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1

21 CFR 582.5217 - Calcium phosphate.  

Code of Federal Regulations, 2011 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and...

2011-04-01

2

21 CFR 582.5217 - Calcium phosphate.  

Code of Federal Regulations, 2012 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and...

2012-04-01

3

21 CFR 582.5217 - Calcium phosphate.  

Code of Federal Regulations, 2010 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and...

2010-04-01

4

Sodium phosphate-derived calcium phosphate cements  

SciTech Connect

Calcium phosphate cements (CPC) were synthesized by the acid-base reaction between sodium phosphate, NaH[sub 2]PO[sub 4] or -(-NaPO[sub 3]-)-[sub n], as the acid solution, and calcium aluminate cements (CAC) as the base reactant at 25 C. The extent of reactivity of -(-NaPO[sub 3]-)-[sub n] with CAC was much higher than that of NaH[sub 2]PO[sub 4], thereby resulting in a compressive strength of > 20 MPa. Sodium calcium orthophosphate (SCOP) salts as amorphous reaction products were responsible for the development of this strength. When this CPC specimen as exposed in an autoclave, in-situ amorphous [r arrow] crystal conversions, such as SCOP [r arrow] hydroxyapatite (HOAp), and Al[sub 2]O[sub 3] [center dot] xH[sub 2]O [r arrow] [gamma]-AlOOH, occurred at [approx] 100 C, while the rate of reaction of the residual CAC with the phosphate reactant was increasingly accelerated by hydrothermal catalysis. Based upon this information, the authors prepared lightweight CPC specimens by hydrothermally treating a low-density cement slurry (1.28 g/cc) consisting of CAC powder, -(-NaPO[sub 3]-)-[sub n] solution, and mullite-hollow microspheres. The characteristics of the autoclaved lightweight specimens were a compressive strength of > 9.0 MPa, water permeability of [approx] 5.0 [times] 10[sup [minus]3] milli darcy, and a low rate of alkali carbonation. The reasons for such a low carbonation rate reflected the presence of a minimum amount of residual CAC, in conjunction with the presence of HOAp and [gamma]-AlOOH phases that are unsusceptible to wet carbonation.

Sugama, T.; Carciello, N.R. (Brookhaven National Lab., Upton, NY (United States))

1995-01-01

5

Sintering of calcium phosphate bioceramics.  

PubMed

Calcium phosphate ceramics have become of prime importance for biological applications in the field of bone tissue engineering. This paper reviews the sintering behaviour of these bioceramics. Conventional pressureless sintering of hydroxyapatite, Ca10(PO4)6(OH)2, a reference compound, has been extensively studied. Its physico-chemistry is detailed. It can be seen as a competition between two thermally activated phenomena that proceed by solid-state diffusion of matter: densification and grain growth. Usually, the objective is to promote the first and prevent the second. Literature data are analysed from sintering maps (i.e. grain growth vs. densification). Sintering trajectories of hydroxyapatite produced by conventional pressureless sintering and non-conventional techniques, including two-step sintering, liquid phase sintering, hot pressing, hot isostatic pressing, ultrahigh pressure, microwave and spark plasma sintering, are presented. Whatever the sintering technique may be, grain growth occurs mainly during the last step of sintering, when the relative bulk density reaches 95% of the maximum value. Though often considered very advantageous, most assisted sintering techniques do not appear very superior to conventional pressureless sintering. Sintering of tricalcium phosphate or biphasic calcium phosphates is also discussed. The chemical composition of calcium phosphate influences the behaviour. Similarly, ionic substitutions in hydroxyapatite or in tricalcium phosphate create lattice defects that modify the sintering rate. Depending on their nature, they can either accelerate or slow down the sintering rate. The thermal stability of compounds at the sintering temperature must also be taken into account. Controlled atmospheres may be required to prevent thermal decomposition, and flash sintering techniques, which allow consolidation at low temperature, can be helpful. PMID:23212081

Champion, E

2013-04-01

6

Next generation calcium phosphate-based biomaterials  

PubMed Central

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

LC, Chow

2009-01-01

7

Application of Calcium Phosphate Materials in Dentistry  

PubMed Central

Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1) application of calcium phosphate into various fields in dentistry; (2) improving mechanical properties of calcium phosphate; (3) biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields. PMID:23878541

Al-Sanabani, Jabr S.; Al-Sanabani, Fadhel A.

