sr uptake. Average Sr uptake was 19.5, 77.0 and 94.7% for the untreated soil, soil treated with sodium phosphate, and soil with apatite, respectively. In desorption experiments, the untreated soil, phosphate treated soil and apatite treated soil released an average of 34.2, 28.8 and 4.8% respectively. The results indicate the potential of forming apatite in soil using soluble reagents for retardation of radionuclide migration.

  4. Pathogenic Role of Basic Calcium Phosphate Crystals in Destructive Arthropathies

    PubMed Central

    Ea, Hang-Korng; Chobaz, Véronique; Nguyen, Christelle; Nasi, Sonia; van Lent, Peter; Daudon, Michel; Dessombz, Arnaud; Bazin, Dominique; McCarthy, Geraldine; Jolles-Haeberli, Brigitte; Ives, Annette; Van Linthoudt, Daniel; So, Alexander; Lioté, Frédéric; Busso, Nathalie

    2013-01-01

    Background basic calcium phosphate (BCP) crystals are commonly found in osteoarthritis (OA) and are associated with cartilage destruction. BCP crystals induce in vitro catabolic responses with the production of metalloproteases and inflammatory cytokines such as interleukin-1 (IL-1). In vivo, IL-1 production induced by BCP crystals is both dependant and independent of NLRP3 inflammasome. We aimed to clarify 1/ the role of BCP crystals in cartilage destruction and 2/ the role of IL-1 and NLRP3 inflammasome in cartilage degradation related to BCP crystals. Methodology/ Principal Findings synovial membranes isolated from OA knees were analysed by alizarin Red and FTIR. Pyrogen free BCP crystals were injected into right knees of WT, NLRP3 -/-, ASC -/-, IL-1? -/- and IL-1?-/- mice and PBS was injected into left knees. To assess the role of IL-1, WT mice were treated by intra-peritoneal injections of anakinra, the IL-1Ra recombinant protein, or PBS. Articular destruction was studied at d4, d17 and d30 assessing synovial inflammation, proteoglycan loss and chondrocyte apoptosis. BCP crystals were frequently found in OA synovial membranes including low grade OA. BCP crystals injected into murine knee joints provoked synovial inflammation characterized by synovial macrophage infiltration that persisted at day 30, cartilage degradation as evidenced by loss of proteoglycan staining by Safranin-O and concomitant expression of VDIPEN epitopes, and increased chondrocyte apoptosis. BCP crystal-induced synovitis was totally independent of IL-1? and IL-1? signalling and no alterations of inflammation were observed in mice deficient for components of the NLRP3-inflammasome, IL-1? or IL-1?. Similarly, treatment with anakinra did not prevent BCP crystal effects. In vitro, BCP crystals elicited enhanced transcription of matrix degrading and pro-inflammatory genes in macrophages. Conclusions/ Significance intra-articular BCP crystals can elicit synovial inflammation and cartilage degradation suggesting that BCP crystals have a direct pathogenic role in OA. The effects are independent of IL-1 and NLRP3 inflammasome. PMID:23468973

  5. Steel corrosion protection by means of alkyd paints pigmented with calcium acid phosphate

    SciTech Connect

    Amo, B. del; Romagnoli, R.; Vetere, V.F. [CIC-CONICET, La Plata (Argentina)

    1999-06-01

    The use of classic anticorrosive pigments is becoming more and more restricted by increasing environmental concerns; they are gradually being replaced by zinc phosphate and related compounds. Other anticorrosive pigments such as surface-exchanged silicas were also proposed. The object of this research is to study the anticorrosive properties of calcium acid phosphate as an inhibitive pigment, introducing a careful selection of complementary pigments in order to achieve an efficient anticorrosive protection. Several alkyd paints were prepared and evaluated through accelerated and electrochemical tests. The nature of the passive film formed was also studied. Paint containing zinc oxide and calcium carbonate (50/50) as complementary pigments showed the best performance in the salt spray test. Zinc oxide and calcium carbonate decreased film permeability and improved steel passivation. The passive film was composed of ferric oxyhydroxide, the pores of which became plugged by ferric phosphate.

  6. The biocompatibility of nanostructured calcium phosphate coated on micro-arc oxidized titanium.

    PubMed

    Li, Yan; Lee, In-Seop; Cui, Fu-Zhai; Choi, Seong-Ho

    2008-05-01

    To achieve improved osseointegration, there have been many efforts to modify the surface composition and topography of dental implants. Recently, the anodic oxidation treatment of titanium (Ti) has attracted a great deal of attention. Meanwhile, calcium phosphate is commonly applied to metallic implants as a coating material for fast fixation and firm implant-bone attachment on the account of its demonstrated bioactive and osteoconductive properties. In the present study, anodized surface and calcium phosphate deposition by electron beam evaporation were combined. Nanostructured calcium phosphate film was deposited on the micro-arc oxidized Ti. New apatite layer formed easily on the coated film when incubating in DPBS solution at 37 degrees C. By adding basic fibroblast growth factor (bFGF) in the DPBS solution, the bFGF could be immobilized in the newly formed apatite layer. The coated film enhanced osseointegration of Ti implants in vivo. PMID:18276003

  7. Ossification vesicles with calcium phosphate in the eyes of the insect Copium teucrii (Hemiptera: Tingidae).

    PubMed

    Garcia-Guinea, Javier C; Jorge, Alberto C; Tormo, Laura; Furio, Marta; Crespo-Feo, Elena; Correcher, Virgilio; Prado-Herrero, Pedro; Soria, Ana C; Sanz, Jesus; Nieves-Aldrey, Jose L

    2011-01-01

    Arthropod eyes are built of repeating units named ommatidia. Each single ommatidium unit contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The insect Copium eye ommatidia include additional calcium-phosphate deposits, not described in insects to date, which can be examined today using a combined set of modern microscopy and spectroscopy techniques. Teucrium gnaphalodes L'Her plants, growing in central Spain, develop galls induced by Copium insects. A survey of C. teucrii adult specimens resulted in surprising environmental scanning electron microscopy (ESEM) images, showing that their bright red eyes contain a calcium-phosphate mineralization. A complete survey of Copium eye specimens was performed by ESEM using energy-dispersive spectroscopy, backscattered electron detector and cathodoluminescence (CL) probes, field emission scanning electron microscopy, micro-Raman spectroscopy, and confocal laser scanning microscopy in order to learn ommatidia features, such as chemical composition, molecular structure, cell membrane, and internal ommatidium eye fluids and calcium-phosphate distribution deposits. The CL panchromatic images distinguish between the calcium-phosphate ommatidium and calcium-phosphate setae, which are more apatite rich. They show Raman bands attributable to bone tissue apatite biomaterials, such as bone, collagen, lipids, and blood, i.e., peptides, amide-S, amide-II, amide-III, and cytochrome P-450 scc. The chemical composition of both galls and leaves of T. gnaphalodes was determined by gas chromatography-mass spectrometry (GC-MS) of their extracts. The spectrometric and microscopic images reveal that the calcium-phosphate mineralization is formed and constrained to Copium ommatidia, which are both matrix vesicles generating mixtures of apatite collagen and operational compound eyes of the insect. PMID:21258761

  8. Elemental bio-imaging of calcium phosphate crystal deposits in knee samples from arthritic patients

    PubMed Central

    Austin, Christine; Hare, Dominic; Rozelle, Andrew L.; Robinson, William H.; Grimm, Rudolf

    2012-01-01

    Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) was employed to image deposits of calcium phosphate based crystals in knee cartilage and synovial fluid from arthritic patients. A reaction/collision cell containing hydrogen minimised plasma interferences on calcium and also improved the image quality without significant sensitivity reduction. Areas of high calcium and phosphorus intensities consistent with crystal deposits were observed for both the cartilage and synovial fluid samples. These areas were also characterised by high magnesium and strontium intensities. Distribution patterns of other elements such as copper and sulfur did not correlate with the crystal deposits. Filtered and non-filtered solutions of calcium phosphate crystals grown in synthetic synovial fluid were also imaged as further evidence of crystal deposits. The crystal deposits were detected in the unfiltered solution, and were absent from the filtered solutions. PMID:21305107

  9. Biomimetic Nanocomposites of Calcium Phosphate and Self-Assembling Triblock and Pentablock Copolymers

    SciTech Connect

    Drew Lenzen Enlow

    2006-08-09

    In an effort to mimic the growth of natural bone, self-assembling, micelle and gel-forming copolymers were used as a template for calcium phosphate precipitation. Because of the cationic characteristics imparted by PDEAEM end group additions to commercially available Pluronic{reg_sign} Fl27, a direct ionic attraction mechanism was utilized and a polymer-brushite nanocomposite spheres were produced. Brushite coated spherical micelles with diameters of {approx}40 nm, and agglomerates of these particles (on the order of 0.5 {mu}m) were obtained. Thickness and durability of the calcium phosphate coating, and the extent of agglomeration were studied. The coating has been shown to be robust enough to retain its integrity even below polymer critical micelle concentration and/or temperature. Calcium phosphate-polymer gel nanocomposites were also prepared. Gel samples appeared as a single phase network of agglomerated spherical micelles, and had a final calcium phosphate concentration of up to 15 wt%. Analysis with x-ray diffraction and NMR indicated a disordered brushite phase with the phosphate groups linking inorganic phase to the polymer.

  10. Mg2+ substituted calcium phosphate nano particles synthesis for non viral gene delivery application.

    PubMed

    Hanifi, A; Fathi, M H; Sadeghi, H Mir Mohammad; Varshosaz, J

    2010-08-01

    Gene therapy provides a unique approach to medicine as it can be adapted towards the treatment of both inherited and acquired diseases. Recently, calcium phosphate vectors as a new generation of the non viral gene delivery nano carriers have been studied because of their biocompatibility and DNA condensation and gene transfer ability. Substituting cations, like magnesium, affects physical and chemical properties of calcium phosphate nano particles. In this study, Mg(2+) substituted calcium phosphate nano particles have been prepared using the simple sol gel method. X-ray diffraction analysis, Fourier transform infra red spectroscopy, transmission electron microscopy, specific surface area analysis, zeta potential measurement and ion release evaluation were used for characterization of the samples. It was concluded that presence of Mg ions decrease particle size and crystallinity of the samples and increase positive surface charge as well as beta tricalcium phosphate fraction in chemical composition of calcium phosphate. These properties result in increasing the DNA condensation ability, specific surface area and dissolution rate of the samples which make them suitable particles for gene delivery application. PMID:20464457

  11. Carboxymethyl cellulose/silica hybrids as templates for calcium phosphate biomimetic mineralization.

    PubMed

    Salama, Ahmed; Abou-Zeid, Ragab E; El-Sakhawy, Mohamed; El-Gendy, Ahmed

    2015-03-01

    Multiphase hybrid materials were synthesized using carboxymethyl cellulose (CMC) as bioactive polymer, silica gel as matrix assisted networks and calcium phosphate as inorganic mineral phase. These hybrids were investigated with infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. Biomimetic crystal growth nucleated from the CMC/silica hybrids was suggested as amorphous calcium phosphate with an evidence that hydroxyapatite, the mineralized component of bone, may be formed at high CMC content. This study provides an efficient approach toward bone-like hybrids with potential bone healing applications. PMID:25526694

  12. Anticariogenicity of Calcium Phosphate Complexes of Tryptic Casein Phosphopeptides in the Rat

    Microsoft Academic Search

    E. C. Reynolds; C. J. Cain; EL Webber; C. L. Black; P. F. Riley; I. H. Johnson; J. W. Perich

    1995-01-01

    Casein phosphopeptides (CPP) stabilize calcium phosphate through the formation of casein-phosphopeptide amorphous calcium-phosphate complexes (CPP-CP). The ability of CPP-CP to reduce caries activity was investigated by use of specific-pathogen-free rats inoculated with Streptococcus sobrinus. The animals consumed a defined cariogenic diet free of dairy products. Solutions (100 pL) of the CPP-CP (0.1, 0.2, 0.5, 1.0% w\\/v) were applied to the

  13. SOILS, SEC 1 SOIL ORGANIC MATTER DYNAMICS & NUTRIENT CYCLING RESEARCH ARTICLE Biogenic calcium phosphate transformation in soils

    E-print Network

    Lehmann, Johannes

    calcium phosphate (Ca-P). However, very little is known about long-term changes of biogenic Ca-P in soilSOILS, SEC 1 · SOIL ORGANIC MATTER DYNAMICS & NUTRIENT CYCLING · RESEARCH ARTICLE Biogenic calcium phosphate transformation in soils over millennial time scales Shinjiro Sato & Eduardo G. Neves & Dawit

  14. In vitro evaluation of different heat-treated radio frequency magnetron sputtered calcium phosphate coatings

    Microsoft Academic Search

    Yan Yonggang; Joop G. C. Wolke; Li Yubao; John A. Jansen

    2007-01-01

    OBJECTIVES: Surface chemical compositions, such as calcium\\/phosphorus ratio and phase content, have a strong influence on the bioactivity and biocompatibility of calcium phosphate (CaP) coatings as applied on orthopedic and dental implants. MATERIAL AND METHODS: Hydroxylapatite (HA) and dicalcium pyrophosphate (DCPP) coatings were prepared on titanium substrates by RF magnetron sputter deposition. The surfaces were left as-prepared (amorphous HA coating;

  15. Absorption of calcium from milks enriched with fructo- oligosaccharides, caseinophosphopeptides, tricalcium phosphate

    Microsoft Academic Search

    Eduardo Lopez-Huertas; Birgit Teucher; Julio J Boza; Antonio Martínez-Férez; Gosia Majsak-Newman; Luis Baro; Juan J Carrero; María Gonzalez-Santiago; Juristo Fonolla; Susan Fairweather-Tait

    Background: Adequate intakes of calcium are required for optimal bone health and protection against chronic disease. Dairy products are an excellent source of calcium. Objective:Theabsorptionofcalciumfromarangeoffortifiedmilks was measured in humans with the use of stable isotopes. Design:Fifteenvolunteersparticipatedinarandomized,controlled, double-blind crossover study. Five types of semi-skimmed (1.9% fat) milk drinks were administered with a light breakfast: standard milk(controlmilk);milkenrichedwithcalciumfrommilksolidsand tricalcium phosphate ((TCP) MSS milk);

  16. Surface potential and osteoblast attraction to calcium phosphate compounds is affected by selected alkaline hydrolysis processing

    Microsoft Academic Search

    I. O. Smith; M. J. Baumann; L. Obadia; J.-M. Bouler

    2004-01-01

    This study examines the link(s) between the suspension behavior of calcium deficient apatites (CDAs) and biphasic calcium phosphate (BCP), as measured by the ?-potential, with respect to both whole bone and osteoblasts. CDA is fabricated by hydrolyzing an acidic CaP such as dicalcium diphosphate dihydrate (DCPD; CaHPO4·2H2O) and has a structure and composition close to bone apatite. Sintering CDA results

  17. Effects of additives on the rheological properties and injectability of a calcium phosphate bone substitute material.

    PubMed

    Wang, Xiupeng; Ye, Jiandong; Wang, Hai

    2006-08-01

    An injectable calcium phosphate bone substitute material has been prepared by mixing amorphous calcium phosphate (ACP) and dicalcium phosphate dihydrate (DCPD) for use in noninvasive surgery, and the influence of additives, such as disodium hydrogen phosphate, polyethylene glycol (PEG), glycerin, and citric acid, on the rheological properties and injectability of the ACP + DCPD cement system have been studied in this work. Novel approach of thixotropy measurement has been used to characterize the stability of the pastes. The results show that the injectability and the setting time can be augmented by the addition of disodium phosphate solution to the paste but reduced by the addition of PEG 200, glycerin, or citric acid to the paste. This study suggests that the injectability and the setting time of the ACP + DCPD bone substitute material can be balanced, and the injectable calcium phosphate bone substitute material with satisfied fluidity and injectability for clinical operation can be prepared by optimizing the additives and their concentrations, according to different clinical requirements. PMID:16362962

  18. Electron microscopic study of the calcium phosphate-induced aggregation and membrane destabilization of cytoskeleton-free erythrocyte vesicles.

    PubMed

    Fassel, T A; Hui, S W; Leonards, K; Ohki, S

    1988-08-18

    Cytoskeleton-free vesicles derived from human erythrocytes were treated with trypsin, chymotrypsin, or neuraminidase followed by calcium, phosphate, or combined calcium/phosphate treatments in order to study the roles of cell surface proteins and glycoproteins in calcium/phosphate-induced cell aggregation and fusion. Vesicle aggregation (a necessary pre-cursor to membrane fusion) and subsequent membrane destabilization (an essential component of fusion) were examined by freeze-fracture electron microscopy. Enzymatic treatment alone had no effect on the morphology of the cytoskeleton-free vesicles. Neither did separate calcium nor phosphate treatments, although the treatment of the cytoskeleton-free vesicles with calcium did reduce their size slightly. Enzymatic pretreatment had no effect on the calcium-induced size changes. In contrast, the combination of calcium and phosphate drastically disrupted the membrane integrity of aggregated cytoskeleton-free vesicles at pH 7.8, although the effect was reduced at lower pH values. The extent of this membrane destabilization was independent of enzyme treatment. Our results indicate: (1) that the cell surface proteins and glycoproteins have only secondary effects on calcium/phosphate-induced cell aggregation and membrane destabilization, (2) that these processes primarily depend on the reaction between calcium and phosphate ions at the membrane surface, and (3) that cytoskeletal elements probably play no active (positive) role in the Ca2+/PO4(3-) induced erythrocyte membrane fusion process, apart from maintaining cell shape. PMID:3401481

  19. Control of renal calcium, phosphate, electrolyte, and water excretion by the calcium-sensing receptor.

    PubMed

    Tyler Miller, R

    2013-06-01

    Through regulation of excretion, the kidney shares responsibility for the metabolic balance of calcium (Ca(2+)) with several other tissues including the GI tract and bone. The balances of Ca(2+) and phosphate (PO4), magnesium (Mg(2+)), sodium (Na(+)), potassium (K(+)), chloride (Cl(-)), and water (H2O) are linked via regulatory systems with overlapping effects and are also controlled by systems specific to each of them. Cloning of the calcium-sensing receptor (CaSR) along with the recognition that mutations in the CaSR gene are responsible for two familial syndromes characterized by abnormalities in the regulation of PTH secretion and Ca(2+) metabolism (Familial Hypocalciuric Hypercalcemia, FHH, and Autosomal Dominant Hypocalcemia, ADH) made it clear that extracellular Ca(2+) (Ca(2+)o) participates in its own regulation via a specific, receptor-mediated mechanism. Demonstration that the CaSR is expressed in the kidney as well as the parathyroid glands combined with more complete characterizations of FHH and ADH established that the effects of elevated Ca(2+) on the kidney (wasting of Na(+), K(+), Cl(-), Ca(2+), Mg(2+) and H2O) are attributable to activation of the CaSR. The advent of positive and negative allosteric modulators of the CaSR along with mouse models with global or tissue-selective deletion of the CaSR in the kidney have allowed a better understanding of the functions of the CaSR in various nephron segments. The biology of the CaSR is more complicated than originally thought and difficult to define precisely owing to the limitations of reagents such as anti-CaSR antibodies and the difficulties inherent in separating direct effects of Ca(2+) on the kidney mediated by the CaSR from associated CaSR-induced changes in PTH. Nevertheless, renal CaSRs have nephron-specific effects that contribute to regulating Ca(2+) in the circulation and urine in a manner that assures a narrow range of Ca(2+)o in the blood and avoids excessively high concentrations of Ca(2+) in the urine. PMID:23856264

  20. RenaGel®, a nonabsorbed calcium- and aluminum-free phosphate binder, lowers serum phosphorus and parathyroid hormone

    Microsoft Academic Search

    EDUARDO A SLATOPOLSKY; STEVEN K BURKE; MAUREEN A DILLON

    1999-01-01

    RenaGel®, a nonabsorbed calcium- and aluminum-free phosphate binder, lowers serum phosphorus and parathyroid hormone.Background.This multicenter, open-label, dose-titration study assessed the safety and efficacy of RenaGel®, a nonabsorbed calcium- and aluminum-free phosphate binder, in lowering serum phosphorus. Secondary outcomes were its effects on serum intact parathyroid hormone (iPTH) and serum lipids.Methods.Phosphate binders were discontinued during a two-week washout period. Patients whose

  1. Synthetic Aragonite (CaCO3) as a Potential Additive in Calcium Phosphate Cements: Evaluation in Tris-free SBF at 37C

    E-print Network

    Tas, A. Cuneyt

    Synthetic Aragonite (CaCO3) as a Potential Additive in Calcium Phosphate Cements: Evaluation apatitic CaP (calcium phosphate) deposits on their sur- faces. Mg-doped (1050 ppm) synthetic aragonite, paint, textile, pharmaceutical, and rubber industries. Calcium phosphate cement (CPC) pastes provide

  2. The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer

    USGS Publications Warehouse

    Kramer, Henry

    1956-01-01

    A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mµ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ± 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.

  3. Plasma spraying induced changes of calcium phosphate ceramic characteristics and the effect on in vitro stability

    Microsoft Academic Search

    S. R. Radin; P. Ducheyne

    1992-01-01

    Plasma spraying is a commonly used technique to apply thin calcium phosphate ceramic coatings. Special consideration is given to retaining the original structure of CPC particles. However, changes are possible. Thus this study focused on plasma spraying induced changes in material characteristics of commercial coatings and their influence onin vitro dissolution. All analysed coatings were found to undergo significant plasma

  4. Lead Retention in a Calcareous Soil Influenced by Calcium and Phosphate Amendments

    EPA Science Inventory

    Phosphate amendments in calcareous lead (Pb)-contaminated soils to immobilize Pb may be hindered due to competition of Pb with calcium (Ca) that may inhibit the retention of Pb as a precipitation mechanism. This study explored the retention of Pb in a calcareous soil spiked and ...

  5. Macroporous biphasic calcium phosphate ceramics: influence of macropore diameter and macroporosity percentage on bone ingrowth

    Microsoft Academic Search

    Olivier Gauthier; Jean-Michel Bouler; Eric Aguado; Paul Pilet; Guy Daculsi

    1998-01-01

    SynopsisA total of 60 cylindrical 6×6 mm samples of a macroporous biphasic calcium phosphate (MBCP) ceramic were impla nted into a distal femoral site in 30 rabbits. These samples represented six kinds of implants with two different macropore diamete rs and three different macroporosity percentages. Analysis of backscattered electron images of implant surfaces analysed by a factorial design method showed

  6. A preliminary study on osteoinduction of two kinds of calcium phosphate ceramics

    Microsoft Academic Search

    Huipin Yuan; Kenji Kurashina; Joost D de Bruijn; Yubao Li; K de Groot; Xingdong Zhang

    1999-01-01

    With respect to the effect of material factors on calcium phosphate biomaterial-induced osteogenesis, the osteoinductive property of two kinds of porous hydroxyapatite ceramics, which were made by different producers, was investigated in dorsal muscles of dogs. One hydroxyapatite ceramic (S-HA), macroporous implants with rough pore walls containing abundant micropores, was made by Sichuan Union University (Chengdu, China); the other hydroxyapatite

  7. Transformation of Amorphous Calcium Phosphate to Crystalline Dahllite in the Radular Teeth of Chitons

    Microsoft Academic Search

    H. A. Lowenstam; S. Weiner

    1985-01-01

    A comparison of infrared spectra from individual teeth along the radula of a chiton (Polyplacophora, Mollusca) shows that the first-formed calcium phosphate mineral is amorphous. Over a period of weeks the mineral transforms to dahllite. The c axes of the dahllite crystals are aligned approximately perpendicular to the tooth surface.

  8. Cost containment using cysteine HCl acidification to increase calcium/phosphate solubility in hyperalimentation solutions.

    PubMed

    Schmidt, G L; Baumgartner, T G; Fischlschweiger, W; Sitren, H S; Thakker, K M; Cerda, J J

    1986-01-01

    The purpose of this study was to determine if (1) the calcium/phosphate insoluble product was inversely related to pH [when cysteine HC1 (CH) was added as neonatal supplementation at 0.5 mM/kg/day to hyperalimentation (HAL) solutions] and (2) the potential cost savings to the hospital. The pH of the HAL solutions was adjusted by adding various amounts of CH to the HAL solution. HAL solutions containing 27 mEq of calcium/liter and 30 mEq (15 mM) of phosphate/liter were compounded. Ten-milliliter aliquots were analyzed at 0, 12, 24, and 48 hr. All samples (n = 56) were filtered (0.22 mu), viewed with 7-10,000 X magnification scanning electron microscopy, and qualitatively analyzed with a Philips Energy Dispersive X-Ray Analysis System equipped with a SW9100 Microprocessor. Calcium/phosphate insoluble product was present in the 0-, 12-, 24-, and 48-hr samples from the CH-free solutions. The solutions containing 759 mg (4.17 mM)/liter of CH however, remained free of precipitant. This investigation demonstrated that addition of CH to HAL can foster significant cost containment (projected $82,000/yr tangible hospital savings) by the elimination of current calcium/phosphate separation procedures for neonates on parenteral nutrition. PMID:3083133

  9. Surface areas by gas adsorption on amorphous calcium phosphate and crystalline hydroxyapatite

    Microsoft Academic Search

    James M. Holmes; Ralph A. Beebe

    1971-01-01

    Surface areas have been measured by the nitrogen gas adsorption method on a number of samples of precipitated calcium phosphates both in the amorphous form (ACP) and in the form of crystalline hydroxyapatite (HA). In all the sample studied the specific surface areas of the HA have from two to four times the values obtained for ACP, reflecting the smaller

  10. Mechanical and structural characterisation of completely degradable polylactic acid\\/calcium phosphate glass scaffolds

    Microsoft Academic Search

    Montse Charles-Harris; Sergio del Valle; Emilie Hentges; Pierre Bleuet; Damien Lacroix; Josep A. Planell

    2007-01-01

    This study involves the mechanical and structural characterisation of completely degradable scaffolds for tissue engineering applications. The scaffolds are a composite of polylactic acid (PLA) and a soluble calcium phosphate glass, and are thus completely degradable. A factorial experimental design was applied to optimise scaffold composition prior to simultaneous microtomography and micromechanical testing. Synchrotron X-ray microtomography combined with in situ

  11. Yolk-Shell Porous Microspheres of Calcium Phosphate Prepared by Using Calcium L-Lactate and Adenosine 5'-Triphosphate Disodium Salt: Application in Protein/Drug Delivery.

    PubMed

    Ding, Guan-Jun; Zhu, Ying-Jie; Qi, Chao; Sun, Tuan-Wei; Wu, Jin; Chen, Feng

    2015-06-26

    A facile and environmentally friendly approach has been developed to prepare yolk-shell porous microspheres of calcium phosphate by using calcium L-lactate pentahydrate (CL) as the calcium source and adenosine 5'-triphosphate disodium salt (ATP) as the phosphate source through the microwave-assisted hydrothermal method. The effects of the concentration of CL, the microwave hydrothermal temperature, and the time on the morphology and crystal phase of the product are investigated. The possible formation mechanism of yolk-shell porous microspheres of calcium phosphate is proposed. Hemoglobin from bovine red cells (Hb) and ibuprofen (IBU) are used to explore the application potential of yolk-shell porous microspheres of calcium phosphate in protein/drug loading and delivery. The experimental results indicate that the as-prepared yolk-shell porous microspheres of calcium phosphate have relatively high protein/drug loading capacity, sustained protein/drug release, favorable pH-responsive release behavior, and a high biocompatibility in the cytotoxicity test. Therefore, the yolk-shell porous microspheres of calcium phosphate have promising applications in various biomedical fields such as protein/drug delivery. PMID:25982303

  12. Carbonate and magnesium interactive effect on calcium phosphate precipitation.

    PubMed

    Cao, Xinde; Harris, Willie

    2008-01-15

    Precipitation of Ca phosphates, an important process in controlling P stability and activity in P-fertilized soils and P-rich wastewater, is often affected by other components. The purpose of this study was to document interactive effects of CO3(2-) and Mg2+ on Ca phosphate precipitation under conditions simulating (i) dairy manure-amended soil leachate (system I; pH 7.1) and (ii) P recovery from flushed dairy manure wastewater (system II; pH 9.2). Hydroxyapatite (HAP) and more soluble amorphous Ca phosphate (ACP) were formed in the control solutions of system I and system II, respectively. Carbonate only slightly affected the crystallinity of the precipitate, but significantly reduced the precipitation rate via CO3(2-) competition for PO4(3-) (system I) or preemptive CaCO3 precipitation (system II). Magnesium severely inhibited both precipitate crystallinity and precipitation rate, allowing formation of ACP in both systems, presumably due to Mg2+ incorporation into the Ca phosphate structure to form Mg2+ -substituted structure that crystallized to whitlockite upon heating. Coexistence of CO32- and Mg2+ in system I showed a synergistic inhibitory effect, compared to their individual presence, probably because both CO3(2-) and Mg2+ were incorporated into the precipitate. However, in system II, the individual inhibitory effect of CO3(2-) or Mg2+ was eliminated when both were present. The likely mechanism involves formation of aqueous MgCO3 (aq) which reduces free CO3(2-) and Mg2+ activities, resulting in less preemptive CaCO3 formation and enhanced Ca phosphate precipitation. PMID:18284143

  13. The nucleation and growth of calcium phosphate onto self-assembled monolayers

    NASA Astrophysics Data System (ADS)

    Tarasevich, Barbara J.

    The nucleation and growth of calcium phosphate is of great importance to the formation of mammalian hard tissue structures such as bone and teeth and for unwanted, ectopic calcium phosphate deposition on arteries and implants. In spite of its importance, the mechanisms of nucleation and growth of calcium phosphate are not well known, but are believed to involve an organic template. The nucleation and growth of calcium phosphate was studied onto model nucleation templates composed of alkanethiol self-assembled monolayers on gold that were developed and tailored to have various surface functionalities, various surface site densities composed of mixtures of two thiols, and various degrees of conformational disorder composed of mixtures of SAMs of various chain lengths. The quartz crystal microbalance was developed as an in-situ technique to study the nucleation and growth kinetics and ex-situ techniques such as X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy were used to assess adsorbate molecular chemistry in the initial stages of deposition. Significant nucleation and growth of calcium phosphate onto SAMs involved the adsorption of solution-formed critical nuclei. This mechanism is in contrast to heterogeneous nucleation and may have important implications for bone formation. An initial slow growth region occurred which involved the adsorption and assembly of solution-formed nanometer-sized particles. A second fast growth period occurred which involved the adsorption and growth of solution-formed critical nuclei or the assembly of supercritical particles. There was evidence for the heterogeneous nucleation of a very low density of crystals at low solution supersaturation. Heterogeneous nucleation may be limited due to the use of planar surfaces and to limits on phosphate adsorption due to electrostatic double layer anisotropy at the charged interfaces. Surface selective deposition was found in the initial slow growth region with growth promoted onto charged SAMs such as carboxylic acid in contrast to hydroxyl, methyl ester, and methyl. The nanoparticle assembly growth mechanism was used to form ultrathin films of calcium phosphate which have not been formed previously. The micron-sized and ultrathin films are of interest as biosensors, bioelectronic devices, and bioactive coatings on implants.

  14. Structure and properties of calcium iron phosphate glasses

    NASA Astrophysics Data System (ADS)

    Qian, Bin; Liang, Xiaofeng; Wang, Cuiling; Yang, Shiyuan

    2013-11-01

    The structural properties of xCaO-(100 - x) (0.4Fe2O3-0.6P2O5) (x = 0, 10, 20, 30, 40, 50 mol%) glasses have been investigated by XRD, DTA, IR and Raman spectroscopy. XRD analysis has confirmed that the majority of samples are X-ray amorphous, and EDS analysis indicates that the glass matrix can accommodate ?30 mol% CaO. IR and Raman spectra show that the glass structure consists predominantly of pyrophosphate (Q1) units. IR spectra indicate that the phosphate network is depolymerized with the addition of CaO content. The density and glass transition temperature (Tg) increase with increasing CaO content for the glasses. This behavior indicates that the addition of CaO improves the strength of the cross-links between the phosphate chains of the glass.

  15. Production of citric and oxalic acids and solubilization of calcium phosphate by Penicillium bilaii.

    PubMed Central

    Cunningham, J E; Kuiack, C

    1992-01-01

    An isolate of Penicillium bilaii previously reported to solubilize mineral phosphates and enhance plant uptake of phosphate was studied. Using agar media with calcium phosphate and the pH indicator alizarin red S, the influence of the medium composition on phosphate solubility and medium acidification was recorded. The major acidic metabolites produced by P. bilaii in a sucrose nitrate liquid medium were found to be oxalic acid and citric acid. Citric acid production was promoted under nitrogen-limited conditions, while oxalic acid production was promoted under carbon-limited conditions. Citric acid was produced in both growth and stationary phases, but oxalic acid production occurred only in stationary phase. When submerged cultures which normally produce acid were induced to sporulate, the culture medium shifted toward alkaline rather than acid reaction with growth. PMID:1622211

  16. Effect of the Intravenous Lipid Emulsions on the Availability of Calcium when using Organic Phosphate in TPN Admixtures

    Microsoft Academic Search

    Jean Claude Chaumeil; Sami Jebnoun; Naima Khrouf; Abderrazek Hedhili; Souad Sfar

    2008-01-01

    Purpose  The addition of high amounts of calcium remains a pharmaceutical concern due to its precipitation with phosphate in total\\u000a parenteral nutrient (TPN) admixtures, compromising also the stability of the lipid emulsion.\\u000a \\u000a \\u000a \\u000a Materials and Methods  Calcium-phosphate solubility was compared when using binary PN solutions versus all-in-one TPN (admixtures with lipid emulsions) in three formulas using organic calcium gluconate and gulcose-1-phosphate.\\u000a \\u000a \\u000a \\u000a Results  It was

  17. Synthesis, characterization and cation adsorption of p-aminobenzoic acid intercalated on calcium phosphate

    SciTech Connect

    Silva, Camila F.N. [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil)] [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil); Lazarin, Angélica M., E-mail: amlazarin2@uem.br [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil); Sernaglia, Rosana L.; Andreotti, Elza I.S. [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil)] [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil)

    2012-06-15

    Graphical abstract: Scanning electron microscopy photographs of calcium phosphate (a) and intercalated with p-aminobenzoic acid (b). Highlights: ? Calcium phosphate was intercalated with p-aminobenzoic acid. ? Guest molecule contains nitrogen and oxygen atoms from amine and carboxylic groups. ? These basic centers are potentially useful for cation coordination in ethanol solution. ? Crystal morphology of compounds is lamellar, it agrees with expected structural characteristics. -- Abstract: Crystalline lamellar calcium phosphate retained 4-aminobenzoic acid inside its cavity without leaching. The intense infrared bands in the 1033 and 1010 cm{sup ?1} interval confirmed the presence of the phosphonate groups attached to the inorganic layer, with sharp and intense peaks in X-ray diffraction patterns, which gave basal distances of 712 and 1578 pm for the original and the intercalated compounds, respectively. Solid-state {sup 31}P nuclear magnetic resonance spectra presented only one peak for the phosphate groups attached to the main inorganic polymeric structure near ?2.4 ppm. The adsorption isotherms from ethanol gave the maximum adsorption capacities of 6.44 and 3.34 mmol g{sup ?1} for nickel and cobalt, respectively, which stability constant and distribution coefficient followed Co > Ni.

  18. Ectopic Osteoid and Bone Formation by Three Calcium-Phosphate Ceramics in Rats, Rabbits and Dogs

    PubMed Central

    Wang, Liao; Zhang, Bi; Bao, Chongyun; Habibovic, Pamela; Hu, Jing; Zhang, Xingdong

    2014-01-01

    Calcium phosphate ceramics with specific physicochemical properties have been shown to induce de novo bone formation upon ectopic implantation in a number of animal models. In this study we explored the influence of physicochemical properties as well as the animal species on material-induced ectopic bone formation. Three bioceramics were used for the study: phase-pure hydroxyapatite (HA) sintered at 1200°C and two biphasic calcium phosphate (BCP) ceramics, consisting of 60 wt.% HA and 40 wt.% TCP (?-Tricalcium phosphate), sintered at either 1100°C or 1200°C. 108 samples of each ceramic were intramuscularly implanted in dogs, rabbits, and rats for 6, 12, and 24 weeks respectively. Histological and histomorphometrical analyses illustrated that ectopic bone and/or osteoid tissue formation was most pronounced in BCP sintered at 1100°C and most limited in HA, independent of the animal model. Concerning the effect of animal species, ectopic bone formation reproducibly occurred in dogs, while in rabbits and rats, new tissue formation was mainly limited to osteoid. The results of this study confirmed that the incidence and the extent of material-induced bone formation are related to both the physicochemical properties of calcium phosphate ceramics and the animal model. PMID:25229501

  19. Characterization of calcium phosphate powders originating from Phyllacanthus imperialis and Trochidae Infundibulum concavus marine shells.

    PubMed

    T?m??an, M; Ozyegin, L S; Oktar, F N; Simon, V

    2013-07-01

    The study reports the preparation and characterization of powders consisting of the different phases of calcium phosphates that were obtained from the naturally derived raw materials of sea-shell origins reacted with H3PO4. Species of sea origin, such as corals and nacres, attracted a special interest in bone tissue engineering area. Nacre shells are built up of calcium carbonate in aragonite form crystallized in an organic matrix. In this work two natural marine origin materials (shells of echinoderm Sputnik sea urchin - Phyllacanthus imperialis and Trochidae Infundibulum concavus mollusk) were involved in the developing powders of calcium phosphate based biomaterials (as raw materials for bone-scaffolds) by hotplate and ultrasound methods. Thermal analyses of the as-prepared materials were made for an assessment of the thermal behavior and heat treatment temperatures. Samples from both sea shells each of them prepared by the above mentioned methods were subjected to thermal treatments at 450 °C and 850 °C in order to evaluate the crystalline transformations of the calcium phosphate structures in the heating process. By X-ray diffraction analyses various calcium phosphate phases were identified. In Sputnik sea urchins originated samples were found predominantly brushite and calcite as a small secondary phase, while in Trochidae I. concavus samples mainly monetite and HA phases were identified. Thermal treatment at 850 °C resulted flat-plate whitlockite crystals - ?-MgTCP [(Ca, Mg)3 (PO4)2] for both samples regardless the preparation method (ultrasound or hotplate) or the targeted Ca/P molar ratio according with XRD patterns. Scanning electron microscopy and Fourier transformed infrared spectroscopy were involved more in the characterization of these materials and the good correlations of the results of these methods were made. PMID:23623070

  20. On the Pressure-Induced Loss of Crystallinity in Zinc- and Calcium-Phosphates

    SciTech Connect

    Shakhvorostov, D.; Mosey, N; Munoz-Paniagua, D; Pereira, G; Song, Y; Kasrai, M; Norton, P; Müser, M

    2008-01-01

    A recently suggested mechanism for the stress memory of various metal phosphates is investigated experimentally. Based on first-principles simulations [N. J. Mosey et al., Science 307, 1612 (2005)], it had been argued that atoms with flexible coordination, such as zinc or heavy-metal cations, act as network-forming agents, undergoing irreversible pressure-induced changes in bonding that lead to increased connectivity between phosphate anions. In the present study, orthophosphates of zinc and calcium were exposed to high pressures on surfaces and in diamond anvil cells. An additional set of first-principles simulations was accomplished on ?-orthophosphate of zinc, which suggested that this material was already cross-linked before compression but that it nevertheless underwent a reversible coordination change under pressure in agreement with the experimental results presented here. Raman spectra indicate an irreversible, pressure-induced loss of long-range crystallinity. The pressures required to induce these changes are around 7 GPa for the zinc phosphates, while they are close to 21 GPa for the calcium phosphates. Hydrogenation of the metal phosphate lowers the threshold pressure by approximately 2-3 GPa in both cases. Moreover, ?-orthophosphate of zinc could be partially amorphisized under nonisotropic pressure on copper foils.

  1. Effect of carbonate and phosphate ratios on the transformation of calcium orthophosphates

    SciTech Connect

    Eliassi, Mohammad Daoud, E-mail: eliassi2007@gmail.com [Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Zhao, Wei [State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences, Yangling 712100 (China); Tan, Wen Feng, E-mail: wenfeng.tan@hotmail.com [Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China)

    2014-07-01

    Graphical abstract: Complexes among phosphate, carbonate and calcium have been prepared via a facile hydrothermal route. The synthesized product at the low (0.15) and the high (1.8) molar ratio of PO{sub 4}{sup 3?}/CO{sub 3}{sup 2?} is calcium phosphate hydrate and hydroxylapatite (HAp), respectively. Molar ratios of PO{sub 4}{sup 3?}/CO{sub 3}{sup 2?} are effective on the reduction of carbonate activity during the crystallization of HAp. - Highlights: • Formation of different complexes from CO{sub 3}{sup 2?}, PO{sub 4}{sup 3?} and Ca{sup 2+} solutions at 60 °C. • Molar ratios of PO{sub 4}{sup 3?}/CO{sub 3}{sup 2} cause changes in phase and size of synthesized products. • Addition of PO{sub 4}{sup 3} inhibited the activity of CO{sub 3}{sup 2?} during bound with Ca{sup 2+}. • The phase transformation was completed, when CO{sub 3}{sup 2?} peaks disappeared in FTIR. • PO{sub 4}{sup 3?}, CO{sub 3}{sup 2?} and Ca{sup 2+} distributed heterogeneously on the surface of precipitation. - Abstract: Complexes among phosphate, carbonate and calcium have been synthesized by a designed hydrothermal method. Effects of carbonate and phosphate ratios on the transformation of calcium-orthophosphates were investigated. With X-ray diffraction measurement the synthesized product at the low (0.15) and the high (1.8) molar ratio of PO{sub 4}{sup 3?}/CO{sub 3}{sup 2?} is calcium phosphate hydrate at pH 9.0, and hydroxylapatite (HAp) at pH 8.0, respectively. Fourier transform infrared spectroscopy of product at the high ratio (1.8) of PO{sub 4}{sup 3?}/CO{sub 3}{sup 2?} shows that the CO{sub 3}{sup 2?} peaks disappear, and the strong peaks at 1412 and 1460 cm{sup ?1} are assigned to the vibrations of PO{sub 4}{sup 3?} in HAp. {sup 31}P nuclear magnetic resonance spectra of products at the low (0.15–0.6) to the high (1.2–1.8) ratios of PO{sub 4}{sup 3?}/CO{sub 3}{sup 2?} are obtained at 2.9 and 2.7 ppm, respectively. Molar ratios of PO{sub 4}{sup 3?}/CO{sub 3}{sup 2?} are effective on the reduction of carbonate activity during the formation and infiltration events of calcium-phosphate surface precipitates, and are subsequently enclosed during HAp formation.

  2. Nonenzymatic Transformation of Amorphous CaCO3 into Calcium Phosphate Mineral after Exposure to Sodium Phosphate in Vitro: Implications for in Vivo Hydroxyapatite Bone Formation.

    PubMed

    Müller, Werner E G; Neufurth, Meik; Huang, Jian; Wang, Kui; Feng, Qingling; Schröder, Heinz C; Diehl-Seifert, Bärbel; Muñoz-Espí, Rafael; Wang, Xiaohong

    2015-06-15

    Studies indicate that mammalian bone formation is initiated at calcium carbonate bioseeds, a process that is driven enzymatically by carbonic anhydrase (CA). We show that amorphous calcium carbonate (ACC) and bicarbonate (HCO3 (-) ) cause induction of expression of the CA in human osteogenic SaOS-2 cells. The mineral deposits formed on the surface of the cells are rich in C, Ca and P. FTIR analysis revealed that ACC, vaterite, and aragonite, after exposure to phosphate, undergo transformation into calcium phosphate. This exchange was not seen for calcite. The changes to ACC, vaterite, and aragonite depended on the concentration of phosphate. The rate of incorporation of phosphate into ACC, vaterite, and aragonite, is significantly accelerated in the presence of a peptide rich in aspartic acid and glutamic acid. We propose that the initial CaCO3 bioseed formation is driven by CA, and that the subsequent conversion to calcium phosphate/calcium hydroxyapatite (exchange of carbonate by phosphate) is a non-enzymatic exchange process. PMID:25871446

  3. Calcium thorium phosphate (Whitlockite-type mineral). Synthesis and structure refinement

    SciTech Connect

    Orlova, A. I., E-mail: oai@uic.nnov.ru [Lobachevsky State University of Nizhni Novgorod (Russian Federation); Khainakov, S. A. [University of Oviedo (Spain); Loginova, E. E.; Oleneva, T. A. [Lobachevsky State University of Nizhni Novgorod (Russian Federation); Garcia Granda, S. [University of Oviedo (Spain); Kurazhkovskaya, V. S. [Moscow State University (Russian Federation)

    2009-07-15

    The crystal structure of a new calcium thorium phosphate has been refined by the full-profile Rietveld method using X-ray powder diffraction data. The sample has been synthesized by the sol-gel technique. The phosphate has been identified by X-ray powder diffraction and IR spectroscopy. The refined composition is represented by the formula Ca{sub 10.26}Th{sub 0.12}(PO{sub 4}){sub 7}. The CaO{sub n} and PO{sub 4} polyhedra are distorted compared to the corresponding polyhedra in the basic compound {beta}-Ca{sub 3}(PO{sub 4}){sub 2}.

  4. Synthesis and characterization of macroporous chitosan\\/calcium phosphate composite scaffolds for tissue engineering

    Microsoft Academic Search

    Y Zhang; Miqin Zhang

    2001-01-01

    Chitosan scaffolds reinforced by beta -tricalcium phosphate (beta -TCP)\\u000a and calcium phosphate invert glass were fabricated with a low-cost,\\u000a bioclean freeze-drying technique via thermally induced phase separation.\\u000a The microstructure, mechanical performance, biodegradation, and\\u000a bioactivity of the scaffolds were studied. The composite scaffolds were\\u000a macroporous, and the pore structures of the scaffolds with beta -TCP and\\u000a the glass appeared very different.

  5. Preliminary evaluation of a novel strong/osteoinductive calcium phosphate cement.

    PubMed

    Qu, Yili; Yang, Yang; Li, Juan; Chen, Zhiqing; Li, Jidong; Tang, Kuangyun; Man, Yi

    2011-09-01

    We developed a novel calcium phosphate cement (CPC) by combining the silk fibroin and osteogenic supplements (?-glycerophosphate, ascorbic acid, and dexamethasone) with ?-tricalcium phosphate cement. Mesenchymal stem cells (MSCs) were cultured on the novel CPC scaffold. Results showed that the novel CPC scaffold was biocompatible and favorable for the adhesion, spreading, and proliferation of MSCs. Osteogenic differentiation of MSCs was confirmed by high osteocalcin content and elevated gene expressions of bone markers, such as alkaline phosphatase, collagen type I, and osteocalcin. Therefore, the novel CPC scaffold may be potentially useful for implant fixation and more rapid new bone formation in moderate load-bearing applications. PMID:20566653

  6. Calcium thorium phosphate (Whitlockite-type mineral). Synthesis and structure refinement

    NASA Astrophysics Data System (ADS)

    Orlova, A. I.; Kha?nakov, S. A.; Loginova, E. E.; Oleneva, T. A.; Granda, S. Garcia; Kurazhkovskaya, V. S.

    2009-07-01

    The crystal structure of a new calcium thorium phosphate has been refined by the full-profile Rietveld method using X-ray powder diffraction data. The sample has been synthesized by the sol-gel technique. The phosphate has been identified by X-ray powder diffraction and IR spectroscopy. The refined composition is represented by the formula Ca10.26Th0.12(PO4)7. The CaO n and PO4 polyhedra are distorted compared to the corresponding polyhedra in the basic compound ?-Ca3(PO4)2.

  7. Identification and quantitive analysis of calcium phosphate microparticles in intestinal tissue by nuclear microscopy

    NASA Astrophysics Data System (ADS)

    Gomez-Morilla, Inmaculada; Thoree, Vinay; Powell, Jonathan J.; Kirkby, Karen J.; Grime, Geoffrey W.

    2006-08-01

    Microscopic particles (0.5-2 ?m diameter), rich in calcium and phosphorus, are found in the lumen of the mid-distal gut of all mammals investigated, including humans, and these may play a role in immuno-surveillance and immune regulation of antigens from food and symbiotic bacteria that are contained in the gut. Whether these particles can cross in to tissue of the intestinal mucosa is unclear. If so, characterising their morphology and chemical composition is an important task in elucidating their function. The analysis of calcium phosphate in biological tissues has been approached in several ways including optical microscopy, scanning electron microscopy and, most recently in this work, with nuclear microscopy. In this paper, we describe the use of microPIXE and microRBS to locate these particles and to determine, accurately, the ratio of phosphorus to calcium using the information on sample thickness obtained from RBS to allow the PIXE ratios to be corrected. A commercial sample of hydroxy apatite was used to demonstrate accuracy and precision of the technique. Then, in a pilot study on intestinal tissue of mice, we demonstrated the presence of calcium phosphate microparticles, consistent with confocal microscopy observations, and we identified the average molar P:Ca molar ratio as 1.0. Further work will confirm the exact chemical speciation of these particles and will examine the influence of differing calcium containing diets on the formation of these microparticles.

  8. Formation of carbonate-apatite crystals after implantation of calcium phosphate ceramics

    Microsoft Academic Search

    G. Daculsi; R. Z. LeGeros; M. Heughebaert; I. Barbieux

    1990-01-01

    Summary  The aims of this study were (1) to determine at the crystal level, the nonspecific biological fate of different types of calcium\\u000a phosphate (Ca?P) ceramics after implantation in various sites (osseous and nonosseous) in animals and (2) to investigate the\\u000a crystallographic association of newly formed apatitic crystals with the Ca?P ceramics.\\u000a \\u000a Noncommercial Ca?P ceramics identified by X-ray diffraction as calcium

  9. Preparation and Properties of Nanoparticles of Calcium Phosphates With Various Ca/P Ratios

    PubMed Central

    Sun, Limin; Chow, Laurence C.; Frukhtbeyn, Stanislav A.; Bonevich, John E.

    2010-01-01

    This study aimed at preparing and studying the properties of nanoparticles of calcium phosphate (nCaP) with Ca/P ratios ranging from 1.0 to 1.67 using a spray-drying technique. Micro-structural analyses suggested that the nCaPs with Ca/P ratios of 1.67 to 1.33 were nano-sized amorphous calcium phosphate (ACP) containing varying amounts of acid phosphate and carbonate. The nCaP with Ca/P ratio of 1 contained only nano-sized low crystalline dicalcium phosphate (DCP). BET measurements of the nCaPs showed specific surface areas of (12 ± 2 to 50 ± 1) m2/g, corresponding to estimated equivalent spherical diameters of (38 to 172) nm. However, dynamic light scattering measurements revealed much larger particles of (380 ± 49 to 768 ± 111) nm, owing to agglomeration of the smaller primary nano particles as revealed by Scanning Electron Microscopy (SEM). Thermodynamic solubility measurements showed that the nCaPs with Ca/P ratio of 1.33 – 1.67 all have similar solubility behavior. The materials were more soluble than the crystalline hydroxyapatite (HA) at pH greater than about 4.7, and more soluble than ?-tricalcium phosphate (?-TCP), octacalcium phosphate (OCP) and DCP at pH above 5.5. Their solubility approached that of ?-tricalcium phosphate (?-TCP) at about pH 7. These nCaPs, which cannot be readily prepared by other currently available methods for nanoparticle preparation, have potential biomedical applications. PMID:21037948

  10. Preparation, Physical-Chemical Characterization, and Cytocompatibility of Polymeric Calcium Phosphate Cements

    PubMed Central

    Khashaba, Rania M.; Moussa, Mervet; Koch, Christopher; Jurgensen, Arthur R.; Missimer, David M.; Rutherford, Ronny L.; Chutkan, Norman B.; Borke, James L.

    2011-01-01

    Aim. Physicochemical mechanical and in vitro biological properties of novel formulations of polymeric calcium phosphate cements (CPCs) were investigated. Methods. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light activated polyalkenoic acid, or polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs. Setting time, compressive and diametral strength of CPCs was compared with zinc polycarboxylate cement (control). Specimens were characterized using X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. In vitro cytotoxicity of CPCs and control was assessed. Results. X-ray diffraction analysis showed hydroxyapatite, monetite, and brushite. Acid-base reaction was confirmed by the appearance of stretching peaks in IR spectra of set cements. SEM revealed rod-like crystals and platy crystals. Setting time of cements was 5–12?min. Type III showed significantly higher strength values compared to control. Type III yielded high biocompatibility. Conclusions. Type III CPCs show promise for dental applications. PMID:21941551

  11. Preparation of novel bioactive nano-calcium phosphate-hydrogel composites

    NASA Astrophysics Data System (ADS)

    Juhasz, Judith A.; Best, Serena M.; Bonfield, William

    2010-02-01

    Nano-sized hydroxyapatite (nHA) and carbonate-substituted hydroxyapatite (nCHA) particles were incorporated into a poly-2-hydroxyethylmethacrylate/polycaprolactone (PHEMA/PCL) hydrogel at a filler content of 10 wt%. Fourier transform infrared absorption, transmission electron microscopy, x-ray diffraction and scanning electron microscopy were used to analyse the physical and chemical characteristics of the calcium phosphate fillers and resultant composites. Nano-sized calcium phosphate particles were produced with a needle-like morphology, average length of 50 nm and an aspect ratio of 3. The nanoparticles were uniformly distributed in the polymer matrix. The addition of both HA and CHA in nano-form enhanced the bioactivity and biocompatibility of the PHEMA/PCL matrix. The carbonate-substitution has allowed for improved bioactivity and biocompatibility of the resultant composite, indicating the potential of this material for use in bone tissue engineering.

  12. Structural aspects of calcium iron phosphate glass containing neodymium oxide

    NASA Astrophysics Data System (ADS)

    Li, Haijian; Liang, Xiaofeng; Wang, Cuiling; Yu, Huijun; Li, Zhen; Yang, Shiyuan

    2014-06-01

    Homogeneous glasses of the xNd2O3sbnd (100 - x)(12CaOsbnd 20Fe2O3sbnd 68P2O5) system were obtained within the 0 ? x ? 10 mol% composition range. The density and molar volume measurements helped to understand the structural changes occurring in these glasses. Vickers-hardness results showed that addition of Nd2O3 strengthened the crosslinking of the glass network. Spectra analysis indicated that Nd2O3 enters in the structure of the phosphate glasses as a network modifier. The depolymerization of the glass network by the addition of Nd2O3 is characterized by the increase in the concentration of pyrophosphate. The decrease of the Q1 terminal oxygen with increasing Nd2O3 content indicated that Psbnd Osbnd Nd bonds participated in the pyrophosphate glass structure, determined from the Raman spectra.

  13. Calcium Gluconate in Phosphate Buffered Saline Increases Gene Delivery with Adenovirus Type 5

    PubMed Central

    Ahonen, Marko T.; Diaconu, Iulia; Pesonen, Sari; Kanerva, Anna; Baumann, Marc; Parviainen, Suvi T.; Spiller, Brad

    2010-01-01

    Background Adenoviruses are attractive vectors for gene therapy because of their stability in vivo and the possibility of production at high titers. Despite exciting preclinical data with various approaches, there are only a few examples of clear efficacy in clinical trials. Effective gene delivery to target cells remains the key variable determining efficacy and thus enhanced transduction methods are important. Methods/Results We found that heated serum could enhance adenovirus 5 mediated gene delivery up to twentyfold. A new protein-level interaction was found between fiber knob and serum transthyretin, but this was not responsible for the observed effect. Instead, we found that heating caused the calcium and phosphate present in the serum mix to precipitate, and this was responsible for enhanced gene delivery. This finding could have relevance for designing preclinical experiments with adenoviruses, since calcium and phosphate are present in many solutions. To translate this into an approach potentially testable in patients, we used calcium gluconate in phosphate buffered saline, both of which are clinically approved, to increase adenoviral gene transfer up to 300-fold in vitro. Gene transfer was increased with or without heating and in a manner independent from the coxsackie-adenovirus receptor. In vivo, in mouse studies, gene delivery was increased 2-, 110-, 12- and 13-fold to tumors, lungs, heart and liver and did not result in increased pro-inflammatory cytokine induction. Antitumor efficacy of a replication competent virus was also increased significantly. Conclusion In summary, adenoviral gene transfer and antitumor efficacy can be enhanced by calcium gluconate in phosphate buffered saline. PMID:20927353

  14. Effect of Microstructural Evolution on Wettability of Laser Coated Calcium Phosphate on Titanium Alloy

    SciTech Connect

    Kurella, Anil K [ORNL; Hu, Michael Z. [ORNL; Dahotre, Narendra B [ORNL

    2008-01-01

    Surface engineering of synthetic implant materials provides an exciting opportunity to mimic natural biomaterials. Surface that are bioactive and textured at multi scale have the potential for easier osseointegration. Ti alloy surfaces known for their biocompatibility are coated with bioactive Calcium Phosphate using a laser source at multiple processing speeds. The resulting surface has multiscale morphology and multi-phase chemical nature. Faster processing speeds showed improved wettability to water along with higher degree of crystallinity in the phases present.

  15. Non-decay type fast-setting calcium phosphate cement: composite with sodium alginate

    Microsoft Academic Search

    Kunio Ishikawa; Youji Miyamoto; Masayuki Kon; Masaru Nagayama; Kenzo Asaoka

    1995-01-01

    Non-decay type fast-setting calcium phosphate cement (nd-FSCPC) was prepared by introducing sodium alginate (0–2.0 wt%) into the liquid phase of FSCPC. nd-FSCPC was stable even when the cement paste was immersed in distilled water immediately after mixing, whereas conventional FSCPC (c-FSCPC) decayed completely within 1 min upon immersion. The setting time of the cement, approximately 5 min, was not dependent

  16. Data on granulometric composition of calcium phosphate obtained by dispersion method

    NASA Astrophysics Data System (ADS)

    Golovanova, O. A.; Chikanova, E. S.; Malyshev, A. V.; Mylnikova, T. S.