2013-01-01

8

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...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2011-04-01

9

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...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2011-04-01

10

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...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2013-04-01

11

21 CFR 582.6215 - Monobasic calcium phosphate.  

...2014-04-01 2014-04-01 false Monobasic calcium phosphate. 582.6215 Section 582...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2014-04-01

12

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...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2012-04-01

13

21 CFR 182.6215 - Monobasic calcium phosphate.  

...2014-04-01 2014-04-01 false Monobasic calcium phosphate. 182.6215 Section 182...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2014-04-01

14

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...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2012-04-01

15

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...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2013-04-01

16

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

E-print Network

Calcium metal to synthesize amorphous or cryptocrystalline calcium phosphates A. Cuneyt Tas Accepted 30 January 2012 Available online 10 February 2012 Keywords: Amorphous Cryptocrystalline Calcium Metal Phosphate Synthesis Metallic calcium was never used before as the calcium source in synthesizing

Tas, A. Cuneyt

17

Calcium orthophosphates in medicine: from ceramics to calcium phosphate cements  

Microsoft Academic Search

Calcium phosphate (CaP) compounds are becoming of increasingly great importance in the fiel of biomaterials and, in particular, as bone substitutes. Recent discoveries have accelerated this process, but have simultaneously rendered the field more complicated for the everyday user. Subtle differences in composition and structure of CaP compounds may have a profound effect on their in vivo behaviour. Therefore, the

M. Bohner

2000-01-01

18

Calcium phosphate ceramics in drug delivery  

NASA Astrophysics Data System (ADS)

Calcium phosphate (CaP) particulates, cements and scaffolds have attracted significant interest as drug delivery vehicles. CaP systems, including both hydroxyapaptite and tricalcium phosphates, possess variable stoichiometry, functionality and dissolution properties which make them suitable for cellular delivery. Their chemical similarity to bone and thus biocompatibility, as well as variable surface charge density contribute to their controlled release properties. Among specific research areas, nanoparticle size, morphology, surface area due to porosity, and chemistry controlled release kinetics are the most active. This article discusses CaP systems in their particulate, cements, and scaffold forms for drug, protein, and growth factor delivery toward orthopedic and dental applications.

Bose, Susmita; Tarafder, Solaiman; Edgington, Joe; Bandyopadhyay, Amit

2011-04-01

19

Injectable bioactive calcium-magnesium phosphate cement for bone regeneration  

Microsoft Academic Search

Novel injectable and degradable calcium-magnesium phosphate cement (CMPC) with rapid-setting characteristic was developed by the introduction of magnesium phosphate cement (MPC) into calcium phosphate cement (CPC). The calcium-magnesium phosphate cement prepared under the optimum P\\/L ratio exhibited good injectability and desired workability. It could set within 10 min at 37 °C in 100% relative humidity and the compressive strength could

Fan Wu; Jiacan Su; Jie Wei; Han Guo; Changsheng Liu

2008-01-01

20

Rickets induced by calcium or phosphate depletion.  

PubMed

We studied the effects of calciopenia and phosphopenia on longitudinal growth, skeletal mineralization, and development of rickets in young Sprague-Dawley rats. At an age of 21 days, two experimental groups were given diets containing 0.02% calcium or 0.02% phosphorus; otherwise the diets were nutritionally adequate. After 7, 14, and 21 days, five animals from each group were randomly chosen. The animals were anaesthetized and blood samples were drawn for analysis of calcium, phosphorus, and immunoreactive parathyroid hormone, whereupon the animals were killed. Length, weight, and specific weight of the left femur were measured. After 28 days on the respective diet the remaining animals were killed and one proximal tibia from each animal was processed for light microscopy and subjected to stereological analysis. Both experimental groups developed progressive growth retardation, more so the phosphate-depleted group. The calciopenic animals developed severe hypocalcaemia and secondary hyperparathyroidism, whereas the phosphate-depleted animals, in spite of marked secondary hypercalcaemia, had unaltered levels of immunoreactive parathyroid hormone. By 28 days both experimental groups displayed rachitic changes, more pronounced in the phosphate-depleted animals. This paper provides quantitative data demonstrating that calciopenia per se may cause rickets in young rats, but that the rachitic changes in this condition are less severe, and the growth pattern different from those in phosphate depletion. PMID:2206984

Abugassa, S; Svensson, O

1990-10-01

21

Rickets induced by calcium or phosphate depletion.  

PubMed Central

We studied the effects of calciopenia and phosphopenia on longitudinal growth, skeletal mineralization, and development of rickets in young Sprague-Dawley rats. At an age of 21 days, two experimental groups were given diets containing 0.02% calcium or 0.02% phosphorus; otherwise the diets were nutritionally adequate. After 7, 14, and 21 days, five animals from each group were randomly chosen. The animals were anaesthetized and blood samples were drawn for analysis of calcium, phosphorus, and immunoreactive parathyroid hormone, whereupon the animals were killed. Length, weight, and specific weight of the left femur were measured. After 28 days on the respective diet the remaining animals were killed and one proximal tibia from each animal was processed for light microscopy and subjected to stereological analysis. Both experimental groups developed progressive growth retardation, more so the phosphate-depleted group. The calciopenic animals developed severe hypocalcaemia and secondary hyperparathyroidism, whereas the phosphate-depleted animals, in spite of marked secondary hypercalcaemia, had unaltered levels of immunoreactive parathyroid hormone. By 28 days both experimental groups displayed rachitic changes, more pronounced in the phosphate-depleted animals. This paper provides quantitative data demonstrating that calciopenia per se may cause rickets in young rats, but that the rachitic changes in this condition are less severe, and the growth pattern different from those in phosphate depletion. Images Fig. 6 Fig. 7 Fig. 8 PMID:2206984

Abugassa, S.; Svensson, O.

1990-01-01

22

Amorphous calcium phosphate and its application in dentistry  

Microsoft Academic Search

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

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

2011-01-01

23

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

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

Barak, Phillip

24

Tissue responses of calcium phosphate cement: a study in dogs  

Microsoft Academic Search

The in vivo properties of a new kind of calcium phosphate cement were investigated in this study. Calcium phosphate cement was implanted as paste into femoral bone and dorsal muscle of dogs for 3 and 6 months, and as prehardened form into thigh muscles of dogs for 1, 2 and 6 months. Histology was performed on thin un-decalcified sections. No

Huipin Yuan; Yubao Li; JD de Bruijn; K de Groot; Xingdong Zhang

2000-01-01

25

Setting Reaction and Hardening of an Apatitic Calcium Phosphate Cement  

Microsoft Academic Search

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 a-tricalcium phosphate containing 17 wt% ?-tricalcium phosphate, and 2 wt% of

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

1997-01-01

26

Injectable bioactive calcium-magnesium phosphate cement for bone regeneration.  

PubMed

Novel injectable and degradable calcium-magnesium phosphate cement (CMPC) with rapid-setting characteristic was developed by the introduction of magnesium phosphate cement (MPC) into calcium phosphate cement (CPC). The calcium-magnesium phosphate cement prepared under the optimum P/L ratio exhibited good injectability and desired workability. It could set within 10 min at 37 degrees C in 100% relative humidity and the compressive strength could reach 47 MPa after setting for 48 h, indicating that the prepared cement has relatively high initial mechanical strength. The results of in vitro degradation experiments demonstrated the good degradability of the injectable CMPC, and its degradation rate occurred significantly faster than that of pure CPC in simulated body fluid (SBF) solution. It can be concluded that the novel injectable calcium-magnesium phosphate cement is highly promising for a wide variety of clinical applications, especially for the development of minimally invasive techniques. PMID:19029607

Wu, Fan; Su, Jiacan; Wei, Jie; Guo, Han; Liu, Changsheng

2008-12-01

27

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

28

Development of a novel calcium phosphate cement composed mainly of calcium sodium phosphate with high osteoconductivity.  

PubMed

Two novel calcium phosphate cements (CPC) have been developed using calcium sodium phosphate (CSP) as the main ingredient. The first of these cements, labeled CAC, contained CSP, ?-tricalcium phosphate (TCP), and anhydrous citric acid, whereas the second, labeled CABC, contained CSP, ?-TCP, ?-TCP, and anhydrous citric acid. Biopex(®)-R (PENTAX, Tokyo, Japan), which is a commercially available CPC (Com-CPC), and OSferion(®) (Olympus Terumo Biomaterials Corp., Tokyo, Japan), which is a commercially available porous ?-TCP, were used as reference controls for analysis. In vitro analysis showed that CABC set in 5.7 ± 0.3 min at 22 °C and had a compressive strength of 86.0 ± 9.7 MPa after 5 days. Furthermore, this material had a compressive strength of 26.7 ± 3.7 MPa after 2 h in physiologic saline. CAC showed a statistically significantly lower compressive strength in the presence of physiologic saline and statistically significantly longer setting times than those of CABC. CABC and CAC exhibited apatite-forming abilities in simulated body fluid that were faster than that of Com-CPC. Samples of the materials were implanted into the femoral condyles of rabbits for in vivo analysis, and subsequent histological examinations revealed that CABC exhibited superior osteoconductivity and equivalent bioresorbability compared with Com-CPC, as well as superior osteoconductivity and bioresorbability compared with CAC. CABC could therefore be used as an alternative bone substitute material. PMID:24671331