    2015-04-01

    The kinetics of calcium phosphate crystallization from model solutions of saliva and liquid phase of dental plaque has been studied by the dispersion method. It was found that the composition of the saliva model system is favorable for the growth of larger crystals. The size of the particles in crystallization varies nonlinearly. As supersaturation grows, the amount of formed particles increases, however, the average rate of crystallite growth decreases.

  17. Effect of human salivary proteins on the precipitation kinetics of calcium phosphate

    Microsoft Academic Search

    E. C. Moreno; K. Varughese; D. I. Hay

    1979-01-01

    Summary  Inhibition of calcium phosphate precipitation in saliva, and prevention of the formation of mineral accretions on tooth surfaces,\\u000a has been ascribed to the existence of inhibiting salivary macromolecules. Marked reductions in the crystal growth rate of\\u000a hydroxyapatite (HA) seeds were measured in supersaturated solutions containing either of two proline-rich proteins, PRP1 or\\u000a PRP3, or statherin; the three macromolecules were isolated

  18. Diphosphonates Inhibit Formation of Calcium Phosphate Crystals in vitro and Pathological Calcification in vivo

    Microsoft Academic Search

    Marion D. Francis; R. Graham G. Russell; Herbert Fleisch

    1969-01-01

    Two diphosphonates containing the P-C-P bond, CH3C(OH)(PO3HNa)2 and H2C(PO3HNa)2, inhibit the crystallization of calcium phosphate in vitro and prevent aortic calcification of rats given large amounts of vitamin D3. The diphosphonates therefore have effects similar to those described for compounds containing the P-O-P bond but are active when administered orally.

  19. Utilizing inverse micelles to synthesize calcium phosphate nanoparticles as nano-carriers

    Microsoft Academic Search

    Jamie YuLing Han; Timothy Thatt Yang Tan; Joachim Say Chye Loo

    The aim of this study was to investigate the feasibility of the inverse micelles (IM) technique in producing protein-loaded\\u000a calcium phosphate nanoparticles (CaP NPs), and to compare this technique with the conventional co-precipitation (co-ppt) technique.\\u000a In this study, bovine serum albumin and lysozyme were used as model proteins. The results show that CaP NPs produced by IM\\u000a were shown to

  20. Calcium phosphate sol-gel-derived coatings on titanium-aluminum-vanadium substrate for biomedical applications

    Microsoft Academic Search

    Lu Gan

    2003-01-01

    Osseointegration of implants to host bone is a necessary requirement for dental and orthopaedic implants. The rate and quality of osseointegration were enhanced through the use of calcium phosphate (Ca-P) films on metallic substrates. The present study investigates the characteristics of Ca-P films applied using sol-gel dip coating methods to sintered porous-surfaced implants. Ca-P films have been formed using Inorganic

  1. The effects of inorganic additives to calcium phosphate on in vitro behavior of osteoblasts and osteoclasts.

    PubMed

    Yang, Liang; Perez-Amodio, Soledad; Barrère-de Groot, Florence Y F; Everts, Vincent; van Blitterswijk, Clemens A; Habibovic, Pamela

    2010-04-01

    This study describes a medium-throughput system based on deposition of calcium phosphate films in multi-well tissue culture plates that can be used to study the effect of inorganic additives on the behavior of osteoblasts and osteoclasts in a standardized manner. All tested elements, copper, zinc, strontium, fluoride and carbonate were homogenously deposited into calcium phosphate films in varying concentrations by using a biomimetic approach. The additives affected morphology and composition of calcium phosphate films to different extent, depending on the concentration used. The effect on proliferation and differentiation of MC3T3-E1 osteoblasts depended on the compound and concentration tested. In general, copper and zinc ions showed an inhibitory effect on osteoblast proliferation, the effect of strontium was concentration dependent, whereas films containing fluoride and carbonate, respectively, augmented osteoblast proliferation. Copper and zinc had no effect or were mild inhibitory on osteoblast differentiation, while strontium, fluoride and carbonate ions demonstrated a clear decrease in differentiation in comparison to the control films without additives. Primary osteoclasts cultured on calcium phosphate films containing additives showed a significantly decreased resorptive activity as compared to the control, independent on the element incorporated. No cytotoxic effect of the elements in the concentrations tested was observed. The system presented in this study mimics bone mineral containing trace elements, making it useful for studying fundamental processes of bone formation and turnover. The present results can be used for modifying bone graft substitutes by addition of inorganic additives in order to affect their performance in bone repair and regeneration. PMID:20122718

  2. Inhibitors of calcium phosphate precipitation and their role in biological mineralization

    NASA Astrophysics Data System (ADS)

    Fleisch, H.

    1981-05-01

    The theoretical concept and the experimental basis of the role of inhibitors of calcium phosphate crystallization and aggregation in the biological mineralization process have been received. Special emphasis has been put on (1) the physiological role of the inhibitor pryrophosphate which occurs naturally in the body fluids of animals and man, (2) the effects of synthetic analogues of pryphosphate, the diphosphonates, which exhibit minealization in vivo and are now used therapeutically in man.

  3. Near-Infrared Emitting Fluorophore Doped Calcium Phosphate Nanoparticles for In Vivo Imaging of Human Breast

    Microsoft Academic Search

    James H. Adair

    2008-01-01

    Early detection is a crucial element for the timely diagnosis and successful treatment of all human cancers but is limited by the sensitivity of current imaging methodologies. We have synthesized and studied bioresorbable calcium phosphate nanoparticles (CPNPs) in which molecules of the near-infrared (NIR) emitting fluorophore,indocyaninegreen(ICG),areembedded.TheICG-CPNPsdemonstrateexceptionalcolloidalandoptical characteristics. Suspensions consisting of 16 nm average diameter particles are colloidally stable in physiological

  4. Injectable PLGA microsphere\\/calcium phosphate cements: physical properties and degradation characteristics

    Microsoft Academic Search

    W. J. E. M. Habraken; J. G. C. Wolke; A. G. Mikos; J. A. Jansen

    2006-01-01

    Calcium phosphate (CaP) cements show an excellent biocompatibility and often have a high mechanical strength, but in general degrade relatively slow. To increase degradation rates, macropores can be introduced into the cement, e.g., by the inclusion of biodegradable microspheres into the cement. The aim of this research is to develop an injectable PLGA microsphere\\/CaP cement with sufficient setting\\/cohesive properties and

  5. Calcium phosphate thin films enhance the response of human mesenchymal stem cells to nanostructured titanium surfaces

    PubMed Central

    Burke, George A; Meenan, Brian J

    2014-01-01

    The development of biomaterial surfaces possessing the topographical cues that can promote mesenchymal stem cell recruitment and, in particular, those capable of subsequently directing osteogenic differentiation is of increasing importance for the advancement of tissue engineering. While it is accepted that it is the interaction with specific nanoscale topography that induces mesenchymal stem cell differentiation, the potential for an attendant bioactive chemistry working in tandem with such nanoscale features to enhance this effect has not been considered to any great extent. This article presents a study of mesenchymal stem cell response to conformal bioactive calcium phosphate thin films sputter deposited onto a polycrystalline titanium nanostructured surface with proven capability to directly induce osteogenic differentiation in human bone marrow–derived mesenchymal stem cells. The sputter deposited surfaces supported high levels of human bone marrow–derived mesenchymal stem cell adherence and proliferation, as determined by DNA quantification. Furthermore, they were also found to be capable of directly promoting significant levels of osteogenic differentiation. Specifically, alkaline phosphatase activity, gene expression and immunocytochemical localisation of key osteogenic markers revealed that the nanostructured titanium surfaces and the bioactive calcium phosphate coatings could direct the differentiation towards an osteogenic lineage. Moreover, the addition of the calcium phosphate chemistry to the topographical profile of the titanium was found to induce increased human bone marrow–derived mesenchymal stem cell differentiation compared to that observed for either the titanium or calcium phosphate coating without an underlying nanostructure. Hence, the results presented here highlight that a clear benefit can be achieved from a surface engineering strategy that combines a defined surface topography with an attendant, conformal bioactive chemistry to enhance the direct osteogenic differentiation of human bone marrow–derived mesenchymal stem cells.

  6. Synthesis of prolonged-release drugs for osteoplasty that are based on chemically modified calcium phosphates

    Microsoft Academic Search

    V. S. Spiridonov; P. G. Mingalev; G. V. Lisichkin; A. V. Sklyarenko; D. E. Satarova; V. B. Kurochkina

    2006-01-01

    In order to use hydroxyapatite and other biocompatible calcium phosphates as carriers for local prolonged-release drug, it\\u000a is necessary to have an active component capable of retaining the preparation deposited onto the carrier surface for a long\\u000a time (at least, for a few days). The grafting of the layer of active functional groups onto the carrier surface is employed\\u000a to

  7. Morphological evolution of precipitates during transformation of amorphous calcium phosphate into octacalcium phosphate in relation to role of intermediate phase

    NASA Astrophysics Data System (ADS)

    Sugiura, Yuki; Onuma, Kazuo; Kimura, Yuki; Miura, Hitoshi; Tsukamoto, Katsuo

    2011-10-01

    Nucleation of amorphous calcium phosphate (ACP) and its phase transformation with a decrease in solution pH were investigated at a constant temperature of 32 °C. A solution containing a mixture of CaCl 2 and KH 2PO 4 was prepared (initial pH=7.7), and a drop was sampled at a constant interval to observe the morphological evolution of the precipitates that formed in the solution. A gel-like solution structure formed immediately after mixing and contained a small amount of sea-urchin-like ACP spherulites (3-20 ?m in size). These spherulites consisted of 1.5-10-?m-long flexible needles that formed simultaneously with numerous ACP spherical particles. They first transformed into ?-tri calcium phosphate-like material (called "pseudo ?-TCP") and then into single crystals of octacalcium phosphate (OCP) without dissolution. The flexible needles in the spherulites changed into blade springs, then into flexible plates, and finally into rigid plates during the transformation. The OCP structure appeared in the pseudo ?-TCP plates and gradually substituted for the ?-TCP structure over time. The macroscopic spherulite morphology of the initial ACP remained unchanged during the phase transformation, suggesting that OCP is a pseudomorph of ACP. This feature was observed only when the ACP spherulites formed in the initial solution. Fiber-like aggregates consisting of ?-TCP single crystals nucleated around the ACP spherical particles and grew over time. They survived until the final stage of the reaction, and OCP polycrystals formed in the mixture of ?-TCP and ACP spheres. The OCP polycrystals gradually substituted for the ACP spheres without phase transformation of ?-TCP into OCP.

  8. Synthesis and characterization of Ag-containing calcium phosphates with various Ca/P ratios.

    PubMed

    Gokcekaya, Ozkan; Ueda, Kyosuke; Narushima, Takayuki; Ergun, Celaletdin

    2015-08-01

    Ag-containing calcium phosphate (CaP) powders were synthesized by a precipitation method using aqueous solutions of calcium nitrate, silver nitrate, and ammonium phosphate. The powders were sintered at temperatures ranging from 1173 to 1473K. The charged atomic ratios of (Ca+Ag)/P and Ag/(Ca+Ag) in solution were varied from 1.33 to 1.67 and from 0 to 0.30, respectively. The Ag content in the as-precipitated CaP powders increased with the charged Ag/(Ca+Ag) atomic ratio in solution and was lower than the charged Ag/(Ca+Ag) value. The as-precipitated CaP powders consisted of hydroxyapatite (HA) as the main phase. Ag nanoparticles were observed on the as-precipitated HA particles under all conditions of Ag addition. After the sintering, HA, ?-TCP (tricalcium phosphate), ?-TCP, and ?-CPP (calcium pyrophosphate) were mainly detected as CaPs on the basis of the Ca/P atomic ratio of the as-precipitated powders. The addition of Ag stabilized the ?-TCP phase, and the distribution of Ag in ?-TCP was homogeneous. A metallic Ag phase coexisted with HA. The solubility of Ag in HA was estimated to be 0.0019-0.0061 (Ag/(Ca+Ag)) atomic ratio, which was lower than that in ?-TCP (higher than 0.0536) and higher than that of ?-CPP (below the detection limit of analyses). PMID:26042697

  9. Preformed chitosan cryogel-biphasic calcium phosphate: a potential injectable biocomposite for pathologic fracture.

    PubMed

    Abueva, Celine Dg; Padalhin, Andrew R; Min, Young-Ki; Lee, Byong-Taek

    2015-08-01

    The increasing interest in chitosan-based biomaterials stems from its desirable physicochemical properties. Although calcium phosphates have been mixed with chitosan to form injectable scaffolds, its application for bone tissue engineering has been limited and is still being explored to improve its clinical translatability. We report a biocomposite comprised of preformed chitosan cryogel with dispersed biphasic calcium phosphate that can flow under moderate pressure allowing passage through a small gauge needle, while maintaining sufficient integrity and strength during injection for gel recovery. The formed samples were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction analysis and protein adsorption measurements. Composite with 1% w/v biphasic calcium phosphate (CSG1) resulted in a homogeneous and rigid final structure. Injectable composite cryogel CSG1 (2.5?±?0.2?N, 23G needle) exhibited good protein adsorption and biocompatibility. Results of subcutaneous implantation in rats reveal relatively high presence of polymorphonuclear cells but with no fibrous encapsulation with the composites, allowing further infiltration of cells within the sample implants. The biocomposite system presents a less-invasive delivery of bone filling material for stabilizing pathologic fractures. PMID:25805056

  10. Cellular Performance Comparison of Biomimetic Calcium Phosphate Coating and Alkaline-Treated Titanium Surface

    PubMed Central

    Wei, Mei

    2013-01-01

    The influence of biomimetic calcium phosphate coating on osteoblasts behavior in vitro is not well established yet. In this study, we investigated the behavior of osteoblastic rat osteosarcoma 17/2.8 cells (ROS17/2.8) on two groups of biomaterial surfaces: alkaline-treated titanium surface (ATT) and biomimetic calcium phosphate coated ATT (CaP). The cell attachment, proliferation, differentiation, and morphology on these surfaces were extensively evaluated to reveal the impact of substrate surface on osteoblastic cell responses. It was found that the ROS17/2.8 cells cultured on the ATT surface had higher attachment and proliferation rates compared to those on the CaP surface. Our results also showed that the calcium phosphate coatings generated in this work have an inhibiting effect on osteoblast adhesion and further influenced the proliferation and differentiation of osteoblast compared to the ATT surface in vitro. Cells on the ATT surface also exhibited a higher alkaline phosphatase activity than on the CaP surface after two weeks of culture. Immunofluorescence staining and scanning electron microscopy results showed that the cells adhered and spread faster on the ATT surface than on the CaP surface. These results collectively suggested that substrate surface properties directly influence cell adhesion on different biomaterials, which would result in further influence on the cell proliferation and differentiation. PMID:24455730

  11. Injectable thermosensitive hydrogel composite with surface-functionalized calcium phosphate as raw materials

    PubMed Central

    Fan, RangRang; Deng, XiaoHui; Zhou, LiangXue; Gao, Xiang; Fan, Min; Wang, YueLong; Guo, Gang

    2014-01-01

    In this study, L-lactide was used to modify the tricalcium phosphate (?-TCP) and tetracalcium phosphate (TTCP) surface which can form functionalized poly(l-lactic acid) (PLLA)-grafted ?-TCP (g-?-TCP) and PLLA-grafted TTCP (g-TTCP) particles. The g-?-TCP and g-TTCP obtained were incorporated into a PEG-PCL-PEG (PECE) matrix to prepare injectable thermosensitive hydrogel composites. The morphology of the hydrogel composites showed that the g-?-TCP and g-TTCP particles dispersed homogeneously into the polymer matrix, and each hydrogel composite had a three-dimensional network structure. Rheologic analysis showed that the composite had good thermosensitivity. Changes in calcium concentration and pH in simulated body fluid solutions confirmed the feasibility of surface-functionalized calcium phosphate for controlled release of calcium. All the results indicate that g-?-TCP/PECE and g-TTCP/PECE hydrogels might be a promising protocol for tissue engineering. PMID:24489468

  12. Development of a calcium phosphate nanocomposite for fast fluorogenic detection of bacteria.

    PubMed

    Martínez, Claudio R; Rodríguez, Tamara L; Zhurbenko, Raisa; Valdés, Ivonne A; Gontijo, Sávio M L; Gomes, Alinne D M; Suarez, Diego F; Sinisterra, Rubén D; Cortés, Maria E

    2014-01-01

    Current procedures for the detection and identification of bacterial infections are laborious, time-consuming, and require a high workload and well-equipped laboratories. Therefore the work presented herein developed a simple, fast, and low cost method for bacterial detection based on hydroxyapatite nanoparticles with a nutritive mixture and the fluorogenic substrate. Calcium phosphate ceramic nanoparticles were characterized and integrated with a nutritive mixture for the early detection of bacteria by visual as well as fluorescence spectroscopy techniques. The composite was obtained by combining calcium phosphate nanoparticles (Ca:P ratio, 1.33:1) with a nutritive mixture of protein hydrolysates and carbon sources, which promote fast bacterial multiplication, and the fluorogenic substrate 4-methylumbellipheryl-?-D-glucuronide (MUG). The composite had an average particle size of 173.2 nm and did not show antibacterial activity against Gram-negative or Gram-positive bacteria. After an Escherichia coli suspension was in contact with the composite for 60-90 min, fluorescence detected under UV light or by fluorescence spectrophotometer indicated the presence of bacteria. Intense fluorescence was observed after incubation for a maximum of 90 min. Thus, this calcium phosphate nanocomposite system may be useful as a model for the development of other nanoparticle composites for detection of early bacterial adhesion. PMID:25197932

  13. Drug delivery from injectable calcium phosphate foams by tailoring the macroporosity-drug interaction.

    PubMed

    Pastorino, David; Canal, Cristina; Ginebra, Maria-Pau

    2015-01-01

    In this work, novel injectable calcium phosphate foams (CPFs) were combined with an antibiotic (doxycycline) to design an innovative dosage form for bone regeneration. The material structure, its drug release profile and antibiotic activity were investigated, while its clinical applicability was assessed through cohesion and injectability tests. Doxycycline had a clear effect on both the micro and macro structure of the CPFs, owing to its role as a nucleating agent of hydroxyapatite and to a drying effect on the paste. Doxycycline-loaded CPFs presented interconnected macroporosity, which increased drug availability compared with calcium phosphate cements, and was a critical parameter controlling the release kinetics which followed a non-Fickian diffusion model. Up to 55% (1mg) of the drug was released progressively in 5days, the percentage released being proportional to the macroporosity of the CPFs. All doxycycline-containing foams had immediate cohesion and were injectable. Moreover, antibacterial activity was observed against Staphylococcus aureus and Escherichia coli. Thus, in addition to enhancing osteoconduction and material resorption, macroporosity enables tuning of the local delivery of drugs from injectable calcium phosphates. PMID:25448345

  14. 3D Printing of Composite Calcium Phosphate and Collagen Scaffolds for Bone Regeneration

    PubMed Central

    Inzana, Jason A.; Olvera, Diana; Fuller, Seth M.; Kelly, James P.; Graeve, Olivia A.; Schwarz, Edward M.; Kates, Stephen L.; Awad, Hani A.

    2014-01-01

    Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1–2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing. PMID:24529628

  15. Europium-doped amorphous calcium phosphate porous nanospheres: preparation and application as luminescent drug carriers.

    PubMed

    Chen, Feng; Zhu, Ying-Jie; Zhang, Kui-Hua; Wu, Jin; Wang, Ke-Wei; Tang, Qi-Li; Mo, Xiu-Mei

    2011-01-01

    Calcium phosphate is the most important inorganic constituent of biological tissues, and synthetic calcium phosphate has been widely used as biomaterials. In this study, a facile method has been developed for the fabrication of amorphous calcium phosphate (ACP)/polylactide-block-monomethoxy(polyethyleneglycol) hybrid nanoparticles and ACP porous nanospheres. Europium-doping is performed to enable photoluminescence (PL) function of ACP porous nanospheres. A high specific surface area of the europium-doped ACP (Eu3+:ACP) porous nanospheres is achieved (126.7 m2/g). PL properties of Eu3+:ACP porous nanospheres are investigated, and the most intense peak at 612 nm is observed at 5 mol% Eu3+ doping. In vitro cytotoxicity experiments indicate that the as-prepared Eu3+:ACP porous nanospheres are biocompatible. In vitro drug release experiments indicate that the ibuprofen-loaded Eu3+:ACP porous nanospheres show a slow and sustained drug release in simulated body fluid. We have found that the cumulative amount of released drug has a linear relationship with the natural logarithm of release time (ln(t)). The Eu3+:ACP porous nanospheres are bioactive, and can transform to hydroxyapatite during drug release. The PL properties of drug-loaded nanocarriers before and after drug release are also investigated. PMID:21711603

  16. Calcium phosphate cement - gelatin powder composite testing in canine models: Clinical implications for treatment of bone defects.

    PubMed

    Yomoda, Mitsuhiro; Sobajima, Satoshi; Kasuya, Akihiro; Neo, Masashi

    2015-05-01

    Previous studies have reported the excellent biocompatibility of calcium phosphate cement. However, calcium phosphate cement needs further improvement in order for it to promote bone replacement and eventual bone substitution, as it exhibits slow biodegradability and thus remains in the body over an extended period of time. In this study, we mixed calcium phosphate cement with gelatin powder in order to create a composite containing macropores with interconnectivity, and we then implanted it into canine femurs from the diaphysis to the distal metaphysis. Eight dogs were divided into the sham group, the control (C0) group with 100 wt% calcium phosphate cement, the C10 group with 90 wt% calcium phosphate cement and 10 wt% gelatin powder, and the C15 group with 85 wt% calcium phosphate cement and 15 wt% gelatin powder. Bone replaceability in C10 and C15 at 3 and 6 months was evaluated by radiography, micro-CT, histomorphometry, and mineral apposition rate. New bone formation was seen in C10 and C15 although that was not seen in C0 at six months. The mineral apposition rate was significantly higher in C15 than in C10 in both the diaphysis and metaphysis, and the composite was found to have excellent biodegradability and bone replaceability in canine subjects. As the composite is easily and rapidly prepared, it is likely to become a new bone substitute for use in clinical settings. PMID:25550332

  17. Biomimetic synthesis of modified calcium phosphate fine powders and their in vitro studies

    SciTech Connect

    Gergulova, R., E-mail: rumigg@yahoo.com; Tepavitcharova, S., E-mail: rumigg@yahoo.com; Rabadjieva, D., E-mail: rumigg@yahoo.com; Sezanova, K., E-mail: rumigg@yahoo.com; Ilieva, R., E-mail: rumigg@yahoo.com [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria); Alexandrova, R.; Andonova-Lilova, B. [Institute of Experimental Morphology, Pathology and Anthropology with Museum, BAS, Acad. G. Bonchev Str., Bl. 25, Sofia (Bulgaria)

    2013-12-16

    Biomimetic approach and subsequent high-temperature treatment were used to synthesize ion modified calcium phosphate fine powders. Thus, using Simulated Body Fluid (SBF) as an ion modifier, a bi-phase mixture of ion modified ?-tricalcium phosphate and hydroxyapatite (?-TCP + HA) was prepared. The use of SBF electrolyte solution enriched with Mg{sup 2+} or Zn{sup 2+} yielded monophase ?-tricalcium phosphate additionally modified with Mg{sup 2+} or Zn{sup 2+} (Mg-?-TCP or Zn-?-TCP). The in vitro behavior of the prepared powders on cell viability and proliferation of murine BALB/c 3T3 fibroblasts and of human Lep 3 cells was studied by MTT test assays and Mosmann method after 72 h incubation. The relative cell viability was calculated.

  18. Surface controlled calcium phosphate formation on three-dimensional bacterial cellulose-based nanofibers.

    PubMed

    Luo, Honglin; Xiong, Guangyao; Zhang, Chen; Li, Deying; Zhu, Yong; Guo, Ruisong; Wan, Yizao

    2015-04-01

    Studies on the early calcium phosphate (Ca-P) formation on nanosized substrates may allow us to understand the biomineralization mechanisms at the molecular level. In this work, in situ formation of Ca-P minerals on bacterial cellulose (BC)-based nanofibers was investigated, for the first time, using the X-ray absorption near-edge structure (XANES) spectroscopy. In addition, the influence of the surface coating of nanofibers on the formation of Ca-P minerals was determined. Combined with XRD analysis, XANES results revealed that the nascent precursor was ACP (amorphous calcium phosphate) which was converted to TCP (?-tricalcium phosphate), then OCP (octacalcium phosphate), and finally to HAP (hydroxyapatite) when phosphorylated BC nanofibers were the templates. However, the formation of nascent precursor and its transformation process varied depending on the nature of the coating material on nanofibrous templates. These results provide new insights into basic mechanisms of mineralization and can lead to the development of novel bioinspired nanostructured materials. PMID:25686980

  19. Association of serum phosphorus and calcium x phosphate product with mortality risk in chronic hemodialysis patients: A national study

    Microsoft Academic Search

    GA Block; TE Hulbert-Shearon; NW Levin; FK Port

    1998-01-01

    Elevated serum phosphorus is a predictable accompaniment of end-stage renal disease (ESRD) in the absence of dietary phosphate restriction or supplemental phosphate binders. The consequences of hyperphosphatemia include the development and progression of secondary hyperparathyroidism and a predisposition to metastatic calcification when the product of serum calcium and phosphorus (Ca x PO4) is elevated. Both of these conditions may contribute

  20. Development of a 3D polymer reinforced calcium phosphate cement scaffold for cranial bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Alge, Daniel L.

    The repair of critical-sized cranial bone defects represents an important clinical challenge. The limitations of autografts and alloplastic materials make a bone tissue engineering strategy desirable, but success depends on the development of an appropriate scaffold. Key scaffold properties include biocompatibility, osteoconductivity, sufficient strength to maintain its structure, and resorbability. Furthermore, amenability to rapid prototyping fabrication methods is desirable, as these approaches offer precise control over scaffold architecture and have the potential for customization. While calcium phosphate cements meet many of these criteria due to their composition and their injectability, which can be leveraged for scaffold fabrication via indirect casting, their mechanical properties are a major limitation. Thus, the overall goal of this work was to develop a 3D polymer reinforced calcium phosphate cement scaffold for use in cranial bone tissue engineering. Dicalcium phosphate dihydrate (DCPD) setting cements are of particular interest because of their excellent resorbability. We demonstrated for the first time that DCPD cement can be prepared from monocalcium phosphate monohydrate (MCPM)/hydroxyapatite (HA) mixtures. However, subsequent characterization revealed that MCPM/HA cements rapidly convert to HA during degradation, which is undesirable and led us to choose a more conventional formulation for scaffold fabrication. In addition, we developed a novel method for calcium phosphate cement reinforcement that is based on infiltrating a pre-set cement structure with a polymer, and then crosslinking the polymer in situ. Unlike prior methods of cement reinforcement, this method can be applied to the reinforcement of 3D scaffolds fabricated by indirect casting. Using our novel method, composites of poly(propylene fumarate) (PPF) reinforced DCPD were prepared and demonstrated as excellent candidate scaffold materials, as they had increased strength and ductility and were biocompatible in vitro. Furthermore, 3D PPF reinforced DCPD scaffolds had strengths comparable to trabecular bone. Based on these results, 3D PPF reinforced DCPD scaffolds were evaluated in vivo using a rabbit calvarial defect model. Although bone formation was not enhanced by the addition of mesenchymal stem cells, significant bone ingrowth from the surrounding tissue was observed. The results of this work provide a foundation for future research on 3D polymer reinforced calcium phosphate cement scaffolds.

  1. Umbilical Cord Stem Cell Seeding on Fast-Resorbable Calcium Phosphate Bone Cement

    PubMed Central

    Zhao, Liang; Detamore, Michael S.; Takagi, Shozo; Chow, Laurence C.

    2010-01-01

    Tissue engineering offers immense promise for bone regeneration. Human umbilical cord mesenchymal stem cells (hUCMSCs) can be collected without invasive procedures required for bone marrow MSCs. The objective of this study was to investigate the physical properties and the differentiation capacity of hUCMSCs on calcium phosphate cement (CPC) scaffolds with improved dissolution/resorption rates. CPC consisted of tetracalcium phosphate and dicalcium phosphate anhydrous, with various tetracalcium phosphate/dicalcium phosphate anhydrous ratios. At 1/3 ratio, CPC had a dissolution rate 40% faster than CPC control at 1/1. The faster-resorbable CPC had strength and modulus similar to CPC control. Their strength and modulus exceeded the reported values for cancellous bone, and were much higher than those of hydrogels and injectable polymers for cell delivery. hUCMSCs attached to the nano-apatitic CPC and proliferated rapidly. hUCMSCs differentiated into the osteogenic lineage, with significant increases in alkaline phosphatase activity, osteocalcin, collagen I, and osterix gene expression. In conclusion, in this study we reported that hUCMSCs attaching to CPC with high dissolution/resorption rate showed excellent proliferation and osteogenic differentiation. hUCMSCs delivered via high-strength CPC have the potential to be an inexhaustible and low-cost alternative to the gold-standard human bone marrow mesenchymal stem cells. These results may broadly impact stem-cell-based tissue engineering. PMID:20388037

  2. Glucose-6-phosphate reduces calcium accumulation in rat brain endoplasmic reticulum

    PubMed Central

    Cole, Jeffrey T.; Kean, William S.; Pollard, Harvey B.; Verma, Ajay; Watson, William D.

    2012-01-01

    Brain cells expend large amounts of energy sequestering calcium (Ca2+), while loss of Ca2+ compartmentalization leads to cell damage or death. Upon cell entry, glucose is converted to glucose-6-phosphate (G6P), a parent substrate to several metabolic major pathways, including glycolysis. In several tissues, G6P alters the ability of the endoplasmic reticulum (ER) to sequester Ca2+. This led to the hypothesis that G6P regulates Ca2+ accumulation by acting as an endogenous ligand for sarco-endoplasmic reticulum calcium ATPase (SERCA). Whole brain ER microsomes were pooled from adult male Sprague-Dawley rats. Using radio-isotopic assays, 45Ca2+ accumulation was quantified following incubation with increasing amounts of G6P, in the presence or absence of thapsigargin, a potent SERCA inhibitor. To qualitatively assess SERCA activity, the simultaneous release of inorganic phosphate (Pi) coupled with Ca2+ accumulation was quantified. Addition of G6P significantly and decreased Ca2+ accumulation in a dose-dependent fashion (1–10 mM). The reduction in Ca2+ accumulation was not significantly different that seen with addition of thapsigargin. Addition of glucose-1-phosphate or fructose-6-phosphate, or other glucose metabolic pathway intermediates, had no effect on Ca2+ accumulation. Further, the release of Pi was markedly decreased, indicating G6P-mediated SERCA inhibition as the responsible mechanism for reduced Ca2+ uptake. Simultaneous addition of thapsigargin and G6P did decrease inorganic phosphate in comparison to either treatment alone, which suggests that the two treatments have different mechanisms of action. Therefore, G6P may be a novel, endogenous regulator of SERCA activity. Additionally, pathological conditions observed during disease states that disrupt glucose homeostasis, may be attributable to Ca2+ dystasis caused by altered G6P regulation of SERCA activity. PMID:22529775

  3. Effect of intravenous calcium and oral sodium phosphate in cows with parturient paresis.

    PubMed

    Braun, U; Dumelin, J; Siegwart, N; Bleul, U; Hässig, M

    2007-06-01

    The goal of this study was to determine whether oral administration of sodium phosphate in conjunction with intravenous calcium is more efficaceous than intravenous calcium alone for the treatment of parturient paresis. Thirty cows with parturient paresis were examined and treated by the same veterinarian. The cows were divided randomly into two groups of 15 cows each. Cows in group A received 500 ml of a 40 per cent calcium borogluconate solution containing 15.65 g calcium gluconate and borogluconate, with a supplement of 6 per cent magnesium hypophosphite (9.85 g magnesium hypophosphite) intravenously over a period of approximately 15 min. Cows in group B received the same treatment as well as 350 g of monobasic sodium phosphate (70 g inorganic phosphate, NaH2PO4 2 H2O, Streuli) dissolved in 0.5 litres of distilled water orally via a stomach tube. After treatment, the heart rate, respiratory rate, rectal temperature, superficial body temperature, rumen motility, appetite and defecation of the cows were monitored every hour for eight h. The cows' attempts to rise and their ability to stand were also noted. Initially, the results of clinical examination and serum electrolyte analyses did not differ between the two groups of cows. Within one hour of treatment, stupor was not observed in any of the cows. The general demeanour after treatment did not differ significantly between the two groups. In both groups, the average rectal temperature increased within two hours of the initiation of treatment, from 38.0 +/- 0.95 degrees C to 38.5 +/- 0.40 degrees C. There was no significant difference in the recovery rate between the groups. Of the 30 cows, 22 (73.3 per cent) stood within eight hours of treatment (10 cows from group A and 12 cows from group B). The type of treatment did not affect the time required to stand: cows in group A stood within 47.3 +/- 44 minutes and cows in group B stood within 24.2 +/- 32 minutes after the start of treatment. Our findings do not support the hypothesis that oral treatment with 350 g of sodium phosphate together with intravenous infusion of calcium in cows with parturient paresis results in an improved outcome, even though all the cows had hypophosphataemia as well as hypocalcaemia. PMID:17645035

  4. In vivo study of calcium phosphate cements: implantation of an ?-tricalcium phosphate\\/dicalcium phosphate dibasic\\/tetracalcium phosphate monoxide cement paste

    Microsoft Academic Search

    K. Kurashina; H. Kurita; M. Hirano; A. Kotani; C. P. A. T. Klein; K. de Groot

    1997-01-01

    ?-Tricalcium phosphate (?-TCP)\\/dicalcium phosphate dibasic (DCPD)\\/tetracalcium phosphate monoxide (TeCP) cement was implanted in paste form into soft tissue (rate subcutaneous sockets) and bone tissue (defects in rabbit mandibles) to evaluate the setting behaviour of the cement and tissue responses to the cement. A histological study of the soft tissue implants revealed thin fibrous capsule formation, the appearance of multinucleated giant

  5. Nanoscale Confinement Controls the Crystallization of Calcium Phosphate: Relevance to Bone Formation

    PubMed Central

    Cantaert, Bram; Beniash, Elia; Meldrum, Fiona C.

    2015-01-01

    A key feature of biomineralization processes is that they take place within confined volumes, in which the local environment can have significant effects on mineral formation. Herein, we investigate the influence of confinement on the formation mechanism and structure of calcium phosphate (CaP). This is of particular relevance to the formation of dentine and bone, structures of which are based on highly mineralized collagen fibrils. CaP was precipitated within 25–300 nm diameter, cylindrical pores of track etched and anodised alumina membranes under physiological conditions, in which this system enables systematic study of the effects of the pore size in the absence of a structural match between the matrix and the growing crystals. Our results show that the main products were polycrystalline hydroxapatite (HAP) rods, together with some single crystal octacalcium phosphate (OCP) rods. Notably, we demonstrate that these were generated though an intermediate amorphous calcium phosphate (ACP) phase, and that ACP is significantly stabilised in confinement. This effect may have significance to the mineralization of bone, which can occur through a transient ACP phase. We also show that orientation of the HAP comparable, or even superior to that seen in bone can be achieved through confinement effects alone. Although this simple experimental system cannot be considered, a direct mimic of the in vivo formation of ultrathin HAP platelets within collagen fibrils, our results show that the effects of physical confinement should not be neglected when considering the mechanisms of formation of structures, such as bones and teeth. PMID:24115275

  6. Injectability of calcium phosphate pastes: Effects of particle size and state of aggregation of ?-tricalcium phosphate powders.

    PubMed

    Torres, P M C; Gouveia, S; Olhero, S; Kaushal, A; Ferreira, J M F

    2015-07-15

    The present study discloses a systematic study about the influence of some relevant experimental variables on injectability of calcium phosphate cements. Non-reactive and reactive pastes were prepared, based on tricalcium phosphate doped with 5mol% (Sr-TCP) that was synthesised by co-precipitation. The varied experimental parameters included: (i) the heat treatment temperature within the range of 800-1100°C; (ii) different milling extents of calcined powders; (iii) the liquid-to-powder ratio (LPR); (iv) the use of powder blends with different particle sizes (PS) and particle size distributions (PSD); (v) the partial replacement of fine powders by large spherical dense granules prepared via freeze granulation method to simulate coarse individual particles. The aim was contributing to better understanding of the effects of PS, PSD, morphology and state of aggregation of the starting powders on injectability of pastes produced thereof. Powders heat treated at 800 and 1000°C with different morphologies but with similar apparent PSD curves obtained by milling/blending originated completely injectable reactive cement pastes at low LPR. This contrasted with non-reactive systems prepared thereof under the same conditions. Hypotheses were put forward to explain why the injectability results collected upon extruding non-reactive pastes cannot be directly transposed to reactive systems. The results obtained underline the interdependent roles of the different powder features and ionic strength in the liquid media on determining the flow and injectability behaviours. PMID:25870171

  7. Effects of different crosslinking methods on the properties of collagen-calcium phosphate composite materials.

    PubMed

    Koz?owska, J; Sionkowska, A

    2015-03-01

    The purpose of this study is the preparation and characterization of porous collagen/calcium phosphates (Col/CaP) composites. Collagen scaffolds with high porosity were prepared by freeze-drying technique. Col/CaP scaffold were created by new method--by deposition of calcium phosphate within collagen matrix in two steps using freeze-drying process before immersing samples in calcium solution. To find the optimal preparative method, we prepared diverse Col/CaP scaffolds using different collagen concentration and various crosslinking method: crosslinking with carbodiimide (EDC/NHS) and dehydrothermal treatment (DHT). This study explores the effect of the different crosslinking method on the properties of scaffolds, such as: microstructure (porosity and density), dissolution, water uptake, mechanical properties and collagenase degradation. The results obtained showed that crosslinking the scaffolds by either EDC/NHS or DHT have good mechanical and morphological properties compatible with their potential application in bone regeneration. The results demonstrated that properties of Col/CaP scaffolds changed significantly with different crosslinking method. However, while EDC/NHS increased the scaffolds' resistance to dissolution and degradation by collagenase, DHT decreased the swelling ratio and resistance to dissolution in PBS solution. Based on our study, 2% collagen concentration and EDC/NHS as crosslinking reagent are recommended to design the scaffold for use in bone engineering. PMID:25542169

  8. [Preventive and remineralization effect over incipient lesions of caries decay by phosphopeptide-amorphous calcium phosphate].

    PubMed

    Juárez-López, María Lilia Adriana; Hernández-Palacios, Rosa Diana; Hernández-Guerrero, Juan Carlos; Jiménez-Farfán, Dolores; Molina-Frechero, Nelly

    2014-01-01

    INTRODUCTION. Dental caries continues to affect a large percentage of Mexican children and currently advises that if diagnosed at an early stage can be reversed with minimally invasive treatments. The casein phosphopeptide amorphous calcium phosphate known as CPP-ACP is a phosphoprotein capable of releasing calcium and phosphate ions in the oral environment promoting remineralization. OBJECTIVE. To evaluate the effect of CPP-ACP with fluoride added in a scholar preventive program. MATERIAL AND METHODS. A cuasi- experimental study was conducted in 104 schools of six years old. The children were classified into three groups and received six months biweekly applications of different treatments: casein phosphopeptide amorphous calcium phosphate added fluoride (CPP-ACPF), sodium fluoride (NaF) and a control group. Clinical evaluation was performed with the laser fluorescence technique (Diagnodent model 2095). 1340 teeth were included: 294 teeth with incipient lesions and 1,046 healthy teeth. Statistical tests of ?2 y Mc Nemar were used. RESULTS. In the group that received the application of CPP-ACPF, 38% of incipient carious lesions were remineralizing compared with 21% in the group receiving the NaF (p < 0.001) and 15% in the control group (p < 0.0001) The percentage of teeth free of caries were preserved in the therapy group phosphoprotein was the biggest. This group also showed the lower proportion of deep carious lesion development (p < 0.0001). CONCLUSION. The application biweekly for six months of CPP-ACPF showed a protective and remineralizing effect on incipient carious lesions. His action was better than the application of NaF. However, to reduce the impact from dental caries in schoolchildren is important to have a comprehensive preventive approach that includes promoting self-care, as well as the application of sealants. PMID:24960324

  9. Antibacterial amorphous calcium phosphate nanocomposites with a quaternary ammonium dimethacrylate and silver nanoparticles

    PubMed Central

    Cheng, Lei; Weir, Michael D.; Xu, Hockin H. K.; Antonucci, Joseph M.; Kraigsley, Alison M.; Lin, Nancy J.; Lin-Gibson, Sheng; Zhou, Xuedong

    2012-01-01

    Objectives Calcium and phosphate ion-releasing resin composites are promising for remineralization. However, there has been no report on incorporating antibacterial agents to these composites. The objective of this study was to develop antibacterial and mechanically-strong nanocomposites incorporating a quaternary ammonium dimethacrylate (QADM), nanoparticles of silver (NAg), and nanoparticles of amorphous calcium phosphate (NACP). Methods The QADM, bis(2-methacryloyloxyethyl) dimethylammonium bromide (ionic dimethacrylate-1), was synthesized from 2-(N,N-dimethylamino)ethyl methacrylate and 2-bromoethyl methacrylate. Ng was synthesized by dissolving Ag 2-ethylhexanoate salt in 2-(tertbutylamino)ethyl methacrylate. Mechanical properties were measured in three-point flexure with bars of 2×2×25 mm (n = 6). Composite disks (diameter = 9 mm, thickness = 2 mm) were inoculated with Streptococcus mutans. The metabolic activity and lactic acid production of biofilms were measured (n = 6). Two commercial composites were used as controls. Results Flexural strength and elastic modulus of NACP+QADM, NACP+NAg, and NACP+QADM+NAg matched those of commercial composites with no antibacterial property (p > 0.1). The NACP+QADM+NAg composite decreased the titer counts of adherent S. mutans biofilms by an order of magnitude, compared to the commercial composites (p < 0.05). The metabolic activity and lactic acid production of biofilms on NACP+QADM+NAg composite were much less than those on commercial composites (p < 0.05). Combining QADM and NAg rendered the nanocomposite more strongly antibacterial than either agent alone (p < 0.05). Significance QADM and NAg were incorporated into calcium phosphate composite for the first time. NACP+QADM+NAg was strongly-antibacterial and greatly reduced the titer counts, metabolic activity, and acid production of S. mutans biofilms, while possessing mechanical properties similar to commercial composites. These nanocomposites are promising to have the double benefits of remineralization and antibacterial capabilities to inhibit dental caries. PMID:22305716

  10. Polymeric-Calcium Phosphate Cement Composites-Material Properties: In Vitro and In Vivo Investigations

    PubMed Central

    Khashaba, Rania M.; Moussa, Mervet M.; Mettenburg, Donald J.; Rueggeberg, Frederick A.; Chutkan, Norman B.; Borke, James L.

    2010-01-01

    New polymeric calcium phosphate cement composites (CPCs) were developed. Cement powder consisting of 60?wt% tetracalcium phosphate, 30?wt% dicalcium phosphate dihydrate, and 10?wt% tricalcium phosphate was combined with either 35%?w/w poly methyl vinyl ether maleic acid or polyacrylic acid to obtain CPC-1 and CPC-2. The setting time and compressive and diametral tensile strength of the CPCs were evaluated and compared with that of a commercial hydroxyapatite cement. In vitro cytotoxicity and in vivo biocompatibility of the two CPCs and hydroxyapatite cement were assessed. The setting time of the cements was 5–15?min. CPC-1 and CPC-2 showed significantly higher compressive and diametral strength values compared to hydroxyapatite cement. CPC-1 and CPC-2 were equivalent to Teflon controls after 1 week. CPC-1, CPC-2, and hydroxyapatite cement elicited a moderate to intense inflammatory reaction at 7 days which decreased over time. CPC-1 and CPC-2 show promise for orthopedic applications. PMID:20811498

  11. Purification and characterization of a rabbit salivary protein, a potent inhibitor of crystal growth of calcium phosphate salts.

    PubMed

    Spielman, A I; Bernstein, A; Hay, D I; Blum, M; Bennick, A

    1991-01-01

    Human saliva is supersaturated with respect to basic calcium phosphate salts but is stabilized by specific macromolecules that inhibit calcium phosphate precipitation. One of the families of inhibitory proteins in human and monkey saliva is the acidic proline-rich proteins. The purpose of this study was to isolate and characterize inhibitors of calcium phosphate precipitation from rabbit parotid saliva. Saliva was fractionated by immunoaffinity chromatography and anion exchange chromatography. Individual fractions were assayed for their ability to inhibit calcium phosphate crystal growth and the fraction associated with the inhibition was purified by repeated anion exchange chromatography, preparative gel electrophoresis and electroelution. A major (APRP) and two minor proteins (AM1, AM2) that were inhibitory were purified. APRP is an acidic proline-rich phospho-glycoprotein and a very potent inhibitor of secondary crystal growth of calcium phosphate as it was active at a concentration of 2 x 10(-8) M in a standard assay. The N-terminal sequence of one APRP was EYENLDGSLAATQNDDD?Q and a clostripain fragment of APRP had the following N-terminal sequence PQHRPPRPGGH-????SPPP?GN???PPP. Although the N-terminal segment of APRP does not resemble that of proline-rich proteins, alignment of the clostripain fragment with the repeat region of such proteins from rat, mouse, monkey and man revealed a high degree of similarity, indicating a structural relationship with the proline-rich protein family. PMID:2012527

  12. Regulation of calcium phosphate sedimentation in biological fluids through post-nucleation shielding

    E-print Network

    Chang, Joshua C

    2015-01-01

    In vertebrates, insufficient availability of calcium and phosphate ions in extracellular fluids leads to loss of bone density and neuronal hyper-excitability. To counteract this problem, calcium ions are present at high concentrations throughout body fluids -- at concentrations exceeding the saturation point. This situation leads to the opposite situation where unwanted mineral sedimentation may occur. Remarkably, ectopic or out-of-place sedimentation into soft tissues is rare, in spite of the thermodynamic driving factors. This fortunate fact is due to the presence of auto-regulatory proteins that are found in abundance in bodily fluids. Yet, many important inflammatory disorders such as atherosclerosis and osteoarthritis are associated with this undesired calcification. Hence, it is important to gain an understanding of the regulatory process and the conditions under which it can go awry. In this Letter, we use ideas from mean-field classical nucleation theory to study the regulation of sedimentation of cal...

  13. Synthesis of terbium doped calcium phosphate nanocrystalline powders by citric acid sol–gel combustion method

    Microsoft Academic Search

    Yingchao Han; Xinyu Wang; Shipu Li; Xionghua Ma

    2009-01-01

    Terbium doped calcium phosphate (Tb-doped CaP) nanocrystalline powders were synthesized by the citric acid sol–gel combustion\\u000a method. The phase composition, morphology and luminescent property of Tb-doped CaP nanocrystalline powders were characterized\\u000a by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, fluorescence spectrophotometer\\u000a and fluorescence microscopy. At 700 °C, Tb-doped CaP nanocrystalline powders are composed of HAP (main phase) and ?-TCP

  14. Ionic liquid-assisted formation of cellulose/calcium phosphate hybrid materials

    PubMed Central

    Salama, Ahmed; Neumann, Mike; Günter, Christina

    2014-01-01

    Summary Cellulose/calcium phosphate hybrid materials were synthesized via an ionic liquid-assisted route. Scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis/differential thermal analysis show that, depending on the reaction conditions, cellulose/hydroxyapatite, cellulose/chlorapatite, or cellulose/monetite composites form. Preliminary studies with MC3T3-E1 pre-osteoblasts show that the cells proliferate on the hybrid materials suggesting that the ionic liquid-based process yields materials that are potentially useful as scaffolds for regenerative therapies. PMID:25247137

  15. Endocytosis precedes dissolution of basic calcium phosphate crystals by murine macrophages

    Microsoft Academic Search

    Jeanna L. Owens; Herman S. Cheung; Daniel J. McCarty

    1986-01-01

    Summary  Murine peritoneal macrophages were incubated with45Ca-labeled basic calcium phosphate (BCP) crystals in the presence or absence of cytochalasin B. Untreated macrophages solubilized\\u000a 30–50% of45Ca-BCP in 24 hours. Dissolution began within 3 hours and was linear thereafter. Twenty-three percent of BCP was cell-associated\\u000a by 3 hours. Endocytosis of crystal occurred continuously throughout the incubation. Endocytosis of crystal did not affect\\u000a the

  16. Macroporous biphasic calcium phosphate efficiency in mastoid cavity obliteration: experimental and clinical findings.

    PubMed

    Daculsi, G; Bagot d'Arc, M; Corlieu, P; Gersdorff, M

    1992-08-01

    Following our previous experimental studies on the performance of macroporous biphasic calcium phosphate (MBCP) in canine mastoid cavities, we used this material in patients requiring surgical intervention. Twenty-two cases were selected, and in eight specific cases a biopsy specimen was taken. Histologic, ultrastructural, and microanalysis studies were performed. This study demonstrates the effectiveness of MBCP implants as bone graft substitutes for mastoid cavity obliteration. Clinical evaluation of the series and histologic and ultrastructural results demonstrated the bioactivity and osteo-conduction of this material, with partial transformation of MBCP granules into lamellar bone after several months. PMID:1497273

  17. Calcium phosphate coating of nickel-titanium shape-memory alloys. Coating procedure and adherence of leukocytes and platelets.

    PubMed

    Choi, Jongsik; Bogdanski, Denise; Köller, Manfred; Esenwein, Stefan A; Müller, Dietmar; Muhr, Gert; Epple, Matthias

    2003-09-01

    Nickel-titanium shape-memory alloys (NiTi-SMA) were coated with calcium phosphate by dipping in oversaturated calcium phosphate solution. The layer thickness (typically 5-20 micrometer) can be varied by choice of the immersion time. The porous nature of the layer of microcrystals makes it mechanically stable enough to withstand both the shape-memory transition upon cooling and heating and also strong bending of the material (superelastic effect). This layer may improve the biocompatibility of NiTi-SMA, particulary for osteosynthetic devices by creating a more physiological surface and by restricting a potential nickel release. The adherence of human leukocytes (peripheral blood mononuclear cells and polymorphonuclear neutrophil granulocytes) and platelets to the calcium phosphate layer was analyzed in vitro. In comparison to non-coated NiTi-SMA, leukocytes and platelets showed a significantly increased adhesion to the coated NiTi-SMA. PMID:12818540

  18. Biomaterial Co-Cr-Mo Alloys Nano Coating Calcium Phosphate Orthopedic Treatment

    NASA Astrophysics Data System (ADS)

    Palaniappan, N.; Inwati, Gajendra Kumar; Singh, Man

    2014-08-01

    The modem study a thermal martensitic transformation of biomedical Co-Cr-Mo alloys and ultimately offers large elongation to failure while maintaining high strength. In the future study, structural evolution and dislocation slip as an elementary process in the martensitic transformation in Co-Cr-Mo alloys were investigated to reveal the origin of their enhanced phase stability due to nitrogen addition and coating of calcium phosphate specimens with and without nitrogen addition were prepared. The N-doped alloys had a single-phase matrix, whereas the N-free alloys had a duplex microstructure. Irrespective of the nitrogen content, dislocations frequently dissociated into Shockley partial dislocations with stacking faults. The Nano range coating of calcium phosphate function as obstacles to the glide of partial dislocations and consequently significantly affect the kinetics of the martensitic transformation. As a result, the formation of marten site plays a crucial role in plastic deformation and wear behavior, the developed nanostructures modification associated with nitrogen addition must be a promising strategy for highly durable orthopedic implants.

  19. Effects of Calcium Phosphate Nanocrystals on Osseointegration of Titanium Implant in Irradiated Bone

    PubMed Central

    Li, Jun Yuan; Pow, Edmond Ho Nang; Kwong, Dora Lai Wan; Cheung, Lim Kwong

    2015-01-01

    Radiotherapy may compromise the integration of implant and cause implant loss. Implant surface modifications have the possibility of promoting cell attachment, cell growth, and bone formation which ultimately enhance the osseointegration process. The present study aimed to investigate the effects of calcium phosphate nanocrystals on implant osseointegration in irradiated bone. Sixteen rabbits were randomly assigned into control and nano-CaP groups, receiving implants with dual acid-etched surface or dual acid-etched surface discretely deposited of nanoscale calcium-phosphate crystals, respectively. The left leg of all the rabbits received 15?Gy radiation, followed by implants placement one week after. Four animals in each group were sacrificed after 4 and 12 weeks, respectively. Implant stability quotient (ISQ), ratio of bone volume to total volume (BV/TV), bone growth rate, and bone-to-implant contact (BIC) were evaluated. The nano-CaP group showed significantly higher ISQ (week 12, P = 0.031) and bone growth rate (week 6, P = 0.021; week 9, P = 0.001) than that in control group. No significant differences in BV/TV and BIC were found between two groups. Titanium implant surface modified with CaP nanocrystals provides a potential alternative to improve bone healing around implant in irradiated bone. PMID:25685809

  20. Multiple prismatic calcium phosphate layers in the jaws of present-day sharks (Chondrichthyes; Selachii).

    PubMed

    Dingerkus, G; Séret, B; Guilbert, E

    1991-01-15

    Jaws of large individuals, over 2 m in total length, of the shark species Carcharodon carcharias (great white shark) and Isurus oxyrinchus (mako shark) of the family Lamnidae, and Galeocerdo cuvieri (tiger shark) and Carcharhinus leucas (bull shark) of the family Carcharhinidae were found to have multiple, up to five, layers of prismatic calcium phosphate surrounding the cartilages. Smaller individuals of these species and other known species of living chondrichthyans have only one layer of prismatic calcium phosphate surrounding the cartilages, as also do most species of fossil chondrichthyans. Two exceptions are the fossil shark genera Xenacanthus and Tamiobatis. Where it is found in living forms, this multiple layered calcification does not appear to be phylogenetic, as it appears to be lacking in other lamnid and carcharhinid genera and species. Rather it appears to be functional, only appearing in larger individuals and species of these two groups, and hence may be necessary to strengthen the jaw cartilages of such individuals for biting. PMID:1999241

  1. O-phospho-L-serine: a modulator of bone healing in calcium-phosphate cements.

    PubMed

    Mai, Ronald; Lux, Romy; Proff, Peter; Lauer, Günter; Pradel, Winnie; Leonhardt, Henry; Reinstorf, Antje; Gelinsky, Michael; Jung, Roland; Eckelt, Uwe; Gedrange, Tomasz; Stadlinger, Bernd

    2008-10-01

    Bone substitution materials are seen as an alternative to autogenous bone transplants in the reconstruction of human bone structures. The aim of the present animal study was to evaluate the clinical handling and the conditions of bone healing after the application of a phosphoserine and collagen-I-modified calcium-phosphate cement (Biozement D). The application of phosphoserine is supposed to influence the texture of the extracellular matrix. Standardised bone defects were created in the lower jaw of 10 adult minipigs. These defects were reconstructed with a pasty calcium-phosphate cement mixture. After a healing time of 4 months, the animals were sacrificed. The mandibles of all animals were resected and non-decalcified histological sections of the areas of interest were prepared. The experiment was evaluated by means of qualitative histology and histomorphometry. The hydroxyapatite cement entirely hardened intraoperatively. Modelling and handling of the cement was facile and the margin fit to the host bone was excellent. Histology showed that resorption started in the periphery and proceeded exceptionally fast. The bony substitution, especially in phosphoserine-endowed cements, was very promising. After a healing period of 4 months, phosphoserine cements showed a bone regeneration of nearly two-thirds of the defect sizes. In the applied animal experiment, the newly developed hydroxyapatite collagen-I cement is well suited for bone substitution due to its easy handling, its excellent integration and good resorption characteristics. The addition of phosphoserine is very promising in terms of influencing resorption features and bone regeneration. PMID:18803525

  2. Effect of human salivary proteins on the precipitation kinetics of calcium phosphate.

    PubMed

    Moreno, E C; Varughese, K; Hay, D I

    1979-08-24

    Inhibition of calcium phosphate precipitation in saliva, and prevention of the formation of mineral accretions on tooth surfaces, has been ascribed to the existence of inhibiting salivary macromolecules. Marked reductions in the crystal growth rate of hydroxyapatite (HA) seeds were measured in supersaturated solutions containing either of two proline-rich proteins, PRP1 or PRP3, or statherin; the three macromolecules were isolated from human parotid saliva. The reductions were also observed when the HA seeds were pretreated with solutions of the macromolecules before adding them to the supersaturated calcium phosphate solution. This effect was very similar in the case of the two PRPs and it was directly related to the extent of adsorption site coverage of these proteins on the HA seeds. The effect of statherin was larger than anticipated from its adsorption behavior. However, comparison on the basis of number of moles adsorbed per unit area of HA shows that the PRP are more effective inhibitors than statherin. The macromolecule concentrations used were considerably lower than those in the salivary secretions, therefore these macromolecules could readily prevent mineral accretion on tooth surfaces through their adsorption onto the enamel surface. PMID:115554

  3. A theranostic agent to enhance osteogenic and magnetic resonance imaging properties of calcium phosphate cements.

    PubMed

    Ventura, Manuela; Sun, Yi; Cremers, Sjef; Borm, Paul; Birgani, Zeinab T; Habibovic, Pamela; Heerschap, Arend; van der Kraan, Peter M; Jansen, John A; Walboomers, X Frank

    2014-02-01

    With biomimetic biomaterials, like calcium phosphate cements (CPCs), non-invasive assessment of tissue regeneration is challenging. This study describes a theranostic agent (TA) to simultaneously enhance both imaging and osteogenic properties of such a bone substitute material. For this purpose, mesoporous silica beads were produced containing an iron oxide core to enhance bone magnetic resonance (MR) contrast. The same beads were functionalized with silane linkers to immobilize the osteoinductive protein BMP-2, and finally received a calcium phosphate coating, before being embedded in the CPC. Both in vitro and in vivo tests were performed. In vitro testing showed that the TA beads did not interfere with essential material properties like cement setting. Furthermore, bioactive BMP-2 could be efficiently released from the carrier-beads. In vivo testing in a femoral condyle defect rat model showed long-term MR contrast enhancement, as well as improved osteogenic capacity. Moreover, the TA was released during CPC degradation and was not incorporated into the newly formed bone. In conclusion, the described TA was shown to be suitable for longitudinal material degradation and bone healing studies. PMID:24342727

  4. Chapter 9: Model Systems for Formation and Dissolution of Calcium Phosphate Minerals

    SciTech Connect

    Orme, C A; Giocondi, J L

    2006-07-29

    Calcium phosphates are the mineral component of bones and teeth. As such there is great interest in understanding the physical mechanisms that underlie their growth, dissolution, and phase stability. Control is often achieved at the cellular level by the manipulation of solution states and the use of crystal growth modulators such as peptides or other organic molecules. This chapter begins with a discussion of solution speciation in body fluids and relates this to important crystal growth parameters such as the supersaturation, pH, ionic strength and the ratio of calcium to phosphate activities. We then discuss the use of scanning probe microscopy as a tool to measure surface kinetics of mineral surfaces evolving in simplified solutions. The two primary themes that we will touch on are the use of microenvironments that temporally evolve the solution state to control growth and dissolution; and the use of various growth modifiers that interact with the solution species or with mineral surfaces to shift growth away from the lowest energy facetted forms. The study of synthetic minerals in simplified solution lays the foundation for understand mineralization process in more complex environments found in the body.