Tanaka, Masashi; Takemoto, Mitsuru; Fujibayashi, Shunsuke; Kawai, Toshiyuki; Tsukanaka, Masako; Takami, Kimiaki; Motojima, Satoshi; Inoue, Hikaru; Nakamura, Takashi; Matsuda, Shuichi

2014-06-01

29

Amorphous calcium phosphate in casein micelles of bovine milk  

Microsoft Academic Search

Summary  The calcium phosphate remaining after hydrazine deproteination of casein micelles isolated from bulk skim milk exhibits under\\u000a the electron microscope a very fine and uniform granularity being formed by small subunits with a true diameter of approximately\\u000a 2.5 nm. This material, which is about 10 percent by weight citrate, termed calcium phosphate citrate (CPC) complex, also contains\\u000a Mg and Zn

T. C. A. McGann; R. D. Kearney; W. Buchheim; A. S. Posner; F. Betts; N. C. Blumenthal

1983-01-01

30

Growth of calcium phosphate on surface-modified cotton  

Microsoft Academic Search

A study of the growth of amorphous calcium phosphate on surface-modified cotton fibres by a combination of scanning electron microscopy\\/electron diffraction X-ray analysis, micro-FTIR and X-ray photoelectron spectroscopy is reported. Cotton fibres phosphorylated by the urea\\/phosphorous acid method and then soaked in saturated Ca(OH)2 for approximately one week were found to stimulate the growth of a calcium phosphate coating on

M. R. Mucalo; Y. Yokogawa; M. Toriyama; T. Suzuki; Y. Kawamoto; F. Nagata; K. Nishizawa

1995-01-01

31

Calcium Phosphate Bioceramics with Tailored Crystallographic Texture for Controlling Cell Adhesion  

E-print Network

Calcium Phosphate Bioceramics with Tailored Crystallographic Texture for Controlling Cell Adhesion at Birmingham, Birmingham, AL, 35294 ABSTRACT The orientation distribution of crystalline grains in calcium. INTRODUCTION The excellent biocompatibility and bioactivity of calcium phosphate nanostructured surfaces offer

Rohrer, Gregory S.

32

Transient amorphous calcium phosphate in forming enamel.  

PubMed

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

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

2009-05-01

33

TRANSIENT AMORPHOUS CALCIUM PHOSPHATE IN FORMING ENAMEL  

PubMed Central

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

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

2009-01-01

34

Review of casein phosphopeptides-amorphous calcium phosphate.  

PubMed

Casein phosphopeptides-amorphous calcium phosphate (CPP-ACP) is a bioactive agent with a base of milk products, which has been formulated from two parts: casein phosphopeptides (CPP) and amorphous calcium phosphate (ACP). CPP was produced from milk protein casein and has a remarkable ability to stabilize calcium phosphate in solution and to substantially increase the level of calcium phosphate in dental plaque. CPP-ACP buffers the free calcium and phosphate ion activities, thereby helping to maintain a state of supersaturation with respect to tooth enamel, reducing demineralisation and promoting remineralisation. The free calcium and phosphate ions move out of the CPP, enter the enamel rods and reform onto apatite crystals. Laboratory, animal and human studies have shown that CPP-ACP inhibits cariogenic activity. CPP-ACP is useful in the treatment of white spot lesions, hypomineralised enamel, mild fluorosis, tooth sensitivity and erosion, and prevents plaque accumulation around brackets and other orthodontic appliances. CPP-ACP also facilitates a normal post-eruptive maturation process and is ideal for protecting primary teeth at a time when oral care is difficult. CPP-ACP has commercial potential as an additive to foods, soft drinks and chewing gum, as well as additive to toothpastes and mouthwashes to control dental caries. PMID:25028684

Reema, Sharma Dhar; Lahiri, Prateek Kumar; Roy, Shantanu Sen

2014-01-01

35

Suitability of Calcium Phosphate Cement for Injection Laryngoplasty in Rabbits  

Microsoft Academic Search

Calcium phosphate cement (CPC) consists of powder and liquid, which become an injectable paste after mixing, self-hardening and recrystallizing to calcium hydroxylapatite (CaHA) after injection into a living body. In this study, we investigated the suitability of CPC as an injectable material for injection laryngoplasty using rabbits. All rabbits underwent left recurrent laryngeal nerve section and injection laryngoplasty with CPC.

Asako Ikeda; Akihiro Shiotani; Yuko Mori; Takekatsu Fujimine; Masayuki Tomifuji; Takuji Takaoka; Kaori Kameyama; Kaoru Ogawa

2006-01-01

36

Physicochemical–mechanical and in vitro biological properties of calcium phosphate cements with doped amorphous calcium phosphates  

Microsoft Academic Search

Calcium phosphate cements (CPCs) are successfully used as bone substitutes in dentistry and orthopaedic applications. This study investigated the physico-chemical–mechanical properties of and in vitro biological properties (cell response) of CPCs prepared with amorphous calcium carbonate phosphate (ACCP) doped with magnesium (ACCP-Mg), zinc (ACCp-Zn) or fluoride (ACCP-F) ions. The experimental CPC consisted of ?-TCP, doped ACCP, and MPCM powders as

Marion Julien; Ibrahim Khairoun; Racquel Z. LeGeros; Severine Delplace; Paul Pilet; Pierre Weiss; Guy Daculsi; Jean Michel Bouler; Jerome Guicheux

2007-01-01

37

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

PubMed

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

Goldsmith, David; Covic, Adrian

2014-06-01

38

Properties of Calcium Phosphate Cements With Different Tetracalcium Phosphate and Dicalcium Phosphate Anhydrous Molar Ratios  

PubMed Central

Calcium phosphate cements (CPCs) were prepared using mixtures of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA), with TTCP/DCPA molar ratios of 1/1, 1/2, or 1/3, with the powder and water as the liquid. Diametral tensile strength (DTS), porosity, and phase composition (powder x-ray diffraction) were determined after the set specimens have been immersed in a physiological-like solution (PLS) for 1 d, 5 d, and 10 d. Cement dissolution rates in an acidified PLS were measured using a dual constant composition method. Setting times ((30 ± 1) min) were the same for all cements. DTS decreased with decreasing TTCP/DCPA ratio and, in some cases, also decreased with PLS immersion time. Porosity and hydroxyapatite (HA) formation increased with PLS immersion time. Cements with TTCP/DCPA ratios of 1/2 and 1/3, which formed calcium-deficient HA, dissolved more rapidly than the cement with a ratio of 1/1. In conclusion, cements may be prepared with a range of TTCP/DCPA ratios, and those with lower ratio had lower strengths but dissolved more rapidly in acidified PLS. PMID:19779581

Hirayama, Satoshi; Takagi, Shozo; Markovic, Milenko; Chow, Laurence C.

2009-01-01

39

Osteoinductivity of Calcium Phosphate Mediated by Connexin 43  

PubMed Central

Recent reports have alluded to the osteoinductive properties of calcium phosphate, yet the cellular processes behind this are not well understood. To gain insight into the molecular mechanisms of this phenomenon, we have conducted a series of in vitro and in vivo experiments using a scaffoldless three dimensional (3D) dental pulp cell (DPC) construct as a physiologically relevant model. We demonstrate that amorphous calcium phosphate (ACP) alters cellular functions and 3D spatial tissue differentiation patterns by increasing local calcium concentration, which modulates connexin 43 (Cx43)-mediated gap junctions. These observations indicate a chemical mechanism for osteoinductivity of calcium phosphates. These results provide new insights for possible roles of mineral phases in bone formation and remodeling. This study also emphasizes the strong effect of scaffold materials on cellular functions and is expected to advance the design of future tissue engineering materials. PMID:23465492

Syed-Picard, Fatima N.; Jayaraman, Thottala; Lam, Raymond S.K.; Beniash, Elia; Sfeir, Charles

2013-01-01

40

Evidence of calcium phosphate depositions in stenotic arteriovenous fistulas.  