  5. Bone morphogenetic protein Smads signaling in mesenchymal stem cells affected by osteoinductive calcium phosphate ceramics.

    PubMed

    Tang, Zhurong; Wang, Zhe; Qing, Fangzhu; Ni, Yilu; Fan, Yujiang; Tan, Yanfei; Zhang, Xingdong

    2015-03-01

    Porous calcium phosphate ceramics (CaP ceramics) could induce ectopic bone formation which was regulated by various signal molecules. In this work, bone marrow mesenchymal stem cells (MSCs) were cultured on the surface of osteoinductive hydroxyapatite (HA) and biphasic calcium phosphate (BCP) ceramics in comparison with control (culture plate) for up to 14 days to detect the signal molecules which might be affected by the CaP ceramics. Without adding osteogenic factors, MSCs cultured on HA and BCP both expressed higher Runx2, Osterix, collagen type I, osteopontin, bone sialoprotein, and osteocalcin at various stages compared with control, thus confirmed the osteoblastic differentiation of MSCs. Later study demonstrated the messenger RNA level of bone morphogenetic protein 2 (BMP2) and BMP4 were also significantly enhanced by HA and BCP. Furthermore, Smad1, 4, 5, and Dlx5, the main molecules in the BMP/Smads signaling pathway, were upregulated by HA and BCP. Moreover, the higher expression of Smads and BMP2, 4 in BCP over HA, corresponded to the better performance of BCP in stimulating in vitro osteoblastic differentiation of MSCs. This was in accordance with the better osteoinductivity of BCP over HA in vivo. Altogether, these results implied that the CaP ceramics may initiate the osteoblastic differentiation of MSCs by influencing the expression of molecules in BMP/Smads pathway. PMID:24889783

  6. Kinetics of aggregation and crystallization of polyaspartic Acid stabilized calcium phosphate particles at high concentrations.

    PubMed

    Krogstad, Daniel V; Wang, Dongbo; Lin-Gibson, Sheng

    2015-05-11

    Bone is an important material to study due to its exceptional mechanical properties and relevance with respect to hard tissue regeneration and repair. A significant effort has been directed toward understanding the bone formation process and the production of synthetic bone mimicking materials. Here, the formation and structural evolution of calcium phosphate (CaP) was investigated in the presence of relatively high concentrations of calcium, phosphate, and polyaspartic acid (pAsp) using dynamic light scattering (DLS) and cryo-transmission electron microscopy (cryo-TEM). The incipient CaP aggregates were comprised of spherical nanoparticles (diameter ? 3-4 nm); they became preferentially aligned over time and eventually transformed into nanorods. The nanorods remained stable in suspension with no signs of further aggregation for at least four months. Detailed cryo-TEM suggested that the CaP nanorods formed through an oriented attachment mechanism. These results show that the reaction concentration greatly influences the mechanism and final properties of CaP. Mechanistic insights gained from this study will facilitate better design and fabrication of bioinspired materials. PMID:25901665

  7. Properties of injectable ready-to-use calcium phosphate cement based on water-immiscible liquid.

    PubMed

    Heinemann, S; Rössler, S; Lemm, M; Ruhnow, M; Nies, B

    2013-04-01

    Calcium phosphate cements (CPCs) are highly valuable materials for filling bone defects and bone augmentation by minimal invasive application via percutaneous injection. In the present study some key features were significantly improved by developing a novel injectable ready-to-use calcium phosphate cement based on water-immiscible carrier liquids. A combination of two surfactants was identified to facilitate the targeted discontinuous exchange of the liquid for water after contact with aqueous solutions, enabling the setting reaction to take place at distinct ratios of cement components to water. This prolonged the shelf life of the pre-mixed paste and enhanced reproducibility during application and setting reactions. The developed paste technology is applicable for different CPC formulations. Evaluations were performed for the formulation of an ?-TCP-based CPC as a representative example for the preparation of injectable pastes with a powder-to-carrier liquid ratio of up to 85:15. We demonstrate that the resulting material retains the desirable properties of conventional CPC counterparts for fast setting, mechanical strength and biocompatibility, shows improved cohesion and will most probably show a similar degree of resorbability due to identical mineral structure of the set products. PMID:23261920

  8. Development of a new calcium phosphate powder-binder system for the 3D printing of patient specific implants

    Microsoft Academic Search

    Alaadien Khalyfa; Sebastian Vogt; Jürgen Weisser; Gabriele Grimm; Annett Rechtenbach; Wolfgang Meyer; Matthias Schnabelrauch

    2007-01-01

    A key requirement for three-dimensional printing (3-DP) of medical implants is the availability of printable and biocompatible\\u000a powder-binder systems. In this study we developed a powder mixture comprising tetracalcium phosphate (TTCP) as reactive component\\u000a and ?-tricalcium phosphate (?-TCP) or calcium sulfate as biodegradable fillers, which can be printed with an aqueous citric\\u000a acid solution. The potential of this material combination

  9. Effect of pyrophosphate ions on the conversion of calcium–lithium–borate glass to hydroxyapatite in aqueous phosphate solution

    Microsoft Academic Search

    Hailuo Fu; Mohamed N. Rahaman; Delbert E. Day; Wenhai Huang

    2010-01-01

    The conversion of glass to a hydroxyapatite (HA) material in an aqueous phosphate solution is used as an indication of the\\u000a bioactive potential of the glass, as well as a low temperature route for preparing biologically useful materials. In this\\u000a work, the effect of varying concentrations of pyrophosphate ions in the phosphate solution on the conversion of a calcium–lithium–borate\\u000a glass

  10. Observation of calcium phosphate powder mixed with an adhesive monomer experimentally developed for direct pulp capping and as a bonding agent

    Microsoft Academic Search

    Yoshiroh KATOH; Masaya SUZUKI; Chikage KATO; Koichi SHINKAI; Masaaki OGAWA; Junichi YAMAUCHI

    2010-01-01

    In this study, morphological shape, elemental distribution and elution properties of Ca, P, Mg in four types of calcium phosphate powder were investigated using SEM, EPMA and ICP-AES. Calcium phosphate powder: OHAp, DCPD, ?-TCP and OCP were observed in the white powder form and in the photopolymerized adhesive monomer they scattered like dispersed fillers in resin composite. In elemental analysis,

  11. Influence of surface microstructure and chemistry on osteoinduction and osteoclastogenesis by biphasic calcium phosphate discs.

    PubMed

    Davison, N L; Su, J; Yuan, H; van den Beucken, J J; de Bruijn, J D; Barrère-de Groot, F

    2015-01-01

    It has been reported that surface microstructural dimensions can influence the osteoinductivity of calcium phosphates (CaPs), and osteoclasts may play a role in this process. We hypothesised that surface structural dimensions of ? 1 ?m trigger osteoinduction and osteoclast formation irrespective of macrostructure (e.g., concavities, interconnected macropores, interparticle space) or surface chemistry. To test this, planar discs made of biphasic calcium phosphate (BCP: 80 % hydroxyapatite, 20 % tricalcium phosphate) were prepared with different surface structural dimensions - either ~ 1 ?m (BCP1150) or ~ 2-4 ?m (BCP1300) - and no macropores or concavities. A third material was made by sputter coating BCP1150 with titanium (BCP1150Ti), thereby changing its surface chemistry but preserving its surface structure and chemical reactivity. After intramuscular implantation in 5 dogs for 12 weeks, BCP1150 formed ectopic bone in 4 out of 5 samples, BCP1150Ti formed ectopic bone in 3 out of 5 samples, and BCP1300 formed no ectopic bone in any of the 5 samples. In vivo, large multinucleated osteoclast-like cells densely colonised BCP1150, smaller osteoclast-like cells formed on BCP1150Ti, and osteoclast-like cells scarcely formed on BCP1300. In vitro, RAW264.7 cells cultured on the surface of BCP1150 and BCP1150Ti in the presence of osteoclast differentiation factor RANKL (receptor activator for NF-?B ligand) proliferated then differentiated into multinucleated osteoclast-like cells with positive tartrate resistant acid phosphatase (TRAP) activity. However, cell proliferation, fusion, and TRAP activity were all significantly inhibited on BCP1300. These results indicate that of the material parameters tested - namely, surface microstructure, macrostructure, and surface chemistry - microstructural dimensions are critical in promoting osteoclastogenesis and triggering ectopic bone formation. PMID:26091730

  12. In vivo degradation of low temperature calcium and magnesium phosphate ceramics in a heterotopic model.

    PubMed

    Klammert, Uwe; Ignatius, Anita; Wolfram, Uwe; Reuther, Tobias; Gbureck, Uwe

    2011-09-01

    Bone replacement using synthetic and degradable materials is desirable in various clinical conditions. Most applied commercial materials are based on hydroxyapatite, which is not chemically degradable under physiological conditions. Here we report the effect of a long-term intramuscular implantation regime on the dissolution of various low temperature calcium and magnesium phosphate ceramics in vivo. The specimens were analysed by consecutive radiographs, micro-computed tomography scans, compressive strength testing, scanning electron microscopy and X-ray diffractometry. After 15months in vivo, the investigated materials brushite (CaHPO(4)·2H(2)O), newberyite (MgHPO(4)·3H(2)O), struvite (MgNH(4)PO(4)·6H(2)O) and hydroxyapatite (Ca(9)(PO(4))(5)HPO(4)OH) showed significant differences regarding changes of their characteristics. Struvite presented the highest loss of mechanical performance (95%), followed by newberyite (67%) and brushite (41%). This was accompanied by both a distinct extent of cement dissolution as well as changes of the phase composition of the retrieved cement implants. While the secondary phosphate phases (brushite, newberyite, struvite) completely dissolved, re-precipitates of whitlockite and octacalcium phosphate were formed in either particulate or whisker-like morphology. Furthermore, for the first time the possibility of a macropore-free volume degradation mechanism of bioceramics was demonstrated. PMID:21658480

  13. In situ synthesis of magnesium-substituted biphasic calcium phosphate and in vitro biodegradation

    SciTech Connect

    Kim, Tae-Wan; Lee, Hyeong-Shin; Kim, Dong-Hyun; Jin, Hyeong-Ho [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)] [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Hwang, Kyu-Hong [School of Nano and Advanced Materials, Gyeongsang National University, Jinju, Kyungnam 660-701 (Korea, Republic of)] [School of Nano and Advanced Materials, Gyeongsang National University, Jinju, Kyungnam 660-701 (Korea, Republic of); Lee, Jong Kook [Department of Advanced Materials Engineering, Chosun University, Gwangju 501-759 (Korea, Republic of)] [Department of Advanced Materials Engineering, Chosun University, Gwangju 501-759 (Korea, Republic of); Park, Hong-Chae [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)] [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Yoon, Seog-Young, E-mail: syy3@pusan.ac.kr [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)] [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

    2012-09-15

    Highlights: ? Mg–BCP were successfully prepared through in situ aqueous co-precipitation method. ? The amount of ?-TCP phase was changed with the magnesium substitution level. ? The substitution of magnesium led to a decrease in the unit cell volume. ? Mg–BCP could be able to develop a new apatite phase on the surface faster than BCP. -- Abstract: In situ preparation of magnesium (Mg) substituted biphasic calcium phosphate (BCP) of hydroxyapatite (HAp)/?-tricalcium phosphate (?-TCP) were carried out through aqueous co-precipitation method. The concentrations of added magnesium were varied with the calcium in order to obtain constant (Ca + Mg)/P ratios of 1.602. X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy were used to characterize the structure of synthesized magnesium substituted BCP powders. The results have shown that substitution of magnesium in the calcium deficient apatites revealed the formation of biphasic mixtures of different HAp/?-TCP ratios after heating at 1000 °C. The ratios of the formation of phase mixtures were dependent on the content of magnesium. After immersing in Hanks’ balanced salt solution (HBSS) for 1 week, 1 wt% magnesium substituted BCP powders were degraded and precipitation started to be formed with small granules consisting of number of flake-like crystal onto the surface of synthesized powders. On the other hand, in the case of pure BCP powders, the formation of new precipitates was detected after immersion in HBSS for 2 weeks. On the basis of these results, magnesium substituted BCP could be able to develop a new apatite phase on the surface in contact with physiological fluids faster than BCP does. In addition, the retention time to produce the new apatite phase in implantation operation for the BCP powder could be controlled by the amount of magnesium substitution.

  14. Magnesium whitlockite, a calcium phosphate crystal of special interest in pathology.

    PubMed

    Lagier, R; Baud, C A

    2003-01-01

    Whitlockite (in fact magnesium whitlockite) is a calcium orthophosphate crystal in which, in biological conditions, magnesium is partly substituted for calcium. Identified in X-ray or electron diffraction patterns, it occurs in physiological or pathological conditions at extra or intratissular sites, mainly in tissues of non-epithelial origin. In a range of pathological calcifications investigated by X-ray diffraction, we noted that whitlockite appeared to be frequently associated with apatite, particularly in "dystrophic calcifications" of tuberculous origin. These personal observations could be correlated with documented data in oral pathology (dental calculus, salivary stones, and dental caries). Whitlockite deposits have also been reported in non-infectious conditions, such as in aortic media, cartilage, and bone tissue. Whereas the formation of both apatite and magnesium whitlockite appears to be caused by the binding of their constituting ions with proteolipids, magnesium inhibits apatite originating from amorphous calcium phosphate to the benefit of whitlockite formation. Possibly, the development of magnesium whitlockite may provide an interesting marker for magnesium metabolism. Further studies linking histology to crystallography might relate the crystal to issues, such as tuberculous calcifications or diseases of bone tissue, and might be useful for potential diagnostic orientation. PMID:12908523

  15. Rapid hydrothermal flow synthesis and characterisation of carbonate- and silicate-substituted calcium phosphates

    PubMed Central

    Knowles, Jonathan C; Rehman, Ihtesham; Darr, Jawwad A

    2013-01-01

    A range of crystalline and nano-sized carbonate- and silicate-substituted hydroxyapatite has been successfully produced by using continuous hydrothermal flow synthesis technology. Ion-substituted calcium phosphates are better candidates for bone replacement applications (due to improved bioactivity) as compared to phase-pure hydroxyapatite. Urea was used as a carbonate source for synthesising phase pure carbonated hydroxyapatite (CO3-HA) with ?5?wt% substituted carbonate content (sample 7.5CO3-HA) and it was found that a further increase in urea concentration in solution resulted in biphasic mixtures of carbonate-substituted hydroxyapatite and calcium carbonate. Transmission electron microscopy images revealed that the particle size of hydroxyapatite decreased with increasing urea concentration. Energy-dispersive X-ray spectroscopy result revealed a calcium deficient apatite with Ca:P molar ratio of 1.45 (±0.04) in sample 7.5CO3-HA. For silicate-substituted hydroxyapatite (SiO4-HA) silicon acetate was used as a silicate ion source. It was observed that a substitution threshold of ?1.1?wt% exists for synthesis of SiO4-HA in the continuous hydrothermal flow synthesis system, which could be due to the decreasing yields with progressive increase in silicon acetate concentration. All the as-precipitated powders (without any additional heat treatments) were analysed using techniques including Transmission electron microscopy, X-ray powder diffraction, Differential scanning calorimetry, Thermogravimetric analysis, Raman spectroscopy and Fourier transform infrared spectroscopy. PMID:22983020

  16. Calcium-sensing receptor regulation of PTH-inhibitable proximal tubule phosphate transport.

    PubMed

    Ba, Jianming; Brown, Dennis; Friedman, Peter A

    2003-12-01

    Inorganic phosphate (Pi) is absorbed by proximal tubules through a cellular pathway that is inhibited by parathyroid hormone (PTH). The calcium-sensing receptor (CaSR) is expressed on apical membranes of proximal tubules. In the present studies, we determined the effect of luminal and/or basolateral PTH on phosphate absorption and tested the hypothesis that CaSR activation blocks PTH-inhibitable phosphate absorption. Single proximal S3 tubules were dissected from the kidneys of mice and studied by the Burg technique. Tubules were bathed with DMEM culture media supplemented with 6% BSA and perfused with an ultrafiltrate prepared from the bathing solution. 33P and FITC-inulin were added to the luminal perfusate to measure phosphate absorption (JPi) and fluid absorption (Jv), respectively. JPi averaged 2.9 pmol.min-1.mm-1 under control conditions and decreased by 20% upon addition of serosal PTH. PTH had no effect on Jv. Inclusion of PTH in the luminal perfusate reduced JPi to 2.1 pmol. min-1. mm-1. Combined addition of PTH to perfusate and bathing solutions reduced JPi to 1.5 pmol. min-1. mm-1 without affecting Jv. Indirect immunofluorescence studies revealed abundant PTH receptor (PTH1R) expression on brush-border membranes, with lower amounts on basolateral membranes. CaSRs were localized primarily, but not exclusively, to brush-border membranes. CaSR activation with luminal Gd3+ abolished the inhibitory action of PTH on JPi. Addition of Gd3+ to the serosal bathing solution had no effect on PTH-sensitive JPi. Gd3+ i.e., PTH-independent JPi. Gd3+ did not affect basal, had no effect on Jv when added to lumen or bath. Dopamine-inhibitable JPi was not affected by Gd3+. Experiments with proximal-like opossum kidney cells showed that elevated extracellular Ca2+ or NPS R467, a type II calcimimetic, inhibited PTH action on Pi uptake. In conclusion, PTH1Rs are expressed on apical and basolateral membranes of mouse proximal tubules. Stimulating apical or basolateral PTH1R inhibits phosphate absorption. CaSR activation specifically regulates PTH-suppressible phosphate absorption. PMID:12952858

  17. Preparation and characterization of calcium phosphate ceramics and composites as bone substitutes

    NASA Astrophysics Data System (ADS)

    Zhang, Xing

    Marine CaCO3 skeletons have tailored architectures created by nature, which give them structural support and other functions. For example, seashells have dense lamellar structures, while coral, cuttlebone and sea urchin spines have interconnected porous structures. In our experiments, seashells, coral and cuttlebone were hydrothermally converted to hydroxyapatite (HAP), and sea urchin spines were converted to Mg-substituted tricalcium phosphate (beta-TCMP), while maintaining their original structures. Partially converted shell samples have mechanical strength, which is close to that of compact human bone. After implantation of converted shell and spine samples in rat femoral defects for 6 weeks, there was newly formed bone growth up to and around the implants. Some new bone was found to migrate through the pores of converted spine samples and grow inward. These results show good bioactivity and osteoconductivity of the implants, indicating the converted shell and spine samples can be used as bone defect fillers. Calcium phosphate powders were prepared through different synthesis methods. Micro-size HAP rods were synthesized by hydrothermal method through a nucleation-growth mechanism. On the other hand, HAP particles, which have good crystallinity, were prepared by wet precipitation with further hydrothermal treatment. beta-TCP or beta-TCMP powders were prepared by a two-step process: wet precipitation of apatitic tricalcium phosphate ('precursor') and calcination of the precursor at 800°C for 3 hours. beta-TCMP or beta-TCP powders were also prepared by solid-state reactions from CaHPO4 and CaCO 3 with/without MgO. Biphasic calcium phosphate, which is mixture of HAP and beta-TCP, can be prepared though mechanical mixing of HAP and beta-TCP powders synthesized as above. Dense beta-TCP and beta-TCMP ceramics can be produced by pressing green bodies at 100MPa and further sintering above 1100°C for 2 hours. beta-TCMP ceramics ˜99.4% relative dense were prepared by this method. Dense beta-TCP ceramics have average strength up to 540MPa. Macroporous beta-TCMP ceramics were produced with sucrose as the porogen following a two-step pressing method. Porous beta-TCMP ceramics were also prepared by replication of polyurethane sponge. beta-TCMP ceramics with porous structures in the center surrounded by dense structures were created. The outside dense structures give the scaffold mechanical strength, while the central porous structures enable cells migration and vascular infiltration, and finally in-growth of new bone into the scaffold.

  18. An electron microscopic study of the formation of amorphous calcium phosphate and its transformation to crystalline apatite

    Microsoft Academic Search

    E. D. Eanes; J. D. Termine; M. U. Nylen

    1973-01-01

    Dried amorphous calcium phosphate (ACP) can exist in discoidal and spheroidal forms. The disk-shaped particles are most prominent in dried ACP specimens isolated immediately following precipitation. The spherical forms become dominant in dried specimens taken from older suspensions. The disk-like morphology is a result of sample drying. Spherules can also arise during the drying step but are present in the

  19. Histological and histomorphometrical study of connective tissue around calcium phosphate coated titanium dental implants in a canine model

    Microsoft Academic Search

    Bao Hong Zhao; Inho Han; Hai Lan Feng; Wei Bai; Fu-Zhai Cui; In-Seop Lee

    2007-01-01

    Connective tissue reaction and collagen fiber orientation were evaluated on the calcium phosphate coated implants made by ion beam assisted deposition, and compared with the uncoated titanium implants. Twelve implants of each group were randomly placed in mandibles after 3 months of premolars extraction in beagle dogs. All the implants were firmly anchored in the bone and had no clinical signs

  20. Protective Action of Phosphate and Calcium-Containing Pigments under the Conditions of the Stress Corrosion Fracture of Steels

    Microsoft Academic Search

    I. M. Zin’; L. M. Bilyi; I. P. Gnyp; M. B. Ratushna

    2004-01-01

    We have established that strontium chromate and a mixture of modified zinc phosphate and calcium-containing pigment inhibit substantially the corrosion of low-carbon steel in slightly acid rain solution. We observed mainly the anodic control of corrosion in the extract of chromate pigment and mixed control in the extract of a mixture of nonchromate pigments. Zinc ions in corrosive media enhance

  1. Computational modelling of the mechanical environment of osteogenesis within a polylactic acid–calcium phosphate glass scaffold

    Microsoft Academic Search

    Jean-Louis Milan; Josep A. Planell; Damien Lacroix

    2009-01-01

    A computational model based on finite element method (FEM) and computational fluid dynamics (CFD) is developed to analyse the mechanical stimuli in a composite scaffold made of polylactic acid (PLA) matrix with calcium phosphate glass (Glass) particles. Different bioreactor loading conditions were simulated within the scaffold. In vitro perfusion conditions were reproduced in the model. Dynamic compression was also reproduced

  2. Inhibition of the growth of urinary calcium hydrogen phosphate dihydrate crystals with aqueous extracts of Tribulus terrestris and Bergenia ligulata

    Microsoft Academic Search

    Vimal S. Joshi; Bharat B. Parekh; Mihir J. Joshi; Ashok D. B. Vaidya

    2005-01-01

    Urinary type calcium hydrogen phosphate dihydrate (CHPD) or Brushite crystals were grown by the single diffusion gel technique in silica hydro-gels. The gel framework acts as a three dimensional crucible in which the crystal nuclei are delicately held in the position of their formation and nutrients are supplied for their growth. This technique can be utilized as a simplified screening

  3. The effect of reaction conditions on formation of wet precipitated calcium phosphates

    NASA Astrophysics Data System (ADS)

    Huang, Chen; Cao, Peng

    2015-03-01

    The precipitation process discussed in the present study involves the addition of alkaline solutions to an acidic calcium phosphate suspension. Several parameters (pH, pH buffer reagent, ageing and stirring) were investigated. The synthesized powders were calcined at 1000°C for 1 h in air, in order to study the thermal stability and crystalline phase compositions. X-ray diffraction (XRD) and ESEM analysis were used for sample characterization. It is found that all these processing parameters affect the crystalline phases evolved and resultant microstructures. Phase evolution occurred at an elevated pH level. The pH buffer reagent would affect both the phase composition and microstructure. Ageing was essential for the phase maturation. Stirring accelerated the reaction process by providing a homogeneous medium for precipitation.

  4. Treatment of toxic metal aqueous solutions: encapsulation in a phosphate-calcium aluminate matrix.

    PubMed

    Fernández, J M; Navarro-Blasco, I; Duran, A; Sirera, R; Alvarez, J I

    2014-07-01

    Polyphosphate-modified calcium aluminate cement matrices were prepared by using aqueous solutions polluted with toxic metals as mixing water to obtain waste-containing solid blocks with improved management and disposal. Synthetically contaminated waters containing either Pb or Cu or Zn were incorporated into phosphoaluminate cement mortars and the effects of the metal's presence on setting time and mechanical performance were assessed. Sorption and leaching tests were also executed and both retention and release patterns were investigated. For all three metals, high uptake capacities as well as percentages of retention larger than 99.9% were measured. Both Pb and Cu were seen to be largely compatible with this cementitious matrix, rendering the obtained blocks suitable for landfilling or for building purposes. However, Zn spoilt the compressive strength values because of its reaction with hydrogen phosphate anions, hindering the development of the binding matrix. PMID:24721638

  5. Calcium phosphate hybrid nanoparticles: self-assembly formation, characterization, and application as an anticancer drug nanocarrier.

    PubMed

    Zhao, Xin-Yu; Zhu, Ying-Jie; Chen, Feng; Lu, Bing-Qiang; Qi, Chao; Zhao, Jing; Wu, Jin

    2013-06-01

    Calcium phosphate hybrid nanoparticles (CaP-HNPs) have been synthesized in aqueous solution through self-assembly by using two oppositely charged polyelectrolytes (poly(diallyldimethylammonium chloride) (PDADMAC) and poly(acrylate sodium) (PAS)) as dual templates. First, the PAS/Ca(2+) and PDADMAC/PO4(3-) complexes form through electrostatic interactions and then two complexes self-assemble into CaP-HNPs after mixing them together. The as-prepared CaP-HNPs exhibit a spherical morphology with a narrow size distribution, good dispersibility, and high colloidal stability in water. The CaP-HNPs are explored as a nanocarrier for the anticancer drug docetaxel (Dtxl). The CaP-HNPs show excellent biocompatibility, high drug-loading capacity, pH-sensitive drug-release behavior, and high anticancer effect after being loaded with Dtxl. Therefore, the as-prepared CaP-HNPs are promising drug nanocarriers for cancer therapy. PMID:23589508

  6. Femtosecond laser induced fixation of calcium alkali phosphate ceramics on titanium alloy bone implant material.

    PubMed

    Symietz, Christian; Lehmann, Erhard; Gildenhaar, Renate; Krüger, Jörg; Berger, Georg

    2010-08-01

    Femtosecond lasers provide a novel method of attaching bioceramic material to a titanium alloy, thereby improving the quality of bone implants. The ultrashort 30 fs laser pulses (790 nm wavelength) penetrate a thin dip-coated layer of fine ceramic powder, while simultaneously melting a surface layer of the underlying metal. The specific adjustment of the laser parameters (pulse energy and number of pulses per spot) avoids unnecessary melting of the bioactive calcium phosphate, and permits a defined thin surface melting of the metal, which in turn is not heated throughout, and therefore maintains its mechanical stability. It is essential to choose laser energy densities that correspond to the interval between the ablation fluences of both materials involved: about 0.1-0.4 Jcm(-2). In this work, we present the first results of this unusual technique, including laser ablation studies, scanning electron microscopy and optical microscope images, combined with EDX data. PMID:20167296

  7. Preparation and properties of ?-calcium sulphate hemihydrate and ?-tricalcium phosphate bone substitute.

    PubMed

    Mao, Keya; Zhou, Feihu; Cui, Fuzai; Li, Jiangtao; Hou, Xijun; Li, Peng; Du, Mingkui; Liang, Maohua; Wang, Yan

    2013-01-01

    Autogenous bone graft carries the risk of complications. In contrast, artificial bone graft provides initial strength and allows new bone ingrowth. In this study, we examined methods of preparation of ?-calcium sulphate hemihydrate (?-CSH) and ?-tricalcium phosphate (?-TCP), and a composite of the two materials. Characterization of the materials was determined with X-ray diffraction, differential thermal analysis (DTA), scanning electron microscopy (SEM), and porosity analysis. ?-TCP exhibited the spatial structure and porosity of normal bone with a macropore size of 50-400 ?m and some 1 ?m micropores. ?-CSH exhibited a regular crystal structure. A combined material was prepared in a 1:1 weight ratio, and in a rabbit model, the rate of new bone mineralization was similar to that of autogenous bone graft. The combined material of ?-TCP and ?-CSH in this study may provide similar efficacy as autogenous bone graft. PMID:23629533

  8. [Latest progress in studies of self-setting calcium phosphate cement].

    PubMed

    Wang, W; Chen, Z; Chen, T

    2000-03-01

    Self-setting calcium phosphate cement(CPC) is a non-ceramic form of hydrxyapatitic artificial bone material (HAP) which was first exclusively produced in America several years ago. CPC is free from the drawbacksto ceramic HAP, including sintering and difficulties in shaping. CPC has the characteristics of simple-producing and easy applyication. In 1991, the clinical application of CPC to repairing the calvarial bone defects was approved, and the results reportedly so far were good or excellent. This paper presents the latest progress in the studies of CPC, concerning the probing into the setting process, the producing of fast-setting and non-decayed types of CPC, the studies of organic compound CPC, the in vitro results of CPC as a drug delivery system, etc. As the research goes on deeply and broadly, CPC is hopefully becoming a standard material in repairing bone defects at the non- or low-bearing site in the future. PMID:10879200

  9. The final phases of calcium and magnesium phosphates precipitated from solutions of high to medium concentration

    NASA Astrophysics Data System (ADS)

    Abbona, Francesco; Lundager Madsen, Hans Erik; Boistelle, Roland

    1988-07-01

    The phases of calcium and magnesium phosphates, which are obtained by evolution at 25°C of the first precipitates in their mother solutions, are described in terms of pH and composition of solutions. The initial conditions were: 0.050M ? [P] ? 0.500M; [P] = [Ca] + [Mg]; 0 ? [Mg]/[Ca] ? 1. The most abundant final phases are brushite, CaHPO 4·2H 2O; monetite, CaHPO 4; newberyite, MgHPO 4·3H 2O and struvite, MgNH 4PO 4·6H 2O. At low concentration whitlockite, Ca 9MgH(PO 4) 7, occurs with the amorphous phase previously precipitated, Ca 3(PO 4) 2·nH 2O. The conditions for stability are discussed and the changes observed are interpreted.

  10. Features of calcium phosphate plasma-sprayed coatings: an in vitro study.

    PubMed

    Klein, C P; Wolke, J G; de Blieck-Hogervorst, J M; de Groot, K

    1994-08-01

    Factors involved with the plasma-spray coating procedure, such as starting powder compound (fluorapatite, hydroxylapatite, magnesium-whitlockite, or tetra-calcium phosphate), powder particle distribution 1-45 or 1-125 microns), powder port gun (port 2 or 6), and post-heat treatment of 1 h at 600 degrees C, were examined for their effects on crystallinity and solubility/stability of the coating. From solubility tests, X-ray diffractometry, and scanning microscopy studies, the solubility and crystallinity were found to be dependent on Ca/P ratio, particle distribution, and post-heat treatment. The post-heat treatment influenced the degree of both crystallinity and solubility. The plasma-spray powder port factor for the hydroxylapatite coatings was not significant. Incubation in buffer of the coatings introduced precipitation at the surfaces of all non-heat-treated coatings except fluorapatite. No precipitation could be observed in any of the heat-treated coatings. PMID:7983094

  11. Trace element doping in calcium phosphate ceramics to Understand osteogenesis and angiogenesis

    PubMed Central

    Bose, Susmita; Fielding, Gary; Tarafder, Solaiman; Bandyopadhyay, Amit

    2013-01-01

    The general trends in synthetic bone grafting materials are shifting towards approaches that can illicit osteoinductive properties. Pharmacologics and biologics have been used in combination with calcium phosphate (CaP) ceramics, however, recently have become the target of scrutiny over the safety. The importance of trace elements in natural bone health is well documented. Ions, e.g. lithium, zinc, magnesium, manganese, silicon, strontium etc. have shown to increase osteogenesis and neovascularization. Incorporation of dopants into CaPs can provide a platform for safe and efficient delivery in clinical applications where increased bone healing is favorable. This review highlights use of trace elements in CaP biomaterials, and offers an insight into the mechanisms of how metal ions can enhance both osteogenesis and angiogenesis. PMID:24012308

  12. Preparation and osteogenic properties of magnesium calcium phosphate biocement scaffolds for bone regeneration

    NASA Astrophysics Data System (ADS)

    Li, X.; Niu, Y.; Guo, H.; Chen, H.; Li, F.; Zhang, J.; Chen, W.; Wu, Z.; Deng, Y.; Wei, J.; Liu, C.

    2013-07-01

    The regenerative treatment of large osseous defects remains a formidable challenge in today. In the present study, we have synthesized biodegradable magnesium calcium phosphate biocement (MCPB) scaffolds with interconnected macroporous structure (100-600 ?m), as well as good bioactivity, biocompatibility and proper degradatibility. The results revealed that the porosity increased from 52% to 80% of MCPB scaffolds while the compressive strength decreased from 6.1 MPa to 1.2 MPa. We further assessed the effects of scaffolds on the rabbit femur cavity defect model in vivo by using synchrotron radiation X-ray microCT and microCT imaging, indicating that the MCPB scaffolds underwent gradually degradation and promoted the extensive neo-bone formation.

  13. Basic calcium phosphate crystal-induced Egr-1 expression stimulates mitogenesis in human fibroblasts

    SciTech Connect

    Zeng, Xiao R. [Department of Biomedical Engineering, University of Miami, Coral Gablek, FL 33146 (United States); Sun Yubo [Division of Rheumatology and Immunology, Department of Medicine, University of Miami School of Medicine, Miami, FL 33101 (United States); Wenger, Leonor [Department of Biomedical Engineering, University of Miami, Coral Gablek, FL 33146 (United States); Cheung, Herman S. [Department of Biomedical Engineering, University of Miami, Coral Gablek, FL 33146 (United States) and Division of Rheumatology and Immunology, Department of Medicine, University of Miami School of Medicine, Miami, FL 33101 (United States) and Research Service and the Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Miami, FL 33125 (United States)]. E-mail: hcheung@med.miami.edu

    2005-05-13

    Previously, we have reported that basic calcium phosphate (BCP) crystals stimulate mitogenesis and synthesis of matrix metalloproteinases in cultured human foreskin and synovial fibroblasts. However, the detailed mechanisms involved are still unclear. In the present study, using RT-PCR and Egr-1 promoter analysis we showed that BCP crystals could stimulate early growth response gene Egr-1 transcription through a PKC{alpha}-dependent p44/p42 MAPK pathway. Using a retrovirus gene expression system (Clontech) to overexpress Egr-1 in human fibroblast BJ-1 cells resulted in promotion of mitogenesis measured either by MTT cell proliferation analysis or by direct cell counting. The results demonstrate that Egr-1 may play a key role in mediating BCP crystal-induced synovial fibroblast mitogenesis.

  14. Biomimetic remineralization of demineralized enamel with nano-complexes of phosphorylated chitosan and amorphous calcium phosphate.

    PubMed

    Zhang, Xu; Li, Yanqiu; Sun, Xiaoxi; Kishen, Anil; Deng, Xuliang; Yang, Xiaoping; Wang, Huajun; Cong, Changhong; Wang, Yinghui; Wu, Mingyao

    2014-12-01

    Remineralization of enamel plays a crucial role in the progression of carious process and the management of early caries lesion. Based on the influence of phosphorylated proteins in biomineralization, the objective of this study was to synthesize nano-complexes of phosphorylated chitosan and amorphous calcium phosphate (Pchi-ACP), and evaluate their ability to remineralize enamel subsurface lesions in vitro. Pchi was synthesized using a previously established chemical method. The biomimetic remineralizing solution containing nano-complexes of Pchi-ACP was prepared by adding CaCl2 and K2HPO4 into Pchi-ACP solution (0.5 % w/v) in sequence. The final concentrations of calcium and phosphate ions were 10 and 6 mM, respectively. The nano-complexes of Pchi-ACP were characterized by Fourier-transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). During testing the enamel lesions were treated with Pchi-ACP and fluoridated remineralizing solutions, respectively. The remineralizing of enamel lesions was examined with field emission electron microscope (FE-SEM) and Micro-CT. ACP was stabilized by Pchi to form nano-complexes that were soluble in water. The size of Pchi-ACP nano-complexes particles was determined to be less than 50 nm. XRD and SAED results confirmed their amorphous phases. FE-SEM and Micro-CT results showed that the remineralizing effect of Pchi-ACP on enamel lesions was similar to that of fluoride. However, the remineralizing rate of Pchi-ACP treatment was significantly higher than that of fluoride treatment (P < 0.05). This study highlighted the potential of nanoparticles functionalized with a natural analogue involved in biomineralization, to remineralize early enamel caries. PMID:25074834

  15. Optimization of the time efficient calcium phosphate coating on electrospun poly(d,l-lactide).

    PubMed

    Luickx, Nathalie; Van Den Vreken, Natasja; Segaert, Jonas; Declercq, Heidi; Cornelissen, Maria; Verbeeck, Ronald

    2015-08-01

    The coating of fibrous polyester constructs with a layer of bioactive calcium phosphate (CP) is efficient to improve the potential use as bone tissue engineering scaffold. In this study, a fast procedure for the coating of electrospun poly(d,l-lactide) (PDLLA) fibers with a CP layer was optimized. The fiber surface was activated by immersion in demineralized water under ultrasonication. The resulting reactive groups served as nucleation points for CP precipitation, induced by alternate dipping of the samples in Ca(2+) and PO4 (3-) rich solutions. Variations in the conditions of the alternate dipping procedure, in particular the number of cycles, concentration and immersion time of both solutions, not only affected the degree of surface mineralization but also the type of deposited CP. For the current experimental conditions, in about 30 minutes either a slightly carbonated calcium deficient apatite (CDAp; Ca10-x-y (PO4 )6-x-y (HPO4 )y (CO3 )x (OH)2-x-y ) or a combination of apatite and dicalcium phosphate dihydrate (DCPD; CaHPO4 .2H2 O) was formed. The cell viability, adhesion, and proliferation of MC3T3-E1 cells on untreated samples were compared with samples coated with either an adequate amount of CDAp, an excess of CDAp or an excess of a combination of apatite and DCDP. After 7 days of culture the number of attached cells was significantly higher on all CP coated samples compared to the untreated PDLLA. In particular, the samples coated with an adequate amount of CDAp showed an exceedingly enhanced cell response with similar cell morphologies as the ones found on the positive control. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2720-2730, 2015. PMID:25630382

  16. Human umbilical cord stem cell encapsulation in calcium phosphate scaffolds for bone engineering

    PubMed Central

    Zhao, Liang; Weir, Michael D.; Xu, Hockin H.K.

    2010-01-01

    Human bone marrow mesenchymal stem cells (hBMSCs) require an invasive procedure to harvest, and have lower self-renewal potential with aging. Umbilical cord mesenchymal stem cells (hUCMSCs) are a relatively new stem cell source; this study reveals a self-setting and load-bearing calcium phosphate construct that encapsulates these stem cells. The flexural strength (mean ± sd; n = 5) of the hUCMSC-encapsulating calcium phosphate cement (CPC) increased from (3.5 ± 1.1) MPa without polyglactin fibers, to (11.7 ± 2.1) MPa with 20% of polyglactin fibers (p < 0.05). hUCMSCs attached to the bone mineral-mimicking scaffold in the osteogenic media and differentiated down the osteogenic lineage, yielding elevated alkaline phosphatase (ALP) and osteocalcin (OC) gene expressions. ALP and OC on the CPC-fiber scaffold was 2-fold those on CPC control without fibers. hUCMSCs encapsulated inside the scaffolds retained excellent viability and cell density. The encapsulated hUCMSCs inside four different constructs successfully differentiated down the osteogenic lineage and synthesized bone minerals, as confirmed by mineral staining, SEM, and XRD. The percentage of mineral area synthesized by the encapsulated hUCMSCs increased from about 3% at day-7, to 12% at day-21 (p < 0.05). In conclusion, this study demonstrated that hUCMSCs encapsulated in the bioengineered scaffolds osteo-differentiated and synthesized bone minerals. The self-setting CPC–chitosan–fiber scaffold supported the viability and osteogenic differentiation of the encapsulated hUCMSCs, and had mechanical strength matching that of cancellous bone. PMID:20149437

  17. Long-term mechanical durability of dental nanocomposites containing amorphous calcium phosphate nanoparticles

    PubMed Central

    Moreau, Jennifer L.; Weir, Michael D.; Giuseppetti, Anthony A.; Chow, Laurence C.; Antonucci, Joseph M.; Xu, Hockin H. K.

    2012-01-01

    Half of all dental restorations fail within 10 years, with secondary caries and restoration fracture being the main reasons. Calcium phosphate (CaP) composites can release Ca and PO4 ions and remineralize tooth lesions. However, there has been no report on their long-term mechanical durability. The objective of this study was to investigate the wear, thermal-cycling, and water-aging of composites containing amorphous calcium phosphate nanoparticles (NACP). NACP of 112-nm and glass particles were used to fabricate four composites: (1) 0% NACP+75% glass; (2) 10% NACP+65% glass; (3) 15% NACP+60% glass; and (4) 20% NACP+50% glass. Flexural strength and elastic modulus of NACP nanocomposites were not degraded by thermal-cycling. Wear depth increased with increasing NACP filler level. Wear depths of NACP nanocomposites after 4 × 105 cycles were within the range for commercial controls. Mechanical properties of all the tested materials decreased with water-aging time. After 2 years, the strengths of NACP nanocomposites were moderately higher than the control composite, and much higher than the resin-modified glass ionomers. The mechanism of strength loss for resin-modified glass ionomer was identified as microcracking and air-bubbles. NACP nanocomposites and control composite were generally free of microcracks and air-bubbles. In conclusion, combining NACP nanoparticles with reinforcement glass particles resulted in novel nanocomposites with long-term mechanical properties higher than those of commercial controls, and wear within the range of commercial controls. These strong long-term properties, plus the Ca-PO4 ion release and acid-neutralization capability reported earlier, suggest that the new NACP nanocomposites may be promising for stress-bearing and caries-inhibiting restorations. PMID:22514160

  18. Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites†

    PubMed Central

    O’Donnell, Justin N.R.; Schumacher, Gary E.; Antonucci, Joseph M.; Skrtic, Drago

    2009-01-01

    Our studies of amorphous calcium phosphate (ACP)-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/re-mineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC) and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-?-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and, ultimately, the suitability of the composites for clinical evaluation. PMID:21966588

  19. Calcium Carbonate Phosphate Binding Ion Exchange Filtration and Accelerated Denitrification Improve Public Health Standards and Combat Eutrophication in Aquatic Ecosystems

    PubMed Central

    Yanamadala, Vijay

    2010-01-01

    Cultural eutrophication, the process by which a lake becomes rich in dissolved nutrients as a result of point and nonpoint pollutant sources, is a major cause of the loss of natural lake ecosystems throughout the world. The process occurs naturally in all lakes, but phosphate-rich nutrient runoff from sources such as storm drains and agricultural runoff is a major cause of excess phosphate-induced eutrophication. Especially in Madrona Marsh, one of the last remaining vernal marshes in the greater Los Angeles area, California, cultural eutrophication has become a major problem. In this study, calcium carbonate was found to be an excellent phosphate binder, reducing up to 70% of the phosphates in a given sample of water, and it posed relatively negligent ecological repercussions. This study involved the testing of this principle in both the laboratory and the real ecosystem. A calcium carbonate lacing procedure was first carried out to determine its efficacy in Madrona Marsh. Through this, ammonia was found to interfere with the solubility of calcium carbonate and therefore to be a hindrance to the reduction of phosphate. Therefore, various approaches for reduction of ammonia were tested, including aeration, use of fiber growth media, and plants, mainly Caulerpa verticellata, chosen for it hardiness, primarily in an attempt to increase population of Nitrobacter and Nitrosomonas. All were successful in moderately reducing ammonia levels. In addition, soil sampling, sediment analysis, microscopic plant analysis, microorganism and macroinvertebrate identification, and rate law formulations were conducted. The effect of phosphate and ammonia reduction on the populations of enterobacteria was also an important focus of this experiment. Varying concentrations of phosphate, ammonia, and calcium carbonate in conjunction with phosphate were tested in Madrona Marsh to determine their effects on the populations of enteropathogens on nonspecific blood agar, MacConkey agar, and Hektoen agar. Initial analyses suggest a strong correlation between phosphate concentrations and bacterial populations; a 66% decrease in phosphate resulted in a 35% reduction in bacterial populations and a 45% reduction in enteropathogenic populations. Likewise, a strong correlation was shown between calcium carbonate concentrations and bacterial reduction greater than that which can be attributed to the phosphate reduction alone. This was followed by the construction of various phosphate binding calcium carbonate filters, which used the ion exchange principle, including a spring loading filter, PVC pipe filter, and a galvanized filter. All were tested with the aid of Stoke's law formulation. The experiment was extremely successful in designing a working phosphate-binding and ammonia-reducing filter, and a large-scale agitator-clarifier filter system is currently being planned for construction in Madrona Marsh; this filter will reduce phosphate and ammonia levels substantially in the following years, bringing ecological, economical, and health-related improvements to the overall ecosystem and habitat. PMID:16381147

  20. Influence of Mg-substitution on the physicochemical properties of calcium phosphate powders

    SciTech Connect

    Marchi, J. [University of Erlangen-Nuernberg, Department of Materials Science-Biomaterials, Henkestr. 91, D-91052 Erlangen (Germany); Institute of Energetic and Nuclear Research (IPEN), Centre of Science and Materials Technology, Department of Ceramics, Av. Prof. Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Dantas, A.C.S. [University of Erlangen-Nuernberg, Department of Materials Science-Biomaterials, Henkestr. 91, D-91052 Erlangen (Germany); Greil, P. [University of Erlangen-Nuernberg, Department of Materials Science-Biomaterials, Henkestr. 91, D-91052 Erlangen (Germany); Bressiani, J.C. [Institute of Energetic and Nuclear Research (IPEN), Centre of Science and Materials Technology, Department of Ceramics, Av. Prof. Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Bressiani, A.H.A. [Institute of Energetic and Nuclear Research (IPEN), Centre of Science and Materials Technology, Department of Ceramics, Av. Prof. Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Mueller, F.A. [University of Erlangen-Nuernberg, Department of Materials Science-Biomaterials, Henkestr. 91, D-91052 Erlangen (Germany)]. E-mail: Frank.Mueller@ww.uni-erlangen.de

    2007-06-05

    Tricalcium phosphate based ceramics (TCP) are bioresorbable and thereby considered to be promising bone replacement materials. The differences in crystal structure between {alpha} and {beta}-TCP phases gives rise for different dissolution rates in vitro and in vivo, which may alter the bioresorbable behavior of TCP ceramics. It is suggested that the addition of magnesium ions, which are also present in biological tissues, stabilizes {beta}-phase to higher temperatures and thus enables the sintering of {beta}-TCP at elevated temperatures compared to Mg free TCP. In this paper, Mg-substituted TCP, with the general formula (Ca{sub 1-x}Mg {sub x}){sub 3}(PO{sub 4}){sub 2} and 0.01 {<=} x {<=} 0.045, were produced by wet chemical synthesis from Ca(OH){sub 2}, H{sub 3}PO{sub 4} and MgO, after calcinations at three different temperatures between 750 and 1050 deg. C. The influence of different amounts of Mg substitution on the physical properties, microstructure, and sintering behavior of calcium phosphate powders was evaluated. Thermal analytical techniques, together with X-ray diffraction analysis, were successfully combined in order to characterize the occurring phase transformations during annealing of the powders. The results show that the addition of small amounts of Mg (up to 1.5 mol%) are adequate to postpone the {beta}-{alpha} TCP phase transformation to 1330 deg. C and to accelerate the densification process during sintering of {beta}-TCP ceramics.

  1. Laser engineered multilayer coating of biphasic calcium phosphate/titanium nanocomposite on metal substrates.

    PubMed

    Zhang, Martin Yi; Ye, Chang; Erasquin, Uriel Joseph; Huynh, Toan; Cai, Chengzhi; Cheng, Gary J

    2011-02-01

    In this work, laser coating of biphasic calcium phosphate/titanium (BCP/Ti) nanocomposite on Ti-6Al-4 V substrates was developed. A continuous wave neodymium-doped yttrium aluminium garnet (Nd:YAG) laser was used to form a robust multilayer of BCP/Ti nanocomposite starting from hydroxyapatite and titanium nanoparticles. In this process, low power coating is realized because of the strong laser-nanoparticle interaction and good sinterability of nanosized titanium. To guide the optimization of laser processing conditions for the coating process, a multiphysics model coupling electromagnetic module with heat transfer module was developed. This model was validated by laser coating experiments. Important features of the coated samples, including microstructures, chemical compositions, and interfacial bonding strength, were characterized. We found that a multilayer of BCP, consisting of 72% hydroxyapatite (HA) and 28% beta-tricalcium phosphate (?-TCP), and titanium nanocomposite was formed on Ti-6Al-4 V substrates. Significantly, the coating/substrate interfacial bonding strength was found to be two times higher than that of the commercial plasma sprayed coatings. Preliminary cell culture studies showed that the resultant BCP/Ti nanocomposite coating supported the adhesion and proliferation of osteoblast-like UMR-106 cells. PMID:21207950

  2. Characterization of calcium phosphate deposited on valve metal by anodic oxidation with polarity inversion.

    PubMed

    Okawa, Seigo; Homma, Kikuo; Kanatani, Mitsugu; Watanabe, Kouichi

    2009-07-01

    Electrochemical deposition of calcium phosphate (CAP) on valve metals such as Ta, Nb, and Zr, was performed by anodic oxidation with alternate polarity inversion at an applied 20 VDC. A saturated hydroxyapatite(HAP)-phosphoric acid solution (pH 3) was used as the electrolyte. FTIR, XRD, and XPS were employed to investigate the detailed characteristics of the deposition. HAP was precipitated on Ta; HAP including brushite and monetite on Nb; and HAP and monetite on Zr. The Ca/P atomic ratios were 1.3-1.5 by XPS, and HPO(4)(2- )bands were detected on Ta by FTIR. Therefore, the HAP precipitated on Ta was a Ca-deficient HAP. In addition, the XPS spectra of the specimens showed that phosphate ions were incorporated into the anodic oxide film. Deposits with nano-grain size were observed by AFM. The results confirmed that CAP with nano-grain size was deposited on valve metals by the anodic oxidation with polarity inversion. PMID:19721291

  3. Calcium Phosphate Based Three-Dimensional Cold Plotted Bone Scaffolds for Critical Size Bone Defects

    PubMed Central

    Bergmann, Christian J. D.; Odekerken, Jim C. E.; Welting, Tim J. M.; Jungwirth, Franz; Devine, Declan; Bouré, Ludovic; Zeiter, Stephan; van Rhijn, Lodewijk W.; Telle, Rainer; Fischer, Horst; Emans, Pieter J.

    2014-01-01

    Bone substitutes, like calcium phosphate, are implemented more frequently in orthopaedic surgery to reconstruct critical size defects, since autograft often results in donor site morbidity and allograft can transmit diseases. A novel bone cement, based on ?-tricalcium phosphate, polyethylene glycol, and trisodium citrate, was developed to allow the rapid manufacturing of scaffolds, by extrusion freeform fabrication, at room temperature. The cement composition exhibits good resorption properties and serves as a basis for customised (e.g., drug or growth factor loaded) scaffolds for critical size bone defects. In vitro toxicity tests confirmed proliferation and differentiation of ATDC5 cells in scaffold-conditioned culture medium. Implantation of scaffolds in the iliac wing of sheep showed bone remodelling throughout the defects, outperforming the empty defects on both mineral volume and density present in the defect after 12 weeks. Both scaffolds outperformed the autograft filled defects on mineral density, while the mineral volume present in the scaffold treated defects was at least equal to the mineral volume present in the autograft treated defects. We conclude that the formulated bone cement composition is suitable for scaffold production at room temperature and that the established scaffold material can serve as a basis for future bone substitutes to enhance de novo bone formation in critical size defects. PMID:24719891

  4. Bacterially produced calcium phosphate nanobiominerals: sorption capacity, site preferences, and stability of captured radionuclides.

    PubMed

    Handley-Sidhu, S; Hriljac, J A; Cuthbert, M O; Renshaw, J C; Pattrick, R A D; Charnock, J M; Stolpe, B; Lead, J R; Baker, S; Macaskie, L E

    2014-06-17

    A Serratia sp. bacterium manufactures amorphous calcium phosphate nanominerals (BHAP); this material has shown increased sorption capacity for divalent radionuclide capture. When heat-treated (?450 °C) the cell biomass is removed and the biominerals are transformed to hydroxyapatite (HAP). Using a multimethod approach, we have elucidated both the site preferences and stability of analogue radionuclide incorporation for Sr, Co, Eu, and U. Strontium incorporates within the bulk amorphous inorganic phase of BHAP; however, once temperature modified to crystalline HAP, bonding was consistent with Sr substitution at the Ca(1) and/or Ca(2) sites. Cobalt incorporation occurs within the bulk inorganic amorphous phase of BHAP and within the amorphous grain boundaries of HAP. Europium (an analogue for trivalent actinides) substituted at the Ca(2) and/or the Ca(3) position of tricalcium phosphate, a known component of HAP grain boundaries. Uranium was surface complexed with no secondary minerals detected. With multiple sites for targeted radionuclide incorporation, high loadings, and good stability against remobilization, BHAP is shown to be a potential material for the remediation of aqueous radionuclide in groundwater. PMID:24823240

  5. Dissolution behavior and early bone apposition of calcium phosphate-coated machined implants

    PubMed Central

    Hwang, Ji-Wan; Lee, Eun-Ung; Lee, Jung-Seok; Jung, Ui-Won; Lee, In-Seop

    2013-01-01

    Purpose Calcium phosphate (CaP)-coated implants promote osseointegration and survival rate. The aim of this study was to (1) analyze the dissolution behavior of the residual CaP particles of removed implants and (2) evaluate bone apposition of CaP-coated machined surface implants at the early healing phase. Methods Mandibular premolars were extracted from five dogs. After eight weeks, the implants were placed according to drilling protocols: a nonmobile implant (NI) group and rotational implant (RI) group. For CaP dissolution behavior analysis, 8 implants were removed after 0, 1, 2, and 4 weeks. The surface morphology and deposition of the coatings were observed. For bone apposition analysis, block sections were obtained after 1-, 2-, and 4-week healing periods and the specimens were analyzed. Results Calcium and phosphorus were detected in the implants that were removed immediately after insertion, and the other implants were composed mainly of titanium. There were no notable differences between the NI and RI groups in terms of the healing process. The bone-to-implant contact and bone density in the RI group showed a remarkable increase after 2 weeks of healing. Conclusions It can be speculated that the CaP coating dissolves early in the healing phase and chemically induces early bone formation regardless of the primary stability. PMID:24455442

  6. Biomimetic apatite formation on calcium phosphate-coated titanium in Dulbecco's phosphate-buffered saline solution containing CaCl(2) with and without fibronectin.