PubMed

This study investigates vascular samples from patients with and without end-stage renal disease (ESRD) to determine the occurrence of calcium depositions. Findings in stenotic arteriovenous (AV)-fistula veins were compared with those of nonstenotic AV-fistula veins, non-AV-fistula veins, and atherosclerotic vessels. Calcium and phosphorus content was measured by means of scanning electron microscopy and its built-in method of energy-dispersive spectrometry (EDS) X-ray analysis. We found calcium and phosphorus in samples from AV fistulas with stenotic areas with a calcium/phosphorus molar ratio of 1. Based on EDS analysis and crystal shape comparison, we conclude that calcium phosphate precipitations in stenotic AV fistulas are brushites with the composition CaHPO(4)*2H(2)O. This specific calcium phosphate deposition was found solely in stenotic AV fistulas, not in nonstenotic AV-fistula veins or non-AV-fistula veins regardless of whether the patient had ESRD. Moreover, this calcium phosphate deposition was different from calcium compounds found in atherosclerotic samples. Whether the precipitation of brushite is primarily involved in the development of vascular-access stenosis or represents a secondary consequence cannot be determined from the present study. PMID:11479165

Olsson, L F; Odselius, R; Ribbe, E; Hegbrant, J

2001-08-01

41

The nucleation and growth of calcium phosphate by amelogenin  

PubMed Central

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 ?g/mL. At higher protein concentrations, the amount of calcium phosphate decreased. The kinetics of nucleation was 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. PMID:19079557

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

2008-01-01

42

The stability mechanisms of an injectable calcium phosphate ceramic suspension  

PubMed Central

Calcium phosphate ceramics are widely used as bone substitutes in dentistry and orthopedic applications. For minimally invasive surgery an injectable calcium phosphate ceramic suspension (ICPCS) was developed. It consists in a biopolymer (hydroxypropylmethylcellulose: HPMC) as matrix and bioactive calcium phosphate ceramics (biphasic calcium phosphate: BCP) as fillers. The stability of the suspension is essential to this generation of “ready to use” injectable biomaterial. But, during storage, the particles settle down. The engineering sciences have long been interested in models describing the settling (or sedimentation) of particles in viscous fluids. Our work is dedicated to the comprehension of the effect of the formulation on the stability of calcium phosphate suspension before and after steam sterilization. The rheological characterization revealed the macromolecular behavior of the suspending medium. The investigations of settling kinetics showed the influence of the BCP particle size and the HPMC concentration on the settling velocity and sediment compactness before and after sterilization. To decrease the sedimentation process, the granule size has to be smaller and the polymer concentration has to increase. A much lower sedimentation velocity, as compared to Stokes law, is observed and interpreted in terms of interactions between the polymer network in solution and the particles. This experimentation highlights the granules spacer property of hydrophilic macromolecules that is a key issue for interconnection control, one of the better ways to improve osteoconduction and bioactivity. PMID:20229185

Fatimi, Ahmed; Tassin, Jean-François; Axelos, Monique A. V.; Weiss, Pierre

2010-01-01

43

In vivo behaviour of three calcium phosphate cements and a magnesium phosphate cement  

Microsoft Academic Search

Three types of calcium phosphate cements and one magnesium phosphate cement were implanted subcutaneously in rats under exclusion of direct cellular contact. Retrieval times were either 1, 2, 4 or 8 weeks. Before and after retrieval the compressive strength, the diametral tensile strength, the quantitative chemical composition, the qualitative phase composition, the FTIR spectrum and the microstructure were determined. The

F. C. M. Driessens; M. G. Boltong; M. I. Zapatero; R. M. H. Verbeeck; W. Bonfield; O. Bérmúdez; E. Fernández; M. P. Ginebra; J. A. Planell

1995-01-01

44

Biodegradable magnetic calcium phosphate nanoformulation for cancer therapy.  

PubMed

We fabricated a magnetic calcium phosphate nanoformulation by the biomineralization of calcium phosphate on the surface of magnetic nanoparticles with abundant amino groups, and thus the inorganic layer of calcium phosphate can improve the biocompatibility and simultaneously the magnetic iron oxide can maintain the magnetic targeting function. Two types of anticancer drug models, doxorubicin hydrochloride and DNA, were entrapped in these nanocarriers, respectively. This delivery system displayed high pH sensitivity in drug-controlled release profile as the dissolution of CaP under acid pH condition. Magnetofection was performed to investigate the intracellular uptake and the anti-proliferative effect of tumor cells in the presence of an external magnet. The transfection of the DNA-loaded magnetic system in A549 and HepG2 tumor cells demonstrated that the magnetic nanoformulation could enhance the transfection efficiency to 30% with an applied external magnetic field. PMID:24462792

Tang, Zhaomin; Zhou, Yangbo; Sun, Huili; Li, Dan; Zhou, Shaobing

2014-05-01

45

Ultrasonic enhancing amorphization during synthesis of calcium phosphate.  