    PubMed

    Chen, Cen; Lee, In-Seop; Zhang, Sheng-Min; Yang, Hyeong Cheol

    2010-06-01

    Calcium phosphate (CaP) thin films with different degrees of crystallinity were coated on the surfaces of commercially pure titanium by electron beam evaporation. The details of apatite nucleation and growth on the coating layer were investigated in Dulbecco's phosphate-buffered saline solutions containing calcium chloride (DPBS) or DPBS with fibronectin (DPBSF). The surfaces of the samples were examined by field emission scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The concentrations of fibronectin and calcium ions (Ca(2+)) were monitored by the bicinchoninic acid method (BCA) and use of a calcium assay kit (DICA-500), respectively. Apatite initially formed at the fastest rate on the CaP-coated samples with the lowest degree of crystallinity and reached the maximum Ca(2+) concentration after immersion in DPBS solution for 15min. After 15min the concentration of Ca(2+) decreased with the growth of apatite on the coating layers. For all the samples the maximum Ca(2+) concentration in the DPBS solutions decreased with increasing crystallinity and immersion time to reach the maximum concentration increased. The presence of fibronectin in the DPBS solutions delayed the formation and affected the morphology of the apatite. Fibronectin incorporated into apatite deposited on the surface of titanium did not affect its biological activity in terms of promoting osteoblast adhesion. PMID:19962459

  7. Preparation, Structure Determination, and Redox Characteristics of New Calcium Copper Phosphates

    NASA Astrophysics Data System (ADS)

    Lazoryak, B. I.; Khan, N.; Morozov, V. A.; Belik, A. A.; Khasanov, S. S.

    1999-06-01

    New calcium copper phosphates o-Ca 19Cu 2(PO 4) 14, r'-Ca 19Cu 2H 1.42(PO 4) 14, and r?-Ca 19Cu 2- yH 2.24(PO 4) 14 (0.64? y?0.7) were synthesized and characterized. The structures of these phosphates were refined using Rietveld analysis. The compound o-Ca 19Cu 2(PO 4) 14 has ?-Ca 3(PO 4) 2-like structure (Space Group R3 c, z=3). Compounds r'-Ca 19Cu 2H 1.42(PO 4) 14 and r?-Ca 19Cu 2- yH 2.24(PO 4) 14 (0.64? y?0.7) have the whitlockite-like structure (Space Group R3 c, z=3). The corresponding crystal data are (i) o-Ca 19Cu 2(PO 4) 14: a=10.3633(1) Å, c=37.242(2) Å, V=3463.8(9) Å 3, Rp=4.24%, Rwp=5.75%; (ii) r'-Ca 19Cu 2H 1.42(PO 4) 14: a=10.3987(1) Å, c=37.300(2) Å, V= 3493.0(9) Å 3, Rp=4.89%, Rwp=6.50%; (iii) r?-Ca 19 Cu 2- yH 2.24(PO 4) 14 (0.64? y?0.7): a=10.3975(1) Å, c= 37.274(2) Å, V=3489.7(9) Å 3, Rp=4.57%, Rwp=6.04%. Redox reactions in calcium/copper double phosphates were investigated by XRD, DTA, DTG, and IR spectroscopy under hydrogen-containing and oxygen-containing atmospheres. These reactions proceed reversibly in the temperature ranges 753-825 K for the reduction process and 973-1173 K for the oxidation process. The redox cycles can be repeated continuously without destroying the crystal lattice.

  8. Effect of Si and Fe doping on calcium phosphate glass fibre reinforced polycaprolactone bone analogous composites.

    PubMed

    Mohammadi, M Shah; Ahmed, I; Muja, N; Almeida, S; Rudd, C D; Bureau, M N; Nazhat, S N

    2012-04-01

    Reinforcing biodegradable polymers with phosphate-based glass fibres (PGF) is of interest for bone repair and regeneration. In addition to increasing the mechanical properties, PGF can also release bioinorganics, as they are water soluble, a property that may be controllably translated into a fully degradable composite. Herein, the effect of Si and Fe on the solubility of calcium-containing phosphate-based glasses (PG) in the system (50P(2)O(5)-40CaO-(10-x)SiO(2)-xFe(2)O(3), where x=0, 5 and 10 mol.%) were investigated. On replacing SiO(2) with Fe(2)O(3), there was an increase in the glass transition temperature and density of the PG, suggesting greater crosslinking of the phosphate chains. This significantly reduced the dissolution rates of degradation and ion release. Two PG formulations, 50P(2)O(5)-40CaO-10Fe(2)O(3) (Fe10) and 50P(2)O(5)-40CaO-5Fe(2)O(3)-5SiO(2) (Fe5Si5), were melt drawn into fibres and randomly incorporated into polycaprolactone (PCL). Initially, the flexural strength and modulus significantly increased with PGF incorporation. In deionized water, PCL-Fe(5)Si(5) displayed a significantly greater weight loss and ion release compared with PCL-Fe10. In simulated body fluid, brushite was formed only on the surface of PCL-Fe(5)Si(5). Dynamic mechanical analysis in phosphate buffered saline (PBS) at 37°C revealed that the PCL-Fe10 storage modulus (E') was unchanged up to day 7, whereas the onset of PCL-Fe(5)Si(5)E' decrease occurred at day 4. At longer-term ageing in PBS, PCL-Fe(5)Si(5) flexural strength and modulus decreased significantly. MC3T3-E1 preosteoblasts seeded onto PCL-PGF grew up to day 7 in culture. PGF can be used to control the properties of biodegradable composites for potential application as bone fracture fixation devices. PMID:22248526

  9. Effect of hydroxyapatite, octacalcium phosphate and calcium phosphate on the auto-flocculation of the microalgae in a high-rate algal pond.

    PubMed

    Baya, D T; Effebi, K R; Tangou, T T; Keffala, C; Vasel, J L

    2013-01-01

    Recovering microalgae is one of the main technological and economic concerns in a high-rate algal pond (HRAP) because of their small size and their low density. This paper emphasizes the characterization (identification and assessment of potential flocculation) of chemical compounds involved in microalgae auto-flocculation in a HRAP. First, thermodynamic simulations were performed, using two models (i.e. Visual Minteq and a simplified thermodynamic model) in order to determine the chemical compounds of interest. Experimental tests were then carried out with these compounds for assessing their flocculation ability. Both models revealed that precipitates of calcium phosphates and their substituted forms were the compounds involved in the auto-flocculation. Moreover, experimental tests showed that the stoichiometric neutralization of algal charges by calcium phosphates (i.e. hydroxyapatite (Ca5(PO4)3OH), octacalcium phosphate (Ca4H(PO4)3) and amorphous calcium phosphate (Ca3(PO4)2)), at a pH within the range 7-10 yields 70-82% recovered algal biomass. The optimum ratio required for algae auto-flocculation was 0.33 Ca5(PO4)3OH/g DM(algae) at pH 10, 0.11 Ca4H(PO4)3/g DM(algae) at pH 7 and 0.23 g Ca3(PO4)2/g DM(algae) at pH 9. Auto-flocculation appears as a simple, sustainable and promising method for efficient harvesting of microalgae in a HRAP. PMID:24350497

  10. Influence of calcium chloride and aprotinin in the in vivo biological performance of a composite combining biphasic calcium phosphate granules and fibrin sealant.

    PubMed

    Le Guehennec, Laurent; Goyenvalle, Eric; Aguado, Eric; Pilet, Paul; Spaethe, Reiner; Daculsi, Guy

    2007-08-01

    Highly bioactive biomaterials have been developed to replace bone grafts in orthopedic revision and maxillofacial surgery for bone augmentation. A mouldable, self-hardening material can be obtained by combining TricOs Biphasic Calcium Phosphate Granules and Tissucol Fibrin Sealant. Two components, calcium chloride and antifibrinolytic agents (aprotinin), are essential for the stability of the fibrin clot. The ingrowth of cells in composites combining sealants without calcium chloride or with a low concentration of aprotinin was evaluated in vivo in an experiment on rabbits. Bone colonization was compared using TricOs alone or with the composite made from TricOs and the standard fibrin sealant. Without the addition of calcium chloride, the calcium ions released by the ceramic component interacted with the components of the sealant too late to stabilize the clot. With a low concentration of aprotinin, the degradation of the clot occurred more quickly, leading to the absence of a scaffold on which the bone cells could colonize the composite. Our results indicate that a stable fibrin scaffold is crucial for bone colonization. The low calcium chloride and low aprotinin groups have shown lower bone growth. Further studies will be necessary to determine the minimal amount of antifibrinolytic agent (aprotinin) necessary to allow the same level of osteogenic activity as the TricOs-fibrin glue composite. PMID:17387594

  11. The room temperature photoluminescence properties of Eu 3+ -doped bi-phase calcium phosphate under visible light

    Microsoft Academic Search

    Han Wang; Jun Yu; Jianqiu Li; Xiaokun Cheng; Zhiliang Huang

    2010-01-01

    The Eu-doped bi-phase calcium phosphate (BCP) phosphors with (Eu + Ca)\\/P = 1.1, 1.3, 1.5, and 1.6 were synthesized for the\\u000a first time by the precipitation method. The BCP phosphors were investigated by the X-ray diffraction (XRD), Fourier transform\\u000a infrared spectroscopy (FTIR), and Photoluminescence (PL) spectra. The XRD and FTIR results indicated that BCP consisted of\\u000a ?-tricalcium phosphate and hydroxyapatite phases. The PL results

  12. The effect of tri-calcium phosphate (TCP) addition on the degradation of polylactide-co-glycolide (PLGA)

    Microsoft Academic Search

    Lisa Maria Ehrenfried; Munnawwar H. Patel; Ruth E. Cameron

    2008-01-01

    This paper investigates the effects of ?-tri-calcium phosphate (?-TCP) addition on the properties of polylactide-co-glycolide\\u000a (PLGA). Samples with additions of 5, 10, 15, 20, 30 and 40 wt% ?-TCP were prepared via a hotpressing method. Long-term in vitro\\u000a studies (up to 60 days) were carried out in pH 7.4 phosphate-buffered saline (PBS). Degradation properties were investigated\\u000a by monitoring pH, water uptake and mass

  13. The effects of nitrogen fertilizer form on the plant availability of phosphate from soil, phosphate rock and mono-calcium phosphate

    Microsoft Academic Search

    J. N. Apthorp; M. J. Hedley; R. W. Tillman

    1987-01-01

    A glasshouse trial using lettuce as the test crop, and laboratory incubations were used to evaluate the influence of various nitrogen fertilizers on the availability of phosphate from an unfertilized loamy sand soil and from the same soil fertilized with Sechura phosphate rock or monocalcium phosphate. The order in which nitrogen fertilizer form increased plant yield and P uptake from

  14. Restoration of parathyroid function after change of phosphate binder from calcium carbonate to lanthanum carbonate in hemodialysis patients with suppressed serum parathyroid hormone.

    PubMed

    Inaba, Masaaki; Okuno, Senji; Nagayama, Harumi; Yamada, Shinsuke; Ishimura, Eiji; Imanishi, Yasuo; Shoji, Shigeichi

    2015-03-01

    Control of phosphate is the most critical in the treatment of chronic kidney disease with mineral and bone disorder (CKD-MBD). Because calcium-containing phosphate binder to CKD patients is known to induce adynamic bone disease with ectopic calcification by increasing calcium load, we examined the effect of lanthanum carbonate (LaC), a non-calcium containing phosphate binder, to restore bone turnover in 27 hemodialysis patients with suppressed parathyroid function (serum intact parathyroid hormone [iPTH] ? 150 pg/mL). At the initiation of LaC administration, the dose of calcium-containing phosphate binder calcium carbonate (CaC) was withdrawn or reduced based on serum phosphate. After initiation of LaC administration, serum calcium and phosphate decreased significantly by 4 weeks, whereas whole PTH and iPTH increased. A significant and positive correlation between decreases of serum calcium, but not phosphate, with increases of whole PTH and iPTH, suggested that the decline in serum calcium with reduction of calcium load by LaC might increase parathyroid function. Serum bone resorption markers, such as serum tartrate-resistant acid phosphatase 5b, and N-telopeptide of type I collagen increased significantly by 4 weeks after LaC administration, which was followed by increases of serum bone formation markers including serum bone alkaline phosphatase, intact procollagen N-propeptide, and osteocalcin. Therefore, it was suggested that LaC attenuated CaC-induced suppression of parathyroid function and bone turnover by decreasing calcium load. In conclusion, replacement of CaC with LaC, either partially or totally, could increase parathyroid function and resultant bone turnover in hemodialysis patients with serum iPTH ? 150 pg/mL. PMID:25556148

  15. Osteogenic properties of calcium phosphate ceramics and fibrin glue based composites.

    PubMed

    Le Nihouannen, Damien; Saffarzadeh, Afchine; Aguado, Eric; Goyenvalle, Eric; Gauthier, Olivier; Moreau, Françoise; Pilet, Paul; Spaethe, Reiner; Daculsi, Guy; Layrolle, Pierre

    2007-02-01

    Calcium phosphate (Ca-P) ceramics are currently used in various types of orthopaedic and maxillofacial applications because of their osteoconductive properties. Fibrin glue is also used in surgery due to its haemostatic, chemotactic and mitogenic properties and also as scaffolds for cell culture and transplantation. In order to adapt to surgical sites, bioceramics are shaped in blocks or granules and preferably in porous forms. Combining these bioceramics with fibrin glue provides a mouldable and self-hardening composite biomaterial. The aim of this work is to study the osteogenic properties of this composite material using two different animal models. The formation of newly formed bone (osteoinduction) and bone healing capacity (osteconduction) have been study in the paravertebral muscles of sheep and in critical sized defects in the femoral condyle of rabbits, respectively. The different implantations sites were filled with composite material associating Ca-P granules and fibrin glue. Ca-P granules of 1-2 mm were composed with 60% of hydroxyapatite and 40% of beta tricalcium phosphate in weight. The fibrin glue was composed of fibrinogen, thrombin and other biological factors. After both intramuscular or intraosseous implantations for 24 weeks and 3, 6, 12 and 24 weeks, samples were analyzed using histology and histomorphometry and mechanical test. In all cases, the newly formed bone was observed in close contact and around the ceramic granules. Depending on method of quantification, 6.7% (with BSEM) or 17% (with micro CT) of bone had formed in the sheep muscles and around 40% in the critical sized bone rabbit defect after 24 weeks. The Ca-P/fibrin material could be used for filling bone cavities in various clinical indications. PMID:17323153

  16. Intrinsic porosity of calcium phosphate cements and its significance for drug delivery and tissue engineering applications.

    PubMed

    Espanol, M; Perez, R A; Montufar, E B; Marichal, C; Sacco, A; Ginebra, M P

    2009-09-01

    One key point in the field of tissue engineering and drug delivery is to provide materials with an adequate porosity. Many events, including nutrient and waste exchange in scaffolds for tissue engineering, as well as the drug-loading capacity and control of the release rate in drug delivery systems, are controlled by the size, shape and distribution of the pores in the material. Calcium phosphate cements (CPCs) possess an intrinsic porosity that is highly suited for these applications, and this porosity can be controlled by modifying some processing parameters. The objective of this work was to characterize and control the intrinsic porosity of alpha-tricalcium phosphate (alpha-TCP) cements, and to investigate its role against adsorption of bovine serum albumin (BSA). Cements with different percentages of open porosity (35-55%) were prepared by modifying the liquid-to-powder ratio. In addition, two different TCP particles were used to yield cements with specific surface areas of approximately 20 and approximately 37m(2)g(-1). Mercury porosimetry analysis on the set cements showed in most cases a bimodal pore size distribution which varied with the processing parameters and affected differently the adsorption and penetration of BSA. The peak occurring at larger pore dimensions controlled the penetration of BSA and was ascribed to the voids generated in between crystal aggregates, while the peak appearing at lower pore sizes was believed to be due to the intercrystallite voids within aggregates. It was found that, at the concentrations studied, the high intrinsic porosity in CPC does not ensure protein penetration unless there is an adequate pore size distribution. PMID:19357005

  17. Mechanism of action of a desensitizing fluoride toothpaste delivering calcium and phosphate ingredients in the treatment of dental hypersensitivity. Part III: Prevention of dye penetration through dentin vs a calcium- and phosphate-free control.

    PubMed

    Winston, Anthony E; Charig, Andrew J; Thong, Stephen

    2010-01-01

    It is generally accepted that the pain of dental hypersensitivity resulting from gum recession is from the movement of fluid within the exposed tubules of dentin, causing changes in pressure on the nerve within the pulpal cavity. One method of treating hypersensitivity is to occlude the tubules, preventing fluid movement. This article discusses the use of a dye penetration technique, which establishes this mechanism of action for a desensitizing fluoride toothpaste containing calcium and phosphate. Two groups of intact teeth were perfectly sealed with enamel paint. Windows 100-micro to 200-micro deep were opened on opposite sides of each tooth at the dentin-enamel junction and briefly etched using 20% polyacrylic acid. One batch of teeth was treated eight times for 30 mins each with a 1:3 slurry of the desensitizing toothpaste and another set with a similar slurry prepared from a calcium- and phosphate-free control. A 0.85% aqueous solution of acid red fuchsin dye was applied to each window and allowed to dry. After a brief rinse, the teeth were sectioned across the windows. Almost no dye penetration was seen in teeth treated with the desensitizing toothpaste; however, extensive penetration through the dentin was visible in the control-treated teeth. The differences in dye penetration for the two sets of teeth were significant by both subjective (P < .001) and objective (P < .01) measures. Tubule occlusion because of calcium and phosphate ions from the desensitizing toothpaste accounts for its tooth desensitizing efficacy. PMID:20158016

  18. Observation of calcium phosphate powder mixed with an adhesive monomer experimentally developed for direct pulp capping and as a bonding agent.

    PubMed

    Katoh, Yoshiroh; Suzuki, Masaya; Kato, Chikage; Shinkai, Koichi; Ogawa, Masaaki; Yamauchi, Junichi

    2010-01-01

    In this study, morphological shape, elemental distribution and elution properties of Ca, P, Mg in four types of calcium phosphate powder were investigated using SEM, EPMA and ICP-AES. Calcium phosphate powder: OHAp, DCPD, beta-TCP and OCP were observed in the white powder form and in the photopolymerized adhesive monomer they scattered like dispersed fillers in resin composite. In elemental analysis, CaKalpha showed a relatively high concentration in relation to PKalpha. In elution analysis, each calcium phosphate showed different elution of Ca and P. But Mg was almost equal to the detection limit of ICP-AES. Namely it was suggested that reparative dentin formation was effectively promoted under the following conditions: a calcification promoting effect by direct contact of the calcium phosphate powder, an ionic effect of Ca and P eluted from the powder located in the vicinity of the exposed pulp and environmental pH change of the surface in exposed pulp. PMID:20379007

  19. CITRIC ACID AS A SET RETARDER FOR CALCIUM ALUMINATE PHOSPHATE CEMENTS.

    SciTech Connect

    SUGAMA,T.; BROTHERS, L.E.

    2005-01-01

    Citric acid added as set retarder significantly contributed to enhancing the setting temperature and to extending the thickening time of a calcium aluminate phosphate (CaP) geothermal cement slurry consisting of calcium aluminate cement (CAC) as the base reactant and sodium polyphosphate (NaP) solution as the acid reactant. The set-retarding activity of citric acid was due to the uptake of Ca{sup 2+} ions from the CAC by carboxylic acid groups within the citric acid. This uptake led to the precipitation of a Ca-complexed carboxylate compound as a set-retarding barrier layer on the CAC grains' surfaces. However, this barrier layer was vulnerable to disintegration by the attack of free Ca{sup 2+} ions from CAC, and also to degradation at elevated temperature, thereby promoting the generation of exothermic energy from acid-base reactions between the CAC and NaP after the barrier was broken. The exothermic reaction energy that was promoted in this way minimized the loss in strength of the citric acid-retarded cement. The phase composition assembled in both retarded and non-retarded cements after autoclaving at 180 C encompassed three reaction products, hydroxyapatite (HOAp), hydrogrossular and boehmite, which are responsible for strengthening the autoclaved cement. The first two reaction products were susceptible to reactions with sulfuric acid and sodium sulfate to form crystalline bassanite scale as the corrosion product. The boehmite phase possessed a great resistance to acid and sulfate. Although the bassanite scales clinging to the cement's surfaces were the major factor governing the loss in weight, they served in protecting the cement from further acid- and sulfate-corrosion until their spallation eventually occurred. Nevertheless, the repetitive processes of HOAp and hydrogrossular {yields} bassanite {yields} spallation played an important role in extending the useful lifetime of CaP cement in a low pH environment at 180 C.

  20. Alpha-tricalcium phosphate (?-TCP): solid state synthesis from different calcium precursors and the hydraulic reactivity.

    PubMed

    Cicek, Gulcin; Aksoy, Eda Ayse; Durucan, Caner; Hasirci, Nesrin

    2011-04-01

    The effects of solid state synthesis process parameters and primary calcium precursor on the cement-type hydration efficiency (at 37 °C) of ?-tricalcium phosphate (Ca(3)(PO(4))(2) or ?-TCP) into hydroxyapatite (Ca(10-x)HPO(4)(PO(4))(6-x)(OH)(2-x) x = 0-1, or HAp) have been investigated. ?-TCP was synthesized by firing of stoichiometric amount of calcium carbonate (CaCO(3)) and monetite (CaHPO(4)) at 1150-1350 °C for 2 h. Three commercial grade CaCO(3) powders of different purity were used as the starting material and the resultant ?-TCP products for all synthesis routes were compared in terms of the material properties and the reactivity. The reactant CaHPO(4) was also custom synthesized from the respective CaCO(3) source. A low firing temperature in the range of 1150-1350°C promoted formation of ?-polymorph as a second phase in the resultant TCP. Meanwhile, higher firing temperatures resulted in phase pure ?-TCP with poor hydraulic reactivity. The extension of firing operation also led to a decrease in the reactivity. It was found that identical synthesis history, morphology, particle size and crystallinity match between the ?-TCPs produced from different CaCO(3) sources do not essentially culminate in products exhibiting similar hydraulic reactivity. The changes in reactivity are arising from differences in the trace amount of impurities found in the CaCO(3) precursors. In this regard, a correlation between the observed hydraulic reactivities and the impurity content of the CaCO(3) powders--as determined by inductively coupled plasma mass spectrometry--has been established. A high level of magnesium impurity in the CaCO(3) almost completely hampers the hydration of ?-TCP. This impurity also favors formation of ?- instead of ?-polymorph in the product of TCP upon firing. PMID:21445656

  1. Interactions between acidic matrix macromolecules and calcium phosphate ester crystals: relevance to carbonate apatite formation in biomineralization.

    PubMed

    Moradian-Oldak, J; Frolow, F; Addadi, L; Weiner, S

    1992-01-22

    Control over crystal growth by acidic matrix macromolecules is an important process in the formation of many mineralized tissues. Earlier studies on the interactions between acidic macromolecules and carboxylate- and carbonate-containing crystals showed that the proteins recognize a specific stereochemical motif on the interacting plane. Here we show that a similar stereochemical motif is recognized by acidic mollusc shell macromolecules interacting with four different organic calcium phosphate-containing crystals. In addition, an acidic protein from vertebrate tooth dentin was also observed to recognize a similar structural motif in one of the crystals. The characteristic motif recognized is composed of rows of calcium ions and phosphates arranged in a plane defined by two free oxygens and a phosphorus atom emerging perpendicular to the affected face. These observations may have a direct bearing on the manner in which control over crystal growth is exerted on carbonate apatite crystals commonly found in vertebrate tissues. PMID:1348121

  2. Influence of ethanol content in the precipitation medium on the composition, structure and reactivity of magnesium-calcium phosphate.

    PubMed

    Babaie, Elham; Zhou, Huan; Lin, Boren; Bhaduri, Sarit B

    2015-08-01

    Biocompatible amorphous magnesium calcium phosphate (AMCP) particles were synthesized using ethanol in precipitation medium from moderately supersaturated solution at pH10. Some synthesis parameters such as, (Mg+Ca):P, Mg:Ca ratio and different drying methods on the structure and stability of as-produced powder was studied and characterized using SEM, XRD and cell cytocompatibility. The results showed that depending on the Mg(2+) concentration, nano crystalline Struvite (MgNH4PO4·6H2O) can also be alternatively formed. However, the as-formed AMCP preserved its amorphous structure after 7days of incubation in SBF for tested phosphate concentration, and equally ionic concentration of magnesium and calcium. PMID:26042708

  3. Covalent attachment of a bioactive hyperbranched polymeric layer to titanium surface for the biomimetic growth of calcium phosphates

    PubMed Central

    Tsiourvas, D.; Arkas, M.; Diplas, S.; Mastrogianni, E.

    2010-01-01

    This work is investigating the chemical grafting on Ti surface of a polymer/calcium phosphate coating of improved adhesion for enhanced bioactivity. For this purpose, a whole new methodology was developed based on covalently attaching a hyperbranched poly(ethylene imine) layer on Ti surface able to promote calcium phosphate formation in a next deposition stage. This was achieved through an intermediate surface silanization step. The research included optimization both of the reaction conditions for covalently grafting the intermediate organosilicon and the subsequent hyperbranched poly(ethylene imine) layers, as well as of the conditions for the mechanical and chemical pretreatment of Ti surface before coating. The reaction steps were monitored employing FTIR and XPS analyses, whereas the surface morphology and structure of the successive coating layers were studied by SEM combined with EDS. The analysis confirmed the successful grafting of the hybrid layer which demonstrated very good ability for hydroxyapatite growth in simulated body fluid. PMID:21069559

  4. The Effect of Calcium Phosphate Particle Shape and Size on their Antibacterial and Osteogenic Activity in the Delivery of Antibiotics in vitro

    PubMed Central

    Uskokovi?, Vuk; Batarni, Samir Shariff; Schweicher, Julien; King, Andrew; Desai, Tejal A.

    2013-01-01

    Powders composed of four morphologically different calcium phosphate particles were prepared by precipitation from aqueous solutions: flaky, brick-like, elongated orthogonal, and spherical. The particles were then loaded with either clindamycin phosphate as the antibiotic of choice, or fluorescein, a model molecule used to assess the drug release properties. A comparison was carried out of the comparative effect of such antibiotic-releasing materials on: sustained drug release profiles; Staphylococcus aureus growth inhibition; and osteogenic propensities in vitro. Raman spectroscopic analysis indicated the presence of various calcium phosphate phases, including monetite (flaky and elongated orthogonal particles), octacalcium phosphate (brick-shaped particles) and hydroxyapatite (spherical particles). Testing the antibiotic-loaded calcium phosphate powders for bacterial growth inhibition demonstrated satisfying antibacterial properties both in broths and on agar plates. All four calcium-phosphate-fluorescein powders exhibited sustained drug release over 21 days. The calcium phosphate sample with the highest specific surface area and the smallest, spherical particle size was the most effective in both drug loading and release, consequently having the highest antibacterial efficiency. Moreover, the highest cell viability, the largest gene expression upregulation of three different osteogenic markers – osteocalcin, osteopontin and Runx2 - as well as the least disrupted cell cytoskeleton and cell morphologies were also noticed for the calcium phosphate powder composed of smallest, spherical nanosized particles. Still, all four powders exerted a viable effect on osteoblastic MC3T3-E1 cells in vitro, as evidenced by both morphological assessments on fluorescently stained cells and measurements of their mitochondrial activity. The obtained results suggest that the nanoscale particle size and the corresponding coarseness of the surface of particle conglomerates as the cell attachment points may present a favorable starting point for the development of calcium-phosphate-based osteogenic drug delivery devices. PMID:23484624

  5. Casein Phosphopeptide-Amorphous Calcium Phosphate Incorporated into Sugar Confections Inhibits the Progression of Enamel Subsurface Lesions in situ

    Microsoft Academic Search

    G. D. Walker; F. Cai; P. Shen; G. G. Adams; C. Reynolds; E. C. Reynolds

    2010-01-01

    Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) has been demonstrated to exhibit anticariogenic activity in randomized, controlled clinical trials of sugar-free gum and a tooth cream. Two randomized, double-blind, crossover studies were conducted to investigate the potential of CPP-ACP added to hard candy confections to slow the progression of enamel subsurface lesions in an in situ model. The confections studied were: (1)

  6. Urinary phosphate\\/creatinine, calcium\\/creatinine, and magnesium\\/creatinine ratios in a healthy pediatric population

    Microsoft Academic Search

    Vera Matos; Guy van Melle; Olivier Boulat; Michèle Markert; Claude Bachmann; Jean-Pierre Guignard

    1997-01-01

    Objective: To determine reference values for urinary phosphate\\/creatinine (Cr) concentration ratios and to complete reference values for urinary calcium\\/creatinine and magnesium\\/creatinine ratios in the second morning urine sample of healthy infants, children, and adolescents.Design: Urinary P\\/Cr, Ca\\/Cr, and Mg\\/Cr ratios were determined from the second morning urine sample. Two urine samples were obtained 1 week apart from most subjects to

  7. Failure to detect an amorphous calcium-phosphate solid phase in bone mineral: A radial distribution function study

    Microsoft Academic Search

    Marc D. Grynpas; Laurence C. Bonar; Melvin J. Glimcher

    1984-01-01

    Summary  X-ray diffraction radial distribution function analysis was used to determine if a significant amount of an amorphous solid\\u000a phase of calcium phosphate exists in bone, and if so, whether the amount varies as a function of age and maturation. Unfractionated\\u000a cortical bone from embryonic and posthatch chicks of various ages and a low-density fraction of embryonic bone were studied.\\u000a No

  8. Cement pinning of osteoporotic distal radius fractures with an injectable calcium phosphate bone substitute: report of 6 cases

    Microsoft Academic Search

    P. Liverneaux; P. Vernet; C. Robert; P. Diacono

    2006-01-01

    The treatment of osteoporotic distal radius fractures is frequently complicated by secondary displacements, mainly because\\u000a of the posterior comminution. This work studies the advantages of injectable calcium phosphate cement, applied in addition\\u000a to osteosynthesis with intrafocal pins. Our series comprises six osteoporotic patients with an average age of 77.5 years,\\u000a showing a fracture of the distal radius osteosynthesized with pins. Cement

  9. The influence of silicon substitution on the properties of spherical- and whisker-like biphasic ? -calcium-phosphate\\/hydroxyapatite particles

    Microsoft Academic Search

    B. Jokic; M. Mitric; M. Popovic; L. Sima; S. M. Petrescu; R. Petrovic; Dj. Janackovic

    In this work, the influence of the morphology of hydroxyapatite particles on silicon substitution through hydrothermal synthesis\\u000a performed under the same conditions was investigated. Spherical- and whisker-like hydroxyapatite particles were obtained starting\\u000a from calcium-nitrate, sodium dihydrogen phosphate, disodium-ethylenediaminetetraacetic acid and urea (used only for the synthesis\\u000a of whisker-like particles) dissolved in aqueous solutions. Silicon was introduced into the solution using

  10. Osseous integration of calcium phosphate in osteoporotic vertebral fractures after kyphoplasty: initial results from a clinical and experimental pilot study

    Microsoft Academic Search

    M. Libicher; J. Hillmeier; U. Liegibel; U. Sommer; W. Pyerin; M. Vetter; H.-P. Meinzer; I. Grafe; P. Meeder; G. Nöldge; P. Nawroth; C. Kasperk

    2006-01-01

    Introduction  This study evaluated the radiological changes at the bone–cement interface of calcium phosphate cement (CPC) and polymethylmethacrylate (PMMA) 12 months after kyphoplasty. In a pilot experiment, we additionally performed a histomorphometric analysis in osteopenic foxhounds to analyze the process of osseous integration of CPC and PMMA.Methods  Twenty postmenopausal female patients with 46 vertebral compression fractures (VCF) were treated by kyphoplasty, utilizing CPC

  11. Pegylated siRNA-loaded calcium phosphate nanoparticle-driven amplification of cancer cell internalization in vivo

    PubMed Central

    Tobin, Lisa A.; Xie, Yili; Tsokos, Maria; Chung, Su I.; Merz, Allison A.; Arnold, Michael A.; Li, Guang; Malech, Harry L.; Kwong, King F.

    2013-01-01

    The cell membrane is a critical barrier to effective delivery for many therapeutics, including those which are nanoparticle-based. Improving nanoparticle transport across the cell membrane remains a fundamental challenge. Cancer cells preferentially internalized pegylated calcium phosphate nanoparticles over normal epithelial cells. Furthermore, non-cytotoxic levels of doxorubicin markedly amplified this difference by increasing free unbound caveolin-1 and resulted in enhanced caveolin-mediated nanoparticle endocytosis in cancer cells. Engineered pegylated siRNA-loaded triple-shell calcium phosphate nanoconstructs incorporating ultra-low levels of doxorubicin recapitulated these effects and delivered increased numbers of siRNA into cancer cells with target-specific results. Systemic administration of nanoparticles in vivo demonstrated highly preferential entry into tumors, little bystander organ biodistribution, and significant tumor growth arrest. In conclusion, siRNA-loaded calcium phosphate nanoparticles incorporating non-cytotoxic amounts of doxorubicin markedly enhances nanoparticle internalization and results in increased payload delivery with concomitant on-target effects. PMID:23369215

  12. MBCP biphasic calcium phosphate granules and tissucol fibrin sealant in rabbit femoral defects: the effect of fibrin on bone ingrowth.

    PubMed

    Le Guehennec, Laurent; Goyenvalle, Eric; Aguado, Eric; Pilet, Paul; Bagot D'Arc, Maurice; Bilban, Melitta; Spaethe, Reiner; Daculsi, Guy

    2005-01-01

    An ageing population implies an increase in bone and dental diseases, which are in turn a source of numerous handicaps. These pathologies are an expensive burden for the European health system. As no specific bioactive materials are efficient enough to cope with this burden, we have to develop an injectable, mouldable, self-hardening bone substitute to support bone tissue reconstruction and augmentation. New, highly bioactive and suitable biomaterials have been developed to replace bone grafts in orthopedic revision and maxillofacial surgery for bone augmentation. These mouldable, self-hardening materials are based on the association of MBCP Biphasic Calcium Phosphate Granules and Tissucol Fibrin Sealant. The in vivo evaluation of ingrowth in relation to the composite was made in an experiment on rabbits. The results indicate that in the presence of fibrin sealant, newly-formed bone developed at a small distance from the surface of the calcium phosphate ceramic. Two different bone apposition processes were identified. Without the fibrin component (MBCP group), bone rested directly on the surface of the granules. This observation is commonly described as osteoconduction in calcium phosphate materials. On the contrary, the presence of the fibrinogen component seemed to modify this standard osteoconduction phenomenon: the newly-formed bone essentially grew at a distance from the surface of the granules, on the fibrillar network, and could be considered as an inductive phenomenon for osteogenic cell differentiation from mesenchymal stem cells. PMID:15754141

  13. Dentin bond strength of a new adhesive system containing calcium phosphate experimentally developed for direct pulp capping.

    PubMed

    Shinkai, Koichi; Taira, Yoshihisa; Suzuki, Masaya; Kato, Chikage; Ebihara, Takashi; Wakaki, Suguru; Seki, Hideaki; Shirono, Manabu; Ogisu, Takahito; Yamauchi, Junichi; Suzuki, Shiro; Katoh, Yoshiroh

    2009-11-01

    The purpose of this study was to evaluate the microtensile bond strength (microTBS) to human dentin of an experimental bonding agent containing calcium phosphates experimentally developed for direct pulp capping. Different concentrations of four types of calcium phosphates were added to an experimental bonding monomer, and six experimental bonding agents were thus prepared. Clearfil SE Bond/Bond was used as the control. Flat dentin surfaces of human molars were assigned to the experimental adhesive systems and the control. After Clearfil SE Bond/Primer was applied to the dentin surface, each experimental bonding agent was applied and photopolymerized, and then a resin composite paste was placed and photopolymerized. The specimens were subjected to microTBS testing. Results revealed that there were no significant differences among the microTBS values of the experimental bonding agents and the control. In other words, the calcium phosphate-containing experimental adhesives did not adversely affect the microTBS to dentin. PMID:20019427

  14. Bioactivity and corrosion properties of gelatin-containing and strontium-doped calcium phosphate composite coating

    NASA Astrophysics Data System (ADS)

    Huang, Yong; Yan, Yajing; Pang, Xiaofeng; Ding, Qiongqiong; Han, Shuguang

    2013-10-01

    To improve coating corrosion resistance and bioactivity, strontium (Sr) and gelatin (GLT) were simultaneously incorporated in calcium phosphate (Ca-P) to form Sr-Ca-P/GLT composite coating on titanium (Ti) by electrodeposition. The surface morphology, chemical composition, phase identification, bond strength, corrosion resistance, and cytocompatibility of the films were studied. Results revealed that the Sr-Ca-P/GLT layer was rough and inhomogeneous, with floral-like crystals or flake agglomerate morphology. The Sr-Ca-P crystals were Sr-doped apatite (hydroxyapatite and brushite), and Sr2+ ions and GLT were homogeneously distributed in the Ca-P coating. The thickness of the composite coating was almost 10 ?m without delamination and/or cracking at the interface. The bond strength of the composite coating was 5.6 ± 1.8 MPa. The Sr-Ca-P/GLT coated Ti had lower corrosion rates than bare Ti, suggesting a protective character of the composite coating. Osteoblast cellular tests demonstrated that the Sr-Ca-P/GLT composite coating better enhanced the in vitro biocompatibility of Ti than Ca-P coating.

  15. Novel doped calcium phosphate-PMMA bone cement composites as levofloxacin delivery systems.

    PubMed

    Matos, Ana C; Marques, Catarina F; Pinto, Rosana V; Ribeiro, Isabel A C; Gonçalves, Lídia M; Vaz, Mário A; Ferreira, J M F; Almeida, António J; Bettencourt, Ana F

    2015-07-25

    Antibiotic-loaded acrylic bone cements (ALABCs) are well-established and cost-effective materials to control the occurrence of bone and joint infections. However, the inexistence of alternative antibiotics other than those already commercially available and the poor ability to bind to bone tissue hampering its biological function are still major drawbacks of ALABCs clinical application. The concept of this research work is to develop a novel bone cement (BC) drug delivery system composed by Mg- and Sr-doped calcium phosphate (CaP) particles as drug carriers loaded into a lactose-modified acrylic BC, which, to the best of our knowledge, has never been reported. CaP particles are known to promote bone ingrowth and current research is focused on using these carriers as antibiotic delivery systems for the treatment of bone infections, like osteomyelitis. Levofloxacin is a fluoroquinolone with anti-staphylococcal activity and adequate penetration into osteoarticular tissues and increasingly being recommended to manage bone-related infections. Also, the lactose-modified BC matrix, with a more porous structure, has already proved to enhance antibiotic release from the BC inner matrix. This novel BC composite biomaterial has shown improved mechanical integrity, biocompatibility maintenance, and sustained release of levofloxacin, with concentrations over the minimum inhibitory concentration values after a 48h while maintaining antibacterial activity over an 8-week period against Staphyloccocus aureus and Staphyloccocus epidermidis, common pathogens associated with bone infections. PMID:26002570

  16. Zero Echo Time Magnetic Resonance Imaging of Contrast-Agent-Enhanced Calcium Phosphate Bone Defect Fillers

    PubMed Central

    Sun, Yi; Ventura, Manuela; Oosterwijk, Egbert; Jansen, John A.; Walboomers, X. Frank

    2013-01-01

    Calcium phosphate cements (CPCs) are widely used bone substitutes. However, CPCs have similar radiopacity as natural bone, rendering them difficult to be differentiated in classical X-ray and computed tomography imaging. As conventional magnetic resonance imaging (MRI) of bone is cumbersome, due to low water content and very short T2 relaxation time, ultra-short echo time (UTE) and zero echo time (ZTE) MRI have been explored for bone visualization. This study examined the possibility to differentiate bone and CPC by MRI. T1 and T2* values determined with UTE MRI showed little difference between bone and CPC; hence, these materials were difficult to separate based on T1 or T2 alone. Incorporation of ultra-small particles of iron oxide and gadopentetatedimeglumine (Gd-DTPA; 1 weight percentage [wt%] and 5?wt% respectively) into CPC resulted in visualization of CPC with decreased intensity on ZTE images in in vitro and ex vivo experiments. However, these additions had unfavorable effects on the solidification time and/or mechanical properties of the CPC, with the exception of 1% Gd-DTPA alone. Therefore, we tested this material in an in vivo experiment. The contrast of CPC was enhanced at an early stage postimplantation, and was significantly reduced in the 8 weeks thereafter. This indicates that ZTE imaging with Gd-DTPA as a contrast agent could be a valid radiation-free method to visualize CPC degradation and bone regeneration in preclinical experiments. PMID:22934755

  17. Cross-linked chitosan improves the mechanical properties of calcium phosphate-chitosan cement.

    PubMed

    Aryaei, Ashkan; Liu, Jason; Jayatissa, Ahalapitiya H; Champa Jayasuriya, A

    2015-09-01

    Calcium phosphate (CaP) cements are highly applicable and valuable materials for filling bone defects by minimally invasive procedures. The chitosan (CS) biopolymer is also considered as one of the promising biomaterial candidates in bone tissue engineering. In the present study, some key features of CaP-CS were significantly improved by developing a novel CaP-CS composite. For this purpose, CS was the first cross-linked with tripolyphosphate (TPP) and then mixed with CaP matrix. A group of CaP-CS samples without cross-linking was also prepared. Samples were fabricated and tested based on the known standards. Additionally, the effect of different powder (P) to liquid (L) ratios was also investigated. Both cross-linked and uncross-linked CaP-CS samples showed excellent washout resistance. The most significant effects were observed on Young's modulus and compressive strength in wet condition as well as surface hardness. In dry conditions, the Young's modulus of cross-linked samples was slightly improved. Based on the presented results, cross-linking does not have a significant effect on porosity. As expected, by increasing the P/L ratio of a sample, ductility and injectability were decreased. However, in the most cases, mechanical properties were enhanced. The results have shown that cross-linking can improve the mechanical properties of CaP-CS and hence it can be used for bone tissue engineering applications. PMID:26046262

  18. Human endothelial colony forming cells undergo vasculogenesis within biphasic calcium phosphate bone tissue engineering constructs.

    PubMed

    Levengood, Sheeny K Lan; Poellmann, Michael J; Clark, Sherrie G; Ingram, David A; Yoder, Mervin C; Johnson, Amy J Wagoner

    2011-12-01

    An important consideration in bone regeneration is the need for expedited neovascularization within the defect site. Formation of a vascular network is critical for cell viability and normal function leading to tissue regeneration, but spontaneous angiogenesis is too slow to yield sufficient vessel formation. In this pilot study, human umbilical cord blood (hUCB)-derived endothelial colony forming cells (ECFCs) were evaluated for in vivo vasculogenesis in the macropores of biphasic calcium phosphate (BCP)/bone morphogenetic protein-2 (BMP-2) bone tissue engineering constructs. Constructs were implanted on the abdominal wall of NOD/SCID mice for 4 weeks. This study demonstrated in vivo vasculogenesis by human ECFCs within the macropore space of BCP/BMP-2 constructs. The human ECFC-derived vessels anastomosed with the host vasculature and perfused vessels were visible in the very center of the 5mm diameter, 2.5mm tall scaffolds. Additionally, the vessels were evenly distributed throughout the construct. This study suggests that scaffolds containing ECFCs have significant potential for expedited neovascularization in bony defects. PMID:21798379

  19. Attachment, proliferation, and chondroinduction of mesenchymal stem cells on porous chitosan-calcium phosphate scaffolds.

    PubMed

    Elder, Steven; Gottipati, Anuhya; Zelenka, Hilary; Bumgardner, Joel

    2013-01-01

    Symptomatic osteochondral lesions occur frequently, but relatively few treatment options are currently available. The purpose of this study was to conduct a preliminary investigation into a new tissue engineering approach to osteochondral regeneration. The concept is a biphasic construct consisting of a porous, osteoconductive chitosan-calcium phosphate scaffold supporting a layer of neocartilage formed by marrow-derived mesenchymal stem cells. Two experiments were conducted to assess the feasibility of this approach. The first experiment characterized the attachment efficiency and proliferation of primary human marrow-derived mesenchymal stem cells seeded relatively sparely onto the scaffold's surface. The second experiment compared two different methods of creating a biphasic construct using a much higher density of primary porcine marrow stromal cells. About 40% of the sparsely seeded human cells attached and proliferated rapidly. Constructs formed by one of the two experimental techniques exhibited a layer of cartilaginous tissue which only partially covered the scaffold's surface due to inadequate adhesion between the cells and the scaffold. This study demonstrates some potential for the approach to yield an implantable biphasic construct, but further development is required to improve cell-scaffold adhesion. PMID:23986794

  20. Attachment, Proliferation, and Chondroinduction of Mesenchymal Stem Cells on Porous Chitosan-Calcium Phosphate Scaffolds

    PubMed Central

    Elder, Steven; Gottipati, Anuhya; Zelenka, Hilary; Bumgardner, Joel

    2013-01-01

    Symptomatic osteochondral lesions occur frequently, but relatively few treatment options are currently available. The purpose of this study was to conduct a preliminary investigation into a new tissue engineering approach to osteochondral regeneration. The concept is a biphasic construct consisting of a porous, osteoconductive chitosan-calcium phosphate scaffold supporting a layer of neocartilage formed by marrow-derived mesenchymal stem cells. Two experiments were conducted to assess the feasibility of this approach. The first experiment characterized the attachment efficiency and proliferation of primary human marrow-derived mesenchymal stem cells seeded relatively sparely onto the scaffold’s surface. The second experiment compared two different methods of creating a biphasic construct using a much higher density of primary porcine marrow stromal cells. About 40% of the sparsely seeded human cells attached and proliferated rapidly. Constructs formed by one of the two experimental techniques exhibited a layer of cartilaginous tissue which only partially covered the scaffold’s surface due to inadequate adhesion between the cells and the scaffold. This study demonstrates some potential for the approach to yield an implantable biphasic construct, but further development is required to improve cell-scaffold adhesion. PMID:23986794

  1. Enhanced photodynamic therapy efficacy of methylene blue-loaded calcium phosphate nanoparticles.

    PubMed

    Seong, Da-Young; Kim, Young-Jin

    2015-05-01

    Although methylene blue (MB) is the most inexpensive photosensitizer with promising applications in the photodynamic therapy (PDT) for its high quantum yield of singlet oxygen generation, the clinical use of MB has been limited by its rapid enzymatic reduction in the biological environment. To enhance PDT efficacy of MB by preventing the enzymatic reduction, we have developed a new mineralization method to produce highly biocompatible MB-loaded calcium phosphate (CaP-MB) nanoparticles in the presence of polymer templates. The resulting CaP-MB nanoparticles exhibited spherical shape with a size of under 50 nm. Fourier transform infrared (FT-IR) and zeta-potential analyses confirmed the insertion of MB into the CaP-MB nanoparticles. The encapsulation of MB in CaP nanoparticles could effectively protect MB from the enzymatic reduction. In addition, the CaP-MB nanoparticles exhibited a good biocompatibility in the dark condition and significantly enhanced PDT efficacy due to apoptotic cell death against human breast cancer cells as compared with free MB, implying that CaP-MB nanoparticle system might be potentially applicable in PDT. PMID:25794464

  2. Laser pulse dependent micro textured calcium phosphate coatings for improved wettability and cell compatibility.

    PubMed

    Paital, Sameer R; He, Wei; Dahotre, Narendra B

    2010-07-01

    Surface wettability of an implant material is an important criterion in biological response as it controls the adsorption of proteins followed by attachment of cells to its surface. Hence, micro-textured calcium phosphate coatings with four length scales were synthesized on Ti-6Al-4V substrates by a laser cladding technique and their effects on wettability and cell adhesion were systematically evaluated. Microstructure and morphological evolutions of the coatings were studied using scanning electron and light optical microscopes respectively. The surface texture of coating defined in terms of a texture parameter was correlated to its wetting behavior. The contact angle of simulated body fluid measured by a static sessile drop technique, demonstrated an increased hydrophilicity with decreasing value of texture parameter. The influence of such textures on the in vitro bioactivity and in vitro biocompatibility were studied by the immersion of the samples in simulated body fluid and mouse MC3T3-E1 osteoblast-like cell culture respectively. PMID:20464459

  3. In vitro bioactivity and biocompatibility of calcium phosphate cements using Hydroxy-propyl-methyl-Cellulose (HPMC)

    NASA Astrophysics Data System (ADS)

    Jyoti, M. Anirban; Thai, Van Viet; Min, Young Ki; Lee, Byong-Taek; Song, Ho-Yeon

    2010-12-01

    In this study, the bioactivity and biocompatibility of new calcium phosphate bone cements (CPC) using Hydroxy-propyl-methyl-Cellulose (HPMC) was evaluated to understand the effect of HPMC on bone-bonding apatite formation and biocompatibility. In vitro bioactivity was investigated by incubating the CPC samples containing different ratios of HPMC (0%, 2% and 4% HPMC) in simulated body fluid (SBF) for 2, 7, 14 and 28 days. The formation of bone like apatite was confirmed on CPC surfaces by SEM and XRD analysis. Higher HPMC content of CPC showed faster apatite deposition in SBF. A high Ca ion dissolution profile was also reported with an increase of pH in all samples in SBF. The apatite formation ability of these CPC samples was found to be dependent on both surface chemistry and immersion time in SBF. The In vitro cytotoxicity test showed that the CPC samples with 4% HPMC were fairly cytocompatible for fibroblast L-929 cells. SEM images showed that MG-63 cells were successfully attached to the CPC samples and well proliferated.

  4. Bi-layered calcium phosphate cement-based composite scaffold mimicking natural bone structure

    NASA Astrophysics Data System (ADS)

    He, Fupo; Ye, Jiandong

    2013-08-01

    In this study, a core/shell bi-layered calcium phosphate cement (CPC)-based composite scaffold with adjustable compressive strength, which mimicked the structure of natural cortical/cancellous bone, was fabricated. The dense tubular CPC shell was prepared by isostatic pressing CPC powder with a specially designed mould. A porous CPC core with unidirectional lamellar pore structure was fabricated inside the cavity of dense tubular CPC shell by unidirectional freeze casting, followed by infiltration of poly(lactic-co-glycolic acid) and immobilization of collagen. The compressive strength of bi-layered CPC-based composite scaffold can be controlled by varying thickness ratio of dense layer to porous layer. Compared to the scaffold without dense shell, the pore interconnection of bi-layered scaffold was not obviously compromised because of its high unidirectional interconnectivity but poor three dimensional interconnectivity. The in vitro results showed that the rat bone marrow stromal cells attached and proliferated well on the bi-layered CPC-based composite scaffold. This novel bi-layered CPC-based composite scaffold is promising for bone repair.

  5. Interactions binding mineral and organic phases in nanocomposites based on bacterial cellulose and calcium phosphates.

    PubMed

    Tolmachev, D A; Lukasheva, N V

    2012-09-18

    The interactions responsible for the adhesion of calcium phosphate (CP) nanocrystals and bacterial cellulose (BC) nanofibrils in the composite material obtained by mixing aqueous suspensions of presynthesized CP and BC and the dependence of these interactions on the CP morphology and chemical structure have been elucidated by molecular mechanics calculations of the CP-BC interfacial structures. The interactions between the superficial CP and BC crystal layers have been simulated. Two crystalline CP structures (i.e., hydroxyapatite (HAP) and whitlockite) with two morphologies (plate-shaped and rod-shaped) were considered. Electrostatics has been found to be the major contributor to the adhesion of the CP crystallites and BC nanofibers, and the formation of interfacial hydrogen bonds makes a minor contribution to the interaction energy. It has also been found that, in general, the energy gain resulting from whitlockite-BC binding is greater than that for HAP-BC binding, and the binding of the rod-shaped crystallites of whitlockite with BC is the most profitable. The energy loss and entropy gain upon replacement of the BC-water and CP-water contacts by the BC-CP contacts have been estimated. PMID:22880938

  6. The role of Carboxydothermus hydrogenoformans in the conversion of calcium phosphate from amorphous to crystalline state.

    PubMed

    Haddad, Mathieu; Vali, Hojatollah; Paquette, Jeanne; Guiot, Serge R

    2014-01-01

    Two previously unknown modes of biomineralization observed in the presence of Carboxydothermus hydrogenoformans are presented. Following the addition of NaHCO3 and the formation of an amorphous calcium phosphate precipitate in a DSMZ medium inoculated with C. hydrogenoformans, two distinct crystalline solids were recovered after 15 and 30 days of incubation. The first of these solids occurred as micrometric clusters of blocky, angular crystals, which were associated with bacterial biofilm. The second solid occurred as 30-50 nm nanorods that were found scattered among the organic products of bacterial lysis. The biphasic mixture of solids was clearly dominated by the first phase. The X-ray diffractometry (XRD) peaks and Fourier transform infrared spectroscopy (FTIR) spectrum of this biphasic material consistently showed features characteristic of Mg-whitlockite. No organic content or protein could be identified by dissolving the solids. In both cases, the mode of biomineralization appears to be biologically induced rather than biologically controlled. Since Mg is known to be a strong inhibitor of the nucleation and growth of CaP, C. hydrogenoformans may act by providing sites that chelate Mg or form complexes with it, thus decreasing its activity as nucleation and crystal growth inhibitor. The synthesis of whitlockite and nano-HAP-like material by C. hydrogenoformans demonstrates the versatility of this organism also known for its ability to perform the water-gas shift reaction, and may have applications in bacterially mediated synthesis of CaP materials, as an environmentally friendly alternative process. PMID:24586811

  7. The Role of Carboxydothermus hydrogenoformans in the Conversion of Calcium Phosphate from Amorphous to Crystalline State

    PubMed Central

    Haddad, Mathieu; Vali, Hojatollah; Paquette, Jeanne; Guiot, Serge R.

    2014-01-01

    Two previously unknown modes of biomineralization observed in the presence of Carboxydothermus hydrogenoformans are presented. Following the addition of NaHCO3 and the formation of an amorphous calcium phosphate precipitate in a DSMZ medium inoculated with C. hydrogenoformans, two distinct crystalline solids were recovered after 15 and 30 days of incubation. The first of these solids occurred as micrometric clusters of blocky, angular crystals, which were associated with bacterial biofilm. The second solid occurred as 30–50 nm nanorods that were found scattered among the organic products of bacterial lysis. The biphasic mixture of solids was clearly dominated by the first phase. The X-ray diffractometry (XRD) peaks and Fourier transform infrared spectroscopy (FTIR) spectrum of this biphasic material consistently showed features characteristic of Mg-whitlockite. No organic content or protein could be identified by dissolving the solids. In both cases, the mode of biomineralization appears to be biologically induced rather than biologically controlled. Since Mg is known to be a strong inhibitor of the nucleation and growth of CaP, C. hydrogenoformans may act by providing sites that chelate Mg or form complexes with it, thus decreasing its activity as nucleation and crystal growth inhibitor. The synthesis of whitlockite and nano-HAP-like material by C. hydrogenoformans demonstrates the versatility of this organism also known for its ability to perform the water-gas shift reaction, and may have applications in bacterially mediated synthesis of CaP materials, as an environmentally friendly alternative process. PMID:24586811

  8. Bone response to radio frequency sputtered calcium phosphate implants and titanium implants in vivo.

    PubMed

    Ong, J L; Bessho, K; Cavin, R; Carnes, D L

    2002-01-01

    The objective of this study was to evaluate the effect of radio frequency sputtered calcium phosphate (CaP) coatings of titanium (Ti) implants on the bond strength at the bone-implant interface and percent bone contact length. Cylindrical coated or noncoated implants (4.0-mm diameter by 8-mm long) were implanted for 3 and 12 weeks. At 3 weeks after implant placement, the ultimate interfacial strengths for as-deposited CaP-coated and heat-treated CaP-coated implants were 2.29 +/- 0.14 MPa and 1.28 +/- 0.04 MPa, respectively. These ultimate interfacial strength values at 3 weeks were statistically greater than the mean ultimate interfacial strength for control Ti implants (0.67 +/- 0.13 MPa). At 12 weeks after implant placement, no statistical differences in the mean ultimate interfacial strengths were observed between the as-deposited CaP-coated, heat-treated CaP-coated, and control Ti implants. Histomorphometric evaluation indicated greater percent bone contact lengths for the as-deposited CaP-coated implants compared with the heat-treated CaP-coated and control Ti implants 3 and 12 weeks after implant placement. PMID:11745552

  9. Influence of precursor solution parameters on chemical properties of calcium phosphate coatings prepared using Electrostatic Spray Deposition (ESD).

    PubMed

    Leeuwenburgh, S C G; Wolke, J G C; Schoonman, J; Jansen, J A

    2004-02-01

    A novel coating technique, referred to as Electrostatic Spray Deposition (ESD), was used to deposit calcium phosphate (CaP) coatings with a variety of chemical properties. The relationship between the composition of the precursor solutions and the crystal and molecular structure of the deposited coatings was investigated by means of X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR) and Energy Dispersive Spectroscopy (EDS). It was shown that the relative Ca/P ratio in the precursor solution, the absolute precursor concentration, the acidity of the precursor solution and the type of Ca-precursor strongly influenced the chemical nature of the deposited CaP coatings. Various crystal phases and phase mixtures were obtained, such as carbonate apatite, beta-TCP, Mg-substituted whitlockite, monetite, beta/gamma-pyrophosphate, and calcite. It was shown that carbonate plays an essential role in the chemical mechanism of coating formation. Carbonate is formed due to a decomposition reaction of organic solvents. Depending on deposition conditions, carbonate anions (a) react with acidic phosphate groups, (b) are incorporated into apatitic calcium phosphate phases, and (c) react with excessive Ca(2+) cations in case of phosphate-deficient precursor solutions. PMID:14607502

  10. Reciprocal regulation of calcium-/phosphate-regulating hormones in cyclists during the Giro d'Italia 3-week stage race.

    PubMed

    Lombardi, G; Corsetti, R; Lanteri, P; Grasso, D; Vianello, E; Marazzi, M G; Graziani, R; Colombini, A; Galliera, E; Corsi Romanelli, M M; Banfi, G

    2014-10-01

    Calcium and phosphate are essential for cell functions, and their serum concentrations result from the balance between intestinal absorption, bony storage, and urinary excretion. Fibroblast growth factor 23 (FGF23), expressed by osteocytes and osteoblasts, acts in the kidney, leading to hypophosphatemia and low 1,25-dihydroxycholecalciferol synthesis, but suppresses parathyroid function. The aim of this study was to explore the effects of a high-energy demanding cycling race on this bone-kidney-parathyroid axis. We studied nine cyclists during the 2011 Giro d'Italia stage race. Pre-analytical and analytical phases followed academic and anti-doping recommendations. Serum parathyroid hormone (PTH), 25(OH)D, total calcium, inorganic phosphorus, and plasma FGF23 were measured on days -1, 12, and 22 and corrected for changes in plasma volume. Dietary calcium and phosphorus, anthropometric parameters (height, weight, and body mass index) and indexes of metabolic effort (net energy expenditure, power output) were recorded. Dietary calcium and phosphorus intakes were kept at the same levels throughout the race. Twenty-five (OH)D, PTH, and calcium concentrations remained stable. FGF23 increased 50% with a positive correlation with the indexes of metabolic effort and, consequently, phosphorous decreased, although only in the first half. The strong metabolic effort acts on the bone-kidney-parathyroid system, and the rise in FGF23 plasma concentration might be aimed at maintaining calcium and phosphorus homeostasis. PMID:23647316

  11. Changes in calcium phosphate on bone surfaces and in lining cells after the administration of parathyroid hormone or calcitonin

    SciTech Connect

    Norimatsu, H.; Yamamoto, T.; Ozawa, H.; Talmage, R.V.

    1982-04-01

    Small doses of parathyroid hormone and calcitonin were injected into thyroparathyroidectomized newborn rats to investigate the histological and chemical changes in bone surfaces and in mitochondrial granules of bone lining cells. Nondecalcified tissue specimens were observed under transmission electron microscope, electron probe X-ray microanalyzer, and microdiffraction after freeze substitution preparation of tibia shafts. Amorphous calcium phosphate, which appears as clusters and globules by this freeze substitution preparation, appears on the bone surfaces in a short time after the administration of a small dose of calcitonin. The Ca:PO4 ratio in the mitochondria of bone lining cells rises slightly with a small dose of parathyroid hormone and is reduced with a small dose of calcitonin. These data support the postulate that both parathyroid hormone and calcitonin act directly on bone lining cells in the process of influencing calcium concentrations of blood and temporarily storing calcium at bone surfaces.

  12. Calcium

    MedlinePLUS

    ... Consumer Datos en español Health Professional Other Resources Calcium Fact Sheet for Consumers What is calcium and what does it do? Calcium is a ... find out more about calcium? Disclaimer How much calcium do I need? The amount of calcium you ...

  13. Effects of oyster shell electrolysate (active absorbable calcium) as a phosphate binder

    Microsoft Academic Search

    Yasuki Hashimoto; Masaaki Fukase; Tatsuo Tsukamoto; Yoshihiro Yamamoto; Kazuto Ikeda; Masamichi Nakai; Tadao Fujimi; Takuo Fujita

    1990-01-01

    Effect of oral calcium load on calcium metabolism was studied in 6 healthy subjects. Calcium carbonate (3.75 g) and Oyster\\u000a Shell Electrolysate (OSE, 3.0 g) were orally administrated in a cross-over design to provide 1.5 g elementary calcim to each\\u000a subject twice at 1 week interval. No significant differences were found in the increments of serum calcium, blood ionized\\u000a calcium

  14. Kinetics of apatite formation on a calcium-silicate cement for root-end filling during ageing in physiological-like phosphate solutions

    Microsoft Academic Search

    Maria Giovanna Gandolfi; Paola Taddei; Anna Tinti; Elettra De Stefano Dorigo; Piermaria Luigi Rossi; Carlo Prati

    2010-01-01

    The bioactivity of calcium silicate mineral trioxide aggregate (MTA) cements has been attributed to their ability to produce\\u000a apatite in presence of phosphate-containing fluids. This study evaluated surface morphology and chemical transformations of\\u000a an experimental accelerated calcium-silicate cement as a function of soaking time in different phosphate-containing solutions.\\u000a Cement discs were immersed in Dulbecco’s phosphate-buffered saline (DPBS) or Hank’s balanced

  15. Engineering of pulsed laser deposited calcium phosphate biomaterials in controlled atmospheres

    NASA Astrophysics Data System (ADS)

    Drukteinis, Saulius E.

    Synthetic calcium phosphates (CAP) such as hydroxyapatite (HA) have been used as regenerative bone graft materials and also as thin films to improve the integration of biomedical implant devices within skeletal tissue. Pulsed laser deposition (PLD) can deposit crystalline HA with significant adhesion on titanium biomaterials. However, there are PLD processing constraints due to the complex physical and chemical interactions occurring simultaneously during PLD, which influence ablation plume formation and development. In this investigation PLD CAP films were engineered with a focus on novel decoupling of partial pressure of H2O (g) ( PH2O ) from total background pressure, in combination with substrate heat treatment and laser energy density control. Characterization of these films was performed with X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Fourier Transform Infrared Spectroscopy, and Optical Profilometry. In vitro cellular adhesion testing was also performed using osteoblast (MC3T3) cell lines to evaluate adhesion of bone-forming cells on processed PLD CAP samples. Preferred a-axis orientation films were deposited in H2O (g) saturated atmospheres with reduced laser fluence (< 4 J/cm2). Crystalline HA/tetracalcium phosphate (TTCP) films were deposited in H2O ( g)-deficient atmospheres with higher laser fluence (> 3 J/cm 2). Varied PH2O resulted in control of biphasic HA/TTCP composition with increasing TTCP at lower PH2O . These were dense continuous films composed of micron-scale particles. Cellular adhesion assays did not demonstrate a significant difference between osteoblast adhesion density on HA films compared with biphasic HA/TTCP films. Room temperature PLD at varied PH2O combined with furnace heat treatment resulted in controlled variation in surface amplitude parameters including surface roughness (S a), root mean square (Sq), peak to valley height (St), and ten-point height ( Sz). These discontinuous films were composed of nano-scale particles and resulted in significant osteoblast adhesion compared to control samples or to PLD CAP films deposited on heated substrates. Surface amplitude parameters (Sa, Sq, St, and Sz) correlated with osteoblast adhesion. This new approach of control over H2O ( g) operating atmospheres enabled the deposition of unique PLD CAP films with potential use as thin films for biomedical implants or as regenerative bone graft materials. Keywords: hydroxyapatite, pulsed laser deposition, biomaterials.

  16. Calcium phosphate sol-gel-derived coatings on titanium-aluminum-vanadium substrate for biomedical applications

    NASA Astrophysics Data System (ADS)

    Gan, Lu

    Osseointegration of implants to host bone is a necessary requirement for dental and orthopaedic implants. The rate and quality of osseointegration were enhanced through the use of calcium phosphate (Ca-P) films on metallic substrates. The present study investigates the characteristics of Ca-P films applied using sol-gel dip coating methods to sintered porous-surfaced implants. Ca-P films have been formed using Inorganic Route and Organic Route processes. It has been shown that both approaches resulted in the formation of carbonated hydroxyapatite but with different Ca/P ratios as well as different surface textures and film structures, the Inorganic Route-formed film being more porous at its outermost surface, and having a more irregular topography. An interfacial reaction product (calcium titanium oxide) was detected for the Inorganic Route-formed coatings while this interfacial phase was not detectable in the Organic Route-formed coatings. The interface tensile and shear adhesion strength properties of Ca-P films have been evaluated using an improved direct pull-off testing (ASTM C633) and a substrate straining method, respectively. For both Ca-P films, the adhesive tensile strength was higher than the failure stress of ˜38 MPa occurring between the Ca-P films and the glue or in the glue. A shear lag approach revealed a shear strength of 347 +/- 64MPa and 280 +/- 28MPa for the Inorganic Route and the Organic Route Ca-P films, respectively. In vivo animal model studies have been performed to compare the effect on early bone formation of sintered porous-surfaced implants that had been modified through the addition of Ca-P film. In Group I study (i.e. Inorganic Route-formed Ca-P-coated implants vs. non-coated implants), it has been found that the Inorganic Route-formed Ca-P film significantly enhances the early rate of bone ingrowth for sintered porous-surfaced implants. However, in Group II study (i.e. Organic Route-formed Ca-P-coated implants vs. non-coated implants), significant improvement was not observed for the Organic Route-formed Ca-P film. It is speculated that the slightly different surface topography and film density between the two Ca-P films result in a different amounts of protein adsorption on the implant surface at the early stage, which further affects the following processes leading to osseointegration.

  17. Development of collagen-hydroxyapatite nanostructured composites via a calcium phosphate precursor mechanism

    NASA Astrophysics Data System (ADS)

    Jee, Sang Soo

    Bone is an interpenetrating inorganic/organic composite that consists of mineralized collagen fibrils, which is hierarchically organized into various structures. The structure of mineralized collagen fibril, in which nano-crystals of hydroxyapatite are embedded within the collagen fibrils, provides remarkable mechanical and bio-resorptive properties. Therefore, there have been many attempts to produce collagen-hydroxyapatite composites having a bone-like structure. However, duplication of even the most fundamental level of bone structure has not been easily achieved by conventional nucleation and growth techniques, which are based on the most widely accepted hypothesis of bone mineralization. In nature, the collagen fibril is mineralized via intrafibrillar mineralization, which produces preferentially oriented hydroxyapatite nano-crystals occupying the interstices in collagen fibrils. Our group has demonstrated that intrafibrillar mineralization can be achieved by using a new method based on the Polymer-Induced Liquid-Precursor (PILP) mineralization process. In the PILP process, a poly-anionic additive can produce an amorphous calcium phosphate precursor which enables us to achieve intrafibrillar mineralization of collagen. It is thought that the precursor is pulled into the interstices of the collagen fibrils via capillary forces, and upon solidification and crystallization of the precursor produces an interpenetrating composite with the nanostructured architecture of bone. In this dissertation, to demonstrate the effectiveness of the PILP process on the intrafibrillar mineralization of collagen fibril, various collagen scaffolds, such as turkey tendon, bovine tendon and synthetic collagen sponge, were mineralized by the PILP process. Various poly-aspartates with different molecular weight were also used for the optimization of the PILP process for the mineralization of the collagen scaffolds. With the systematic researches, we discovered that the molecular weight of poly-aspartic acid affects the degree of intrafibrillar mineralization of collagen scaffolds. High molecular weight poly-aspartic acid could produce a stable and dispersed amorphous precursor, leading to a high degree of intrafibrillar mineralization. The mineral content of the collagen sponge mineralized using high molecular weight poly-aspartic acid was equivalent to the mineral content of bone. According to X-ray diffraction analysis of the mineralized collagen, the size and composition of the intrafibrillar hydroxyapatite produced by the PILP process were almost identical to carbonated hydroxyapatite in bone. The selective area electron diffraction patterns indicated that the [001] direction of hydroxyapatite is roughly aligned along the c-axis of collagen fibril, leading to the formation 002 arcs. Using dark field imaging, it was possible to visualize the preferentially oriented hydroxyapatite in TEM. Thermal analysis of mineralized collagen also showed a reduction in the thermal stability of collagen, which is similar to that observed in the collagen in bone, due to the presence of intrafibrillar hydroxyapatite. Now, we confidently suggest that the PILP process can provide a new way to develop synthetic bone-like composites whose nano-structure is very close to the nano-structure of natural bone. Moreover, we hope that our successful intrafibrillar mineralization of collagen via the precursor mechanism revives discussion of hypothesis of bone mineralization via the amorphous calcium phosphate phase.

  18. AMORPHOUS CALCIUM PHOSPHATE COMPOSITES AND THEIR EFFECT ON COMPOSITE-ADHESIVE-DENTIN BONDING

    PubMed Central

    Antonucci, J.M.; O’Donnell, J.N.R.; Schumacher, G.E.; Skrtic, D.

    2009-01-01

    This study evaluates the bond strength and related properties of photo-polymerizable, remineralizing amorphous calcium phosphate (ACP) polymeric composite-adhesive systems to dentin after various periods of aqueous aging at 37 °C. An experimental ACP base and lining composite was made from a photo-activated resin comprising 2,2-bis[p-(2’-hydroxy-3’-methacryloxypropoxy)phenyl]propane (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA) and zirconyl dimethacrylate (ZrDMA); designated BTHZ. An experimental orthodontic composite was formulated from a photo-activated resin comprising ethoxylated bisphenol A dimethacrylate (EBPADMA), TEGDMA, HEMA and methacryloxyethyl phthalate (MEP); designated ETHM. In both composite series three fillers were compared: 1) freshly precipitated zirconium-modified ACP freshly precipitated (as-prepared Zr-ACP), 2) milled Zr-ACP and 3) an ion-leachable fluoride glass. In addition to the shear bond strength (SBS), work to fracture and failure modes of the orthodontic composites were determined. The SBS of the base and lining ACP composites appeared unaffected by filler type or immersion time. In the orthodontic ACP composite series, milled ACP composites showed initial mechanical advantages over as-prepared ACP composites, and produced higher incidence of a failure mode consistent with stronger adhesion. After six months of aqueous exposure, 80 % of specimens failed at the dentin-primer interface, with a 42 % overall reduction in bond strength. BTHZ and ETHM based ACP composites are potentially effective anti-demineralizing-remineralizing agents with possible clinical utility as protective base-liners and orthodontic cements, respectively. The analysis of the bond strength and failure modalities suggests that milled ACP composites may offer greater potential in clinical applications. PMID:19696914

  19. Incorporation of bioactive glass in calcium phosphate cement: material characterization and in vitro degradation.

    PubMed

    Renno, A C M; Nejadnik, M R; van de Watering, F C J; Crovace, M C; Zanotto, E D; Hoefnagels, J P M; Wolke, J G C; Jansen, J A; van den Beucken, J J J P

    2013-08-01

    Calcium phosphate cements (CPCs) have been widely used as an alternative to biological grafts due to their excellent osteoconductive properties. Although degradation has been improved by using poly(D,L-lactic-co-glycolic) acid (PLGA) microspheres as porogens, the biological performance of CPC/PLGA composites is insufficient to stimulate bone healing in large bone defects. In this context, the aim of this study was to investigate the effect of incorporating osteopromotive bioactive glass (BG; up to 50 wt %) on setting properties, in vitro degradation behavior and morphological characteristics of CPC/BG and CPC/PLGA/BG. The results revealed that the initial and final setting time of the composites increased with increasing amounts of incorporated BG. The degradation test showed a BG-dependent increasing effect on pH of CPC/BG and CPC/PLGA/BG pre-set scaffolds immersed in PBS compared to CPC and CPC/PLGA equivalents. Whereas no effects on mass loss were observed for CPC and CPC/BG pre-set scaffolds, CPC/PLGA/BG pre-set scaffolds showed an accelerated mass loss compared with CPC/PLGA equivalents. Morphologically, no changes were observed for CPC and CPC/BG pre-set scaffolds. In contrast, CPC/PLGA and CPC/PLGA/BG showed apparent degradation of PLGA microspheres and faster loss of integrity for CPC/PLGA/BG pre-set scaffolds compared with CPC/PLGA equivalents. Based on the present in vitro results, it can be concluded that BG can be successfully introduced into CPC and CPC/PLGA without exceeding the setting time beyond clinically acceptable values. All injectable composites containing BG had suitable handling properties and specifically CPC/PLGA/BG showed an increased rate of mass loss. Future investigations should focus on translating these findings to in vivo applications. PMID:23364896

  20. Evaluation of human polymorphonuclear behavior on textured titanium and calcium-phosphate coated surfaces.

    PubMed

    Moura, Camilla C G; Machado, Juliana R; Silva, Marcos V; Rodrigues, Denise B R; Zanetta-Barbosa, Darceny; Jimbo, Ryo; Tovar, Nick; Coelho, Paulo G

    2013-06-01

    Few studies have evaluated the effects of titanium (Ti) surface modifications on polymorphonuclear neutrophils (PMNs). Human PMNs' viability and release of key mediators-such as IL1?, IL6, TNF?, IL12, IL10, IL4, TGF?1, IL8, IP-10, and Mig-were evaluated on three different Ti surface treatments: (1) machined Ti; (2) alumina-blasted and acid-etched Ti (AB/AE); and (3) calcium phosphate coating of 300-500 nm by ion beam onto the AB/AE Ti surface (CaP). A polystyrene surface was used as a negative control. The PMNs were purified from whole human blood and cultured for 6 h. Cell viability was determined by flow cytometry, and the supernatant was evaluated to determine the levels of cytokines and chemokines. Results showed that the percentage of viable cells was significantly lower on the CaP surface compared to the control (p < 0.05) relative to the other groups. No differences in the levels of IL8, MIG, and IP10 were detected between groups. Significantly higher levels of IL1? (p = 0.046) and TNF? (p = 0.016) were detected for the CaP surfaces compared to AB/AE surface only. The levels of IL4, IL10, and TGF?1 secreted from the PMNs in the CaP group were significantly lower than in the control and machined groups (p < 0.05) that were statistically comparable to AB/AE. Overall, the addition of a thin CaP coating to the AB/AE Ti surface influenced the secretion profile of pro-inflammatory cytokines due to the higher release of pro-inflammatory cytokines (IL1? and TNF?) on these surfaces. PMID:23598427

  1. Preparation of Calcium Phosphate Cement and Polymethyl Methacrylate for Biological Composite Bone Cements

    PubMed Central

    Yang, Jun; Zhang, Kairui; Zhang, Sheng; Fan, Jiping; Guo, Xinhui; Dong, Weiqiang; Wang, Shengnan; Chen, Yirong; Yu, Bin

    2015-01-01

    Background We studied the biological safety, biomechanics, and tissue compatibility of calcium phosphate cement and Polymethyl Methacrylate composite bone cement mixed in different ratios. Material/Methods CPC and PMMA were mixed in different ratios (3: 1, 2: 1, 1: 1, 1: 2, 1: 5, 1: 10, 1: 15, and 1: 20). PMMA solvent is a general solvent containing a dissolved preparation of the composite bone cement specific to a given specimen to determine biological safety, biomechanics, and tissue compatibility. Results The CPC/PMMA (33%) group, CPC/PMMA (50%) group, CPC/PMMA (67%) group, and CPC/PMMA (75%) group were more in line with the composite bone cement without cytotoxicity requirements. The compressive strength of the CPC/PMMA (67%) group and CPC/PMMA (75%) group was 20Mpa–30Mpa, while that of the CPC/PMMA (4.8%) group, CPC/PMMA (6.25%) group, CPC/PMMA (9.1%) group, CPC/PMMA (16.7%) group, CPC/PMMA (33%) group, and CPC/PMMA (50%) group was 40Mpa–70Mpa. Curing time was longer in the CPC group (more than 11 min) and shorter in the PMMA group (less than 2 min). The results of weight loss rate showed that there were no significant differences between the CPC/PMMA group (4.8%, 6.25%, 9.1%, 16.7%, 33%) and PMMA control group (p>0.05). With the decrease of CPC content, the rate of weight loss gradually decreased. Conclusions The CPC/PMMA (50%) group, CPC/PMMA (67%) group, and CPC/PMMA (75%) group provide greater variability and selectivity for the composite bone cement in obtaining better application. PMID:25904398

  2. Inhibition of calcium phosphate precipitation by human salivary statherin: structure-activity relationships.

    PubMed

    Schwartz, S S; Hay, D I; Schluckebier, S K

    1992-06-01

    Previous studies of human statherin showed the active region for inhibition of secondary calcium phosphate precipitation (crystal growth) to reside in the highly charged amino-terminal one-third of this molecule, and the neutral tyrosine-, glutamine- and proline-rich carboxy-terminal two-thirds of the molecule is required for maximal inhibition of primary (spontaneous) precipitation. The purpose of the present study was to define more clearly the activities of these different molecular segments of statherin with respect to the two kinds of inhibitory activities. Peptides from statherin were prepared by specific proteolysis using trypsin, endoproteinase Arg-C, and activated factor X to produce the amino-terminal hexa-, nona- and decapeptides, respectively, and carboxypeptidase-A was used to obtain a peptide extending from residue 1 to about residues 32-37. The peptides were purified by anion exchange and gel filtration chromatography, and characterized and quantified by amino-acid analysis. Serially diluted samples of statherin and derived peptides were assayed to determine the concentrations, giving a standard 50% inhibition of precipitation (C50%) in assay systems designed for this purpose using polyaspartate as a standard. Results are expressed as (C50% statherin)/(C50% peptide). For inhibition of primary precipitation, these values were peptide(1-6), 0.20; peptide(1-9), 0.15; peptide(1-31/35), 0.24. For inhibition of secondary precipitation, the values were peptide(1-6), 3.8; peptide(1-9), 2.8; peptide(1-10), 1.9; peptide(1-32/37), 1.5. These quantitative findings show that maximum inhibition of primary precipitation by statherin requires the entire molecule. Thus, removal of a relatively small segment of its carboxy-terminal region results in a substantial reduction in inhibitory activity.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1525706

  3. Adaptive responses of calcium and phosphate homeostasis in goats to low nitrogen intake: renal aspects.

    PubMed

    Starke, S; Huber, K

    2014-10-01

    In a previous study, in goats, we showed that apart from variations in dietary calcium (Ca) and phosphorus intake, also low dietary nitrogen (N) intake altered plasma concentrations of hormones, which regulate Ca and phosphate (Pi ) homeostasis. These hormonal responses in goats were in accordance with findings in monogastric animals and humans with low protein intake. In the aforementioned studies, alterations of electrolyte transport in the kidneys were also observed. However, whether renal electrolyte transport in goats is also involved in the adaptation of Ca and Pi homeostasis to low N intake remains unknown. Thus, the aim of the present study was to investigate whether in addition to the hormonal changes, as observed in our former study, renal Ca transport and renal Pi transport were also altered by low N intake in goats. Therefore, in kidney samples from the goats used in our former study, the protein expression of Ca and Pi transporters and of related regulatory proteins was examined. Furthermore, the uptake of Pi into isolated brush border membrane vesicles (BBMV) was detected. The results showed that the protein amount of the renal sodium-dependent Pi transporter NaPi IIa was elevated, and concomitantly, protein expression of its upstream regulators, the parathyroid hormone receptor and the extracellular signal-regulated kinases 1 and 2 was decreased. However, Pi uptake into renal BBMV was not enhanced. Furthermore, protein expression of the renal Ca channel, the transient receptor potential cation channel subfamily V member 5 (TRPV5) and of the vitamin D receptor was not influenced by dietary N reduction. We conclude that regulation of renal Pi transporter expression in goats is involved in the adaptation of electrolyte homeostasis to low N intake. PMID:24283774

  4. Prevascularization of biofunctional calcium phosphate cement for dental and craniofacial repairs

    PubMed Central

    Chen, Wenchuan; Thein-Han, WahWah; Weir, Michael D.; Chen, Qianming; Xu, Hockin H.K.

    2014-01-01

    Objectives Calcium phosphate cement (CPC) is promising for dental and craniofacial repairs. Vascularization in bone tissue engineering constructs is currently a major challenge. The objectives of this study were to investigate the prevascularization of macroporous CPC via coculturing human umbilical vein endothelial cells (HUVEC) and human osteoblasts (HOB), and determine the effect of RGD in CPC on microcapillary formation for the first time. Methods Macroporous CPC scaffold was prepared using CPC powder, chitosan liquid and gas-foaming porogen. Chitosan was grafted with Arg-Gly-Asp (RGD) to biofunctionalize the CPC. HUVEC and HOB were cocultured on macroporous CPC-RGD and CPC control without RGD for up to 42 d. The osteogenic and angiogenic differentiation, bone matrix mineral synthesis, and formation of microcapillary-like structures were measured. Results RGD-grafting in CPC increased the genes expressions of osteogenic and angiogenic differentiation markers than those of CPC control without RGD. Cell-synthesized bone mineral content also increased on CPC-RGD, compared to CPC control (p < 0.05). Immunostaining with endothelial marker showed that the amount of microcapillary-like structures on CPC scaffolds increased with time. At 42 d, the cumulative vessel length for CPC-RGD scaffold was 1.69-fold that of CPC control. SEM examination confirmed the morphology of self-assembled microcapillary-like structures on CPC scaffolds. Significance HUVEC+HOB coculture on macroporous CPC scaffold successfully achieved prevascularization. RGD incorporation in CPC enhanced osteogenic differentiation, bone mineral synthesis, and microcapillary-like structure formation. The novel prevascularized CPC-RGD constructs are promising for dental, craniofacial and orthopedic applications. PMID:24731858

  5. Protective potential of casein phosphopeptide amorphous calcium phosphate containing paste on enamel surfaces

    PubMed Central

    Somasundaram, Padmini; Vimala, N; Mandke, Lalita Gauri

    2013-01-01

    Background: Dental caries remains the most common dental disease facing mankind. Prevention of initiation and interruption in progression of early lesions are the desirable modes of caries management. There is a scope for agents, which may be used to enhance anti - caries activity. This need has redirected research to develop novel preventive agents that can act as an adjunct to fluoride or independent of it. Casein Phosphopeptide – Amorphous Calcium Phosphate (CPP-ACP) is one such agent that has been proposed to have anti cariogenic properties. Aim: The purpose of this in vitro study was to evaluate the effect of paste containing CPP-ACP, MI Paste, on enamel remineralization. Materials and Methods: This study consisted of 30 samples embedded in orthodontic resin with either the buccal or lingual surface exposed. The samples were assigned to either a CPP-ACP containing paste; Fluoridated toothpaste; or a control group. The groups were then subjected to cycling in a demineralizing solution and a remineralizing solution. Groups II and III received prior application of MI paste and Fluoridated toothpaste respectively followed by cycling in a demineralizing solution and a remineralizing solution. Following 14 days of cycling, the samples were sectioned and examined using confocal microscopy. The lesion depth, were evaluated. Statistical Analysis: Image Proplus software was used to analyze the images. The values were statistically evaluated using one – way ANOVA and Scheffe's Test. Results and Conclusion: Within the limitations of the study it was concluded that enamel surfaces treated with the CPP-ACP paste exhibited the least lesion depths followed by the enamel surfaces treated with the fluoridated tooth paste and control group respectively. PMID:23716969

  6. Differential loading methods for BMP-2 within injectable calcium phosphate cement.

    PubMed

    van de Watering, Floor C J; Molkenboer-Kuenen, Janneke D M; Boerman, Otto C; van den Beucken, Jeroen J J P; Jansen, John A

    2012-12-28

    Clinical application of calcium phosphate cement (CPC; with incorporated polymeric porogens) in an injectable form implicates that loading methods for growth factors are limited. In view of this, the current study evaluated the in vitro and in vivo release kinetics of bone morphogenetic protein-2 (BMP-2) loaded on poly(d,l-lactic-co-glycolic acid) (PLGA) microparticles (CPC/PLGA), BMP-2 incorporation into the liquid phase of CPC (CPC/liquid), and BMP-2 absorbed to the surface of preset, porous CPC (CPC/surface) as a control via an in vitro release experiment and in vivo using microSPECT imaging with (125)I-labeled BMP-2. In addition, the osteoinductive capacity of scaffolds generated via the different BMP-2 loading methods was assessed in a subcutaneous rat model. Additional controls consisted of porous CPC scaffolds (CPC/porous) and CPC/PLGA (CPC/control) without BMP-2 loading. The results revealed that it is feasible to load BMP-2 into CPC via adsorption to PLGA-microparticles or the liquid phase of CPC, which resulted in a similar release profile over the course of 28 days, despite distinct protein distribution patterns. Compared to CPC-scaffolds with surface-loaded BMP-2, these loading methods showed a similar release profile, except for a significantly decreased burst release. As such, the observed osteoinductive capacity for only CPC-scaffolds with surface-loaded BMP-2 is likely to be related to this difference in burst release. It remains unclear to what extent the differential BMP-2 loading methods for injectable CPC can affect the biological response in a bone environment. PMID:22800584

  7. Gas-Foaming Calcium Phosphate Cement Scaffold Encapsulating Human Umbilical Cord Stem Cells

    PubMed Central

    Chen, Wenchuan; Zhou, Hongzhi; Tang, Minghui; Weir, Michael D.; Bao, Chongyun

    2012-01-01

    Tissue engineering approaches are promising to meet the increasing need for bone regeneration. Calcium phosphate cement (CPC) can be injected and self-set to form a scaffold with excellent osteoconductivity. The objectives of this study were to develop a macroporous CPC–chitosan–fiber construct containing alginate–fibrin microbeads encapsulating human umbilical cord mesenchymal stem cells (hUCMSCs) and to investigate hUCMSC release from the degrading microbeads and proliferation inside the porous CPC construct. The hUCMSC-encapsulated microbeads were completely wrapped inside the CPC paste, with the gas-foaming porogen creating macropores in CPC to provide for access to culture media. Increasing the porogen content in CPC significantly increased the cell viability, from 49% of live cells in CPC with 0% porogen to 86% of live cells in CPC with 15% porogen. The alginate–fibrin microbeads started to degrade and release the cells inside CPC at 7 days. The released cells started to proliferate inside the macroporous CPC construct. The live cell number inside CPC increased from 270 cells/mm2 at 1 day to 350 cells/mm2 at 21 days. The pore volume fraction of CPC increased from 46.8% to 78.4% using the gas-foaming method, with macropore sizes of approximately 100 to 400??m. The strength of the CPC–chitosan–fiber scaffold at 15% porogen was 3.8?MPa, which approximated the reported 3.5?MPa for cancellous bone. In conclusion, a novel gas-foaming macroporous CPC construct containing degradable alginate–fibrin microbeads was developed that encapsulated hUCMSCs. The cells had good viability while wrapped inside the porous CPC construct. The degradable microbeads in CPC quickly released the cells, which proliferated over time inside the porous CPC. Self-setting, strong CPC with alginate–fibrin microbeads for stem cell delivery is promising for bone tissue engineering applications. PMID:22011243

  8. Self-setting collagen-calcium phosphate bone cement: Mechanical and cellular properties

    PubMed Central

    Moreau, Jennifer L.; Weir, Michael D.; Xu, Hockin H.K.

    2008-01-01

    Calcium phosphate cement (CPC) can conform to complex bone cavities and set in-situ to form bioresorbable hydroxyapatite. The aim of this study was to develop a CPC-collagen composite with improved fracture resistance, and to investigate the effects of collagen on mechanical and cellular properties. A type-I bovine-collagen was incorporated into CPC. MC3T3-E1 osteoblasts were cultured. At CPC powder/liquid mass ratio of 3, the work-of-fracture (mean±sd; n=6) was increased from (22±4) J/m2 at 0% collagen, to (381±119) J/m2 at 5% collagen (p?0.05). At 2.5–5% of collagen, the flexural strength at powder/liquid ratios of 3 and 3.5 was 8–10 MPa. They matched the previously-reported 2–11 MPa of sintered porous hydroxyapatite implants. SEM revealed that the collagen fibers were covered with nano-apatite crystals and bonded to the CPC matrix. Higher collagen content increased the osteoblast cell attachment (p?0.05). The number of live cells per specimen area was (382±99) cells/mm2 on CPC containing 5% collagen, higher than (173±42) cells/mm2 at 0% collagen (p?0.05). The cytoplasmic extensions of the cells anchored to the nano-apatite crystals of the CPC matrix. In summary, collagen was incorporated into in situ-setting, nano-apatitic CPC, achieving a 10-fold increase in work-of-fracture (toughness) and 2-fold increase in osteoblast cell attachment. This moldable/injectable, mechanically-strong, nano-apatite-collagen composite may enhance bone regeneration in moderate stress-bearing applications. PMID:18985758

  9. Strong, macroporous, and in situ-setting calcium phosphate cement-layered structures

    PubMed Central

    Xu, Hockin H.K.; Burguera, Elena F.; Carey, Lisa E.

    2009-01-01

    Calcium phosphate cement (CPC) is highly promising for clinical uses due to its in situ-setting ability, excellent osteoconductivity and bone-replacement capability. However, the low strength limits its use to non-load-bearing applications. The objectives of this study were to develop a layered CPC structure by combining a macroporous CPC layer with a strong CPC layer, and to investigate the effects of porosity and layer thickness ratios. The rationale was for the macroporous layer to accept tissue ingrowth, while the fiber-reinforced strong layer would provide the needed early-strength. A biopolymer chitosan was incorporated to strengthen both layers. Flexural strength, S (mean±sd; n = 6) of CPC-scaffold decreased from (9.7±1.2) to (1.8±0.3) MPa (p<0.05), when the porosity increased from 44.6% to 66.2%. However, with a strong-layer reinforcement, S increased to (25.2±6.7) and (10.0±1.4) MPa, respectively, at these two porosities. These strengths matched/exceeded the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. Relationships were established between S and the ratio of strong layer thickness/specimen thickness, a/h:S = (17.6 a/h+3.2) MPa. The scaffold contained macropores with a macropore length (mean±sd; n = 147) of (183±73) ?m, suitable for cell infiltration and tissue ingrowth. Nano-sized hydroxyapatite crystals were observed to form the scaffold matrix of CPC with chitosan. In summary, a layered CPC implant, combining a macroporous CPC with a strong CPC, was developed. Mechanical strength and macroporosity are conflicting requirements. However, the novel functionally graded CPC enabled a relatively high strength and macroporosity to be simultaneously achieved. Such an in situ-hardening nano-apatite may be useful in moderate stress-bearing applications, with macroporosity to enhance tissue ingrowth and implant resorption. PMID:17574665

  10. Low temperature fabrication of high strength porous calcium phosphate and the evaluation of the osteoconductivity.

    PubMed

    Yu, Xianzhu; Cai, Shu; Xu, Guohua; Zhou, Wei; Wang, Dongmei

    2009-10-01

    Porous NaO(2)-MgO-CaO-P(2)O(5) bioglass doped beta-tri-calcium phosphate (beta-TCP) bioceramic possessing high mechanical properties and well pore structure with high porosity and high pore connectivity has been prepared through dipping method with the porous polyurethane as the pore forming template. The sintering mechanism and the mechanical properties of the bioglass doped beta-TCP scaffold have been investigated by the X-ray diffraction (XRD) analysis, Scanning electron microscope (SEM) and thermal differential analysis (DTA). The scaffold's in vivo osteoconductivity has been evaluated by implantation of scaffolds into the femurs of New Zealand rabbits. The results show that the porous structure can achieve the densification process at a low temperature about 950 degrees C by a solid solution sintering mechanism and hence dense macropore scaffold with a compressive strength of 4.32 MPa when the porosity is 75% has been obtained. The in vivo test shows that the Na(2)O-MgO-CaO-P(2)O(5) bioglass doped porous beta-TCP bioceramic has a relatively fast bone formation after implantation; after 1 month implantation new deposited bone tissue has been detected on the strut of the porous scaffold and degraded particles also has been found on the surface of the new formed bone. After 6 months implantation the porous scaffold has been thoroughly covered with new formed bone. Results show that the Na(2)O-MgO-CaO-P(2)O(5) bioglass doped porous beta-TCP bioceramic is potential bone tissue engineering scaffold for orthopedic use. PMID:19424778

  11. Ready-to-use injectable calcium phosphate bone cement paste as drug carrier.

    PubMed

    Vorndran, E; Geffers, M; Ewald, A; Lemm, M; Nies, B; Gbureck, U

    2013-12-01

    Current developments in calcium phosphate cement (CPC) technology concern the use of ready-to-use injectable cement pastes by dispersing the cement powder in a water-miscible solvent, such that, after injection into the physiological environment, setting of cements occurs by diffusion of water into the cement paste. It has also been demonstrated recently that the combination of a water-immiscible carrier liquid combined with suitable surfactants facilitates a discontinuous liquid exchange in CPC, enabling the cement setting reaction to take place. This paper reports on the use of these novel cement paste formulations as a controlled release system of antibiotics (gentamicin, vancomycin). Cement pastes were applied either as a one-component material, in which the solid drugs were physically dispersed, or as a two-component system, where the drugs were dissolved in an aqueous phase that was homogeneously mixed with the cement paste using a static mixing device during injection. Drug release profiles of both antibiotics from pre-mixed one- and two-component cements were characterized by an initial burst release of ?7-28%, followed by a typical square root of time release kinetic for vancomycin. Gentamicin release rates also decreased during the first days of the release study, but after ?1 week, the release rates were more or less constant over a period of several weeks. This anomalous release kinetic was attributed to participation of the sulfate counter ion in the cement setting reaction altering the drug solubility. The drug-loaded cement pastes showed high antimicrobial potency against Staphylococcus aureus in an agar diffusion test regime, while other cement properties such as mechanical performance or phase composition after setting were only marginally affected. PMID:23954526

  12. [Comparative study of bioactive calcium phosphate ceramics after implantation in spongy bone in dogs. Histologic, ultrastructural and electron probe microanalysis].

    PubMed

    Daculsi, G; Passuti, N; Martin, S; Le Nihouannen, J C; Brulliard, V; Delecrin, J; Kerebel, B

    1989-01-01

    An experimental model of posterior spine arthrodesis in dogs was created using 3 types of calcium phosphate biomaterials already known for their applications as bone substitutes, namely: hydroxyapatite (HA), which is not readily resorbable; highly resorbable tricalcium phosphate (TCP); and a mixture of HA and TCP (BCP), the resorbability of which depends on the proportion of HA and TCP. The BCP implants had a macroporous structure, whilst the HA and TCP implants were used in dense form. The creation of macropores increases the surface exchange area, thus enabling the osseous colonization processes. By carefully removing the posterior articular facets it was possible to remove the articular surfaces and to fit into each appropriate location a block a few millimeters in diameter. The anatomopathological assessment was performed using histological methods, transmission electron microscopy, and energy dispersion microprobe analysis. Our results indicate that calcium phosphate ceramics may be used as bone substitutes for carrying out arthrodeses, provided (1) immediate immobilization using a spine containment technique is effected; (2) their chemical composition is sufficiently stable over time; (3) they are sufficiently bioactive so as to allow their colonization and replacement by bone. PMID:2740538

  13. Calcium

    MedlinePLUS

    ... of calcium dietary supplements are carbonate and citrate. Calcium carbonate is inexpensive, but is absorbed best when taken ... antacid products, such as Tums® and Rolaids®, contain calcium carbonate. Each pill or chew provides 200–400 mg ...

  14. Similar healthy osteoclast and osteoblast activity on nanocrystalline hydroxyapatite and nanoparticles of tri-calcium phosphate compared to natural bone

    PubMed Central

    MacMillan, Adam K; Lamberti, Francis V; Moulton, Julia N; Geilich, Benjamin M; Webster, Thomas J

    2014-01-01

    While there have been numerous studies to determine osteoblast (bone forming cell) functions on nanocrystalline compared to micron crystalline ceramics, there have been few studies which have examined osteoclast activity (including tartrate-resistant acid phosphatase, formation of resorption pits, size of resorption pits, and receptor activator of nuclear factor ?B [RANK]). This is despite the fact that osteoclasts are an important part of maintaining healthy bone since they resorb bone during the bone remodeling process. Moreover, while it is now well documented that bone formation is enhanced on nanoceramics compared to micron ceramics, some have pondered whether osteoblast functions (such as osteoprotegerin and RANK ligand [RANKL]) are normal (ie, non-diseased) on such materials compared to natural bone. For these reasons, the objective of the present in vitro study was to determine various functions of osteoclasts and osteoblasts on nanocrystalline and micron crystalline hydroxyapatite as well as tri-calcium phosphate materials and compare such results to cortical and cancellous bone. Results showed for the first time similar osteoclast activity (including tartrate-resistant acid phosphatase, formation of resorption pits, size of resorption pits, and RANK) and osteoblast activity (osteoprotegerin and RANKL) on nanocrystalline hydroxyapatite compared to natural bone, whereas osteoclast and osteoblast functions on micron crystalline versions of these ceramics were much different than natural bone. In this manner, this study provides additional evidence that nanocrystalline calcium phosphates can serve as suitable synthetic analogs to natural bone to improve numerous orthopedic applications. It also provides the first data of healthy osteoclast and osteoblast functions on nanocrystalline calcium phosphates compared to natural bone. PMID:25506216

  15. Calcium phosphate cement reinforcement by polymer infiltration and in situ curing: a method for 3D scaffold reinforcement.

    PubMed

    Alge, Daniel L; Chu, Tien-Min Gabriel

    2010-08-01

    This study describes a novel method of calcium phosphate cement reinforcement based on infiltrating a pre-set cement with a reactive polymer and then cross-linking the polymer in situ. This method can be used to reinforce 3D calcium phosphate cement scaffolds, which we demonstrate using poly(ethylene glycol) diacrylate (PEGDA) as a model reinforcing polymer. The compressive strength of a 3D scaffold comprised of orthogonally intersecting beams was increased from 0.31 +/- 0.06 MPa to 1.65 +/- 0.13 MPa using PEGDA 600. In addition, the mechanical properties of reinforced cement were characterized using three PEGDA molecular weights (200, 400, and 600 Da) and three cement powder to liquid (P/L) ratios (0.8, 1.0, and 1.43). Higher molecular weight increased reinforcement efficacy, and P/L controlled cement porosity and determined the extent of polymer incorporation. Although increasing polymer incorporation resulted in a transition from brittle, cement-like behavior to ductile, polymer-like behavior, maximizing polymer incorporation was not advantageous. Polymerization shrinkage produced microcracks in the cement, which reduced the mechanical properties. The most effective reinforcement was achieved with P/L of 1.43 and PEGDA 600. In this group, flexural strength increased from 0.44 +/- 0.12 MPa to 7.04 +/- 0.51 MPa, maximum displacement from 0.05 +/- 0.01 mm to 1.44 +/- 0.17 mm, and work of fracture from 0.64 +/- 0.10 J/m(2) to 677.96 +/- 70.88 J/m(2) compared to non-reinforced controls. These results demonstrate the effectiveness of our novel reinforcement method, as well as its potential for fabricating reinforced 3D calcium phosphate cement scaffolds useful for bone tissue engineering. PMID:20186776

  16. Porous-coated uncemented components in experimental total hip arthroplasty in dogs. Effect of plasma-sprayed calcium phosphate coatings on bone ingrowth.

    PubMed

    Jasty, M; Rubash, H E; Paiement, G D; Bragdon, C R; Parr, J; Harris, W H

    1992-07-01

    The effect of a thin plasma-sprayed, calcium phosphate ceramic coating on bone ingrowth into titanium fiber mesh porous-surfaced prostheses was examined in a controlled canine cementless total hip arthroplasty model. Bone ingrowth was quantified using backscattered scanning electron microscopy of undemineralized sections. When good contact between the bone and porous coating was present, the calcium phosphate-coated prostheses contained significantly higher amounts of bone ingrowth at three weeks postimplantation than the uncoated control prostheses. At six weeks, however, there was no significant difference in the amount of bone ingrowth between the coated prostheses and uncoated prostheses. The ingrown bone seemed to be more intimately associated with the calcium phosphate-coated porous surfaces than the uncoated porous surfaces. When gaps at the bone-porous coating interface occurred, the calcium phosphate coating did not enhance bone ingrowth across those gaps. Plasma-sprayed calcium phosphate coatings may be useful in enhancing the early ingrowth of bone into porous-surfaced joint replacement prostheses, but they may lack long-term effectiveness. The coatings were not effective in enhancing bone ingrowth across gaps between the porous surface and the bone bed prepared at surgery. PMID:1611761

  17. Effect of calcium phosphate coating and rhBMP-2 on bone regeneration in rabbit calvaria using poly(propylene fumarate) scaffolds.

    PubMed

    Dadsetan, Mahrokh; Guda, Teja; Runge, M Brett; Mijares, Dindo; LeGeros, Racquel Z; LeGeros, John P; Silliman, David T; Lu, Lichun; Wenke, Joseph C; Brown Baer, Pamela R; Yaszemski, Michael J

    2015-05-01

    Various calcium phosphate based coatings have been evaluated for better bony integration of metallic implants and are currently being investigated to improve the surface bioactivity of polymeric scaffolds. The aim of this study was to evaluate the role of calcium phosphate coating and simultaneous delivery of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the in vivo bone regeneration capacity of biodegradable, porous poly(propylene fumarate) (PPF) scaffolds. PPF scaffolds were coated with three different calcium phosphate formulations: magnesium-substituted ?-tricalcium phosphate (?-TCMP), carbonated hydroxyapatite (synthetic bone mineral, SBM) and biphasic calcium phosphate (BCP). In vivo bone regeneration was evaluated by implantation of scaffolds in a critical-sized rabbit calvarial defect loaded with different doses of rhBMP-2. Our data demonstrated that scaffolds with each of the calcium phosphate coatings were capable of sustaining rhBMP-2 release and retained an open porous structure. After 6weeks of implantation, micro-computed tomography revealed that the rhBMP-2 dose had a significant effect on bone formation within the scaffolds and that the SBM-coated scaffolds regenerated significantly greater bone than BCP-coated scaffolds. Mechanical testing of the defects also indicated restoration of strength in the SBM and ?-TCMP with rhBMP-2 delivery. Histology results demonstrated bone growth immediately adjacent to the scaffold surface, indicating good osteointegration and osteoconductivity for coated scaffolds. The results obtained in this study suggest that the coated scaffold platform demonstrated a synergistic effect between calcium phosphate coatings and rhBMP-2 delivery and may provide a promising platform for the functional restoration of large bone defects. PMID:25575855

  18. VS-501: A NOVEL, NON-ABSORBED, CALCIUM- AND ALUMINUM-FREE, HIGHLY EFFECTIVE PHOSPHATE BINDER DERIVED FROM NATURAL PLANT POLYMER.

    PubMed

    Wu-Wong, J Ruth; Chen, Yung-Wu; Gaffin, Robert; Hall, Andy; Wong, Jonathan T; Xiong, Joseph; Wessale, Jerry L

    2014-06-01

    Inadequate control of serum phosphate in chronic kidney disease can lead to pathologies of clinical importance. Effectiveness of on-market phosphate binders is limited by safety concerns and low compliance due to high pill size/burden and gastrointestinal discomfort. VS-501 is a non-absorbed, calcium- and aluminum-free, chemically-modified, plant-derived polymer. In vitro studies show that VS-501 has a high density and a low swell volume when exposed to simulated gastric fluid (vs. sevelamer). When male Sprague Dawley (SD) rats on normal diet were treated with VS-501 or sevelamer, serum phosphate was not significantly altered, but urinary phosphate levels decreased by >90%. VS-501 had no effect on serum calcium (Ca) or urinary Ca, while 3% sevelamer significantly increased serum and urine Ca. In 5/6 nephrectomized (NX) uremic SD rats on high-phosphate diet, increasing dietary phosphate led to an increase in serum and urine phosphate, which was prevented in rats treated with VS-501 or sevelamer (0.2-5% in food). High phosphate diet also increased serum FGF-23 and parathyroid hormone in 5/6 NX rats, which was prevented by VS-501 or sevelamer. VS-501 or sevelamer increased fecal phosphate in a dose-dependent manner. More aortic calcification was observed in 5/6 NX rats treated with 5% sevelamer, while VS-501 and sevelamer did not show significant effects on cardiac parameters, fibrosis, intestine histology and intestinal sodium-dependent phosphate cotransporter gene expression. These results suggest that VS-501 is effective in binding phosphate with no effects on calcium homeostasis, and may have improved pill burden and gastrointestinal side effects. PMID:25197556

  19. The crystallinity of calcium phosphate powders influenced by the conditions of neutralized procedure with citric acid additions

    SciTech Connect

    Li Chengfeng [School of Materials Science and Engineering, Shandong University of Technology, No. 12 Zhangzhou Road, 255049 Zibo, Shandong (China)], E-mail: cfli@sdut.edu.cn

    2009-05-06

    Calcium phosphate powders with nano-sized crystallinity were synthesized by neutralization using calcium hydroxide and orthophosphoric acid with the assistance of citric acid. The influence of processing parameters, such as free or additive citric acid, synthetic temperature and ripening time, on the crystallinity of hydroxyapatite were investigated. The results of X-ray diffraction and microstructure observations showed that the crystallinity and morphology of nano-sized hydroxyapatite particles were influenced by the presence or absence of citric acid. It was found that the crystallinities and crystallite sizes of hydroxyapatite powders prepared with the additive citric acid increased with increasing synthetic temperature and ripening time. Especially, the crystallinities of (h k 0) planes were raised and more homogeneously grown particles were obtained with increasing synthetic temperature.

  20. Effect of calcium, phosphate and nitrogen on cell growth and biosynthesis of cell wall polysaccharides by Silene vulgaris cell culture.

    PubMed

    Günter, Elena A; Ovodov, Yury S

    2005-06-29

    Medium nutrients such as calcium, phosphorus, nitrogen and nitrate to ammonium ratio have significant influence on the growth, biosynthetic and biochemical characteristics of polysaccharides produced by Silene vulgaris (M.) G. cell culture. Cell growth and production of polysaccharides was limited by an absence of any of these components in the medium. Optimal growth of the callus and production of arabinogalactan were achieved at 1.5-4.5 microM calcium while the optimal production of pectin named silenan was observed at 3.0-4.5 microM. The phosphate contents in the medium in the range of 0.63-3.75 microM were favorable for callus growth. Production of silenan was maximal at 1.25-3.75 microM phosphate. Optimal growth of the callus was achieved at 30-90 microM nitrogen. Maximal production of silenan was observed at 60 microM nitrogen while the optimal production of arabinogalactan was at 90 microM nitrogen (at ratio of NH(4)(+):NO(3)(-) as 1:2). A presence both of nitrate and ammonium is needed for the silenan biosynthesis (the NH(4)(+):NO(3)(-) ratio as 1:1 and 1:2). Yields and volumetric production of arabinogalactan were maximal at deletion of ammonium from the nutrient medium (ratio 0:1). Absence of calcium or nitrogen in the medium leads to a decrease of the galacturonic acid residues in silenan. The galactose residues contents in arabinogalactan were decreased in the absence of nitrogen and calcium in the medium. PMID:15878212

  1. Calcium and inorganic phosphate transport in embryonic chick intestine: triiodothyronine enhances the genomic action of 1,25-dihydroxycholecalciferol.

    PubMed

    Cross, H S; Peterlik, M

    1988-12-01

    The influence of triiodothyronine (T3) on the induction of intestinal calcium and inorganic phosphate (Pi) transport by 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) was studied in 48 h cultures of embryonic chick jejunum. While T3 alone had no effect on calcium uptake by gut segments cultured on d 20 of embryonic development, the thyroid hormone amplified the effect of 1,25-(OH)2D3 on calcium transport and effectively shifted the dose-response curve to lower 1,25-(OH)2D3 concentrations. T3 had a dual effect on Pi uptake by cultured jejunum: It induced transport activity even in the absence of the steroid hormone, and, in addition, synergistically raised 1,25-(OH)2D3-related Pi uptake. In d 17 embryonic small intestine, which does not respond to 1,25-(OH)2D3 by a significant increase in Pi transport, T3 permitted the induction of Pi transport by the sterol. In general, the thyroid hormone enhanced the responsiveness of cultured embryonic intestine toward 1,25-(OH)2D3 by two orders of magnitude, resulting in facilitated induction of calcium and Pi transport by the sterol and, in particular, modulated the stage-specific expression of 1,25-(OH)2D3 action on intestinal Pi transport. PMID:3210081

  2. Culture Human Mesenchymal Stem Cells With Calcium Phosphate Cement Scaffolds for Bone Repair

    PubMed Central

    Weir, Michael D.; Xu, Hockin H. K.

    2010-01-01

    Because of its moldability and excellent osteoconductivity, calcium phosphate cement (CPC) is highly promising for craniofacial and orthopedic applications. The objectives of this study were to investigate the response of human mesenchymal stem cells (hMSCs) to a high-strength CPC-chitosan scaffold and to examine cell proliferation and osteogenic differentiation. hMSCs were seeded onto CPC-chitosan composite, CPC control, and tissue culture polystyrene (TCPS). Alkaline phosphatase activity (ALP) and mineralization of hMSCs were measured. CPC-chitosan had a flexural strength (mean ± SD; n = 5) of (19.5 ± 1.4) MPa, higher than (8.0 ± 1.4) MPa of CPC control (p < 0.05). The percentage of live hMSCs on CPC-chitosan was (90.5 ± 1.3)% at 8 days, matching (90.7 ± 3.8)% of CPC control (p > 0.1). The CPC-chitosan surface area covered by the attached hMSCs increased from (51 ± 11)% at 1 day to (90 ± 4)% at 8 days (p < 0.05), matching those of CPC control (p > 0.1). Hence, the CPC strength was significantly increased via chitosan without compromising the hMSC response. At 8 days, there was a significant increase in ALP of cells in osteogenic media (10.99 ± 0.93) [(mM pNpp/min)/(?g DNA)] versus control media (3.62 ± 0.40) (p < 0.05). hMSCs in osteogenic media exhibited greater mineralization area of (47.5 ± 19.7)% compared with (6.1 ± 2.3)% in control medium on TCPS (p < 0.05). In conclusion, hMSCs showed excellent attachment and viability on the strong and tough CPC-chitosan scaffold, matching the hMSC response on CPC control. hMSCs were successfully differentiated down the osteogenic lineage. Hence, the strong, in situ hardening CPC-chitosan scaffold may be useful as a moderate load-bearing vehicle to deliver hMSCs for maxillofacial and orthopedic bone tissue engineering. PMID:20091907

  3. Renal tubular sites of altered calcium transport in phosphate-depleted rats.

    PubMed

    Lau, K; Agus, Z S; Goldberg, M; Goldfarb, S

    1979-12-01

    Increased calcium (Ca) excretion is characteristic of chronic phosphate (PO(4)) depletion (PD). To study the changes in tubular transport and the site of the hypocalciuric effect of PO(4) administration, clearance and micropuncture experiments were performed in intact rats pair fed either a control diet (0.5% PO(4)) or a PO(4)-depleted (PD) diet (0.01% PO(4)) plus Al(OH(3)) and in parathyroidectomized (PTX) PD rats, infused either with saline or with neutral sodium PO(4). Intact PD rats, compared with intact rats on a control diet, exhibited a lower plasma ultrafiltrable (UF) PO(4) (5.8+/-0.5 vs. 7.8+/-0.3 mg/dl), higher fractional excretion (FE) of Ca (4.1+/-1.2 vs. 0.6+/-0.1%), and reduced FE PO(4) (0.1+/-0.01 vs. 10.2+/-1.8%). Tubular fluid/plasma inulin was lower in the late proximal tubule of PD rats, associated with increases in fractional delivery (FD) from the proximal tubule of Na and Ca.The%FD of Ca to the early distal tubule of PD rats was increased (20+/-3 vs. 11+/-2%), but this difference was abolished by the late distal tubule (5.1+/-1.2 vs. 3.3+/-0.9%). In PTX-PD rats, PO(4) infusion increased plasma UF PO(4) (13.8+/-0.7 vs. 7.8+/-0.7 mg/dl). FE of Ca was reduced (1.08+/-0.35 vs. 4.59+/-1.57%) without correcting the increased Ca delivery to the late distal tubule. These data indicate that PD impairs Ca reabsorption in tubular segments before but not within the distal convoluted tubule, so that hypercalciuria is ultimately a result of decreased Ca transport either in the terminal nephron or in deeper nephrons where PO(4) infusion stimulates Ca transport independent of parathyroid hormone or changes in the filtered load of Ca. PMID:500833

  4. Mesenchymal stem cell proliferation and differentiation on an injectable calcium phosphate - chitosan composite scaffold

    PubMed Central

    Moreau, Jennifer L.; Xu, Hockin H.K.

    2009-01-01

    Calcium phosphate cement (CPC) can be molded or injected to form a scaffold in situ, has excellent osteoconductivity, and can be resorbed and replaced by new bone. However, its low strength limits CPC to non-stress-bearing repairs. Chitosan could be used to reinforce CPC, but mesenchymal stem cell (MSC) interactions with CPC-chitosan scaffold have not been examined. The objective of this study was to investigate MSC proliferation and osteogenic differentiation on high-strength CPC-chitosan scaffold. MSCs were harvested from rat bone marrow. At CPC powder/liquid (P/L) mass ratio of 2, flexural strength (mean ± sd; n = 5) was (10.0 ± 1.1) MPa for CPC-chitosan, higher than (3.7 ± 0.6) MPa for CPC (p < 0.05). At P/L of 3, strength was (15.7 ± 1.7) MPa for CPC-chitosan, higher than (10.2 ± 1.8) MPa for CPC (p < 0.05). Percentage of live MSCs attaching to scaffolds increased from 85% at 1 day to 99% at 14 days. There were (180 ± 37) cells/mm2 on scaffold at 1 day; cells proliferated to (1808 ± 317) cells/mm2 at 14 days. SEM showed MSCs with healthy spreading and anchored on nano-apatite crystals via cytoplasmic processes. Alkaline phosphatase activity (ALP) was (557 ± 171) (pNPP mM/min)/(?g DNA) for MSCs on CPC-chitosan, higher than (159 ± 47) on CPC (p < 0.05). Both were higher than (35 ± 32) of baseline ALP for undifferentiated MSCs on tissue-culture plastic (p < 0.05). In summary, CPC-chitosan scaffold had higher strength than CPC. MSC proliferation on CPC-chitosan matched that of the FDA-approved CPC control. MSCs on the scaffolds differentiated down the osteogenic lineage and expressed high levels of bone marker ALP. Hence, the stronger CPC-chitosan scaffold may be useful for stem cell-based bone regeneration in moderate load-bearing maxillofacial and orthopedic applications. PMID:19187958

  5. Silica- and Zirconia-Hybridized Amorphous Calcium Phosphate: Effect on Transformation to Hydroxyapatite

    NSDL National Science Digital Library

    Skrtic, D.