PubMed

Amorphous calcium phosphate (ACP) has great application potential in biomaterials field due to its non-cytotoxicity, high bioactivity, good cytocompatibility, and so on. The results of this research demonstrated that ultrasonic obviously enhanced amorphization during synthesis of calcium phosphate. The ACP phase was relatively ideal when the solvent of Ca(NO3)2·4H2O was ethanol and the solvent of (NH4)2HPO4 was a mixture of water and ethanol, under ultrasonic. In-situ crystallization of ACP could be observed by HRTEM. The mechanism on the effects of ultrasonic on amorphization of the synthesized calcium phosphate was discussed. It was suggested that ultrasonic synthesis might be a facile method to prepare pure and safe ACP related biomaterials. PMID:24035140

He, Kun; Xiao, Gui-Yong; Xu, Wen-Hua; Zhu, Rui-Fu; Lu, Yu-Peng

2014-03-01

46

The Ca/P range of nanoapatitic calcium phosphate cements.  

PubMed

Nanoapatites are apatites consisting of nanometer size crystals. The commercial calcium phosphate cements set by the precipitation of nanoapatitic calcium phosphates in the range 1.5 < or = Ca/P < 1.8. In this study it is shown that a continuum of nanoapatites can precipitate in the range 0.8 < Ca/P< or = 1.5. In order to be formed these nanoapatites need to incorporate K+ ions. In addition they can incorporate some Na+ ions. Upon immersion in aqueous solutions these nanoapatites loose phosphate, K+ and Na+ so that in an open system they are transformed into calcium deficient hydroxyapatite Ca9(HPO4)(PO4)5OH within about 2 months. PMID:12162334

Driessens, F C M; Boltong, M G; de Maeyer, E A P; Wenz, R; Nies, B; Planell, J A

2002-10-01

47

Alternative technique for calcium phosphate coating on titanium alloy implants.  

PubMed

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

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

2014-01-01

48

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

PubMed

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

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

2014-05-01

49

Morphological evaluation of osteoblasts cultured on different calcium phosphate ceramics  

Microsoft Academic Search

The objective of these investigations was to develop an in vitro test system for evaluating novel rapidly resorbable calcium phosphate ceramics of varying composition. Rat bone marrow cells were cultured on the disc-shaped test substrates for 14 days. Five calcium phosphates were examined: R1, CaNaPO4; R1M2, composed of CaNaPO4 and MgNaPO4; R12, composed of CaNaPO4 and Mg2SiO4; R1 + 9%

C. Knabe; R. Gildenhaar; G. Berger; W. Ostapowicz; R. Fitzner; R. J. Radlanski; U. Gross

1997-01-01

50

Optimization of calcium phosphate fine ceramic powders preparation  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

51

Phosphate-bonded calcium aluminate cements  

DOEpatents

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.

Sugama, T.

1993-09-21

52

Phosphate-bonded calcium aluminate cements  

DOEpatents

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.degree. C. to about 300.degree. 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.

Sugama, Toshifumi (Mastic Beach, NY)

1993-01-01

53

Investigating calcium polyphosphate addition to a conventional calcium phosphate cement for bone-interfacing applications  

Microsoft Academic Search

Calcium phosphate cements (CPCs) are of great interest in bone regeneration applications because of their biocompatibility and osteoconductivity, and as delivery vehicles for therapeutics; however, delivery applications have been limited by adverse interactions between therapeutics and the cement setting reaction. Amorphous calcium polyphosphate (CPP) yields a biodegradable material with a demonstrated drug delivery capacity following appropriate processing. The incorporation of