    2002-01-01

    The goal of this study was to determine the effect that silica and zirconia have on the stability of bioactive amorphous calcium phosphate (ACP) mineral, i.e., in retarding its transformation to hydroxyapatite (HAP). The glassforming agents, tetraethoxysilane and zirconyl chloride, were introduced individually during the low-temperature preparation of ACP. These hybrid ACPs (Si-ACP and Zr-ACP, respectively) as well as the control, unhybridized ACP (u-ACP), were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, specific surface area measurements, and chemical analysis (Ca/PO4 ratio of the solids) before being dispersed in one of the following four test solutions: N-2-hydroxyethylpiperazine- N8-2-ethanesulfonic acid (HEPES)-buffered (pH = 7.40) saline solutions with 0 mg/g fluoride (test solution A1), 1 mg/g fluoride (test solution A2), and 10 mg/g fluoride (test solution A3), or a lactic acid-containing solution (pH = 5.10, adjusted with NaOH; test solution B). Aliquots were taken at predetermined time intervals for solution Ca and PO4 analysis. Solids isolated after 30 and 90 min exposure to solution B as well as the final dissolution/transformation products from all four solution experiments were analyzed by Fourier transform infrared spectroscopy and X-ray diffraction. Regardless of the type of experimental solution used, slower conversion to HAP was observed with the hybrid ACPs compared with u-ACP. The retarding effect of the Si or Zr species in the hybridized ACPs is probably due to these ions specifically blocking, by adsorption, potential sites for HAP nucleation and growth. The stability of ACP toward HAP conversion increased in the following order: u-ACP < Si-ACP < Zr-ACP. Hybrid ACP fillers, especially Zr-ACP, could be utilized in applications in which it is desired to enhance performance of composites, sealants, and/or adhesives in preventing demineralization or actively promoting remineralization.

  6. Advances in synthesis of calcium phosphate crystals with controlled size and shape.

    PubMed

    Lin, Kaili; Wu, Chengtie; Chang, Jiang

    2014-10-01

    Calcium phosphate (CaP) materials have a wide range of applications, including biomaterials, adsorbents, chemical engineering materials, catalysts and catalyst supports and mechanical reinforcements. The size and shape of CaP crystals and aggregates play critical roles in their applications. The main inorganic building blocks of human bones and teeth are nanocrystalline CaPs; recently, much progress has been made in the application of CaP nanocrystals and their composites for clinical repair of damaged bone and tooth. For example, CaPs with special micro- and nanostructures can better imitate the biomimetic features of human bone and tooth, and this offers significantly enhanced biological performances. Therefore, the design of CaP nano-/microcrystals, and the shape and hierarchical structures of CaPs, have great potential to revolutionize the field of hard tissue engineering, starting from bone/tooth repair and augmentation to controlled drug delivery devices. Previously, a number of reviews have reported the synthesis and properties of CaP materials, especially for hydroxyapatite (HAp). However, most of them mainly focused on the characterizations and physicochemical and biological properties of HAp particles. There are few reviews about the control of particle size and size distribution of CaPs, and in particular the control of nano-/microstructures on bulk CaP ceramic surfaces, which is a big challenge technically and may have great potential in tissue engineering applications. This review summarizes the current state of the art for the synthesis of CaP crystals with controlled sizes from the nano- to the macroscale, and the diverse shapes including the zero-dimensional shapes of particles and spheres, the one-dimensional shapes of rods, fibers, wires and whiskers, the two-dimensional shapes of sheets, disks, plates, belts, ribbons and flakes and the three-dimensional (3-D) shapes of porous, hollow, and biomimetic structures similar to biological bone and tooth. In addition, this review will also summarize studies on the controlled formation of nano-/microstructures on the surface of bulk ceramics, and the preparation of macroscopical bone grafts with 3-D architecture nano-/microstructured surfaces. Moreover, the possible directions of future research and development in this field, such as the detailed mechanisms behind the size and shape control in various strategies, the importance of theoretical simulation, self-assembly, biomineralization and sacrificial precursor strategies in the fabrication of biomimetic bone-like and enamel-like CaP materials are proposed. PMID:24954909

  7. 40 CFR 422.30 - Applicability; description of the phosphate subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...calcium phosphate and human food grade calcium phosphate from...acid. The production of human food grade calcium phosphate creates waste water pollutants not completely...The standards set for human food grade calcium phosphates...

  8. 40 CFR 422.30 - Applicability; description of the phosphate subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...calcium phosphate and human food grade calcium phosphate from...acid. The production of human food grade calcium phosphate creates waste water pollutants not completely...The standards set for human food grade calcium phosphates...

  9. 40 CFR 422.30 - Applicability; description of the phosphate subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...calcium phosphate and human food grade calcium phosphate from...acid. The production of human food grade calcium phosphate creates waste water pollutants not completely...The standards set for human food grade calcium phosphates...

  10. 40 CFR 422.30 - Applicability; description of the phosphate subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...calcium phosphate and human food grade calcium phosphate from...acid. The production of human food grade calcium phosphate creates waste water pollutants not completely...The standards set for human food grade calcium phosphates...

  11. 40 CFR 422.30 - Applicability; description of the phosphate subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...calcium phosphate and human food grade calcium phosphate from...acid. The production of human food grade calcium phosphate creates waste water pollutants not completely...The standards set for human food grade calcium phosphates...

  12. Response of osteoblast-like MC3T3-E1 cells on bioactive titanium fabricated by a chemical treatment process using a calcium-phosphate slurry.

    PubMed

    Ohtsu, Naofumi; Hirano, Mitsuhiro; Arai, Hirofumi

    2014-11-01

    We recently developed a chemical treatment process using a calcium-phosphate slurry for fabricating new layers consisting of hydroxyapatite and titanium dioxide (TiO2) on titanium (Ti) substrate. In this study, the response of osteoblast-like MC3T3-E1 cells on Ti substrate treated with a calcium-phosphate slurry was investigated to elucidate its behavior in a biological environment. The cellular adhesiveness and proliferation capacity did not differ significantly between the treated and untreated Ti substrates, suggesting that the slurry treatment did not cause cytotoxicity. The slurry treatment did not affect the increase in alkaline phosphatase activity after the induction of cell differentiation, whereas it was found to be significantly advantageous for the calcification behavior on the slurry-treated Ti substrate. In consequence, the hard-tissue compatibility of Ti is expected to be improved by the chemical treatment process using a calcium-phosphate slurry. PMID:24307316

  13. Towards high throughput tissue engineering: development of chitosan-calcium phosphate scaffolds for engineering bone tissue from embryonic stem cells

    PubMed Central

    Ko, Junghyuk; Kolehmainen, Kathleen; Ahmed, Farid; Jun, Martin BG; Willerth, Stephanie M

    2012-01-01

    Tissue engineering strategies have shown promise for the repair of damaged organs, including bone. One of the major challenges associated with tissue engineering is how to scale up such processes for high throughput manufacturing of biomaterial scaffolds used to support stem cell culture. Generation of certain types of 3D biomaterial scaffolds, including chitosan-calcium phosphate blends, involves a slow fabrication process followed by a lengthy required freeze drying step. This work investigates the use of automated microwave vacuum drying technology as an alternative to traditional freeze drying as a method of fabricating chitosan-calcium phosphate scaffolds for supporting embryonic stem cell cultures. Scaffolds produced using both drying techniques possess similar properties when characterized using scanning electron microscopy and this paper is the first to report that both types of these scaffolds support undifferentiated embryonic stem cell culture as well as promote stem cell differentiation into osteogenic lineages when treated with the appropriate factors. Compared to existing scaffold manufacturing processes using freeze drying, the use of microwave vacuum drying will lead to faster production times while reducing the costs, enabling high-throughput manufacturing of biomaterial scaffolds for stem cell applications. PMID:23671800

  14. Fabrication of porous scaffolds by three-dimensional plotting of a pasty calcium phosphate bone cement under mild conditions.

    PubMed

    Lode, Anja; Meissner, Katrin; Luo, Yongxiang; Sonntag, Frank; Glorius, Stefan; Nies, Berthold; Vater, Corina; Despang, Florian; Hanke, Thomas; Gelinsky, Michael

    2014-09-01

    The major advantage of hydroxyapatite (HA)-forming calcium phosphate cements (CPCs) used as bone replacement materials is their setting under physiological conditions without the necessity for thermal treatment that allows the incorporation of biological factors. In the present study, we have combined the biocompatible consolidation of CPCs with the potential of rapid prototyping (RP) techniques to generate calcium phosphate-based scaffolds with defined inner and outer morphology. We demonstrate the application of the RP technique three-dimensional (3D) plotting for the fabrication of HA cement scaffolds. This was realized by utilizing a paste-like CPC (P-CPC) which is stable as a malleable paste and whose setting reaction is initiated only after contact with aqueous solutions. The P-CPC showed good processability in the 3D plotting process and allowed the fabrication of stable?3D structures of different geometries with adequate mechanical stability and compressive strength. The cytocompatibility of the plotted P-CPC scaffolds was demonstrated in a cell culture experiment with human mesenchymal stem cells. The mild conditions during 3D plotting and post-processing and the realization of the whole procedure under sterile conditions make this approach highly attractive for fabrication of individualized implants with respect to patient-specific requirements by simultaneous plotting of biological components. PMID:22933381

  15. Bone tissue formation with human mesenchymal stem cells and biphasic calcium phosphate ceramics: the local implication of osteoclasts and macrophages.

    PubMed

    Gamblin, Anne-Laure; Brennan, Meadhbh A; Renaud, Audrey; Yagita, Hideo; Lézot, Frédéric; Heymann, Dominique; Trichet, Valérie; Layrolle, Pierre

    2014-12-01

    Human mesenchymal stem cells (hMSC) have immunomodulative properties and, associated with calcium phosphate (CaP) ceramics, induce bone tissue repair. However, the mechanisms of osteoinduction by hMSC with CaP are not clearly established, in particular the role of osteoclasts and macrophages. Biphasic calcium phosphate (BCP) particles were implanted with or without hMSC in the paratibial muscles of nude mice. hMSC increased osteoblastic gene expression at 1 week, the presence of macrophages at 2 and 4 weeks, osteoclastogenesis at 4 and 8 weeks, and osteogenesis at 4 and 8 weeks. hMSC disappeared from the implantation site after 2 weeks, indicating that hMSC were inducers rather than effectors of bone formation. Induced blockage of osteoclastogenesis by anti-Rankl treatment significantly impaired bone formation, revealing the pivotal role of osteoclasts in bone formation. In summary, hMSC positively influence the body foreign reaction by attracting circulating haematopoietic stem cells and inducing their differentiation into macrophages M1 and osteoclasts, thus favouring bone formation. PMID:25176068

  16. Chemically controlled formation of a DNA/calcium phosphate coprecipitate: application for transfection of mature hippocampal neurons.

    PubMed

    Goetze, Bernhard; Grunewald, Barbara; Baldassa, Simona; Kiebler, Michael

    2004-09-15

    Numerous methods exist for transfecting postmitotic neurons, for example, DNA/calcium phosphate coprecipitation, cationic lipids, viruses, and physical methods such as microinjection, electroporation, and biolistics. Most methods, however, are either toxic to the cell, yield only poor transfection efficiencies, or cells have to be electroporated before plating. In this article, we present a standardized and fast transfection method using DNA/calcium phosphate coprecipitates that efficiently transfer DNA into mature, postmitotic hippocampal neurons. Shifting to CO(2)-independent media with a well-defined pH allows for the tight control of the coprecipitate formation and for adjusting the transfection parameters for the individual DNA plasmid used. The two critical parameters for reproducible and efficient transfections are: the precise pH during crystal formation, and the incubation time of the cells with the coprecipitate. This improved procedure now enables biochemical approaches. By transfecting a dominant-positive Ras mutant, we activate the Erk/MAP kinase signal transduction pathway. Furthermore, using a siRNA plasmid directed against MAP2, the level of an endogenously expressed protein is down-regulated upon transfection. These two approaches demonstrate that the presented transient transfection method can now be used to address questions on a biochemical level in hippocampal neurons. PMID:15307155

  17. Influence of pulse ratio on codeposition of copper species with calcium phosphate coatings on titanium by means of electrochemically assisted deposition.

    PubMed

    Wolf-Brandstetter, Cornelia; Oswald, Steffen; Bierbaum, Susanne; Wiesmann, Hans-Peter; Scharnweber, Dieter

    2014-01-01

    Aim of this study was to combine the well-known biocompatibility and ostoeconductivity of thin calcium phosphate coatings on titanium with proangiogenic signals from codeposited copper species. Copper species could be integrated in mineral layers based on hydroxyapatite by means of electrochemically assisted deposition from electrolytes containing calcium, phosphate, and copper ions. Different combinations of duration and intensity of galvanostatic pulses result in different amounts of deposited calcium phosphate and of copper species even for the same applied total charge. Absolute amounts of copper varied between 2.1 and 6.9 ?g/cm², and the copper was distributed homogeneously as shown by EDX mapping. The presence of copper did not change the crystalline phase of deposited calcium phosphate (hydroxyapatite) but provoked a significant decrease in deposited amounts by factor 3 to 4. The copper was deposited mainly as Cu(I) species with a minor fraction of basic copper phosphates. Reduction of copper occurred not only at the surface of titanium but also within the hydroxyapatite coating due to the reaction with hydrogen produced by the electrolysis of water during the cathodic polarization of the substrate. PMID:23908003

  18. Editorial on the original article entitled “3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration” published in the Biomaterials on February 14, 2014

    PubMed Central

    Li, Lan

    2015-01-01

    The paper entitled “3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration” published in the Biomaterials recently illuminated the way to make particular scaffolds with calcium phosphate (CaP) powder, phosphoric acid, type I collagen and Tween 80 in low temperature. After the optimal concentration of each component was determined, the scaffolds were evaluated in a critically sized murine femoral defect model and exhibited good material properties. We made some related introduction of materials applied in 3D printing for bone tissue engineering based on this article to demonstrate the current progress in this field of study.

  19. Editorial on the original article entitled "3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration" published in the Biomaterials on February 14, 2014.

    PubMed

    Li, Lan; Jiang, Qing

    2015-05-01

    The paper entitled "3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration" published in the Biomaterials recently illuminated the way to make particular scaffolds with calcium phosphate (CaP) powder, phosphoric acid, type I collagen and Tween 80 in low temperature. After the optimal concentration of each component was determined, the scaffolds were evaluated in a critically sized murine femoral defect model and exhibited good material properties. We made some related introduction of materials applied in 3D printing for bone tissue engineering based on this article to demonstrate the current progress in this field of study. PMID:26046065

  20. Scanning electron microscopy and energy-dispersive X-ray microanalysis studies of several human calculi containing calcium phosphate crystals.

    PubMed

    Kodaka, T; Debari, K; Sano, T; Yamada, M

    1994-01-01

    Human calcium phosphate calculi: two sialoliths, a urolith, a rhinolith, and a tonsillolith were investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The sialoliths and urolith had appositional shells with thick cortices, respectively, around several nuclei composed of calcospherulites and a rubber-film fragment. The rhinolith had a thin cortex with appositional laminations around a glomerulus-like mass of calcified cotton-like strings. The tonsillolith had a rough cortex with appositional laminations. Its porous interior was composed of numerous calcified conglomerates with microorganisms and calcified masses with fine appositional laminations around the conglomerates. The major crystals were identified as biological apatites (AP) with a sand-grain rather than a needle-like shape, and plate-shaped octacalcium phosphate (OCP). The AP deposits of the rhinolith probably were associated with magnesium (Mg) phosphates or contained Mg. No OCP was found in the rhinolith. The AP deposits were mainly formed by extracellular calcification. Hexahedral crystals, identified as Mg-containing whitlockite (WH), were precipitated in the internal spaces of the AP and OCP deposits. The rhinolith nucleus consisted of WH crystal deposits only. PMID:7701299

  1. Phosphate binders and metabolic acidosis in patients undergoing maintenance hemodialysis—sevelamer hydrochloride, calcium carbonate, and bixalomer.

    PubMed

    Sanai, Toru; Tada, Hideo; Ono, Takashi; Fukumitsu, Toma

    2015-01-01

    The serum bicarbonate (HCO3(-)) levels are decreased in chronic hemodialysis (HD) patients treated with sevelamer hydrochloride (SH). We assessed the effects of bixalomer on the chronic metabolic acidosis in these patients. We examined 12 of the 122 consecutive Japanese patients with end-stage renal disease on HD, who orally ingested a dose of SH (?2250?mg), and an arterial blood gas analysis and biochemical analysis were performed before HD. Patients whose serum HCO3(-) levels were under 18?mmol/L were changed from SH to the same dose of bixalomer. A total of 12 patients were treated with a large amount of SH. Metabolic acidosis (a serum HCO3(-) level under 18?mmol/L) was found in eight patients. These patients were also treated with or without small dose of calcium carbonate (1.2?±?1.1?g). The dose of SH was changed to that of bixalomer. After 1 month, the serum HCO3(-) levels increased from 16.3?±?1.4 to 19.6?±?1.7?mmol/L (P?calcium carbonate with SH. In the present study, the development of chronic metabolic acidosis was induced by HCl containing phosphate binders, such as SH, and partially ameliorated by calcium carbonate, then subsequently improved after changing the treatment to bixalomer. PMID:24980286

  2. In vitro and in vivo evaluation of the biocompatibility of a calcium phosphate/poly(lactic-co-glycolic acid) composite.

    PubMed

    Gala-García, A; Carneiro, M B H; Silva, G A B; Ferreira, L S; Vieira, L Q; Marques, M M; Sinisterra, R D; Cortes, M E

    2012-07-01

    This study assess the effects of bioceramic and poly(lactic-co-glycolic acid) composite (BCP/PLGA) on the viability of cultured macrophages and human dental pulp fibroblasts, and we sought to elucidate the temporal profile of the reaction of pulp capping with a composite of bioceramic of calcium phosphate and biodegradable polymer in the progression of delayed dentine bridge after (30 and 60 days) in vivo. Histological evaluation of inflammatory infiltrate and dentin bridge formation were performed after 30 and 60 days. There was similar progressive fibroblast growth in all groups and the macrophages showed viability. The in vivo study showed that of the three experimental groups: BCP/PLGA composite, BCP and calcium hydroxide (Ca(OH)(2)) dentin bridging was the most prevalent (90 %) in the BCP/PLGA composite after 30 days, mild to moderate inflammatory response was present throughout the pulp after 30 days. After 60 days was observed dentine bridging in 60 % and necrosis in 40 %, in both groups. The results indicate that understanding BCP/PLGA composite is biocompatible and by the best tissue response as compared to calcium hydroxide in direct pulp capping may be important in the mechanism of delayed dentine bridge after 30 and 60 days. PMID:22569732

  3. Calcium and phosphate: a duet of ions playing for bone health.

    PubMed

    Bonjour, Jean-Philippe

    2011-10-01

    The acquisition and maintenance of bone mass and strength are influenced by environmental factors, including physical activity and nutrition. Among micronutrients, calcium (Ca) and inorganic (i) phosphate (P) are the two main constituents of hydroxyapatite, the bone mineral that strengthens the mechanical resistance of the organic matrix. Bone contains about 99% and 80% of the body's entire supply of Ca and P, respectively. The Ca/P mass ratio in bone is 2.2, which is similar to that measured in human milk. The initial step of Ca-Pi crystal nucleation takes place within matrix vesicles that bud from the plasma membrane of osteogenic cells and migrate into the extracellular skeletal compartment. They are endowed with a transport system that accumulates Pi inside the matrix vesicles, followed by the influx of Ca ions. This process leads to the formation of hydroxyapatite crystal and its subsequent association with the organic matrix collagen fibrils. In addition to this structural role, both Ca and Pi positively influence the activity of bone-forming and bone-resorbing cells. Pi plays a role in the maturation of osteocytes, the most abundant cells in bone. Osteocytes are implicated in bone mineralization and systemic Pi homeostasis. They produce fibroblast growth factor-23, a hormonal regulator of renal Pi reabsorption and 1,25-dihydroxy vitamin D production. This relationship is in keeping with the concept proposed several decades ago of a bone-kidney link in Pi homeostasis. In contrast to their tight association in bone formation and resorption, Ca and Pi renal reabsorption processes are independent from each other, driven by distinct molecular machineries. The distinct renal control is related to the different extraskeletal functions that Ca and Pi play in cellular metabolism. At both the renal and the intestinal levels, interactions of Ca and Pi have been documented that have important implications in the acquisition and maintenance of bone health, as well as in osteoporosis management. In the kidney, increased Pi intake enhances Ca reabsorption and Ca balance. During growth and adulthood, administration of Ca-Pi in a ratio close to that of dairy products leads to positive effects on bone health. In contrast, when separately ingested as pharmaceutical salt supplements, thus inducing large differences between Ca and Pi concentrations in the intestinal lumen, they might have adverse effects on bone health. In osteoporotic patients treated with anabolic agents, a Ca-Pi supplement appears to be preferable to carbonate or citrate Ca salt. In conclusion, Ca and Pi constitute a key duo for appropriate bone mineral acquisition and maintenance throughout life. Outside the skeleton, their essential but distinct physiological functions are controlled by specific transporters and hormonal systems that also serve to secure the appropriate supply of Ca and Pi for bone health. Key teaching points: Bone contains about 99% and 80% of the body's supply of Ca and P, respectively, as hydroxyapatite and has a Ca/P mass ratio of about 2.2, close to that measured in human milk. The first step of Ca-Pi crystal nucleation takes place within matrix vesicles that bud from the plasma membrane of osteogenic cells. In addition to their structural role, both Ca and Pi influence bone-forming and bone-resorbing cells. There is a bone-kidney link in Pi homeostasis in which fibroblast growth factor-23, a molecule produced by osteocytes, appears to play a pivotal role. In contrast to their tight association during bone formation and resorption, both intestinal and renal Ca and Pi processes are independent of each other. Observational and interventional studies suggest that Ca-Pi salt or dairy products can exert positive effects on bone acquisition and maintenance. PMID:22081690

  4. Multi-scale osteointegration and neovascularization of biphasic calcium phosphate bone scaffolds

    NASA Astrophysics Data System (ADS)

    Lan, Sheeny K.

    Bone grafts are utilized clinically to guide tissue regeneration. Autologous bone and allogeneic bone are the current clinical standards. However, there are significant limitations to their use. To address the need for alternatives to autograft and allograft, researchers have worked to develop synthetic grafts, also referred to as scaffolds. Despite extensive efforts in this area, a gap persists between basic research and clinical application. In particular, solutions for repairing critical size and/or load-bearing defects are lacking. The aim of this thesis work was to address two critical barriers preventing design of successful tissue engineering constructs for bone regeneration within critical size and/or load-bearing defects. Those barriers are insufficient osteointegration and slow neovascularization. In this work, the effects of scaffold microporosity, recombinant human bone morphogenetic protein-2 delivery and endothelial colony forming cell vasculogenesis were evaluated in the context of bone formation in vivo. This was accomplished to better understand the role of these factors in bone regeneration, which may translate to improvements in tissue engineering construct design. Biphasic calcium phosphate (BCP) scaffolds with controlled macro- and microporosity were implanted in porcine mandibular defects. Evaluation of the BCP scaffolds after in vivo implantation showed, for the first time, osteocytes embedded in bone within scaffold micropores (< 10 microm) as well as the most extensive bone growth into micropores to date with bone penetration throughout rods 394 microm in diameter. The result is the first truly osteointegrated bone scaffolds with integration occurring at both the macro and micro length scales, leaving no "dead space" or discontinuities of bone in the defect site. The scaffold forms a living composite upon integration with regenerating bone and this has significant implications with regard to improved scaffold mechanical properties. The presence of osteocytes within scaffold micropores is an indication of scaffold osteoinductivity because a chemotactic factor must be present to induce cell migration into pores on the order of the cell diameter. It is likely that the scaffold undergoes in vivo modifications involving formation of a biological apatite layer within scaffold micropores and possibly co-precipitation of endogenous osteoinductive proteins. To further investigate the effects of scaffold osteoinductivity, BCP scaffolds were implanted in porcine mandibular defects with rhBMP-2, which was partially sequestered in the micropores. Cell migration into osteoinductive scaffold micropores can be enhanced through the delivery of exogenous rhBMP-2 further promoting multi-scale osteointegration. Finally, endothelial colony forming cells (ECFCs) isolated from human umbilical cord blood (UCB) were evaluated in terms of their in vivo vasculogenic potential in the context of bone formation. This work was completed to determine if ECFCs could be utilized in a bone tissue engineering construct to promote neovascularization. ECFCs were combined with a BCP scaffold and rhBMP-2 and implanted subcutaneously on the abdominal wall of NOD/SCID mice. The result was formation of perfused human vessels within BCP scaffold macropores that were present at 4 weeks. The high density and persistence of human vessels at four weeks indicates that human UCB ECFCs exceed their reported in vivo vasculogenic potential when combined with rhBMP-2 and a BCP scaffold. This shows a dual role for BMP-2 in the context of bone regeneration. Collectively, the thesis demonstrates that (1) the design of synthetic bone scaffolds should include controlled multi-scale porosity to promote multi-scale osteointegration, which may significantly improve scaffold mechanical properties and (2) human umbilical cord blood-derived endothelial colony forming cells have potential for promoting neovascularization in a bone defect when combined with rhBMP-2.

  5. Calcium

    MedlinePLUS

    ... you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with soft bones that you eat, such as canned sardines and salmon Calcium-enriched foods such as breakfast ... tofu. Check the product labels. The exact amount of calcium you need ...

  6. Comparative Studies with Three-Week-Old Chickens, Turkeys, Ducks, and Quails on the Response in Phosphorus Utilization to a Supplementation of Monobasic Calcium Phosphate1

    Microsoft Academic Search

    M. Rodehutscord; A. Dieckmann

    We studied whether the availability of P isdifferentamongpoultryspecies.Abasaldietwasmixed mainly based on corn, potato protein, and dried egg white. It was calculated according to the recommenda- tions for young turkeys with the exception of P and Ca concentrations, which were deficient. Monobasic calcium phosphate (MCP) was added in graded levels, and ana- lyzed P concentrations in the 7 diets were (in

  7. Parathyroid gland hormones in the skeletal development of the ovine foetus: the effect of parathyroidectomy with calcium and phosphate infusion.

    PubMed

    Aaron, J E; Abbas, S K; Colwell, A; Eastell, R; Oakley, B A; Russell, R G; Care, A D

    1992-02-01

    It has been confirmed that the foetal parathyroid glands are important in development and that thyroparathyroidectomy (TXPTX) of the ovine foetus with thyroxine (T4) replacement leads to hypocalcaemia, retarded skeletal development, depressed calcification and rickets, relative to thyroidectomy plus T4 replacement. Histomorphometric and biochemical (urinary excretion of deoxypyridinoline) indices of bone resorption are also reduced. However, skeletal calcification can be restored to normal by long-term infusion of the TXPTX foetuses with phosphate and calcium sufficient to normalise the plasma Ca2+ x Pi ion product. Nevertheless, depressed resorption, reduced osteoblast numbers and delayed development persisted. The evidence suggests that the abnormally low number of resorption cavities and osteoclasts may result from the reduction in circulatory parathyroid-hormone-related protein consequent upon the removal of the foetal parathyroid glands and that this hypercalcaemic factor has a direct effect upon the process of resorption and primary trabecular remodelling of the foetal skeleton. PMID:1576487

  8. Characterization of calcium, phosphate and peroxide interactions in activation of mitochondrial swelling using derivative of the swelling curves.

    PubMed

    Drahota, Zden?k; Endlicher, René; Sta?ková, Pavla; Rychtrmoc, David; Milerová, Marie; Cervinková, Zuzana

    2012-06-01

    We describe a new method for the analysis of mitochondrial swelling curves. Using classical swelling curves, only the maximum extent of the swelling can be calculated in a numerical form. However, taking the derivative of the classical swelling curves enables the evaluation of two additional parameters of the swelling process in a numerical form, namely, the maximum swelling rate after the addition of the swelling inducer (as dA???/10 s) and the time (in sec) at which the maximum swelling rate after the addition of the swelling inducer is obtained. The use of these three parameters enables the better characterization of the swelling process as demonstrated by the evaluation of calcium and phosphate interactions in the opening of the mitochondrial permeability transition pore and by the characterization of the peroxide potentiating action. PMID:22562401

  9. Artefactual nanoparticle activation of the inflammasome platform: in vitro evidence with a nano-formed calcium phosphate

    PubMed Central

    Pele, Laetitia; Haas, Carolin T; Hewitt, Rachel; Faria, Nuno; Brown, Andy; Powell, Jonathan

    2015-01-01

    Aim To determine whether in vitro experimental conditions dictate cellular activation of the inflammasome by apatitic calcium phosphate nanoparticles. Material & methods The responses of blood-derived primary human cells to in situ-formed apatite were investigated under different experimental conditions to assess the effect of aseptic culture, cell rest and duration of particle exposure. Cell death and particle uptake were assessed, while IL-1? and caspase 1 responses, with and without lipopolysaccharide prestimulation, were evaluated as markers of inflammasome activation. Results Under carefully addressed experimental conditions, apatitic nanoparticles did not induce cell death or engage the inflammasome platform, although both could be triggered through artefacts of experimentation. Conclusion In vitro studies often predict that engineered nanoparticles, such as synthetic apatite, are candidates for inflammasome activation and, hence, are toxic. However, the experimental setting must be very carefully considered as it may promote false-positive outcomes. PMID:24991724

  10. Effect of particle size of an amorphous calcium phosphate filler on the mechanical strength and ion release of polymeric composites

    PubMed Central

    Lee, Soo-Young; Regnault, W.F.; Antonucci, J.M.; Skrtic, D.

    2008-01-01

    The random clustering of amorphous calcium phosphate (ACP) particles within resin matrices is thought to diminish the strength of their polymerized composites. The objective of this study was to elucidate the effect of ball-milling on the particle size distribution (PSD) of ACP fillers and assess if improved dispersion of milled ACP in methacrylate resin sufficiently enhanced filler/matrix interactions to result in improved biaxial flexure strength (BFS) without compromising the remineralizing potential of the composites. Un-milled and wet milled zirconia-hybridized ACP (Zr-ACP) fillers were characterized by PSD analysis, X-ray diffraction, thermogravimetric and chemical analysis, infrared spectroscopy and scanning electron microscopy. Composite specimens made from a photoactivated, ternary methacrylate resin admixed with a mass fraction of 40 % of un-milled or milled Zr-ACP were evaluated for the BFS (dry and wet) and for the release of calcium and phosphate ions into saline solutions. While having no apparent effect on the structure, composition and/or morphology/topology of the fillers, milling significantly reduced the average size of Zr-ACP particulates (median diameter, dm = 0.9 ?m ± 0.2 ?m) and the spread of their PSD. Better dispersion of milled Zr-ACP in the resins resulted in the improved BFS of the composites, even after aqueous soaking, and also gave a satisfactory ion release profile. The demonstrated improvement in the mechanical stability of anti-demineralizing/remineralizing ACP composites based on milled Zr-ACP filler may be beneficial in potentially extending their dental utility. PMID:16649181

  11. The homing of bone marrow MSCs to non-osseous sites for ectopic bone formation induced by osteoinductive calcium phosphate

    PubMed Central

    Song, Guodong; Habibovic, Pamela; Bao, Chongyun; Hu, Jing; van Blitterswijk, Clemens A.; Yuan, Huipin; Chen, Wenchuan; Xu, Hockin H.K.

    2013-01-01

    Osteoinductive biomaterials are promising for bone repair. There is no direct proof that bone marrow mesenchymal stem cells (BMSCs) home to non-osseous sites and participate in ectopic bone formation induced by osteoinductive bioceramics. The objective of this study was to use a sex-mismatched beagle dog model to investigate BMSC homing via blood circulation to participate in ectopic bone formation via osteoinductive biomaterial. BMSCs of male dogs were injected into female femoral marrow cavity. The survival and stable chimerism of donor BMSCs in recipients were confirmed with polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH). Biphasic calcium phosphate (BCP) granules were implanted in dorsal muscles of female dogs. Y chromosomes were detected in samples harvested from female dogs which had received male BMSCs. At 4 weeks, cells with Y-chromosomes were distributed in the new bone matrix throughout the BCP granule implant. At 6 weeks, cells with Y chromosomes were present in newly mineralized woven bone. TRAP positive osteoclast-like cells were observed in 4-week implants, and the number of such cells decreased from 4 to 6 weeks. These results show that osteoprogenitors were recruited from bone marrow and homed to ectopic site to serve as a cell source for calcium phosphate-induced bone formation. In conclusion, BMSCs were demonstrated to migrate from bone marrow through blood circulation to non-osseous bioceramic implant site to contribute to ectopic bone formation in a canine model. BCP induced new bone in muscles without growth factor delivery, showing excellent osteoinductivity that could be useful for bone tissue engineering. PMID:23298780

  12. The synergic effect of polylactide fiber and calcium phosphate particle reinforcement in poly epsilon-caprolactone-based composite scaffolds.

    PubMed

    Guarino, V; Ambrosio, L

    2008-11-01

    In this work, three-dimensional porous composite scaffolds, based on poly(epsilon-caprolactone) (PCL), were fabricated through the combination of a filament winding technique and a phase inversion/salt leaching process. Sodium chloride crystals were used as the porogen agent, and poly(lactic acid) (PLA) fibers and calcium phosphates as reinforcement. The aim of the current work is to assess the effective synergistic role of bioactive particles (i.e. alpha-tricalcium phosphates (alpha-TCP)) and PLA fibers on the morphology and mechanical response of the final scaffold. Morphological investigations performed on fiber-reinforced composite scaffolds with different PCL/alpha-TCP volume ratios (0%, 13%, 20% and 26%) show a high porosity degree (ca. 80%), pore interconnection and a homogeneous distribution of pores within the scaffold. More specifically, a bimodal pore size distribution was observed. This comprised microporosity (pores with radii ranging from 0.1 to 10 microm, which were strictly related to solvent extraction) and macroporosity (pores with radii from 10 to 300 microm, which were ascribable to the leaching of porogen elements). Static compressive tests showed that the effect of alpha-TCP on the mechanical response was to increase the elastic modulus up to a maximum value of 2.21+/-0.24 MPa, depending on the concentration of alpha-TCP added. This effect may be explained through the interaction of calcium-deficient hydroxyapatite crystals, formed as a consequence of a hydrolysis reaction of alpha-TCP, and the fiber-reinforced polymer matrix. The correct balance between chemical composition and spatial organization of reinforcement systems allows the attainment of an ideal compromise between mechanical response and bioactive potential, facilitating the development of composite scaffolds for bone tissue engineering applications. PMID:18571487

  13. The effect of particle size on the osteointegration of injectable silicate-substituted calcium phosphate bone substitute materials

    PubMed Central

    Coathup, Melanie J; Cai, Qian; Campion, Charlie; Buckland, Thomas; Blunn, Gordon W

    2013-01-01

    Calcium phosphate (CaP) particles as a carrier in an injectable bone filler allows less invasive treatment of bony defects. The effect of changing granule size within a poloxamer filler on the osteointegration of silicate-substituted calcium phosphate (SiCaP) bone substitute materials was investigated in an ovine critical-sized femoral condyle defect model. Treatment group (TG) 1 consisted of SiCaP granules sized 1000–2000 ?m in diameter (100 vol %). TG2 investigated a granule size of 250–500 ?m (75 vol %), TG3 a granule size of 90–125 ?m (75 vol %) and TG4 a granule size of 90–125 ?m (50 vol %). Following a 4 and 8 week in vivo period, bone area, bone-implant contact, and remaining implant area were quantified within each defect. At 4 weeks, significantly increased bone formation was measured in TG2 (13.32% ± 1.38%) when compared with all other groups (p = 0.021 in all cases). Bone in contact with the bone substitute surface was also significantly higher in TG2. At 8 weeks most new bone was associated within defects containing the smallest granule size investigated (at the lower volume) (TG4) (42.78 ± 3.36%) however this group was also associated with higher amounts of fragmented SiCaP. These smaller particles were phagocytosed by macrophages and did not appear to have a negative influence on healing. In conclusion, SiCaP granules of 250–500 ?m in size may be a more suitable scaffold when used as an injectable bone filler and may be a convenient method for treating bony defects. © 2013 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 101B: 902–910, 2013 PMID:23362131

  14. Multifunctional calcium phosphate nano-contrast agent for combined nuclear, magnetic and near-infrared in vivo imaging.

    PubMed

    Ashokan, Anusha; Gowd, Genekehal S; Somasundaram, Vijay H; Bhupathi, Arun; Peethambaran, Reshmi; Unni, A K K; Palaniswamy, Shanmugasundaram; Nair, Shantikumar V; Koyakutty, Manzoor

    2013-09-01

    Combination of three imaging techniques such as nuclear, magnetic and near-infrared fluorescence can aid in improved diagnosis of disease by synergizing specific advantages of each of these techniques such as deep tissue penetration of radiation signals, anatomical and functional details provided by magnetic contrast and better spatial resolution of optical signals. In the present work, we report the development of a multimodal contrast agent based on calcium phosphate nanoparticles (nCP), doped with both indocyanine green (ICG) and Gadolinium (Gd(3+)), and labeled with 99m-Technetium-methylene diphosphonate ((99m)Tc-MDP) for combined optical, magnetic and nuclear imaging. In order to obtain the desired tri-modal contrast properties, the concentrations of ICG, Gd(3+) and (99m)Tc were optimized at ?0.15wt%, 3.38at% and ?0.002ng/mg of nCP, respectively. The leaching-out of ICG was protected by an additional coating of polyethyleneimine (PEI). Toxicological evaluation of the final construct carried out on healthy human mononuclear cells, red-blood cells and platelets, showed excellent hemocompatibility. In vivo multimodal imaging using mice models revealed the ability to provide near-infrared, magnetic and nuclear contrast simultaneously. The nanoparticles also showed the potential for improved MR based angio-imaging of liver. Retention of intravenously administrated nanoparticles in the liver was reduced with PEGylation and the clearance was observed within 48h without causing any major histological changes in vital organs. Thus, we developed a non-toxic tri-modal nano-contrast agent using calcium phosphate nanoparticles and demonstrated its potential for combined nuclear, magnetic and near-infrared imaging in vivo. PMID:23791501

  15. Electrostatic spray deposition (ESD) of calcium phosphate coatings, an in vitro study with osteoblast-like cells.

    PubMed

    Siebers, M C; Walboomers, X F; Leeuwenburgh, S C G; Wolke, J G C; Jansen, J A

    2004-05-01

    Electrostatic spray deposition (ESD) is a recently developed technique to deposit a calcium phosphate (CaP) coating upon substrates. With this technique, an organic solvent containing calcium and phosphate is pumped through a nozzle. Between the nozzle and substrate a high voltage is applied. As a consequence, droplets coming out the nozzle disperse into a spray, and this spray is deposited upon the substrate. When the solvent has evaporated, a coating is formed on the substrate. ESD allows for a variation in coating composition and morphology. Titanium alloy (TiAl6V4) substrates were coated with a CaP layer using two different methods; radio frequency magnetron sputtering, and ESD. These surfaces were characterized with X-ray diffraction, Fourier transform infrared spectroscopy, an universal surface tester, scanning electron microscopy, and energy dispersive spectrometry. Subsequently, bone marrow cells were isolated from rat femora and cultured 1, 4, 8, 14 and 16 days. Cell proliferation, alkaline phosphatase activity, and osteocalcin concentration were assayed. RT-PCR was done for collagen type I and osteocalcin. SEM was also performed to observe cellular behaviour during culture. Two separate runs of the experiment were performed. In the first run, osteoblast-like cells on both CaP coatings showed similar results in all assays. In the second run, proliferation and osteogenic expression had increased on ESD coatings. On basis of these results, we conclude that the novel ESD coating behaved similar to, or even better than the known RF magnetron sputter coating. Thus, ESD could be a valid addition to already existing CaP coating processes. PMID:14741616

  16. Strontium-Doped Calcium Phosphate and Hydroxyapatite Granules Promote Different Inflammatory and Bone Remodelling Responses in Normal and Ovariectomised Rats

    PubMed Central

    Xia, Wei; Emanuelsson, Lena; Norlindh, Birgitta; Omar, Omar; Thomsen, Peter

    2013-01-01

    The healing of bone defects may be hindered by systemic conditions such as osteoporosis. Calcium phosphates, with or without ion substitutions, may provide advantages for bone augmentation. However, the mechanism of bone formation with these materials is unclear. The aim of this study was to evaluate the healing process in bone defects implanted with hydroxyapatite (HA) or strontium-doped calcium phosphate (SCP) granules, in non-ovariectomised (non-OVX) and ovariectomised (OVX) rats. After 0 (baseline), six and 28d, bone samples were harvested for gene expression analysis, histology and histomorphometry. Tumour necrosis factor-? (TNF-?), at six days, was higher in the HA, in non-OVX and OVX, whereas interleukin-6 (IL-6), at six and 28d, was higher in SCP, but only in non-OVX. Both materials produced a similar expression of the receptor activator of nuclear factor kappa-B ligand (RANKL). Higher expression of osteoclastic markers, calcitonin receptor (CR) and cathepsin K (CatK), were detected in the HA group, irrespective of non-OVX or OVX. The overall bone formation was comparable between HA and SCP, but with topological differences. The bone area was higher in the defect centre of the HA group, mainly in the OVX, and in the defect periphery of the SCP group, in both non-OVX and OVX. It is concluded that HA and SCP granules result in comparable bone formation in trabecular bone defects. As judged by gene expression and histological analyses, the two materials induced different inflammatory and bone remodelling responses. The modulatory effects are associated with differences in the spatial distribution of the newly formed bone. PMID:24376855

  17. Structural characterization and biological fluid interaction of Sol-Gel-derived Mg-substituted biphasic calcium phosphate ceramics.

    PubMed

    Gomes, S; Renaudin, G; Jallot, E; Nedelec, J-M

    2009-02-01

    Sol-Gel chemistry has been used to prepare undoped and Mg-substituted biphasic calcium phosphate (BCP) ceramics composed of hydroxyapatite (HAp) and whitlockite (beta-TCP) phases. Different series of samples have been synthesized with different Mg-doping levels (from 0 to 5 atomic % of Ca atoms substituted) and different temperatures of calcination (from 500 to 1100 degrees C). All of the powdered samples were systematically treated by Rietveld refinement to extract the quantitative phase analysis and the structural and microstructural parameters, to locate the Mg crystallographic sites, and to refine the composition of the Mg-substituted phases. The temperature dependence of the weight amount ratio between HAp and beta-TCP is not monotonic because of the formation of minor phases such as Ca(2)P(2)O(7), CaO, MgO, and CaCO(3) and certainly an amorphous phase. On the other hand, the Mg stabilizing feature on the beta-TCP phase has been evidenced and explained. The mechanism of stabilization by small Mg(2+) is different from that by large Sr(2+). Nevertheless, in both cases, the beta-TCP stabilization is realized by an improvement of the environment of the Ca4 site unusually face-coordinated to a PO(4) tetrahedron. The substitution of a Mg atom in the Ca5 site allows considerable improvement of the bond valence sum of the unusual Ca4 polyhedron. The temperatures of calcination combined with the amount of Mg atoms introduced allow monitoring of the phase composition of the BCP ceramics as well as their microstructural properties. The bioactivity properties of the BCP samples are improved by the presence of Mg atoms in the structure of the beta-TCP phase. The mechanism of improvement is mainly attributed to an accelerated kinetic of precipitation of a calcium phosphate layer at the surface comprising HAp and/or beta-TCP phases. PMID:20353243

  18. Characterisation of Calcium Phosphate Crystals on Calcified Human Aortic Vascular Smooth Muscle Cells and Potential Role of Magnesium

    PubMed Central

    Louvet, Loïc; Bazin, Dominique; Büchel, Janine; Steppan, Sonja; Passlick-Deetjen, Jutta; Massy, Ziad A.

    2015-01-01

    Background Cardiovascular disease including vascular calcification (VC) remains the leading cause of death in patients suffering from chronic kidney disease (CKD). The process of VC seems likely to be a tightly regulated process where vascular smooth muscle cells are playing a key role rather than just a mere passive precipitation of calcium phosphate. Characterisation of the chemical and crystalline structure of VC was mainly led in patients or animal models with CKD. Likewise, Mg2+ was found to be protective in living cells although a potential role for Mg2+ could not be excluded on crystal formation and precipitation. In this study, the crystal formation and the role of Mg2+ were investigated in an in vitro model of primary human aortic vascular smooth muscle cells (HAVSMC) with physical techniques. Methodology/Principal Findings In HAVSMC incubated with increased Ca x Pi medium, only calcium phosphate apatite crystals (CPA) were detected by Micro-Fourier Transform InfraRed spectroscopy (µFTIR) and Field Effect Scanning Electron Microscope (FE — SEM) and Energy Dispersive X-ray spectrometry (EDX) at the cell layer level. Supplementation with Mg2+ did not alter the crystal composition or structure. The crystal deposition was preferentially positioned near or directly on cells as pictured by FE — SEM observations and EDX measurements. Large µFTIR maps revealed spots of CPA crystals that were associated to the cellular layout. This qualitative analysis suggests a potential beneficial effect of Mg2+ at 5 mM in noticeably reducing the number and intensities of CPA µFTIR spots. Conclusions/Significance For the first time in a model of HAVSMC, induced calcification led to the formation of the sole CPA crystals. Our data seems to exclude a physicochemical role of Mg2+ in altering the CPA crystal growth, composition or structure. Furthermore, Mg2+ beneficial role in attenuating VC should be linked to an active cellular role. PMID:25607936

  19. Calibration of C and O isotope fractionation during experimental formation of calcium-phosphate

    NASA Astrophysics Data System (ADS)

    Conrad, Anika C.; Böttcher, Michael E.; Fiebig, Jens; Dellwig, Olaf; Grathoff, Georg; Leipe, Thomas; Schmidt, Burkhard C.; Schmiedinger, Iris; Wacker, Ulrike

    2015-04-01

    The stable isotope analysis of the carbonate molecule bond in the phosphate-bearing mineral apatite provides a potential paleothermometer [1], but has also been used to address metabolism upon bio-apatite formation [2]. In the crystal lattice of apatite the carbonate group may substitute for both the hydroxyl ion and the phosphate in the crystal lattice, thereby potentially resulting in different isotope discrimination patterns. Within the EXCALIBOR project, stable isotope fractionation is investigated in biogenic apatites that were formed under known temperatures and in abiotic Ca phosphates precipitated under controlled laboratory conditions. Here, we report on the results from the synthesis experiments. Carbonate apatite was prepared at temperatures between 10° and 60°C by the precipitation from aqueous solutions or the transformation of CaCO3 precursors, taking care for a complete isotopic pre-equilibration in the aqueous carbonate system. Besides the analysis of the geochemical and stable isotope composition of the Ca phosphates and solutes, the solids were characterized by powder X-ray diffraction, FTIR and micro Raman spectroscopy. The latter techniques allow for an estimate of the position of the carbonate group (A/B type substitution) in the crystal lattice of apatite and will help to explore if this crystal chemical feature is associated with distinct stable isotope fractionation effects. Research is supported by Deutsche Forschungsgemeinschaft (DFG) during the EXCALIBOR project References [1] Lecuyer et al. (2010) GCA; [2] DeNiro & Epstein (1978) GCA

  20. In vivo behavior of three different injectable hydraulic calcium phosphate cements

    Microsoft Academic Search

    D. Apelt; F. Theiss; A. O. El-Warrak; K. Zlinszky; R. Bettschart-Wolfisberger; M. Bohner; S. Matter; J. A. Auer; B. von Rechenberg

    2004-01-01

    Two dicalcium phosphate dihydrate (DCPD) hydraulic cements and one apatite hydraulic cement were implanted in epiphyseal and metaphyseal, cylindrical bone defects of sheep. The in vivo study was performed to assess the biocompatibility of the DCPD cements, using the apatite cement as control. After time periods of 2, 4 and 6 months the cement samples were clinically and histologically evaluated.

  1. Casein Aggregates Built Step-by-Step on Charged Polyelectrolyte Film Surfaces Are Calcium Phosphate-cemented*

    PubMed Central

    Nagy, Krisztina; Pilbat, Ana-Maria; Groma, Géza; Szalontai, Balázs; Cuisinier, Frédéric J. G.

    2010-01-01

    The possible mechanism of casein aggregation and micelle buildup was studied in a new approach by letting ?-casein adsorb from low concentration (0.1 mg·ml?1) solutions onto the charged surfaces of polyelectrolyte films. It was found that ?-casein could adsorb onto both positively and negatively charged surfaces. However, only when its negative phosphoseryl clusters remained free, i.e. when it adsorbed onto a negative surface, could calcium phosphate (CaP) nanoclusters bind to the casein molecules. Once the CaP clusters were in place, step-by-step building of multilayered casein architectures became possible. The presence of CaP was essential; neither Ca2+ nor phosphate could alone facilitate casein aggregation. Thus, it seems that CaP is the organizing motive in the casein micelle formation. Atomic force microscopy revealed that even a single adsorbed casein layer was composed of very small (in the range of tens of nanometers) spherical forms. The stiffness of the adsorbed casein layer largely increased in the presence of CaP. On this basis, we can imagine that casein micelles emerge according to the following scheme. The amphipathic casein monomers aggregate into oligomers via hydrophobic interactions even in the absence of CaP. Full scale, CaP-carrying micelles could materialize by interlocking these casein oligomers with CaP nanoclusters. Such a mechanism would not contradict former experimental results and could offer a synthesis between the submicelle and the block copolymer models of casein micelles. PMID:20921229

  2. CALCIUM PHOSPHATE GRANULES IN THE HEPATOPANCREAS OF THE BLUE CRAB CALLINECTES SAPIDUS

    Microsoft Academic Search

    GERALD L. BECKER; CHUNG-HO CHEN; JOHN W. GREENAWALT; ALBERT L. LEHNINGER

    1974-01-01

    21205 ABSTRACT The hepatopancreas of the adult male blue crab Callinectes sapidusin intermolt was found to contain substantial amounts of calcium, magnesium, and inorganic phosphorus, averaging about 260, 20, and 250 µg-atoms per g wet tissue, respectively, accounting for over 10% of the tissue dry weight . Electron microscopy of the intact tissue showed three qualitatively different granular structures having

  3. Effects of Addition of Mannitol Crystals on the Porosity and Dissolution Rates of a Calcium Phosphate Cement

    PubMed Central

    Vazquez, Debra; Takagi, Shozo; Frukhtbeyn, Stan; Chow, Laurence C.

    2010-01-01

    The bone defect repair functions of calcium phosphate cement (CPC) are related to its osteoconductivity and its gradual replacement by new bone. Adding mannitol to CPC may enhance its bone repair potential by increasing CPCs macroporosity and dissolution rate. The objective of the study was to assess microporosity and macroporosity and dissolution rates for CPC mixed with mannitol. Three groups of CPC discs were prepared by combining an equimolar mixture of tetracalcium phosphate and anhydrous dicalcium phosphate with (0 %, 10 %, or 50 %) mass fraction (hereafter expressed as mass %) of mannitol. Macroporosity and microporosity of the samples were calculated from volume and mass measurements of the discs. Discs were then placed in a pH 3.0 demineralizing solution simulating acidified physiological solution, and dissolution rates were measured by a previously described constant-composition titration method. Pure CPC exhibited no macropores and microporosity (mean ± s.d.; n = 5) of (46.8 ± 0.8) % volume fraction (hereafter expressed as vol %). Adding 10 mass % mannitol resulted in 15.6 ± 3.9 vol % macroporosity and 39.4 ± 1.8 vol % microporosity, and adding 50 mass % mannitol produced 54.7 ± 0.8 vol % macroporosity and 21.1 ± 0.4 vol % microporosity. The dissolution rates (mean ± s.d.; n = 5) of CPC with (0, 10, and 50) mass % mannitol incorporation were (30.6 ± 3.4, 44.8 ± 10.2, and 54.7 ± 3.6, respectively) ?g · cm?2 · min?1, or (0.018 ± 0.002, 0.032 ± 0.007, and 0.072 ± 0.005, respectively) ?L · cm?2 · min?1. Adding either 10 mass % or 50 mass % mannitol into CPC significantly (p < 0.05) increased CPC dissolution rates. Adding mannitol readily increased macroporosity and dissolution rate of CPC, which may enhance the capacity of CPC to be osteoconductive. PMID:21037951

  4. Microscopic, crystallographic and adherence properties of plasma-sprayed calcium phosphate coatings on Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Tufekci, Eser

    Recently, plasma-spayed titanium implants have become very popular in the dentistry because of their biocompatibility and ability of providing osseointegration with the surrounding bone. Although there are numerous published studies on these materials, information and standards are still lacking. This study investigated the miscrostructural, crystallographic and adherence properties of plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V substrates. The microstructures of the coatings and the elemental interdiffusion near the coating/substrate interface were investigated using a scanning electron microscope (SEM) equipped with x-ray energy-dispersive spectroscopy (EDS). X-ray diffraction analyses performed on Ti-6Al-4V coupons prepared with different percent crystallinities have provided structural information such as degree of crystallinity, phases present, average crystallite size, as well as the residual stresses within the coating. For evaluation of the adherence of the coatings to the substrates, experimental rods were subjected to torsion. The fracture surfaces were analyzed using SEM/EDS to develop a new methodology to determine the percent adherence of the coatings. SEM studies indicated that the surface microstructures of commercial dental implants were consistent with the plasma-spraying. In cross-section, coatings exhibited minimal porosity and limited interdiffusion of titanium and calcium at the coating/substrate interface. X-ray diffraction analyses indicated that the highest crystallinity coatings consisted of almost entirely HA and an amorphous calcium phosphate phase. As the coating crystallinity decreased, increasing amounts of alpha- and beta-tricalcium phosphate and tetracalcium phosphate were detected. The mean percent crystallinity for the three sets of coatings ranged from 50-60%. The mean HA crystallite size for the three sets of coatings ranged from about 0.02-0.04 mum. Differences in mean interplanar spacings for three selected crystallographic planes of HA, compared with the pure ICDD (International Center for Diffraction Data) powder standards, implied that coatings had a nonuniform state of tensile stresses (0-130 MPa). The EDS analyses of the fractured coating surfaces indicated that the percent coating adherence was approximately 20%, which appeared to be comparable to that observed in SEM photomicrographs.

  5. 3D printing of bone substitute implants using calcium phosphate and bioactive glasses

    Microsoft Academic Search

    Christian Bergmann; Markus Lindner; Wen Zhang; Karolina Koczur; Armin Kirsten; Rainer Telle; Horst Fischer

    2010-01-01

    Customized implants for bone replacement are a great help for a surgeon to remodel maxillofacial or craniofacial defects in an esthetical way, and to significantly reduce operation times. The hypothesis of this study was that a composite of ?-tricalcium phosphate (?-TCP) and a bioactive glass similar to the 45S5 Henchglass® is suitable to manufacture customized implants via 3D-printing process. The

  6. Effects of emulsifying salts on the turbidity and calcium-phosphate-protein interactions in casein micelles.

    PubMed

    Mizuno, R; Lucey, J A

    2005-09-01

    Influence of emulsifying salts (ES) on some physical properties of casein micelles was investigated. A reconstituted milk protein concentrate (MPC) solution (5% wt/wt) was used as the protein source and the effects of ES [0 to 2.0% (wt/wt)] were estimated by measuring turbidity, acid-base titration curves and amount of casein-bound Ca and inorganic P (P(i)). Various ES, trisodium citrate (TSC), or sodium phosphates (ortho-, pyro-, or hexameta-) were added to MPC solution, and all samples were adjusted to pH 5.8. Acid-base buffering curves were used to observe changes in the amount and type of insoluble Ca phosphates. An increase in the concentration of TSC added to MPC solution decreased turbidity, buffering at pH approximately 5 (contributed by colloidal Ca phosphate), and amount of casein-bound Ca and P(i). Addition of up to 0.7% disodium orthophosphate (DSP) did not significantly influence turbidity, buffering curves, or amount of casein-bound Ca and P(i). When higher concentrations (i.e., > or =1.0%) of DSP were added, there was a slow decrease in turbidity. With increasing concentration of added tetrasodium pyrophosphate (TSPP), turbidity and buffering at pH approximately 5 decreased, and amount of casein-bound Ca and P(i) increased. When small concentrations (i.e., 0.1%) of sodium hexameta-phosphate were added, effects were similar to those when TSPP were added but when higher concentrations (i.e., > or =0.5%) were added, the buffering peak shifted to a higher pH value, and amount of casein-bound Ca and P(i) decreased. These results suggested that each type of ES influenced casein micelles by different mechanisms. PMID:16107395

  7. Synthesis and characterization of calcium phosphate loaded with Ho-166 and Sm-153: a novel biomaterial for treatment of spine metastases.

    PubMed

    Donanzam, B A; Campos, T P R; Dalmázio, I; Valente, E S

    2013-12-01

    Spine metastases are a common and painful complication of cancer. A novel concept of treatment combines the in situ vertebroplasty with radiotherapy employing radioactive bone cement into the human vertebrae. Thus, investigations concerning possible bioactive and radioactive cements become a relevant theme. In this work, we have synthesized calcium phosphate bioceramics incorporated with Ho and Sm nuclides using sol-gel technique. Characterizations were performed using X-ray diffractometry, infrared spectroscopy, scanning electron microscopy, instrumental neutron activation analysis, and gamma spectroscopy. Results showed bioceramics composed by multiphasic calcium phosphates along with holmium and samarium phosphates, with 8.9 and 13.7 % of Sm and Ho in weight, respectively. After neutron activation, the Ho-166 and Sm-153 beta-emitters were identified and quantified on the bioceramics with activities estimated at 32.5 and 14.5 MBq/mg of Sm-153 and Ho-166 bioceramic powder, respectively. These radioactive calcium phosphate bioceramics can compose suitable radioactive cements to radiovertebroplasty. PMID:23912793

  8. Probing albumin adsorption onto calcium phosphates by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry

    PubMed Central

    Baio, J. E.; Weidner, T.; Interlandi, G.; Mendoza-Barrera, C.; Canavan, H. E.; Michel, R.; Castner, D. G.

    2011-01-01

    In this study the binding and assembly of bovine serum albumin (BSA) onto three different calcium phosphate phases (hydroxyapatite, dibasic calcium phosphate dihydrate, and ?-tricalcium phosphate) was investigated using a combination of x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). XPS was used to record adsorption isotherms and to quantify the amount of BSA adsorbed onto the different CaP surfaces. On all three surfaces, a monolayer of adsorbed BSA was formed. ToF-SIMS was then used to investigate how the structure of BSA changes upon surface binding. ToF-SIMS data from BSA films on the three CaP surfaces showed intensity differences of secondary ions originating from both hydrophobic and hydrophilic amino acids. For a more quantitative examination of structural changes, the authors developed a ratio comparing the sum of intensities of secondary ions from hydrophobic and hydrophilic residues. A small, but statistically significant, increase in the value of this ratio (7%) was observed between a BSA film on hydroxyapatite versus dibasic calcium phosphate dihydrate. From this ratio, the authors can make some initial hypotheses about what specific changes in BSA structure relate to these differences observed in the ToF-SIMS data. PMID:22267900

  9. Injectable calcium phosphate-alginate-chitosan microencapsulated MC3T3-E1 cell paste for bone tissue engineering in vivo.

    PubMed

    Qiao, Pengyan; Wang, Juan; Xie, Qiufei; Li, Fangfang; Dong, Limin; Xu, Tao

    2013-12-01

    Osteoblasts or stem cells have been delivered into injectable calcium phosphate cement (CPC) to improve its effectiveness and biological function. However, the osteogenic potential of the new construct in vivo has been rarely reported, and there are no reports on alginate-chitosan microencapsulated osteoblasts mixed with CPC. This study aimed to develop alginate-chitosan microencapsulated mouse osteoblast MC3T3-E1 cells (AC-cells), evaluate the osteogenic potential of a calcium phosphate cement complex with these AC-cells (CPC-AC-cell), and trace the implanted MC3T3-E1 cells in vivo. MC3T3-E1 cells were embedded in alginate microcapsules, cultured in osteogenic medium for 7 days, and then covered with chitosan before mixing with a paste of ?-tricalcium phosphate/calcium phosphate cement (?-TCP/CPC). The construct was injected into the dorsal subcutaneous area of nude mice. Lamellar-bone-like mineralization, newly formed collagen and angiogenesis were observed at 4 weeks. At 8 weeks, areas of newly formed collagen expanded; further absorption of ?-TCP/CPC and osteoid-like structures could be seen. Cell tracing in vivo showed that implanted MC3T3-E1 cells were clearly visible at 2 weeks. These in vivo results indicate that the novel injectable CPC-AC-cell construct is promising for bone tissue engineering applications. PMID:24094170

  10. Effects of carboxymethyl cellulose-based saliva substitutes with varying degrees of saturation with respect to calcium phosphates on artificial enamel lesions.

    PubMed

    Meyer-Lueckel, H; Cölfen, H; Verch, A; Tschoppe, P

    2010-01-01

    The aim of the present study was to evaluate the effects of experimental saliva substitutes based on carboxymethyl cellulose (CMC) differing in degrees of saturation with respect to calcium phosphates on the mineral loss of enamel in vitro. Demineralized bovine specimens (subsurface lesions) were exposed to one of six experimental CMC-based solutions with theoretical degrees of saturation with respect to octacalcium phosphate (S(OCP)) of S0, S0.5, S1, S2, S4, and S8 for 10 weeks. A previously studied saliva substitute (Glandosane) and two aqueous solutions (C0 and C1) served as controls. Mineral losses and lesion depths before and after storage were evaluated from microradiographs. Free and bound calcium as well as phosphate and fluoride concentrations were determined. According to these measurements, S(OCP) of S2, S4, and S8 was 0.3, 1.1, and 3.4, respectively. Storage in Glandosane and both negative controls resulted in significant demineralization (p < 0.05). Only S2 significantly remineralized the specimens (p < 0.05). All other solutions showed neutral effects. No significant differences in mineralization between S0 and C0 as well as between S1 and C1 could be observed (p > 0.05). It can be concluded that a CMC-based solution actually unsaturated with respect to octacalcium phosphate (S2) shows most pronounced remineralization capability under the conditions chosen. This might be explained by a more favorable balance between calcium bound to CMC in an adsorbed layer at the enamel-liquid interface and heterogeneous nucleation of calcium phosphates within a solution compared to solutions either supersaturated or having lower levels of saturation. PMID:20357442

  11. Association Studies of Calcium-Sensing Receptor (CaSR) Polymorphisms with Serum Concentrations of Glucose and Phosphate, and Vascular Calcification in Renal Transplant Recipients

    PubMed Central

    Maréchal, Céline; Jadoul, Michel; Devuyst, Olivier; Thakker, Rajesh V.

    2015-01-01

    Background Cardiovascular disease is the major cause of death in renal transplant recipients (RTRs) and linked to arterial calcification. The calcium-sensing receptor (CaSR), a G-protein coupled receptor, plays a pivotal role in extracellular calcium homeostasis and is expressed in the intimal and medial layers of the arterial wall. We investigated whether common CASR gene variants are predictors for aortic and coronary artery calcification or influence risk factors such as serum calcium, phosphate and glucose concentrations in RTRs. Methods Two hundred and eighty four RTRs were investigated for associations between three CASR promoter region single nucleotide polymorphisms (SNPs) (rs115759455, rs7652589, rs1501899), three non-synonymous CASR coding region SNPs (A986S, R990G, Q1011E), and aortic and coronary artery calcium mass scores, cardiovascular outcomes and calcification risk factors that included serum phosphate, calcium, total cholesterol and glucose concentrations. Results Multivariate analysis revealed that RTRs homozygous for the minor allele (SS) of the A986S SNP, when compared to those homozygous for the major allele (AA), had raised serum glucose concentrations (8.7±5.4 vs. 5.7±2.1 mmol/L, P<0.05). In addition, RTRs who were heterozygous (CT) at the rs115759455 SNP, when compared to those homozygous for the major allele (CC), had higher serum phosphate concentrations (1.1±0.3 vs. 1.0±0.2 mmol/L, P<0.05). CASR SNPs were not significant determinants for aortic or coronary artery calcification, and were not associated with cardiovascular outcomes or mortality in this RTR cohort. Conclusions Common CASR SNPs may be independent predictors of serum glucose and phosphate concentrations, but are not determinants of vascular calcification or cardiovascular outcomes. PMID:25786244

  12. Structural arrangements at the interface between plasma sprayed calcium phosphates and bone.

    PubMed

    de Bruijn, J D; Bovell, Y P; van Blitterswijk, C A

    1994-06-01

    Plasma sprayed coatings of tetracalcium phosphate, magnesium whitlockite and three types of hydroxyapatite, varying in degree of crystallinity, were evaluated with light microscopy, scanning electron microscopy and backscatter electron microscopy (BSE) after implantation periods of 1, 2 and 4 wk in rat femora. BSE revealed that both tetracalcium phosphate and semi-crystalline hydroxyapatite underwent distinct bulk degradation and loss of relatively large particles. Amorphous hydroxyapatite showed a gradual surface degradation, indicated by a transition zone varying in grey level between that of the coating and bone tissue, while degradation was negligible with the highly crystalline material and magnesium whitlockite. Degradation appeared to be related to bone apposition, since more bone seemed to be present on amorphous hydroxyapatite and tetracalcium phosphate, as compared to highly crystalline hydroxyapatite and magnesium whitlockite coatings. At the interface between bone and magnesium whitlockite, a seam of unmineralized bone-like tissue was frequently seen with light microscopy, while few areas with bone contact were present. X-ray microanalysis revealed that both the magnesium whitlockite coating and the unmineralized bone-like tissue contained substantial amounts of aluminium which, in addition to possible influences of magnesium, may have caused the impaired mineralization. The results of this preliminary study indicate that, with regard to early bone formation, amorphous hydroxyapatite coatings seem to be beneficial over highly crystalline coatings. However, further experiments should be performed to give conclusive data on (i) the statistical significance of the differences in bone apposition rate, and (ii) the long-term behaviour of both amorphous and highly crystalline coatings in bone and their relation to implant performance. PMID:7918907

  13. Calcium

    MedlinePLUS

    ... prevent falls in women, but not in men. Metabolic syndrome. Some evidence suggests that getting more calcium from ... vitamin D, might lower the risk of developing metabolic syndrome. Cancer. Research shows that healthy older women who ...

  14. Effect of feeding high calcium levels and soft phosphate in the diet of laying hens

    E-print Network

    Durham, James Ivey

    1961-01-01

    and the Poultry Science Departmert of the Agricultural and Mechanical College of Texas for the opportunity and facilities to pursue graduate worl. . To Dr. R. E. Davles for his contirued assistance throughout the course of this study. To fellow graduate... Correlation Cc attic. ients. Table 14 Simple Correlation Cceit'icients. . PIGCItES Pigure 1 Percent. Egg P eduction of Mens Peri Vs&tying Die":rry Calcium Levels of Oyster She11 Flour in the frsstr &n. . . . . . . . 'lS Figure 2 Per¢ Egg Prociu. cion...

  15. X-ray powder diffraction patterns of calcium phosphates analyzed by the Rietveld method.

    PubMed

    Keller, L

    1995-11-01

    Least-square refinement of x-ray powder diffraction patterns analyzed by the Rietveld method can yield structural information which had been unattainable or at least elaborate to obtain by conventional pattern analysis. The Rietveld method calculates a powder pattern on the basis of a structural model as well as the characteristics of the instrument used, and minimizes the differences between the intensities observed and the intensities calculated. The method is applied on patterns produced powders or polycrystalline solids on conventional powder diffractometers. For materials containing more than one crystalline phase with known structures such as hydroxyapatite (HA) and whitlockite (beta-TCP), pattern analysis yields phase quantification without internal or external standards. Refinement of the lattice parameters a0 and c0 determines the degree of dehydroxylation in plasma-sprayed HA coatings. The presence of amorphous Ca phosphates in HA coatings is detected by background modeling. The calculation of entire powder patterns allows discrimination of small concentrations of poorly crystallized Ca phosphate phases against the background, and prevents gross aberrations in estimating secondary phases. Even detect structures such as an OH-deficient HA lattice can be detected through slight differences in diffracted intensity by which the pattern calculated deviates from the pattern observed. PMID:8582909

  16. The effect of calcium phosphate composite scaffolds on the osteogenic differentiation of rabbit dental pulp stem cells.

    PubMed

    Ling, Ling E; Feng, Lin; Liu, Hong-Chen; Wang, Dong-Sheng; Shi, Zhan-Ping; Wang, Jun-Cheng; Luo, Wei; Lv, Yan

    2015-05-01

    The objective of this study is to compare the effects of the two calcium phosphate composite scaffolds on the attachment, proliferation, and osteogenic differentiation of rabbit dental pulp stem cells (DPSCs). One nano-hydroxyapatite/collagen/poly (l-lactide) (nHAC/PLA), imitating the composition and the micro-structure characteristics of the natural bone, was made by Beijing Allgens Medical Science & Technology Co., Ltd. (China). The other beta-tricalcium phosphate (?-TCP), being fully interoperability globular pore structure, was provided by Shanghai Bio-lu Biomaterials Co, Ltd. (China). We compared the absorption water rate and the protein adsorption rate of two scaffolds and the characterization of DPSCs cultured on the culture plate and both scaffolds under osteogenic differentiation media (ODM) treatment. The constructs were then implanted subcutaneously into the back of severely combined immunodeficient (SCID) mice for 8 and 12 weeks to compare their bone formation capacity. The results showed that the ODM-treated DPSCs expressed osteocalcin (OCN), bone sialoprotein (BSP), type I collagen (COLI) and osteopontin (OPN) by immunofluorescence staining. Positive alkaline phosphatase (ALP) staining, calcium deposition and calcium nodules were also observed on the ODM-treated DPSCs. The absorption water rate and protein adsorption rate of nHAC/PLA was significantly higher than ?-TCP. The initial attachment of DPSCs seeded onto nHAC/PLA was significantly higher than that onto ?-TCP; and the proliferation rate of the cells was also significantly higher than that of ?-TCP on 1, 3, and 7 days of cell culture. The ALP activity, calcium/phosphorus content and mineral formation of DPSCs?+??-TCP were significantly higher than DPSCs?+?nHAC/LA. When implanted into the back of SCID mice, nHAC/PLA alone had no new bone formation, newly formed mature bone and osteoid were only observed in ?-TCP alone, DPSCs?+?nHAC/PLA and DPSCs?+??-TCP, and this three groups displayed increased bone formation over the 12-week period. The percentage of total bone formation area had no difference between DPSCs?+??-TCP and DPSCs?+?nHAC/PLA at each time point, but the percentage of mature bone formation area of DPSCs?+??-TCP was significantly higher than that of DPSCs?+?nHAC/PLA. Our results demonstrated that the DPSCs on nHAC/PLA had a better proliferation, and that the DPSCs on ?-TCP had a more mineralization in vitro, much more newly formed mature bones in vivo were presented in DPSCs?+??-TCP group. These findings have provided a further knowledge that scaffold architecture has different influence on the attachment, proliferation and differentiation of cells. This study may provide insight into the clinical periodontal bone tissue repair with DPSCs?+??-TCP construct. PMID:25131439

  17. The viability of mouse spermatogonial germ cells on a novel scaffold, containing human serum albumin and calcium phosphate nanoparticles

    PubMed Central

    Yadegar, Mona; Hekmatimoghaddam, Seyed Hossein; Nezami Saridar, Saeide; Jebali, Ali

    2015-01-01

    Background: In spermatogenesis, spermatogonial cells differentiate to the haploid gametes. It has been shown that spermatogenesis can be done at in vitro condition. In vitro spermatogenesis may provide an open window to treat male infertility. Objective: The aim of this study was to evaluate the effects of a novel scaffold containing human serum albumin (HSA)/tri calcium phosphate nanoparticles (TCP NPs) on the mouse spermatogonial cell line (SCL). Materials and Methods: First, TCP NPs were synthesized by reaction of calcium nitrate and diammonium phosphate at pH 13. Then, serial concentrations of TCP NPs were separately added to 500 mg/mL HSA, and incubated in the 100oC water for 30 min. In the next step, each scaffold was cut (2×2mm), placed into sterile well of microplate, and then incubated for 1, 2, and 3 days at 37oC with mouse SCL. After incubation, the cytotoxicity of the scaffolds was evaluated by different tests including 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) assay, vital staining, and cell counting. On the other hand, the release of TCP NPs and HSA from the scaffolds was measured. Results: Based on microscopic observation, the size of cavities for all scaffolds was near 200-500 µm, and the size of TCP NPs was near 50-100 nm. All toxicity tests showed that the increase of TCP concentration in the scaffold did not affect mouse SCL. It means that the percentage of cell viability, LDH release, vital cells, and cell quantity was 85%, 105%, 90%, and 110%, respectively. But, the increase of incubation time led to increase of LDH release (up to 115%) and cell count (up to 115%). Also, little decrease of cell viability and vital cells was seen when incubation time was increased. Here, no release of TCP NPs and HSA was seen after increase of TCP concentration and incubation time. Conclusion: It can be concluded that the increase of TCP concentration in HSA/ TCP NPs scaffold does not lead to cytotoxicity. On the other hand, the increase of incubation time leads to increase of mouse SCL cell death. In this study, it was found that TCP NPs and HSA could not release from the scaffolds. In future, both proliferation and differentiation of mouse SCL on HSA/TCP NPs scaffold must be checked over more wide incubation times. PMID:26000004

  18. Processing highly porous calcium phosphate ceramics for use in bioreactor cores for culturing human liver cells in-vitro

    NASA Astrophysics Data System (ADS)

    Finoli, Anthony

    Chronic liver disease is the 11th highest cause of death in the United States claiming over 30,000 lives in 2009. The current treatment for chronic liver failure is liver transplantation but the availability of tissue is far less than the number of patients in need. To develop human liver tissue in the lab a 3D culturing environment must be created to support the growth of a complex tissue. Hydroxyapatite (HAp) has been chosen as a scaffold material because of its biocompatibility in the body and the ability to create a bioresorbable scaffold. By using a ceramic material, it is possible to create a three dimensional, protective environment in which tissue can grow. The first part of this study is to examine the behavior of adult human liver cells grown on composites of HAp and different biocompatible hydrogels. Porous HAp has been created using an emulsion foaming technique and cells are injected into the structure after being suspended in a hydrogel and are kept in culture for up to 28 days. Functional assays, gene expression and fluorescent microscopy will be used to examine these cultures. The second part of this study will be to develop a processing technique to create a resorbable scaffold that incorporates a vascular system template. Previous experiments have shown the high temperature decomposition of HAp into resorbable calcium phosphates will be used to create a multiphase material. By controlling the amount of transformation product formed, it is proposed that the resorption of the scaffold can be tailored. To introduce a pore network to guide the growth of a vascular system, a positive-negative casting technique has also been developed. A positive polymer copy can be made of a natural vascular system and ceramic is foamed around the copy. During sintering, the polymer is pyrolyzed leaving a multiscale pore network in the ceramic. By combining these techniques, it is proposed that a calcium phosphate bioreactor core can be processed that is suitable for the culturing of human liver tissue.

  19. A new method for the preparation of bioactive calcium phosphate films hybridized with 1alpha,25-dihydroxyvitamin D3.

    PubMed

    Jung, Jae-Young; Hong, Yun-Jung; Choi, Yong Seok; Jeong, Sunjoo; Lee, Woo-Kul

    2009-12-01

    The primary goal of this investigation was to develop a calcium phosphate film hybridized with 1alpha,25-dihydroxyvitamin D(3) for the improvement of osteoconductivity of bone substitutes. The hybrid films (hCaP) were prepared at the different concentrations of 1 x 10(-10), 1 x 10(-8), and 1 x 10(-6) M designated as hCaPL, hCaPM, and hCaPH, respectively. The change of the hormone concentration during the preparation of the hybrid films did not cause significant variations on the physical properties of hCaPs, i.e. surface morphology and roughness. On the other hand, X-ray photon spectroscope (XPS) measurements revealed that the concentration change affected the chemical composition of the hybrid films. Recruitment of osteoblast-like MG-63 cells was considerably improved on hCaPs compared to tissue culture plate (TCP). However, cell proliferation on hCaPs was substantially suppressed and inversely proportional to the hormone concentration used. It was observed that bone-like nodules which consisted of bead-like components and well-developed matrix were rapidly formed on hCaPs. Masson's trichrome and safranin-O stainings elucidated that the bead-like components were MG-63 cells. Safranin-O staining showed that proteoglycan was produced actively. These results indicate that the cells cultured on hCaPs were strongly stimulated by the hormone to produce proteoglycan which can be considered as an induction of premature bone formation. The number of the nodules was increased with hormone concentration and most pronounced at the hCaPH. Gene expression patterns of alkaline phosphatase (ALP), transforming growth factor-beta (TGF-beta), and osteopontin (OPN) were strongly modulated by hybridized the hormone. For ALP and OPN, gene expressions were activated earlier on hCaPs than untreated calcium phosphate (CaP) confirming the effect of the hybridization was substantial. The TGF-beta gene expression was immediately activated after seeding but difference between samples was not significant suggesting that the gene expression was modulated not by the hormone hybridization but by CaP itself. As a result, hybridization of 1,25(OH)(2)D(3) with CaP can be a potentially strong candidate to promote osteoconductivity of implant materials. PMID:19593649

  20. The synergistic effects of Chinese herb and injectable calcium silicate/?-tricalcium phosphate composite on an osteogenic accelerator in vitro.

    PubMed

    Huang, Ming-Hsien; Kao, Chia-Tze; Chen, Yi-Wen; Hsu, Tuan-Ti; Shieh, Den-En; Huang, Tsui-Hsien; Shie, Ming-You

    2015-04-01

    This study investigates the physicochemical and biological effects of traditional Chinese medicines on the ?-tricalcium phosphate (?-TCP)/calcium silicate (CS) composites of bone cells using human dental pulp cell. CS is an osteoconductive and bioactive material. For this research we have combined ?-TCP and CS and check its effectiveness, a series of ?-TCP/CS composites with different ratios of Xu Duan (XD) were prepared to make new bioactive and biodegradable biocomposites for bone repair. XD has been used in Traditional Chinese Medicine for hundreds of years as an antiosteoporosis, tonic and antiaging agent for the therapy of low back pain, traumatic hematoma, threatened abortion and bone fractures. Formation of bone-like apatite, the diametral tensile strength, and weight loss of composites were considered before and after immersion in simulated body fluid (SBF). In addition, we also examined the effects of XD released from ?-TCP/CS composites and in vitro human dental pulp cell (hDPCs) and studied its behavior. The results show the XD-contained paste did not give any demixing when the weight ratio of XD increased to 5-10 % due to the filter-pressing effect during extrusion through the syringe. After immersion in SBF, the microstructure image showed a dense bone-like apatite layer covered on the ?-TCP/CS/XD composites. In vitro cell experiments shows that the XD-rich composites promote human dental pulp cells (hDPCs) proliferation and differentiation. However, when the XD quantity in the composite is more than 5 %, the amount of cells and osteogenesis protein of hDPCs were stimulated by XD released from ?-TCP/CS composites. The combination of XD in degradation of ?-TCP and osteogenesis of CS gives strong reason to believe that these calcium-based composite cements may prove to be promising bone repair materials. PMID:25786397

  1. An investigation of the chemical synthesis and high-temperature sintering behaviour of calcium hydroxyapatite (HA) and tricalcium phosphate (TCP) bioceramics.

    PubMed

    Cüneyt Ta?, A; Korkusuz, F; Timuçin, M; Akka?, N

    1997-02-01

    The experimental conditions for the synthesis of sub-micrometre, spherical particles of calcium hydroxyapatite [Ca10(PO4)6(OH)2] (HA) and tricalcium phosphate [Ca3(PO4)2] (TCP) are investigated through chemical coprecipitation from the aqueous solutions of calcium nitrate and di-ammonium hydrogen phosphate salts. The precipitation process employed was also found to be suitable for the production of sub-micrometre HA/TCP composite powders in situ. The synthesized pure HA and TCP powders were found to be stable even at 1300 degrees C in air for prolonged heating times. Bioceramic sample characterization was achieved by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and density and surface area measurements. Crystallographic analyses of HA powders were performed by the Rietveld method on the powder XRD data. PMID:15348776

  2. Preparation and Characterization of a Calcium Phosphate Ceramic for the Immobilization of Chloride-containing Intermediate Level Waste

    SciTech Connect

    Metcalfe, Brian; Donald, Ian W.; Scheele, Randall D.; Strachan, Denis M.

    2003-12-01

    Attention has recently been given to the immobilization of special categories of radioactive wastes, some of which contain high concentrations of actinide chlorides. Although vitrification in phosphate glass has been proposed, this was rejected because of the high losses of chloride. On the basis of non-radioactive and, more recently, radioactive studies, we have shown that calcium phosphate is an effective host for immobilizing the chloride constituents [1]. In this instance, the chlorine is retained as chloride, rather than evolved as a chlorine-bearing gas. The immobilized product is in the form of a free-flowing, non-hygroscopic powder, in which the chlorides are chemically combined within the mineral phases chlorapatite [Ca5(PO4)3Cl] and spodiosite [Ca2(PO4)Cl]. Data from studies on non-radioactive simulated waste consisting of a mixture of CaCl2 and SmCl3, and radioactive simulated waste composed of CaCl2 with PuCl3 or PuCl3 and AmCl3, are presented and compared. The XRD data confirm the presence of chlorapatite and spodiosite in the non-radioactive and radioactive materials. The durability of all specimens was measured with a modified MCC-1 test. Releases of Cl after 28 days were 1.6 x 10-3 g m-2 for the non-radioactive specimens and 7 x 10-3 g m-2 for the Pu-bearing specimens. Releases of Ca after 28 days were 0.3 x 10-3 and 2.0 x 10-3 g m-2 for the non-radioactive composition and the Pu composition, respectively, whilst release of Pu from the radioactive specimens was lower for the mixed Pu/Am specimen at 1.2 x 10-5g m-2. The release of Am from the mixed Pu/Am composition was exceptionally low at 2.4 x 10-7 g m-2. Overall, the release rate data suggest that the ceramics dissolve congruently, followed by precipitation of Sm, Pu and Am as less soluble phases, possibly oxides or phosphates. The differences in behaviour noted between non-radioactive and radioactive specimens are interpreted in terms of the crystal chemistry of the individual systems.

  3. Nucleation and growth of calcium phosphates in the presence of fibrinogen on titanium implants with four potentially bioactive surface preparations. An in vitro study

    Microsoft Academic Search

    Anna Arvidsson; Fredrik Currie; Per Kjellin; Young-Taeg Sul; Victoria Stenport

    2009-01-01

    The aim of this study was to compare the nucleating and crystal growth behaviour of calcium phosphates on four types of potentially\\u000a bioactive surfaces, using the simulated body fluid (SBF) model with added fibrinogen. Blasted titanium discs were modified\\u000a by alkali and heat treatment, anodic oxidation, fluoride treatment, or hydroxyapatite coating. The discs were immersed in\\u000a SBF with fibrinogen for

  4. Determination of Sr isotopes in calcium phosphates using laser ablation inductively coupled plasma mass spectrometry and their application to archaeological tooth enamel

    Microsoft Academic Search

    M. S. A. Horstwood; J. A. Evans; J. Montgomery

    2008-01-01

    The determination of accurate Sr isotope ratios in calcium phosphate matrices by laser ablation multi-collector ICP-MS is demonstrated as possible even with low Sr concentration archaeological material. Multiple on-line interference correction routines for doubly-charged REE, Ca dimers and Rb with additional calibration against TIMS-characterised materials are required to achieve this. The calibration strategy proposed uses both inorganic and biogenic apatite

  5. Osteoprotegerin (OPG) Production by Cells in the Osteoblast Lineage is Regulated by Pulsed Electromagnetic Fields in Cultures Grown on Calcium Phosphate Substrates

    Microsoft Academic Search

    Zvi Schwartz; Maya Fisher; Christoph H. Lohmann; Bruce J. Simon; Barbara D. Boyan

    2009-01-01

    Pulsed electromagnetic fields (PEMF) used clinically to stimulate bone formation enhance the osteogenic effects of BMP-2 on\\u000a human mesenchymal stem cells (MSCs) if the MSCs are grown in osteogenic medium and are cultured on calcium phosphate (CaP)\\u000a surfaces rather than tissue culture polystyrene plastic (TCPS). This study tested if PEMF’s effects on cells in the osteoblast\\u000a lineage are substrate dependent

  6. Kinetics of apatite formation on a calcium-silicate cement for root-end filling during ageing in physiological-like phosphate solutions.

    PubMed

    Gandolfi, Maria Giovanna; Taddei, Paola; Tinti, Anna; De Stefano Dorigo, Elettra; Rossi, Piermaria Luigi; Prati, Carlo

    2010-12-01

    The bioactivity of calcium silicate mineral trioxide aggregate (MTA) cements has been attributed to their ability to produce apatite in presence of phosphate-containing fluids. This study evaluated surface morphology and chemical transformations of an experimental accelerated calcium-silicate cement as a function of soaking time in different phosphate-containing solutions. Cement discs were immersed in Dulbecco's phosphate-buffered saline (DPBS) or Hank's balanced salt solution (HBSS) for different times (1-180 days) and analysed by scanning electron microscopy connected with an energy dispersive X-ray analysis (SEM-EDX) and micro-Raman spectroscopy. SEM-EDX revealed Ca and P peaks after 14 days in DPBS. A thin Ca- and P-rich crystalline coating layer was detected after 60 days. A thicker multilayered coating was observed after 180 days. Micro-Raman disclosed the 965-cm(-1) phosphate band at 7 days only on samples stored in DPBS and later the 590- and 435-cm(-1) phosphate bands. After 60-180 days, a layer approximately 200-900 ?m thick formed displaying the bands of carbonated apatite (at 1,077, 965, 590, 435 cm(-1)) and calcite (at 1,088, 713, 280 cm(-1)). On HBSS-soaked, only calcite bands were observed until 90 days, and just after 180 days, a thin apatite-calcite layer appeared. Micro-Raman and SEM-EDX demonstrated the mineralization induction capacity of calcium-silicate cements (MTAs and Portland cements) with the formation of apatite after 7 days in DPBS. Longer time is necessary to observe bioactivity when cements are immersed in HBSS. PMID:19943072

  7. Complete covalent structure of a proline-rich phosphoprotein, PRP-2, an inhibitor of calcium phosphate crystal growth from human parotid saliva.

    PubMed

    Schlesinger, D H; Hay, D I

    1986-04-01

    Human salivary secretions contain many proteins in which proline forms an unusually large fraction of the amino-acid residues present, typically from 20% to over 40%. These proteins are also unusually rich in glycine and glutamine, generally account for over half the total protein in saliva, and include acidic, basic and glycosylated molecules. The functions of most of these are not clearly defined. One group, however, the acidic proline-rich phosphoproteins (PRP), have been shown to be potent inhibitors of secondary precipitation (crystal growth) of calcium phosphate salts. Acting together with a salivary protein inhibitor of primary precipitation of calcium phosphates, statherin, the PRP stabilize saliva which is supersaturated with respect to the calcium phosphate salts which form dental enamel. These inhibitory activities act to provide a protective, reparative, but stable environment for dental enamel, which is important for maintaining the health of the teeth. The PRP are a complex group of phosphoproteins which include four major and at least eight minor members. The primary structures of three of the major proteins have been determined. These are PRP-1, also designated Protein-C, PRP-3, also designated Protein-A (17), and PRP-4. The designations PRP-1,-2,-3 and -4 will be used here. The purpose of this paper is to report the complete primary structure of PRP-2 as a further step towards establishing the structural basis of the biological activity of the PRP, and clarifying the genetic and biosynthetic relationships of these closely related proteins. PMID:3710693

  8. The effect of casein phosphopeptide amorphous calcium phosphate on the in vitro shear bond strength of orthodontic brackets

    PubMed Central

    Park, Sun-Youn; Cha, Jung-Yul; Kim, Kyoung-Nam

    2013-01-01

    Objective The purpose of this study was to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on the shear bond strength (SBS) of brackets bonded to non-demineralized teeth with either phosphoric acid etching or self-etching primer. Methods Sixty human premolars were randomly assigned to 1 of 4 treatment groups (n = 15 each): phosphoric acid etching (group 1); self-etching primer (group 2); CPP-ACP for 2 weeks + phosphoric acid etching (group 3), and CPP-ACP for 2 weeks + self-etching primer (group 4). After bonding of the maxillary premolar metal brackets, specimens were subjected to shear forces in a testing machine. Scanning electron microscopy was used to observe etching patterns on the enamel surfaces of all teeth. A 2-way analysis of variance was used to test for effects of CPP-ACP and etching system on SBS. Results Significantly higher mean SBSs were observed in groups subjected to phosphoric acid etching (i.e., groups 1 and 3; p < 0.05). On the other hand, SBSs did not appear to be influenced by CPP-ACP (i.e., groups 3 and 4; p > 0.05). We observed a uniform and clear etched pattern on the enamel surface of the phosphoric acid etching groups. Conclusions CPP-ACP does not significantly affect the SBS of orthodontic brackets bonded to non-demineralized teeth, regardless of which adhesive method is used to bond the brackets. PMID:23504444

  9. Comparing the Effects of Whey Extract and Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) on Enamel Microhardness

    PubMed Central

    Rezvani, Mohammad Bagher; Karimi, Mehrdad; Akhavan Rasoolzade, Raheleh; Haghgoo, Roza

    2015-01-01

    Statement of the Problem With the recent focus of researches on the development of non-invasive treatment modalities, the non-invasive treatment of early carious lesions by remineralization would bring a major advance in the clinical management of these dental defects. Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is considered to be effective in tooth remineralization. Purpose The aim of this in-vitro study was to compare the effects of whey and CPP-ACP in increasing the enamel microhardness. Materials and Method Microhardness of 30 sound human permanent premolars was measured before and after 8-minute immersion of samples in Coca-Cola. The teeth were then randomly divided into 3 groups and were immersed in artificial saliva, whey, and tooth mousse for 10 minutes. The changes of microhardness within each group and among the groups were recorded and analyzed using paired t-test. Results The microhardness increased in each group and between the groups; this increase was statistically significant (p= 0.009). Conclusion The effect of whey on increasing the enamel microhardness was more than that of tooth mousse. PMID:25759858

  10. Protein coated microcrystals formulated with model antigens and modified with calcium phosphate exhibit enhanced phagocytosis and immunogenicity?

    PubMed Central

    Jones, Sarah; Asokanathan, Catpagavalli; Kmiec, Dorota; Irvine, June; Fleck, Roland; Xing, Dorothy; Moore, Barry; Parton, Roger; Coote, John

    2014-01-01

    Protein-coated microcrystals (PCMCs) were investigated as potential vaccine formulations for a range of model antigens. Presentation of antigens as PCMCs increased the antigen-specific IgG responses for all antigens tested, compared to soluble antigens. When compared to conventional aluminium-adjuvanted formulations, PCMCs modified with calcium phosphate (CaP) showed enhanced antigen-specific IgG responses and a decreased antigen-specific IgG1:IgG2a ratio, indicating the induction of a more balanced Th1/Th2 response. The rate of antigen release from CaP PCMCs, in vitro, decreased strongly with increasing CaP loading but their immunogenicity in vivo was not significantly different, suggesting the adjuvanticity was not due to a depot effect. Notably, it was found that CaP modification enhanced the phagocytosis of fluorescent antigen-PCMC particles by J774.2 murine monocyte/macrophage cells compared to soluble antigen or soluble PCMCs. Thus, CaP PCMCs may provide an alternative to conventional aluminium-based acellular vaccines to provide a more balanced Th1/Th2 immune response. PMID:24120484

  11. A Combination of Biphasic Calcium Phosphate Scaffold with Hyaluronic Acid-Gelatin Hydrogel as a New Tool for Bone Regeneration

    PubMed Central

    Nguyen, Thuy Ba Linh

    2014-01-01

    A novel bone substitute was fabricated to enhance bone healing by combining ceramic and polymer materials. In this study, Hyaluronic acid (HyA)–Gelatin (Gel) hydrogel was loaded into a biphasic calcium phosphate (BCP) ceramic, and the resulting scaffold, with unique micro- and macroporous orientation, was evaluated for bone regeneration applications. The fabricated scaffold showed high interconnected porosity, with an average compressive strength of 2.8±0.15?MPa, which is usually recommended for cancellous bone substitution. In vitro cytocompatibility studies were conducted using bone marrow mesenchymal stem cells. The HyA-Gel–loaded BCP scaffold resulted in a significant increase in cell proliferation at 3 (p<0.05) and 7 days (p<0.001) and high alkaline phosphatase activities at 14 and 21 days. Furthermore, the in vivo studies showed that the implanted HyA-Gel–loaded BCP scaffold begins to degrade within 3 months after implantation. Histological sections also confirmed a rapid new bone formation and a high rate of collagen mineralization. A bone matrix formation was confirmed by positive immunohistochemistry staining of osteopontin, osteocalcin, and collagen type I. In vivo expression of extracellular matrix proteins demonstrated that this novel bone substitute holds great promise for use in stimulating new bone regeneration. PMID:24517159

  12. Contact nanofatigue shows crack growth in amorphous calcium phosphate on Ti, Co-Cr and Stainless steel.

    PubMed

    Saber-Samandari, Saeed; Gross, Karlis A

    2013-03-01

    Fatigue testing of load-bearing coated implants is usually very time-consuming and so a new contact nanofatigue test using a nanoindenter has been evaluated. A cube corner indenter provided the fastest indication of failure, through crack formation, compared to a spherical indenter. Contact nanofatigue was performed on a sintered hydroxyapatite and then on amorphous calcium phosphate splats produced on titanium, stainless steel and Co-Cr surfaces, made either at room temperature or on 250°C preheated surfaces. Sintered hydroxyapatite showed continual plastic deformation, but this is not that apparent for splats on metal surfaces. Substrate preheating was found to induce cracking in splats, explained by greater thermal residual stresses. Endurance during contact nanofatigue, measured as time to crack formation, was the lowest for splats on titanium followed by Co-Cr and stainless steel. The splat on titanium showed both cracking and plastic deformation during testing. Good agreement has been reached with previous studies with cracking directed to the substrate without splat delamination. Contact nanofatigue with the nanoindenter easily and quickly identifies cracking events that previously required detection with acoustic emission, and shows good feasibility for mechanical testing of discs and splats produced by thermal spraying, spray forming, laser-ablation, aerosol jet and ink jet printing. PMID:23164945

  13. Calcium phosphate/DNA co-precipitates encapsulated fast-degrading polymer films for substrate-mediated gene delivery.

    PubMed

    Zhang, Qiao; Zhao, Dong; Zhang, Xian-Zheng; Cheng, Si-Xue; Zhuo, Ren-Xi

    2009-10-01

    Calcium-phosphate/deoxyribose nucleic acid (Ca-P/DNA) co-precipitates were deposited on or encapsulated in fast-degrading polymer films with surface erosion degradation mechanism to mediate cell transfection. The polymer, cholic acid functionalized star poly(DL-lactide), was synthesized through the ring-opening polymerization of DL-lactide initiated by cholic acid. The releases of DNA from the Ca-P/DNA co-precipitates deposited film and the Ca-P/DNA co-precipitates encapsulated film were determined and compared. The in vitro gene transfections of HEK293 cells, Hela cells, and NIH 3T3 cells showed that the expression of pGL3-Luc plasmid could be effectively mediated by the Ca-P/DNA co-precipitates deposited and encapsulated polymer films. In addition, the films did not exhibit any additional cytotoxicity to the cells during the transfections, indicating that the fast-degrading polymer films have great potential in localized gene delivery. PMID:19402141

  14. Enhanced healing of rabbit segmental radius defects with surface-coated calcium phosphate cement/bone morphogenetic protein-2 scaffolds.

    PubMed

    Wu, Yi; Hou, Juan; Yin, ManLi; Wang, Jing; Liu, ChangSheng

    2014-11-01

    Large osseous defects remain a difficult clinical problem in orthopedic surgery owing to the limited effective therapeutic options, and bone morphogenetic protein-2 (BMP-2) is useful for its potent osteoinductive properties in bone regeneration. Here we build a strategy to achieve prolonged duration time and help inducting new bone formation by using water-soluble polymers as a protective film. In this study, calcium phosphate cement (CPC) scaffolds were prepared as the matrix and combined with sodium carboxymethyl cellulose (CMC-Na), hydroxypropylmethyl cellulose (HPMC), and polyvinyl alcohol (PVA) respectively to protect from the digestion of rhBMP-2. After being implanted in the mouse thigh muscles, the surface-modified composite scaffolds evidently induced ectopic bone formation. In addition, we further evaluated the in vivo effects of surface-modified scaffolds in a rabbit radius critical defect by radiography, three dimensional micro-computed tomographic (?CT) imaging, synchrotron radiation-based micro-computed tomographic (SR?CT) imaging, histological analysis, and biomechanical measurement. The HPMC-modified CPC scaffold was regarded as the best combination for segmental bone regeneration in rabbit radius. PMID:25280712

  15. Hybrid Calcium Phosphate-Polymeric Micelles Incorporating Gadolinium Chelates for Imaging-Guided Gadolinium Neutron Capture Tumor Therapy.

    PubMed

    Mi, Peng; Dewi, Novriana; Yanagie, Hironobu; Kokuryo, Daisuke; Suzuki, Minoru; Sakurai, Yoshinori; Li, Yanmin; Aoki, Ichio; Ono, Koji; Takahashi, Hiroyuki; Cabral, Horacio; Nishiyama, Nobuhiro; Kataoka, Kazunori

    2015-06-23

    Gadolinium (Gd) chelates-loaded nanocarriers have high potential for achieving magnetic resonance imaging (MRI)-guided Gd neutron capture therapy (GdNCT) of tumors. Herein, we developed calcium phosphate micelles hybridized with PEG-polyanion block copolymers, and incorporated with the clinical MRI contrast agent Gd-diethylenetriaminepentaacetic acid (Gd-DTPA/CaP). The Gd-DTPA/CaP were nontoxic to cancer cells at the concentration of 100 ?M based on Gd-DTPA, while over 50% of the cancer cells were killed by thermal neutron irradiation at this concentration. Moreover, the Gd-DTPA/CaP showed a dramatically increased accumulation of Gd-DTPA in tumors, leading to the selective contrast enhancement of tumor tissues for precise tumor location by MRI. The enhanced tumor-to-blood distribution ratio of Gd-DTPA/CaP resulted in the effective suppression of tumor growth without loss of body weight, indicating the potential of Gd-DTPA/CaP for safe cancer treatment. PMID:26033034

  16. Development of injectable organic/inorganic colloidal composite gels made of self-assembling gelatin nanospheres and calcium phosphate nanocrystals.

    PubMed

    Wang, Huanan; Bongio, Matilde; Farbod, Kambiz; Nijhuis, Arnold W G; van den Beucken, Jeroen; Boerman, Otto C; van Hest, Jan C M; Li, Yubao; Jansen, John A; Leeuwenburgh, Sander C G

    2014-01-01

    Colloidal gels are a particularly attractive class of hydrogels for applications in regenerative medicine, and allow for a "bottom-up" fabrication of multi-functional biomaterials by employing micro- or nanoscale particles as building blocks to assemble into shape-specific bulk scaffolds. So far, however, the synthesis of colloidal composite gels composed of both organic and inorganic particles has hardly been investigated. The current study has focused on the development of injectable colloidal organic-inorganic composite gels using calcium phosphate (CaP) nanoparticles and gelatin (Gel) nanospheres as building blocks. These novel Gel-CaP colloidal composite gels exhibited a strongly enhanced gel elasticity, shear-thinning and self-healing behavior, and gel stability at high ionic strengths, while chemical - potentially cytotoxic - functionalizations were not necessary to introduce sufficiently strong cohesive interactions. Moreover, it was shown in vitro that osteoconductive CaP nanoparticles can be used as an additional tool to reduce the degradation rate of otherwise fast-degradable gelatin nanospheres and fine-tune the control over the release of growth factors. Finally, it was shown that these colloidal composite gels support attachment, spreading and proliferation of cultured stem cells. Based on these results, it can be concluded that proof-of-principle has been obtained for the design of novel advanced composite materials made of nanoscale particulate building blocks which exhibit great potential for use in regenerative medicine. PMID:24012604

  17. The effect of two types chewing gum containing casein phosphopeptide-amorphous calcium phosphate and xylitol on salivary Streptococcus mutans

    PubMed Central

    Emamieh, Shila; Khaterizadeh, Yosra; Goudarzi, Hossein; Ghasemi, Amir; Baghban, Alireza Akbarzadeh; Torabzadeh, Hasan

    2015-01-01

    Aim: The aim was to evaluate the effect of sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and xylitol on salivary Streptococcus mutans. Materials and Methods: A total of 60 dental students of 20-25 years old, who volunteered after checking their health condition and signing an informed consent, were randomly allocated to receive one of the following interventions: (A) Chewing gum containing CPP-ACP; (B) containing xylitol. Subjects within the experimental groups were taken the gums 3 times daily, after each meal for a period of 3 weeks. Pre- and post-intervention unstimulated saliva samples were quantified for S. mutans counts. Results: A statistically significant reduction of salivary S. mutans was displayed in both groups A and B after the intervention when compared with baseline (P < 0.001), and group A shows more statistically significant reduction of salivary S. mutans than group B (P = 0.011). Conclusion: Daily consumption of chewing gum containing CPP-ACP and xylitol significantly reduces the level of salivary S. mutans, but chewing gum containing CPP-ACP can reduce the level of salivary S. mutans in more than xylitol chewing gum.

  18. Role of casein phosphopeptide amorphous calcium phosphate in remineralization of white spot lesions and inhibition of Streptococcus mutans?

    PubMed Central

    Vashisht, Ruchi; Indira, Rajamani; Ramachandran, S; Kumar, Anil; Srinivasan, Manali Ramakrishnan

    2013-01-01

    Introduction: To promote the remineralization by ionic exchange mechanism instead of invasive techniques many remineralizing agents can be used. Objective: To evaluate the remineralization effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on white spot lesions (WSLs) and its inhibitory effect on Streptococcus mutans colonization. Materials and Methods: The study group consisted of 60 subjects exhibiting at least 1-WSL. Subjects were randomly divided into 2 groups: A test group using CPP-ACP cream (GC-Tooth Mousse, Leuven, Belgium) and a control group using only fluoride containing toothpaste for a period of 3-month. Baseline WSLs were scored using DIAGNOdent device (KaVo Germany) and the saliva samples were collected to measure S. mutans counts. After the 3-month period the WSLs were again recorded and the saliva collection was repeated. Result: DIAGNOdent measurements were increased by time (P = 0.002) in the control group and no statistically significant difference (P = 0.217) was found in the test group by the 3-month period. In both groups, the mutans counts were decreased in the 3-month experimental period. Conclusion: These clinical and laboratory results suggested that CPP-ACP containing cream had a slight remineralization effect on the WSL in the 3-month evaluation period however, longer observation is recommended to confirm whether the greater change in WSLs is maintained. PMID:23956538

  19. Fretting wear behavior of calcium phosphate-mullite composites in dry and albumin-containing simulated body fluid conditions.

    PubMed

    Nath, Shekhar; Ummethala, Raghunandan; Basu, Bikramjit

    2010-04-01

    In a recent work, it has been shown that it is possible to achieve a better combination of compressive strength, flexural strength and toughness properties in calcium phosphate (CaP) composites containing 20 and 30 wt% mullite (3Al(2)O(3).2SiO(2)). In view of their potential application as load bearing implants, the present work reports the friction and wear properties of the newly developed composites against zirconia under dry ambient as well as in simulated body fluid (SBF) containing bovine serum albumin (BSA) protein. For comparison, experiments were also conducted on monolithic hydroxyapatite (HAp, Ca(10)(PO(4))(6)(OH)(2)) and mullite under identical conditions. Under the investigated fretting conditions, the mullite-containing composites exhibited higher coefficient of friction (COF) of 0.4-0.6, compared to pure HAp (COF approximately 0.25-0.3). Although the wear resistance of the composites containing 20 or 30 wt% mullite was better in dry conditions, higher wear rate was measured in SBF conditions. The difference in tribological properties has been analyzed in reference to the difference in phase assemblage and mechanical properties. A comparison with some competing biomaterials reveals good potential of the investigated CaP-mullite composites for application as wear resistant implants. PMID:20054617

  20. Lipid-calcium phosphate nanoparticles for delivery to the lymphatic system and SPECT/CT imaging of lymph node metastases.

    PubMed

    Tseng, Yu-Cheng; Xu, Zhenghong; Guley, Kevin; Yuan, Hong; Huang, Leaf

    2014-05-01

    A lipid/calcium/phosphate (LCP) nanoparticle (NP) formulation (particle diameter ?25 nm) with superior siRNA delivery efficiency was developed and reported previously. Here, we describe the successful formulation of (111)In into LCP for SPECT/CT imaging. Imaging and biodistribution studies showed that, polyethylene glycol grafted (111)In-LCP preferentially accumulated in the lymph nodes at ?70% ID/g in both C57BL/6 and nude mice when the improved surface coating method was used. Both the liver and spleen accumulated only ?25% ID/g. Larger LCP (diameter ?67 nm) was less lymphotropic. These results indicate that 25 nm LCP was able to penetrate into tissues, enter the lymphatic system, and accumulate in the lymph nodes via lymphatic drainage due to 1) small size, 2) a well-PEGylated lipid surface, and 3) a slightly negative surface charge. The capability of intravenously injected (111)In-LCP to visualize an enlarged, tumor-loaded sentinel lymph node was demonstrated using a 4T1 breast cancer lymph node metastasis model. Systemic gene delivery to the lymph nodes after IV injection was demonstrated by the expression of red fluorescent protein cDNA. The potential of using LCP for lymphatic drug delivery is discussed. PMID:24613050

  1. Hybrid calcium phosphate coatings with the addition of trace elements and polyaspartic acid by a low-thermal process.

    PubMed

    Xu, Sanzhong; Yang, Xianyan; Chen, Xiaoyi; Lin, Xiangjin; Zhang, Lei; Yang, Guojing; Gao, Changyou; Gou, Zhongru

    2011-06-01

    Research in the field of orthopedic implantology is currently focused on developing methodologies to potentiate osseointegration and to expedite the reestablishment of full functionality. We have developed a simple biomimetic approach for preparing trace elements-codoped calcium phosphate (teCaP) coatings on a titanium substrate. The reaction proceeded via low-thermal incubation in trace elements (TEs)-added simulated body fluid (teSBF) at 90 and 120 °C. The x-ray photoelectron spectroscopy, x-ray diffraction and energy-dispersive x-ray analyses demonstrated that the teCaP coating was the composite of hydroxyapatite and whitlockite, simultaneously doped with magnesium, strontium, zinc and silicon. The addition of polyaspartic acid and TEs into SBF significantly densified the coating. The incubation temperature is another important factor controlling the coating precipitation rate and bonding strength. An incubation temperature of 120 °C could accelerate the coating precipitation and improve the interface bonding strength. The in vitro cell culture investigation indicated that the teCaP coating supported the adhesion and spreading of ovariectomized rat mesenchymal stem cells (rMSCs) and particularly, promoted rMSCs proliferation compared to the CaP coating prepared in SBF. Collectively, from such a biomimetic route there potentially arises a general procedure to prepare a wide range of bioactive teCaP coatings of different composition for osteoporotic osteogenic cells activation response. PMID:21487175

  2. Rapid determination of hydrogen peroxide produced by Lactobacillus using enzyme coupled rhodamine isocyanide/calcium phosphate nanoparticles.

    PubMed

    Viswanathan, Kaliyaperumal; Vadivoo, V S; Raj, G Dhinakar

    2014-11-15

    A sensitive method for detecting hydrogen peroxide (H2O2) using rhodamine isocyanide incorporated calcium phosphate nanoparticles (Rho/CaP) was developed. The synthesized nanoparticles were characterized based on transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction patterns (XRD). To study the application, the nanoparticles were functionalized with horse radish peroxidase (HRP) based on aminopropyl triethoxy silane (APTES) and used as tools to detect H2O2. The detection strategy was based on fluorescence quenching or colorimetric detection. The enzyme immobilized nanoparticles were titrated with different concentrations of H2O2 and a fixed concentration of O-phenylenediamine (OPD). The HRP conjugated Rho/CaP strongly catalyzed H2O2 oxidation of OPD that caused fluorescence quenching at 575 nm. For colorimetric detection, the OPD product was read at 492 nm. In the fluorescence quenching assay, the minimum detectable concentration was ~1 pmol in contrast to ~5 nmol in the colorimetric assay. The minimum detectable concentration by visual detection was ~500 nmol. The specificity of the developed assay method was examined with different interferences which did not produce any significant response. This assay was applied, along with a commercially available kit to compare the H2O2 production capacities of different Lactobacillus strains. The results indicated that the developed assay and commercially available kit methods were highly correlated. The fluorescence quenching kinetics is also discussed. PMID:24886832

  3. A novel injectable, cohesive and toughened Si-HPMC (silanized-hydroxypropyl methylcellulose) composite calcium phosphate cement for bone substitution.

    PubMed

    Liu, Weizhen; Zhang, Jingtao; Rethore, Gildas; Khairoun, Khalid; Pilet, Paul; Tancret, Franck; Bouler, Jean-Michel; Weiss, Pierre

    2014-07-01

    This study reports on the incorporation of the self-setting polysaccharide derivative hydrogel (silanized-hydroxypropyl methylcellulose, Si-HPMC) into the formulation of calcium phosphate cements (CPCs) to develop a novel injectable material for bone substitution. The effects of Si-HPMC on the handling properties (injectability, cohesion and setting time) and mechanical properties (Young's modulus, fracture toughness, flexural and compressive strength) of CPCs were systematically studied. It was found that Si-HPMC could endow composite CPC pastes with an appealing rheological behavior at the early stage of setting, promoting its application in open bone cavities. Moreover, Si-HPMC gave the composite CPC good injectability and cohesion, and reduced the setting time. Si-HPMC increased the porosity of CPCs after hardening, especially the macroporosity as a result of entrapped air bubbles; however, it improved, rather than compromised, the mechanical properties of composite CPCs, which demonstrates a strong toughening and strengthening effect. In view of the above, the Si-HPMC composite CPC may be particularly promising as bone substitute material for clinic application. PMID:24657196

  4. A Novel Application of Calcium Phosphate-Based Bone Cement as an Adjunct Procedure in Adult Craniofacial Reconstruction

    PubMed Central

    Ho, Samuel; Nallathamby, Vigneswaran; Ng, Huiwen; Ho, Michelle; Wong, Marcus

    2011-01-01

    Secondary corrective osteotomy of malunited craniofacial fractures can be a challenging proposition. The exposure, extrusion, and palpability of the titanium implants used become a genuine concern especially in areas of relatively thin skin, such as the periorbital region. Restoring a satisfactory contour to the midface is another major task for the plastic surgeon. Bone cement used to reconstruct craniofacial defects has existed for many years. However, most applications have been as a substitute for autogenous bone grafts for defects less than 25 cm2. In this article, we present two cases of malunited facial fractures that underwent corrective osteotomy, during which we felt that despite the conventional osteotomy and reduction techniques, there was still either a small remnant step deformity or suboptimal contour smoothness due to prominence of the implants used. We thus used bone cement as a resurfacing medium over titanium implants to restore good malar contour and reduce the palpability and exposure rate of the titanium implants. We report good patient satisfaction with contour correction with no increase in wound infection rates or any delay in wound healing. There was initial chemosis associated with the use of the bone cement, which resolved in both patients within 3 to 4 weeks. Postoperative computed tomography showed some degree of osteointegration but no fraction of the bone cement. Calcium phosphate bone cement thus presents an attractive adjunctive method for midfacial contour resurfacing, when used in conjunction with conventional osteotomy procedures and as an onlay over prominent titanium implants. PMID:23205176

  5. Direct write assembly of calcium phosphate scaffolds using a water-based hydrogel.

    PubMed

    Franco, J; Hunger, P; Launey, M E; Tomsia, A P; Saiz, E

    2010-01-01

    The development of materials to support bone regeneration requires flexible fabrication technologies able to tailor chemistry and architecture for specific applications. In this work we describe the preparation of ceramic-based inks for robotic-assisted deposition (robocasting) using Pluronic F-127 solutions. This approach allows the preparation of pseudoplastic inks with solid contents ranging between 30 and 50 vol.%, enabling them to flow through a narrow printing nozzle while supporting the weight of the printed structure. Ink formulation does not require manipulation of the pH or the use of highly volatile organic components. Therefore, the approach can be used to prepare materials with a wide range of compositions, and here we use it to build hydroxyapatite (HA), beta-tricalcium phosphate (beta-TCP) and biphasic (HA/beta-TCP) structures. The flow of the inks is controlled by the Pluronic content and the particle size distribution of the ceramic powders. The use of wide size distributions favors flow through the narrow printing nozzles and we have been able to use printing nozzles as narrow as 100 microm in diameter, applying relatively low printing pressures. The microporosity of the printed lines increases with increasing Pluronic content and lower sintering temperatures. Microporosity can play a key role in determining the biological response to the materials, but it also affects the strength of the structure. PMID:19563923

  6. Nanouric acid or nanocalcium phosphate as central nidus to induce calcium oxalate stone formation: a high-resolution transmission electron microscopy study on urinary nanocrystallites

    PubMed Central

    Gao, Jie; Xue, Jun-Fa; Xu, Meng; Gui, Bao-Song; Wang, Feng-Xin; Ouyang, Jian-Ming

    2014-01-01

    Purpose This study aimed to accurately analyze the relationship between calcium oxalate (CaOx) stone formation and the components of urinary nanocrystallites. Method High-resolution transmission electron microscopy (HRTEM), selected area electron diffraction, fast Fourier transformation of HRTEM, and energy dispersive X-ray spectroscopy were performed to analyze the components of these nanocrystallites. Results The main components of CaOx stones are calcium oxalate monohydrate and a small amount of dehydrate, while those of urinary nanocrystallites are calcium oxalate monohydrate, uric acid, and calcium phosphate. The mechanism of formation of CaOx stones was discussed based on the components of urinary nanocrystallites. Conclusion The formation of CaOx stones is closely related both to the properties of urinary nanocrystallites and to the urinary components. The combination of HRTEM, fast Fourier transformation, selected area electron diffraction, and energy dispersive X-ray spectroscopy could be accurately performed to analyze the components of single urinary nanocrystallites. This result provides evidence for nanouric acid and/or nanocalcium phosphate crystallites as the central nidus to induce CaOx stone formation. PMID:25258530

  7. Calcium-Citrate-Phosphate Solution Injection for In Situ Strontium-90 Immobilization

    NASA Astrophysics Data System (ADS)

    Fruchter, J. S.; Vermeul, V.; Szecsody, J.; Williams, M. D.; Fritz, B. G.

    2010-12-01

    Sr-90 present in groundwater and the vadose zone at the Hanford 100N area due to past waste disposal practices has reached the nearby Columbia River, as evidenced by Sr-90 concentrations in near river wells and aquifer tubes and near shore sediments. Sr-90 is currently being remediated by adsorption onto apatite (55 times stronger than Sr-90 adsorption to sediment), followed by incorporation of the Sr-90 into the apatite structure. If the Sr-90 can remain immobilized for 300 years (~ten 29.1-yr half-lives of Sr-90 decay), it will have decayed below regulatory limits to Y-90 and to stable Zr-90. Apatite [Ca10(PO4)6(OH)2] is being precipitated in situ by injection of an aqueous solution of Ca-citrate and Na-phosphate through a series of injection wells spaced 30 ft on center, forming a 300-ft-long permeable reactive barrier. Design criteria for the injection operations were based on 1) amendment volume and mass injected, 2) amendment arrival at adjacent wells, 3) water-level elevation during treatment, and 4) injection rate limitations associated with well plugging. An evaluation of compliance with these injection design criteria was used to assess operational performance and identify candidate wells for supplemental treatment. Injection design criteria were not fully met at 8 of the 16 injection well locations, with the primary deficiency at 4 of 8 locations being the limited vertical extent of Hanford formation treatment due to low-river-stage conditions during the injection. Wells whose extent of treatment did not meet design criteria were recommended for retreatment. Although injection design criteria were not fully met at a significant number of well locations, aqueous performance assessment monitoring data collected to date indicate good barrier performance. Aqueous Sr-90 monitoring in four compliance monitoring wells over a year following the high concentration injections indicates 84% to 95% decrease in Sr-90 concentrations (relative to the low and high end of the baseline range, respectively). In addition, post treatment sediment cores were collected to quantify the amount of apatite that was formed from the barrier-emplacement operations. Results indicate that the processes that account for the observed reduction in aqueous Sr-90 concentrations include: a) incorporation of Sr-90 into apatite (about 39.4% of the total Sr-90 mass in the core), b) ion exchange flushing due to the Ca-citrate-PO4 solution injection (about 47% of the mass), and c) a small increase in Sr-90 adsorbed to sediment and apatite precipitate.

  8. Study on the bonding strength between calcium phosphate/chitosan composite coatings and a Mg alloy substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Dai, Chang-Song; Wei, Jie; Wen, Zhao-Hui

    2012-11-01

    In order to improve the bonding strength between calcium phosphate/chitosan composite coatings and a micro-arc oxidized (MAO)-AZ91D Mg alloy, different influencing parameters were investigated in the process of electrophoretic deposition (EPD) followed by conversion in a phosphate buffer solution (PBS). Surface morphology and phase constituents of the as-prepared materials were investigated by using X-ray diffractometer (XRD), Fourier-transformed infrared spectrophotometer (FTIR), Raman spectrometer, scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS), and a thermo gravimetric and differential thermal analyzer (TG-DTA). Scratch tests were carried out to study the bonding properties between the coatings and the substrates. In vitro immersion tests were conducted to determine the corrosion behaviors of samples with and without deposit layers through electrochemical experiments. In the EPD process, the acetic acid content in the electrophoresis suspension and the electrophoretic voltage played important roles in improving the bonding properties, while the contents of chitosan (CS) and nano-hydroxyapatite (nHA, Ca10(PO4)6(OH)2) in the suspension had less significant influences on the mechanical bonding strength. It was observed that the coatings showed the excellent bonding property when an electrophoretic voltage was in a range of 40-110 V with other reagent amounts as follows: acetic acid: 4.5 vol.%, CS ? 0.25 g, nHA ? 2.0 g in 200 ml of a CS-acetic acid aqueous solution and nHA ? 2.5 g in 300 ml of absolute ethanol. The morphology of the composite coating obtained under the above optimal condition had a flake-like crystal structure. The EPD in the nHA/CS-acetic acid/ethanol suspension resulted in hydroxyapatite, chitosan, brushite (DCPD, CaHPO4·2H2O) and Ca(OH)2 in the coatings. After the as-prepared coating materials were immersed into PBS, Ca(OH)2 could be converted into HA and DCPD. The results of the electrochemical tests manifested that the corrosion resistance of the Mg alloy was improved by coating this composite film.

  9. Amorphous calcium phosphate nanoparticles could function as a novel cancer therapeutic agent by employing a suitable targeted drug delivery platform

    NASA Astrophysics Data System (ADS)

    Pourbaghi-Masouleh, Milad; Hosseini, Vahid

    2013-10-01

    Employment of nanovehicular system for delivering apoptogenic agent to cancer cells for inducing apoptosis has widely been investigated. Loading efficacy and controlled release of the agents are of the inseparable obstacles that hamper the efforts in reaching an efficacious targeted cancer therapy method. When the carrier itself is apoptogenic, then there is no need to load the carrier with apoptogenic agent and just delivering of the particle to the specific location matters. Hence, we hypothesize that amorphous calcium phosphate nanoparticle (ACPN) is a potent candidate for apoptosis induction, although encapsulation in liposome shell, and surface decoration with targeting ligand (TL), and cell-penetrating peptide (CPP) plays a pivotal role in the employment of this agent. It is well understood that elevation in cytosolic Ca2+ ([Ca2+]c) would result in the induction of apoptosis. ACPN has the potential to cause imbalance in this medium by elevating [Ca2+]c. Owning to the fact that the nanoparticles should be delivered into cytosol, it is necessary to trap them in a liposomal shell for evading endocytosis. It was demonstrated that employment of the trans-activator of transcription (TAT) as CPP eminently enhances the efficacy of endosomal escape; therefore, the platform is designed in a way that TAT is positioned on the surface of the liposome. Due to the fact that the apoptosis should be induced in sole cancer cells, Folate as TL is also attached on the surface of the liposome. This hypothesis heralds the new generation of chemotherapeutic agents and platforms which could have less side effect than the most common ones, in addition to other advantages they have.

  10. Casein phosphopeptide-amorphous calcium phosphate incorporated into sugar confections inhibits the progression of enamel subsurface lesions in situ.

    PubMed

    Walker, G D; Cai, F; Shen, P; Adams, G G; Reynolds, C; Reynolds, E C

    2010-01-01

    Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) has been demonstrated to exhibit anticariogenic activity in randomized, controlled clinical trials of sugar-free gum and a tooth cream. Two randomized, double-blind, crossover studies were conducted to investigate the potential of CPP-ACP added to hard candy confections to slow the progression of enamel subsurface lesions in an in situ model. The confections studied were: (1) control sugar (65% sucrose + 33% glucose syrup); (2) control sugar-free; (3) sugar + 0.5% (w/w) CPP-ACP; (4) sugar + 1.0% (w/w) CPP-ACP; (5) sugar-free + 0.5% (w/w) CPP-ACP. Participants (10 and 14 in study 1 and 2) wore a removable palatal appliance containing enamel half-slabs with subsurface lesions, except for meals and oral hygiene procedures, and consumed 1 confection 6 times a day for 10 days. The enamel half-slabs were inset to allow the development of plaque on the enamel surface. Participants rested for 1 week before crossing over to another confection. The appliances were stored in a humid container at 37 degrees C when not in the mouth. After each treatment period, the enamel half-slabs were removed, paired with their demineralized control half-slabs, embedded, sectioned and then analysed using transverse microradiography. In both studies consumption of the control sugar confection resulted in significant demineralization (progression) of the enamel subsurface lesions. However, consumption of the sugar confections containing CPP-ACP did not result in lesion progression, but in fact in significant remineralization (regression) of the lesions. Remineralization by consumption of the sugar + 1.0% CPP-ACP confection was significantly greater than that obtained with the sugar-free confection. PMID:20090326

  11. Elutions of metal ions from dental casting alloys and their effect on calcium phosphate precipitation and transformation.

    PubMed

    Hidaka, S; Okamoto, Y; Abe, K

    1994-02-01

    The elution characteristics of metal ions from dental casting alloys were studied in vitro. Large amounts of nickel (0.12-4.94 mg/cm2) and chromium (< 0.01-0.63 mg/cm2) were solubilized from the surface of seven brands of nickel-chromium alloy in either 1% lactic acid or 0.05% hydrochloric acid solutions. The elution of chromium from two brands of cobalt-chromium alloys in both eluents was below the detection limit or less than 0.01 mg/cm2. The elution of tin, copper, and zinc from a gold-palladium-silver alloy in both eluents was below the detection limit or less than 0.01 and 0.04 mg/cm2. Some amounts of tin (0.19-1.92 mg/cm2) and zinc (0.56-1.73 mg/cm2) were eluted from a silver alloy in both eluents. The effects of five eluting metal ions, i.e., nickel, chromium, tin, copper, and zinc, on the conversion of amorphous calcium phosphate (ACP) to hydroxyapatite (HAP) in vitro also were studied by a pH drop method. All divalent cations except for chromium decreased the rate of HAP transformation and elongated the induction time. Nickel had an inhibitory effect comparable to 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) on the rate of HAP transformation. Tin, copper, and zinc inhibited similarly, but the inhibition was weaker than that by nickel. Chromium did not inhibit these reactions. PMID:8207028

  12. In ovo delivery of Newcastle disease virus conjugated hybrid calcium phosphate nanoparticle and to study the cytokine profile induction.

    PubMed

    Viswanathan, Kaliyaperumal; Rathish, P; Gopinath, V P; Janice, R; Raj, G Dhinakar

    2014-12-01

    In this report, the hybrid calcium phosphate (CaP) nanoparticles were synthesized and functionalized with Newcastle disease virus (NDV). These nanoparticles were synthesized by a combination of co-precipitation and polymerization process and functionalized with amino propyl triethoxy silane before coupling to NDV. The 5-dimethylthiazol-2-yl-2, 5-diphenyltetrazolium bromide (MTT) assay of chicken spleen cells incubated with these nanoparticles indicated that, these particles did not exert any significant cytotoxicity. The effects of hybrid CaP nanoparticles on cell cycle were assayed using a flow cytometer. The results demonstrated that the cell viability and proliferation capacity of spleen cells were not affected by hybrid CaP nanoparticles compared with their control cells. The hybrid CaP nanoparticles were characterized by scanning/transmission electron microscopy (SEM/TEM); Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction patterns (XRD), Raman spectroscopy and energy-dispersive X-ray spectroscopy (EDX). These methods revealed that NDV was successfully conjugated on nanoparticles. The ability of the hybrid CaP nanoparticles to induce different cytokine mRNAs in the spleen cells of 18-day old embryonated chicken eggs (ECEs) was studied by quantitative real time polymerase chain reaction (qRT-PCR). NDV conjugated particles induced a high expression of Th1 cytokines such as interferon (IFN)-?, tumor necrosis factor (TNF)-? of and Th2 cytokines, interleukin (IL) 6 and IL-10. Uncoupled NDV induced only Th1 cytokines, IFN-?, INF-? and TNF-?. The hybrid particles alone did not induce any cytokines. This confirmed that nanoparticle coupling could induce differential cytokine profiles and hence can be used as an alternate strategy to direct favorable immune responses in animals or chickens using appropriate vaccination carrier. PMID:25491865

  13. Fixation of bioactive calcium alkali phosphate on Ti6Al4V implant material with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Symietz, Christian; Lehmann, Erhard; Gildenhaar, Renate; Koter, Robert; Berger, Georg; Krüger, Jörg

    2011-04-01

    Bone implants made of metal, often titanium or the titanium alloy Ti6Al4V, need to be surface treated to become bioactive. This enables the formation of a firm and durable connection of the prosthesis with the living bone. We present a new method to uniformly cover Ti6Al4V with a thin layer of ceramics that imitates bone material. These calcium alkali phosphates, called GB14 and Ca10, are applied to the metal by dip coating of metal plates into an aqueous slurry containing the fine ceramic powder. The dried samples are illuminated with the 790 nm radiation of a pulsed femtosecond laser. If the laser fluence is set to a value just below the ablation threshold of the ceramic (ca. 0.4 J/cm 2) the 30 fs laser pulses penetrate the partly transparent ceramic layer of 20-40 ?m thickness. The remaining laser fluence at the ceramic-metal interface is still high enough to generate a thin metal melt layer leading to the ceramic fixation on the metal. The laser processing step is only possible because Ti6Al4V has a lower ablation threshold (between 0.1 and 0.15 J/cm 2) than the ceramic material. After laser treatment in a fluence range between 0.1 and 0.4 J/cm 2, only the particles in contact with the metal withstand a post-laser treatment (ultrasonic cleaning). The non-irradiated rest of the layer is washed off. In this work, we present results of a successful ceramic fixation extending over larger areas. This is fundamental for future applications of arbitrarily shaped implants.

  14. PEGylated carboxymethyl chitosan/calcium phosphate hybrid anionic nanoparticles mediated hTERT siRNA delivery for anticancer therapy.

    PubMed

    Xie, Ying; Qiao, Hongzhi; Su, Zhigui; Chen, Minglei; Ping, Qineng; Sun, Minjie

    2014-09-01

    Lack of safe and effective delivery vehicle is the main obstacle for siRNA mediated cancer therapy. In this study, we synthesized a pH-sensitive polymer of PEG grafted carboxymethyl chitosan (PEG-CMCS) and developed anionic-charged hybrid nanoparticles of PEG-CMCS and calcium phosphate (CaP) for siRNA delivery through a single-step self-assembly method in aqueous condition. The formed nanoparticles with charge of around -8.25 mv and average diameter of 102.1 nm exhibited efficient siRNA encapsulation and enhanced colloidal and serum stability. The test in vitro indicated that the nanoparticles entered into HepG2 cells by endocytosis, and achieved endosomal escape of siRNA effectively due to the pH-responsive disassembly of nanoparticles and dissolution of CaP in the endosome. Reporter gene silencing assay showed that luciferase siRNA delivered by the anionic nanoparticles could achieve gene silencing efficacy comparable to that of conventional Lipofectamine 2000. Additionally, dramatic hTERT knockdown mediated by the anionic nanoparticles transfection induced significant apoptosis of HepG2 cells in vitro. After intravenous injection in tumor-bearing BALB/c nude mice, the nanoparticles specifically accumulated into tumor regions by EPR effect, leading to efficient and specific gene silencing sequentially. Most importantly, the nanoparticles carrying hTERT siRNA inhibited tumor growth significantly via silencing hTERT expression and inducing cells apoptosis in HepG2 tumor xenograft. Moreover, comprehensive safety studies of the nanoparticles confirmed their superior safety both in vitro and in vivo. We concluded that the PEG-CMCS/CaP hybrid anionic nanoparticles possessed potential as a safe and effective siRNA delivery system for anticancer therapy. PMID:24939077

  15. Using scratch testing to measure the adhesion strength of calcium phosphate coatings applied to poly(carbonate urethane) substrates.

    PubMed

    Barnes, Dunstan; Johnson, Scott; Snell, Robert; Best, Serena

    2012-02-01

    Bioactive coatings are applied to components of modern orthopædic implants to improve the host tissue response to the implants. Such coatings cannot be applied to polymeric implants by high-temperature techniques, because the use of high temperatures may critically degrade the polymer substrate. Regardless of the coating technique that is used, the coating must be sufficiently well adhered to the underlying substrate to provide any practical benefit. This paper investigates the use of scratch testing to measure the adhesion strength of calcium phosphate (CaP) coatings that were applied to a poly(carbonate urethane) (PCU) substrate by an aqueous process at temperatures of 19, 28, 37, and 50 °C. This work represents the first time that scratch testing analysis has been used to study CaP coatings deposited by an aqueous, low-temperature process on to a polymer substrate. Scratch testing was shown to be a useful technique for obtaining comparative, rather than absolute, values of adhesion strength for hard coatings formed on a compliant substrate. Generally, the coating temperature was not found to influence the CaP-PCU adhesion strength. Although CaP coatings formed at 19 °C exhibited considerably lower adhesion strengths than CaP coatings formed at 28, 37, and 50 °C, this finding was attributable to the inconsistency of CaP coatings formed on the PCU substrates at 19 °C. The coating-substrate adhesion strength was measured for CaP coatings of four different coating ages (0, 1, 2, and 3 years). CaP coatings that were aged for 0, 1, or 2 years exhibited similar coating-substrate adhesion strengths to each other. In contrast, CaP coatings that were aged for 3 years demonstrated considerably lower coating-substrate adhesion strengths. The observed reduction in adhesion strength with age was thought to be attributable to suspected "drying out" of the CaP coatings. PMID:22301182

  16. Effect of Potassium Magnesium Citrate and Vitamin B-6 Prophylaxis for Recurrent and Multiple Calcium Oxalate and Phosphate Urolithiasis

    PubMed Central

    Shaik, Ahammad Basha; Bokkisam, Suneel

    2014-01-01

    Purpose To study the effects of long-term treatment with potassium magnesium citrate and vitamin B-6 prophylaxis (Urikind-KM6; 1,100-mg potassium citrate, 375-mg magnesium citrate, and 20-mg pyridoxine hydrochloride/5 mL) every 8 hours over 3 years. Materials and Methods A total of 247 patients with recurrent idiopathic hypocitraturia with or without hyperuricosuria and randomized controls were studied prospectively for 3 years. The total patients were divided into three groups. Control group 1 consisted of 61 patients (24.7%) who had moderate to severe hypocitraturia with or without hyperuricosuria and were recurrent stone formers but discontinued prophylaxis because of drug intolerance within 1 month of therapy. Control group 2 constituted 53 patients (21.5%) who were first-time stone formers and who had mild hypocitraturia with or without hyperuricosuria and were not put on prophylactic therapy and were followed for 3.16±0.08 years. Control group 3 constituted 133 patients (54.8%) who were recurrent stone formers who had moderate to severe hypocitraturia with or without hyperuricosuria and were put on prophylaxis therapy and were followed for 3.16±0.08 years. All patients were followed up at 6-month intervals. Results Potassium magnesium citrate prophylaxis produced a sustained increase in 24-hour urinary citrate excretion from initially low values (221.79±13.39 mg/dL) to within normal to high limits (604.04±5.00 mg/dL) at the 6-month follow-up. Urinary pH rose significantly from 5.62±0.2 to 6.87±0.01 and was maintained at 6.87±0.01. The stone recurrence rate declined from 3.23±1.04 per patient per year to 0.35±0.47 per patient per year. Conclusions Potassium magnesium citrate prophylaxis was effective in reducing the recurrence of calcium oxalate and phosphate urolithiasis. PMID:24955227

  17. Fetuin-A and Albumin Alter Cytotoxic Effects of Calcium Phosphate Nanoparticles on Human Vascular Smooth Muscle Cells

    PubMed Central

    Dautova, Yana; Kozlova, Diana; Skepper, Jeremy N.; Epple, Matthias; Bootman, Martin D.; Proudfoot, Diane

    2014-01-01

    Calcification is a detrimental process in vascular ageing and in diseases such as atherosclerosis and arthritis. In particular, small calcium phosphate (CaP) crystal deposits are associated with inflammation and atherosclerotic plaque de-stabilisation. We previously reported that CaP particles caused human vascular smooth muscle cell (VSMC) death and that serum reduced the toxic effects of the particles. Here, we found that the serum proteins fetuin-A and albumin (?1 µM) reduced intracellular Ca2+ elevations and cell death in VSMCs in response to CaP particles. In addition, CaP particles functionalised with fetuin-A, but not albumin, were less toxic than naked CaP particles. Electron microscopic studies revealed that CaP particles were internalised in different ways; via macropinocytosis, membrane invagination or plasma membrane damage, which occurred within 10 minutes of exposure to particles. However, cell death did not occur until approximately 30 minutes, suggesting that plasma membrane repair and survival mechanisms were activated. In the presence of fetuin-A, CaP particle-induced damage was inhibited and CaP/plasma membrane interactions and particle uptake were delayed. Fetuin-A also reduced dissolution of CaP particles under acidic conditions, which may contribute to its cytoprotective effects after CaP particle exposure to VSMCs. These studies are particularly relevant to the calcification observed in blood vessels in patients with kidney disease, where circulating levels of fetuin-A and albumin are low, and in pathological situations where CaP crystal formation outweighs calcification-inhibitory mechanisms. PMID:24849210

  18. Fatigue and human umbilical cord stem cell seeding characteristics of calcium phosphate–chitosan–biodegradable fiber scaffolds

    PubMed Central

    Zhao, Liang; Burguera, Elena F.; Xu, Hockin H.K.; Amin, Nikhil; Ryou, Heon; Arola, Dwayne D.

    2010-01-01

    Calcium phosphate cement (CPC) has in situ-setting ability and bioactivity, but the brittleness and low strength limit CPC to only non-load-bearing bone repairs. Human umbilical cord mesenchymal stem cells (hUCMSCs) can be harvested without an invasive procedure required for the commonly studied bone marrow MSCs. However, little has been reported on hUCMSC delivery via bioactive scaffolds for bone tissue engineering. The objectives of this study were to develop CPC scaffolds with improved resistance to fatigue and fracture, and to investigate hUCMSC delivery for bone tissue engineering. In fast fracture, CPC with 15% chitosan and 20% polyglactin fibers (CPC–chitosan–fiber scaffold) had flexural strength of 26 MPa, higher than 10 MPa for CPC control (p < 0.05). In cyclic loading, CPC–chitosan–fiber specimens that survived 2 × 106 cycles had the maximum stress of 10 MPa, compared to 5 MPa of CPC control. CPC–chitosan–fiber specimens that failed after multiple cycles had a mean stress-to-failure of 9 MPa, compared to 5.8 MPa for CPC control (p < 0.05). hUCMSCs showed excellent viability when seeded on CPC and CPC–chitosan–fiber scaffolds. The percentage of live cells reached 96–99%. Cell density was about 300 cells/mm2 at day 1; it proliferated to 700 cells/mm2 at day 4. Wst-1 assay showed that the stronger CPC–chitosan–fiber scaffold had hUCMSC viability that matched the CPC control (p > 0.1). In summary, this study showed that chitosan and polyglactin fibers substantially increased the fatigue resistance of CPC, and that hUCMSCs had excellent proliferation and viability on the scaffolds. PMID:19850337

  19. Mechanical properties and in vitro cellular behavior of zinc-containing nano-bioactive glass doped biphasic calcium phosphate bone substitutes.

    PubMed

    Badr-Mohammadi, Mohammad-Reza; Hesaraki, Saeed; Zamanian, Ali

    2014-01-01

    In the present study, different amounts (0.5-5 wt%) of a sol gel-derived zinc-containing nano-bioactive glass (NBG-Zn) powder were added to biphasic calcium phosphate (BCP). The mixtures were sintered at 1,100-1,300 °C and physical characteristics, mechanical properties, phase composition and morphology of them were studied. The samples were also soaked in human blood plasma for 15 days to evaluate variations in their surface morphologies. Rat calvarium-derived osteoblastic cells were seeded on tops of various samples and cell adhesion, proliferation, and alkaline phosphatase activity were evaluated at different culturing periods. The maximum bending strength (62 MPa) was obtained for BCP containing 0.5 wt% NBG-Zn at temperature 1,200 °C. This value was approximately 80% higher than that of pure BCP. The bending strength failed when both sintering temperature and amount of added NBG-Zn increased. At 1,100 °C, NBG-Zn additive did not change the phase composition of BCP. At temperatures 1,200 and 1,300 °C, both alpha-tricalcium calcium phosphate (?-TCP) and beta-tricalcium phosphate (?-TCP and) phases were detected. However, adding higher amount of NBG-Zn to BCP resulted in elevation of ?-TCP at 1,200 °C and progression of ?-TCP at 1,300 °C. Based on the microscopic observations, adding 0.5 wt% NBG-Zn to BCP led to disappearance of grain boundaries, reduction of micropores and formation of a monolithic microstructure. No calcium phosphate precipitation was observed on sample surfaces after soaking in blood plasma, but some pores were produced by phase dissolution. The size and volume of these pores were directly proportional to NBG-Zn content. Based on the cell studies, both BCP and NBG-Zn-added BCP samples supported attachment and proliferation of osteoblasts, but higher alkaline phosphatase enzyme was synthesized within the cells cultured on NBG-Zn-added BCP. Overall, biphasic calcium phosphate materials with improved mechanical and biological properties can be produced by using small quantity of zinc-containing bioactive glass particles. PMID:24101184

  20. Br J Nutr . Author manuscript Calcium carbonate suppresses haem toxicity markers without calcium

    E-print Network

    Paris-Sud XI, Université de

    calcium phosphate side effects on colon carcinogenesis Ossama Allam , Diane Bahuaud , Sylviane Taché. Unexpectedly, high-calcium phosphate control diet-fed rats had more preneoplastic lesions in the colon than low-calcium, in contrast with previously tested calcium phosphate diet. The results suggest that calcium carbonate

  1. Solid-State 31P and 1H NMR Investigations of Amorphous and Crystalline Calcium Phosphates Grown Biomimetically From a Mesoporous Bioactive Glass

    PubMed Central

    2011-01-01

    By exploiting 1H and 31P magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy, we explore the proton and orthophosphate environments in biomimetic amorphous calcium phosphate (ACP) and hydroxy-apatite (HA), as grown in vitro at the surface of a 10CaO–85SiO2–5P2O5 mesoporous bioactive glass (MBG) in either a simulated body fluid or buffered water. Transmission electron microscopy confirmed the presence of a calcium phosphate layer comprising nanocrystalline HA. Two-dimensional 1H–31P heteronuclear correlation NMR established predominantly 1H2O?31PO43– and O1H?31PO43– contacts in the amorphous and crystalline component, respectively, of the MBG surface-layer; these two pairs exhibit distinctly different 1H?31P cross-polarization dynamics, revealing a twice as large squared effective 1H–31P dipolar coupling constant in ACP compared with HA. These respective observations are mirrored in synthetic (well-crystalline) HA, and the amorphous calcium orthophosphate (CaP) clusters that are present in the pristine MBG pore walls: besides highlighting very similar local 1H and 31P environments in synthetic and biomimetic HA, our findings evidence closely related NMR characteristics, and thereby similar local structures, of the CaP clusters in the pristine MBG relative to biomimetic ACP. PMID:22132242

  2. Physicochemical Characterization and In Vivo Evaluation of Amorphous and Partially Crystalline Calcium Phosphate Coatings Fabricated on Ti-6Al-4V Implants by the Plasma Spray Method

    PubMed Central

    Bonfante, Estevam A.; Witek, Lukasz; Tovar, Nick; Suzuki, Marcelo; Marin, Charles; Granato, Rodrigo; Coelho, Paulo G.

    2012-01-01

    Objective. To characterize the topographic and chemical properties of 2 bioceramic coated plateau root form implant surfaces and evaluate their histomorphometric differences at 6 and 12 weeks in vivo. Methods. Plasma sprayed hydroxyapatite (PSHA) and amorphous calcium phosphate (ACP) surfaces were characterized by scanning electron microscopy (SEM), interferometry (IFM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). Implants were placed in the radius epiphysis, and the right limb of dogs provided implants that remained for 6 weeks, and the left limb provided implants that remained 12 weeks in vivo. Thin sections were prepared for bone-to-implant contact (BIC) and bone-area-fraction occupancy (BAFO) measurements (evaluated by Friedman analysis P < 0.05). Results. Significantly, higher Sa (P < 0.03) and Sq (P < 0.02) were observed for ACP relative to PSHA. Chemical analysis revealed significantly higher HA, calcium phosphate, and calcium pyrophosphate for the PSHA surface. BIC and BAFO measurements showed no differences between surfaces. Lamellar bone formation in close contact with implant surfaces and within the healing chambers was observed for both groups. Conclusion. Given topographical and chemical differences between PSHA and ACP surfaces, bone morphology and histomorphometric evaluated parameters showed that both surfaces were osseoconductive in plateau root form implants. PMID:22969806

  3. Optimization of the activation and nucleation steps in the precipitation of a calcium phosphate primer layer on electrospun poly(?-caprolactone).

    PubMed

    Luickx, Nathalie; Van den Vreken, Natasja; D'Oosterlinck, Willem; Van der Schueren, Lien; Declercq, Heidi; De Clerck, Karen; Cornelissen, Maria; Verbeeck, Ronald

    2015-02-01

    The present study aimed to optimize the procedure for coating electrospun poly(?-caprolactone) (PCL) fibers with a calcium phosphate (CP) layer in order to improve their potential as bone tissue engineering scaffold. In particular, attention was paid to the reproducibility of the procedure, the morphology of the coating, and the preservation of the porous structure of the scaffold. Ethanol dipping followed by an ultrasonic assisted hydrolysis of the fiber surface with sodium hydroxide solution efficiently activated the surface. The resulting reactive groups served as nucleation points for CP precipitation, induced by alternate dipping of the samples in calcium and phosphate rich solutions. By controlling the deposition, a reproducible thin layer of CP was grown onto the fiber surface. The deposited CP was identified as calcium-deficient apatite (CDHAp). Analysis of the cell viability, adhesion, and proliferation of MC3T3-E1 cells on untreated and CDHAp coated PCL scaffolds showed that the CDHAp coating enhanced the cell response, as the number of attached cells was higher in comparison to the untreated PCL and cells on the CDHAp coated samples showed similar morphologies as the ones found in the positive control. PMID:24733786

  4. Effects of pulsed current and H{sub 2}O{sub 2} amount on the composition of electrodeposited calcium phosphate coatings

    SciTech Connect

    Drevet, R., E-mail: richard.drevet@univ-reims.fr [INSERM UMR-S 926 URCA CHU, 1 rue Marechal Juin 51096 Reims Cedex (France); Benhayoune, H.; Wortham, L.; Potiron, S. [INSERM UMR-S 926 URCA CHU, 1 rue Marechal Juin 51096 Reims Cedex (France); Douglade, J. [L.A.C.M.-D.T.I. EA 4302 URCA, Moulin de la Housse BP 1039 51687 Reims Cedex 02 (France); Laurent-Maquin, D. [INSERM UMR-S 926 URCA CHU, 1 rue Marechal Juin 51096 Reims Cedex (France)

    2010-08-15

    Calcium phosphate coatings on Ti6Al4V substrates were elaborated by pulsed electrodeposition with hydrogen peroxide (H{sub 2}O{sub 2}) into electrolyte. The surface morphology and the chemical composition of the coatings were characterized by scanning electron microscopy (SEM) associated to Energy Dispersive X-ray Spectroscopy (EDXS) for X-ray microanalysis. The obtained results were systematically confirmed at the nanometre scale analysis using scanning transmission electron microscopy (STEM). Moreover, X-ray diffraction (XRD) was performed in order to identify the coatings phases. The results showed that pulsed electrodeposition without H{sub 2}O{sub 2} into electrolyte followed by heat treatment favoured coatings made of two phases which are stoichiometric hydroxyapatite (HAP) and {beta}-tricalcium phosphate ({beta}-TCP). On the other hand the addition of an optimized H{sub 2}O{sub 2} amount into electrolyte led to adherent and uniform coatings mainly made of stoichiometric hydroxyapatite (HAP).

  5. The effects of intracellular injections of phosphate on intracellular calcium and force in single fibres of mouse skeletal muscle

    Microsoft Academic Search

    H. Westerblad; David G. Allen

    1996-01-01

    Intracellular inorganic phosphate increases during muscle fatigue and may be responsible for certain of the changes in muscle\\u000a function observed in fatigue. To test this hypothesis inorganic phosphate was micro-injected in single mouse muscle fibres\\u000a which were also injected with indo-I to measure intracellular Ca2+. Following phosphate injection, intracellular Ca2+, both at rest and during tetani, was reduced as was

  6. Silicon, iron and titanium doped calcium phosphate-based glass reinforced biodegradable polyester composites as bone analogous materials

    NASA Astrophysics Data System (ADS)

    Shah Mohammadi, Maziar

    Bone defects resulting from disease or traumatic injury is a major health care problem worldwide. Tissue engineering offers an alternative approach to repair and regenerate bone through the use of a cell-scaffold construct. The scaffold should be biodegradable, biocompatible, porous with an open pore structure, and should be able to withstand the applied forces. Phosphate-based glasses (PGs) may be used as reinforcing agents in degradable composites since their degradation can be predicted and controlled through their chemistry. This doctoral dissertation describes the development and evaluation of PGs reinforced biodegradable polyesters for intended applications in bone augmentation and regeneration. This research was divided into three main objectives: 1) Investigating the composition dependent properties of novel PG formulations by doping a sodium-free calcium phosphate-based glass with SiO2, Fe2O3, and TiO2. Accordingly, (50P2 O5-40CaO- xSiO2-(10-x)Fe2O3, where x = 10, 5 and 0 mol.%) and (50P2O5-40CaO-xSiO 2-(10-x)TiO2 where x = 10, 7, 5, 3 and 0 mol.%) formulations were developed and characterised. SiO2 incorporation led to increased solubility, ion release, pH reduction, as well as hydrophilicity, surface energy, and surface polarity. In contrast, doping with Fe2O 3 or TiO2 resulted in more durable glasses, and improved cell attachment and viability. It was hypothesised that the presence of SiO 2 in the TiO2-doped formulations could up-regulate the ionic release from the PG leading to higher alkaline phosphatase activity of MC3T3-E1 cells. 2) Incorporating Si, Fe, and Ti doped PGs as fillers, either as particulates (PGPs) or fibres (PGFs), into biodegradable polyesters (polycaprolactone (PCL) and semi-crystalline and amorphous poly(lactic acid) (PLA and PDLLA)) with the aim of developing degradable bone analogous composites. It was found that PG composition and geometry dictated the weight loss, ionic release, and mechanical properties of the composites. It was also hypothesised that a potential reaction between Si and the ester bond led to the formation of carboxylate by-products resulting in a lower molecular weight polymer, thus affecting the mechanical properties of the composites. Cytocompatibility assessment with MC3T3-E1 pre-osteoblasts showed that these composites were cytocompatible, and cell alignment along the PGFs was observed possibly due to their favourable ionic release properties. 3) Investigating the solid-state foaming using carbon dioxide (CO 2) of PDLLA-PGP composites with up to 30 vol.% filler content. While PDLLA foams resulted in 92% porosity, the porosity of the composites ranged between 79 and 91% which decreased with PGP content. In addition, a reduction in pore size was observed with increasing PGP content; however, the pore size maintained its range of 200-500 ?m in all composite foams, suitable for bone tissue engineering applications. The percentage of open pores increased significantly with PGP content (up to 78% at 30 vol.% PGP). Compressive strength and modulus of PDLLA-PGP foams showed up to approximately 3-fold increase at 30 vol.% PGP content compared to neat PDLLA foams.

  7. Umbilical cord and bone marrow mesenchymal stem cell seeding on macroporous calcium phosphate for bone regeneration in rat cranial defects

    PubMed Central

    Chen, Wenchuan; Liu, Jun; Manuchehrabadi, Navid; Weir, Michael D.; Zhu, Zhimin; Xu, Hockin H.K.

    2014-01-01

    Human umbilical cord mesenchymal stem cells (hUCMSCs) are inexhaustible and can be harvested at a low cost without an invasive procedure. However, there has been no report on comparing hUCMSCs with human bone marrow MSCs (hBMSCs) for bone regeneration in vivo. The aim of this study was to investigate hUCMSC and hBMSC seeding on macroporous calcium phosphate cement (CPC), and to compare their bone regeneration in critical-sized cranial defects in rats. Cell attachment, osteogenic differentiation and mineral synthesis on RGD-modified macroporous CPC were investigated in vitro. Scaffolds with cells were implanted in 8-mm defects of athymic rats. Bone regeneration was investigated via micro-CT and histological analysis at 4, 12, and 24 weeks. Three groups were tested: CPC with hUCMSCs, CPC with hBMSCs, and CPC control without cells. Percentage of live cells and cell density on CPC in vitro were similarly good for hUCMSCs and hBMSCs. Both cells had high osteogenic expressions of alkaline phosphatase, osteocalcin, collagen I, and Runx2. Bone mineral density and trabecular thickness in hUCMSC and hBMSC groups in vivo were greater than those of CPC control group. New bone amount for hUCMSC-CPC and hBMSC-CPC constructs was increased by 57% and 88%, respectively, while blood vessel density was increased by 15% and 20%, than CPC control group at 24 weeks. hUCMSC-CPC and hBMSC-CPC groups generally had statistically similar bone mineral density, new bone amount and vessel density. In conclusion, hUCMSCs seeded on CPC were shown to match the bone regeneration efficacy of hBMSCs in vivo for the first time. Both hUCMSC-CPC and hBMSC-CPC constructs generated much more new bone and blood vessels than CPC without cells. Macroporous RGD-grafted CPC with stem cell seeding is promising for craniofacial and orthopedic repairs. PMID:24054499

  8. Dtermination par traage isotopique de la valeur fertilisante du phosphate alumino-calci-

    E-print Network

    Paris-Sud XI, Université de

    of aluminium-calcium phosphate, diammonium phosphate and rock phosphate. The efficiency of 3 phosphate fertilizers (diammonium phosphate (DAP), aluminium-calcium phosphate and rock phosphate), labelled with P32Détermination par traçage isotopique de la valeur fertilisante du phosphate alumino-calci- que

  9. Human growth hormone locally released in bone sites by calcium-phosphate biomaterial stimulates ceramic bone substitution without systemic effects: a rabbit study.

    PubMed

    Guicheux, J; Gauthier, O; Aguado, E; Pilet, P; Couillaud, S; Jegou, D; Daculsi, G; Heymann, D

    1998-04-01

    Calcium-phosphate bone replacement biomaterial has been used as a drug carrier for therapeutic agents. This study investigated the efficacy of local administration of human growth hormone (hGH) by macroporous biphasic calcium phosphate (MBCP) implants in improving the bone substitution qualities of ceramics. hGH release from MBCP implants loaded with 1 microg of hGH was rapid during the first 48 h and then sustained for a total of 9 days. Immunolocalization of hGH in vitro and in vivo by transmission electron microscopy showed its presence inside the material, indicating that it was able to penetrate within the porosity of the ceramic during the adsorption process. MBCP cylinders (6 x 6 mm) were loaded with 0.1, 1, and 10 microg of hGH and implanted into rabbit femurs (n = 40). The effects of locally released hGH on bone ingrowth and ceramic resorption were evaluated by scanning electron microscopy and image analysis. The results indicated that hGH increased bone ingrowth (+65%) and ceramic resorption (+140%) significantly in comparison with control implants and that the increase was dose dependent. Biochemical parameters monitored in rabbit plasma and urine, as well as the absence of any significant difference between contralateral implants and the control, indicated that hGH did not produce detectable systemic effects. Thus, the use of MBCP appears to be effective for local delivery of hGH, resulting in improved bone substitution. PMID:9556073

  10. The effects of CeO{sub 2} addition on crystallization behavior and pore size in microporous calcium titanium phosphate glass ceramics

    SciTech Connect

    Soleimani, F., E-mail: F.Soleimani@yahoo.com [Department of Materials Engineering, Faculty of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of); Rezvani, M., E-mail: M_Rezvani@tabrizu.ac.ir [Department of Materials Engineering, Faculty of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2012-06-15

    Highlights: ? We prepare a phosphate glass ceramic in the system of CaO–TiO{sub 2}–P{sub 2}O{sub 5} and add 2 to 6 mol% CeO{sub 2} to it. We determine the optimum percentage of CeO{sub 2} addition. ? We study phase separation, suitable time and temperature for crystallization in the microporous Calcium Titanium Phosphate Glass Ceramics utilizing DTA, SEM and XRD. ? We investigate on pore size utilizing BET and SEM techniques before and after CeO{sub 2} addition. ? CeO{sub 2} increases the pore size in the Calcium Titanium Phosphate Glass Ceramics. -- Abstract: In this research the effect of the addition of CeO{sub 2} to microporous Calcium Titanium Phosphate glass ceramics was studied. Different molar percentages of CeO{sub 2} were added to three samples of a base glass whose composition was P{sub 2}O{sub 5} 30, CaO 45, TiO{sub 2} 25 (mol%). The first sample had 2 mol% CeO{sub 2}, the second sample had 4 mol% CeO{sub 2}, and the third sample had 6 mol% CeO{sub 2}. The fourth sample did not contain any CeO{sub 2}. The glass samples were melted and crystallized to bulk glass ceramics by a conventional method. Differential Thermal Analysis (DTA) was utilized to determine the appropriate nucleation and crystallization temperatures. Among the samples, the DTA curve of the sample which had 2 mol% CeO{sub 2} had the sharpest crystallization peak. Therefore, this sample was chosen to prepare the glass ceramics. Using X-ray Diffraction (XRD) it was found that in all samples ?-Ca{sub 3}(PO{sub 4}){sub 2} and CaTi{sub 4}(PO{sub 4}){sub 6} were the major phases. The ?-Ca{sub 3}(PO{sub 4}){sub 2} phase was dissolved away by soaking the glass ceramics in HCl, leaving a porous skeleton of CaTi{sub 4}(PO{sub 4}){sub 6}. CeO{sub 2} addition increased the glass transition temperature and decreased the crystallization time and temperature. It was shown that CeO{sub 2} addition resulted in an increase in the mean pore diameter while the specific surface area decreased. The median pore diameter and specific surface area were determined as 27 nm and 14 m{sup 2}/g, respectively, for the sample containing 2 mol% CeO{sub 2}.

  11. Calcium phosphate scaffolds for bone tissue engineering and self-association PEG-PLLA diblock copolymer for controlled drug delivery system

    NASA Astrophysics Data System (ADS)

    Jongpaiboonkit, Leenaporn

    In scaffold-based bone tissue engineering, the existing three-dimensional scaffolds have proved less than ideal for actual applications, not only because they lack mechanical strength, but also because they do not guarantee interconnected channels. In this work, complex three-dimensional porous dicalcium phosphate dihydrate cement (DCPD) scaffolds with control interconnected pores were successfully manufactured by combining a computationally designed using an image-based approach and a fabrication technique by indirect solid freeform fabrication (ISFF) or 'lost mold' method via casting. The scaffold fabrication can be done at physiological temperatures; the macroporosity and interconnected pore network are incorporated while the microporosity is maintained. Therefore, it is possible for any biological factor such as growth factor or bone cell to be added during scaffold manufacturing. Calcium phosphate cement is a bioceramic with potential applications for bone-tissue engineering because of its excellent biocompatibility and bone-replacement behavior over long periods. Cement must be cast in complex molds to achieve specific design of macropores with chosen size and connectivity. Unlike the fluid ceramic slurries, the DCPD cement was a more viscous paste before setting. The thorough characterization of cement slip is investigated and optimized. The complex calcium phosphate cement scaffolds (macroporosity between 33%--70%) were thoroughly examined using a non-destructive micro-computed tomography. The effects of void variance and fabrication defects on mechanical properties of the scaffolds were evaluated and compared. Image-based finite element analysis was applied to predict the mechanical behavior of the designed and the fabricated scaffolds. The latter was subsequently mechanically tested. The computational prediction of effective stiffness constants and stress distribution of the scaffolds correlated well with the experiments and showed that the calcium phosphate cement scaffolds have mechanical properties that lie within the range of human trabecular bone. By employing an ex vivo gene therapy, scaffolds were then implanted subcutaneously to demonstrate tissue in-growth. The implanted scaffolds were evaluated histologically, mechanically, and using micro-computed tomography. The implant was found to be surrounded by a large amount of bone as well as within the scaffold pores at the four weeks time point. Almost the entire implant was enveloped by new bone after eight weeks of implantation. These techniques allow us to investigate the bone formation and the scaffold degradation both qualitatively and quantitatively. These results show that by integrating the computationally designed, biodegradable osteoconductive DCPD matrix, and ex vivo gene therapy, have potential for engineering of biomimetic scaffolds and scaffolds for complex biomechanical applications.

  12. 1,25-Dihydroxyvitamin D 3\\/VDR-mediated induction of FGF23 as well as transcriptional control of other bone anabolic and catabolic genes that orchestrate the regulation of phosphate and calcium mineral metabolism

    Microsoft Academic Search

    Thomas K. Barthel; Douglas R. Mathern; G. Kerr Whitfield; Carol A. Haussler; H. Andrew Hopper; Jui-Cheng Hsieh; Stephanie A. Slater; Grace Hsieh; Magdalena Kaczmarska; Peter W. Jurutka; Olga I. Kolek; Fayez K. Ghishan; Mark R. Haussler

    2007-01-01

    1,25-Dihydroxyvitamin D3 (1,25D) is known primarily as a regulator of calcium, but 1,25D also promotes phosphate absorption from intestine, reabsorption from kidney, and bone mineral resorption. FGF23 is a newly discovered phosphaturic hormone that, like PTH, lowers serum phosphate by inhibiting renal reabsorption via Npt2a. We show that 1,25D strongly upregulates FGF23 in bone. FGF23 then represses 1?-OHase activity in

  13. Calcium phosphate deposition rate, structure and osteoconductivity on electrospun poly(l-lactic acid) matrix using electrodeposition or simulated body fluid incubation

    PubMed Central

    He, Chuanglong; Jin, Xiaobing; Ma, Peter X.

    2013-01-01

    Mineralized nanofibrous scaffolds have been proposed as promising scaffolds for bone regeneration due to their ability to mimic both nanoscale architecture and chemical composition of natural bone extracellular matrix (ECM). In this study, a novel electrodeposition method was compared with an extensively explored simulated body fluid (SBF) incubation method in terms of the deposition rate, chemical composition, and morphology of calcium phosphate formed on electrospun fibrous thin matrices with a fiber diameter in the range from about 200 nm to about 1400 nm prepared using 6, 8, 10 and 12 wt% poly(l-lactic acid) (PLLA) solutions in a mixture of dichloromethane and acetone (2:1 in volume). The effects of the surface modification using the two mineralization techniques on osteoblastic cell (MC3T3-E1) proliferation and differentiation were also examined. It was found that electrodeposition was two to three orders of magnitude faster than the SBF method in mineralizing the fibrous matrices, reducing the mineralization time from about two weeks to an hour to achieve the same amounts of mineralization. The mineralization rate also varied with the fiber diameter but in opposite directions between the two mineralization methods. As a general trend, the increase of fiber diameter resulted in a faster mineralization rate for the electrodeposition method but a slower mineralization rate for the SBF incubation method. Using the electrodeposition method, one can control the chemical composition and morphology of the calcium phosphate by varying the electric deposition potential and electrolyte temperature to tune the mixture of dicalcium phosphate dihydrate (DCPD) and hydroxy apatite (HAp). Using the SBF method, one can only obtain a low crystallinity HAp. The mineralized electrospun PLLA fibrous matrices from either method similarly facilitate the proliferation and osteogenic differentiation of preosteoblastic MC3T3-E1 cells as compared to neat PLLA matrices. Therefore, the electrodeposition method can be utilized as a fast and versatile technique to fabricate mineralized nanofibrous scaffolds for bone tissue engineering. PMID:24012605

  14. Influence of calcium, iron and pH on phosphate availability for microbial mineralization of organic chemicals

    SciTech Connect

    Robertson, B.K.; Alexander, M. (Cornell Univ., Ithaca, NY (United States))

    1992-01-01

    A study was conducted to determine some of the factors affecting the P requirement for the biodegradation of p-nitrophenol, phenol, and glucose by Pseudomonas and Corynebacterium strains. Mineralization of glucose was rapid and the Pseudomonas sp. grew extensively in solutions with 5 and 10 mM phosphate, but the rate and extent of degradation were low and the bacterial population never became abundant in media with 0.2 mM phosphate. Similar results were obtained with the Corynebacterium sp. growing in media containing p-nitrophenol or phenol and in solutions with a purified phosphate salt. The extent of growth of the Corynebacterium sp. was reduced with 2 or 10 mM phosphate in media containing high Fe concentrations. Ca at 5 mM but not 0.5 mM inhibited p-nitrophenol mineralization by the Corynebacterium sp. with phosphate concentrations from 0.2 to 5.0 mM. Phenol mineralization by the Pseudomonas sp. in medium with 0.2 mM phosphate was rapid at pH 5.2, but the bacteria had little or no activity at pH 8.0. In contrast, the activity was greater at pH 8.0 than at pH 5.2 when the culture contained 10 mM phosphate. These effects of pH were similar in media with 5 mM Ca or no added Ca. The authors conclude that the effect of P on bacterial degradation can be influenced by the pH and the concentrations of Fe and Ca.

  15. Surface remineralization potential of casein phosphopeptide-amorphous calcium phosphate on enamel eroded by cola-drinks: An in-situ model study

    PubMed Central

    Grewal, Navneet; Kudupudi, Vinod; Grewal, Sukrit

    2013-01-01

    Aim: The aim of this study was to investigate the remineralization potential of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on enamel eroded by cola drinks. Subjects and Methods: A total of 30 healthy subjects were selected from a random sample of 1200 children and divided into two groups of 15 each wherein calcium and phosphorus analyses and scanning electron microscope (SEM) analysis was carried out to investigate the remineralization of enamel surface. A total of 30 non-carious premolar teeth were selected from the human tooth bank (HTB) to prepare the in-situ appliance. Three enamel slabs were prepared from the same. One enamel slab was used to obtain baseline values and the other two were embedded into the upper palatal appliances prepared on the subjects’ maxillary working model. The subjects wore the appliance after which 30 ml cola drink exposure was given. After 15 days, the slabs were removed and subjected to respective analysis. Statistical Analysis Used: Means of all the readings of soluble calcium and phosphorous levels at baseline,post cola-drink exposure and post cpp-acp application were subjected to statistical analysis SPSS11.5 version. Comparison within groups and between groups was carried out using ANOVA and F-values at 1% level of significance. Results: Decrease in calcium solubility of enamel in the CPP-ACP application group as compared to post-cola drink exposure group (P < 0.05) was seen. Distinctive change in surface topography of enamel in the post-CPP-ACP application group as compared to post-cola drink exposure group was observed. Conclusion: CPP-ACP significantly promoted remineralization of enamel eroded by cola drinks as revealed by significant morphological changes seen in SEM magnification and spectrophotometric analyses. PMID:24124299

  16. Ultra-Small-Angle X-ray Scattering – X-ray Photon Correlation Spectroscopy Studies of Incipient Structural Changes in Amorphous Calcium Phosphate Based Dental Composites

    PubMed Central

    Zhang, F.; Allen, A.J.; Levine, L.E.; Espinal, L.; Antonucci, J.M.; Skrtic, D.; O’Donnell, J.N.R.; Ilavsky, J.

    2012-01-01

    The local structural changes in amorphous calcium phosphate (ACP) based dental composites were studied under isothermal conditions using both static, bulk measurement techniques and a recently developed methodology based on combined ultra-small angle X-ray scattering – X-ray photon correlation spectroscopy (USAXS-XPCS), which permits a dynamic approach. While results from conventional bulk measurements do not show clear signs of structural change, USAXS-XPCS results reveal unambiguous evidence for local structural variations on a similar time scale to that of water loss in the ACP fillers. A thermal-expansion based simulation indicates that thermal behavior alone does not account for the observed dynamics. Together, these results suggest that changes in the water content of ACP affect the composite morphology due to changes in ACP structure that occur without an amorphous-to-crystalline conversion. It is also noted that biomedical materials research could benefit greatly from USAXS-XPCS, a dynamic approach. PMID:22374649

  17. Prevention of bone mineral changes induced by bed rest: Modification by static compression simulating weight bearing, combined supplementation of oral calcium and phosphate, calcitonin injections, oscillating compression, the oral diophosphonatedisodium etidronate, and lower body negative pressure

    NASA Technical Reports Server (NTRS)

    Schneider, V. S.; Hulley, S. B.; Donaldson, C. L.; Vogel, J. M.; Rosen, S. N.; Hantman, D. A.; Lockwood, D. R.; Seid, D.; Hyatt, K. H.; Jacobson, L. B.

    1974-01-01

    The phenomenon of calcium loss during bed rest was found to be analogous to the loss of bone material which occurs in the hypogravic environment of space flight. Ways of preventing this occurrence are investigated. A group of healthy adult males underwent 24-30 weeks of continuous bed rest. Some of them were given an exercise program designed to resemble normal ambulatory activity; another subgroup was fed supplemental potassium phosphate. The results from a 12-week period of treatment were compared with those untreated bed rest periods. The potassium phosphate supplements prevented the hypercalciuria of bed rest, but fecal calcium tended to increase. The exercise program did not diminish the negative calcium balance. Neither treatment affected the heavy loss of mineral from the calcaneus. Several additional studies are developed to examine the problem further.

  18. In situ precipitation of amorphous calcium phosphate and ciprofloxacin crystals during the formation of chitosan hydrogels and its application for drug delivery purposes.

    PubMed

    Nardecchia, Stefania; Gutiérrez, María C; Serrano, M Concepción; Dentini, Mariella; Barbetta, Andrea; Ferrer, M Luisa; del Monte, Francisco

    2012-11-13

    The immobilization of more than one single substance within the structure of a biocompatible polymer provides multifunctional biomaterials with attractive and enhanced properties. In the context of bone tissue engineering, it could be of great interest to synthesize a biomaterial that simultaneously contains amorphous calcium phosphate (ACP), to favor calcium and phosphate precipitation and promote osteogenesis, and an antibiotic such as ciprofloxacin (CFX) that can, eventually, avoid infections resulting after surgical scaffold implantation. However, the co-immobilization of multiple substances is by no means a trivial issue because of the enhanced number of interactions that can take place. One of the main issues is controlling not only the diverse solid forms that individual substances can eventually adopt, but also the forces responsible for the self-organization of the individual components. The latter determines whether phase-separated structures or conjugated architectures are obtained and, consequently, may dramatically affect their functionality. Herein, we have observed-by SEM, TEM, and solid-state NMR-that enzymatically-assisted coprecipitation of ACP and CFX resulted in phase-separated structures. Thus, CFX crystals showed identical morphology to that obtained in the absence of ACP, but the size was smaller. Neither the size nor the morphology of ACP exhibited significant differences whether precipitated with or without CFX, but, in the former case, ACP was stabilized over a wider range of pH and temperature. Finally, by using this methodology and the ice segregation induced self-assembly process (ISISA), we have successfully co-immobilized ACP and CFX in chitosan-based scaffolds. Interestingly, the presence of ACP exerted significant control on the CFX release from these materials. PMID:23088184

  19. A review of protein structure and gene organisation for proteins associated with mineralised tissue and calcium phosphate stabilisation encoded on human chromosome 4.

    PubMed

    Huq, N Laila; Cross, Keith J; Ung, Men; Reynolds, Eric C

    2005-07-01

    Several proteins associated with mineralised tissue (teeth and bone) or involved in calcium phosphate stabilisation in the body fluids, milk and saliva have been mapped to the q arm of human chromosome 4. These include the dentine/bone proteins dentine sialophosphoprotein (DSPP), dentine matrix protein 1 (DMP1), bone sialoprotein (BSP), matrix extracellular phosphoglycoprotein, osteopontin (OPN), enamelin, ameloblastin, milk caseins, salivary statherin, and proline-rich proteins. The proposed function of those that are multiphosphorylated is: (i) the stabilisation of calcium phosphate in solution (e.g. casein, statherin) preventing spontaneous precipitation and seeded-crystal growth or (ii) promoting biomineralisation (e.g. the phosphophoryn domain of DSPP), where the protein described as a template macromolecule, is proposed to act as a nucleator/promoter of crystal growth. The genes of these proteins have been subjected to conserved chromosomal synteny during mammalian evolution. The multiphosphorylated proteins statherin, caseins, phosphophoryn, BSP and OPN have been characterised as intrinsically disordered. The codon usage patterns for the amino acid serine reveal a bias for AGC and AGT codons within the human genes dspp, dmp1 and bsp, mouse dspp and dmp1 but not significantly for statherin or caseins. This pattern was also observed in the gene encoding hen phosvitin that also contains stretches of multiphosphorylated serines and in the dmp1 gene sequences of mammalian, reptilian and avian classes. In conclusion, these intrinsically disordered multiphosphorylated proteins are the translation products of genes displaying examples of codon usage bias, internal repeats and conserved chromosomal synteny within the mammalian class. PMID:15892946

  20. Mechanism of action of a desensitizing fluoride toothpaste delivering calcium and phosphate ingredients in the treatment of dental hypersensitivity. Part II: comparison with a professional treatment for tooth hypersensitivity.

    PubMed

    Charig, Andrew J; Thong, Stephen; Flores, Florita; Gupta, Shivank; Major, Elizabeth; Winston, Anthony E

    2009-01-01

    Tooth hypersensitivity can occur when gum recession causes exposure of dentin. Tiny tubules, which permeate dentin, provide open passageways from the mouth to the intradental nerve in the pulpal cavity. Under such circumstances, stimuli in the mouth can cause pressure on the intradental nerve, leading to pain. Sealing the outside of the tubules with an impermeable substance can effectively treat hypersensitivity. One such clinically proven composition is a professionally applied tooth desensitizer, which has been shown to initially produce a layer of amorphous calcium phosphate (ACP) on the surface of dentin. Under the influence of fluoride, ACP reforms as hydroxyapatite (HAP), which has essentially the same composition as tooth mineral. Three fluoride toothpastes that deliver calcium and phosphate salts to the teeth also have been demonstrated in clinical trials to relieve hypersensitivity. This study compared the mechanism of action of these toothpastes to that of the professional desensitizer. A single application of the professional desensitizer or multiple applications of any of the three toothpastes was shown to reduce dentin permeability. A conventional fluoride toothpaste also was found to inhibit fluid flow through the dentin but to a lesser degree than the other toothpastes. The desensitizer and the three toothpastes were found to occlude the dentinal tubules with a layer of calcium phosphate that had a calcium-to-phosphate ratio consistent with the formation of ACP or HAP. The morphology of the coherent mineral layer formed by Arm & Hammer Enamel Care Sensitive was similar, especially to that produced by the desensitizer. In contrast, the conventional toothpaste left localized areas of surface residue composed of silica particles. The mechanism of action of the three toothpastes that deliver calcium and phosphate salts is the same as that of the professional desensitizer. PMID:19998729