Jennifer Lynn Krausher

2010-01-01

54

Molecular mechanisms of crystallization impacting calcium phosphate cements  

PubMed Central

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

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

2010-01-01

55

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

E-print Network

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

Tas, A. Cuneyt

56

USE OF VATERITE AND CALCITE IN FORMING CALCIUM PHOSPHATE CEMENT A. Cuneyt Tas  

E-print Network

USE OF VATERITE AND CALCITE IN FORMING CALCIUM PHOSPHATE CEMENT SCAFFOLDS A. Cuneyt Tas Department calcium phosphate (CaP+CaCO3) cements have been developed. The common point in these cements in the end-product of these cements was carbonated, Ca-deficient, apatitic calcium phosphate, together

Tas, A. Cuneyt

57

Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence of cortical fixation  

E-print Network

Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence Keywords: Screw fixation Pullout force Calcium phosphate cement Osteoporotic bone a b s t r a c with cement. Previous studies have shown that bone augmentation with Calcium Phosphate (CaP) cement

Guerraoui, Rachid

58

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

E-print Network

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

Amrhein, Valentin

59

Calcium, magnesium, and phosphate abnormalities in the emergency department.  

PubMed

Derangements of calcium, magnesium, and phosphate are associated with increased morbidity and mortality. These minerals have vital roles in the cellular physiology of the neuromuscular and cardiovascular systems. This article describes the pathophysiology of these mineral disorders. It aims to provide the emergency practitioner with an overview of the diagnosis and management of these disorders. PMID:24766937

Chang, Wan-Tsu W; Radin, Bethany; McCurdy, Michael T

2014-05-01

60

Atomic Structure of Intracellular Amorphous Calcium Phosphate Deposits  

Microsoft Academic Search

The radial distribution function calculated from x-ray diffraction of mineralized cytoplasmic structures isolated from the hepatopancreas of the blue crab (Callinectes sapidus) is very similar to that previously found for synthetic amorphous calcium phosphate. Both types of mineral apparently have only short-range atomic order, represented as a neutral ion cluster of about 10 angstrom in longest dimension, whose probable composition

F. Betts; N. C. Blumenthal; A. S. Posner; G. L. Becker; A. L. Lehninger

1975-01-01

61

Original article Acid gelation of colloidal calcium phosphate-  

E-print Network

of 45% total Ca and 30% total phosphorus, to an increase in sodium content and pH of milk, to lower, especially for -casein. The pH value at which the milk sample begins to gel increased for low mineral of acid gels. colloidal calcium phosphate / CCP / acid milk gel / dialysis ­ 90 °C 10 min pH

Paris-Sud XI, Université de

62

Main characteristics of calcium phosphate coatings obtained by laser cladding  

Microsoft Academic Search

Laser surface cladding has become an extensively used technique in metallurgical applications in order to improve surface properties of materials. We have proposed this technique in the field of biomaterials to coat the surface of titanium alloy substrates used in orthopaedical implants with a calcium phosphate (CaP) bioceramic to promote the growth of the bone when the implant is inserted

F. Lusquiños; J. Pou; M. Boutinguiza; F. Quintero; R. Soto; B. León; M. Pérez-Amor

2005-01-01

63

Calcium phosphate porous composites and ceramics prospective as bone implants  

NASA Astrophysics Data System (ADS)

Two types of calcium phosphate materials prospective as bone implants were prepared in the shape of granules and their biochemical behavior was tested by in vivo studies: (i) composite materials consisting of gelatin and bi-phase ion modified calcium phosphate Mg,Zn-(HA + ?-TCP); and (ii) ceramics of ion modified calcium phosphate Mg,Zn-(HA + ?-TCP). The starting fine powders were prepared by the method of biomimetic precipitation of the precursors followed by hightemperature treatment. Then granules were prepared by dispersion in liquid paraffin of a thick suspension containing 20% of gelatin gel and thus prepared calcium phosphate powders (1:1 ratios). The composite granules were obtained by subsequent hardening in a glutaraldehyde solution, while the highly porous ceramic granules - by further sintering at 1100°C. The in vivo behavior of both types of granules was tested in experimental rat models. Bone defects were created in rat tibia and were filled with the implants. Biochemical studies were performed. Three months after operation both bio-materials displayed analogous behavior.

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

2013-12-01

64

Growth of calcium phosphate on phosphorylated chitin fibres.  

PubMed

Calcium phosphate growth on chitin phosphorylated fibres was studied using scanning electron microscopy and energy dispersive X-ray analysis (SEM, EDX), micro-Fourier transform infrared spectroscopy (FTIR), and solid state magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. The C6 chemical shift positions of 13C MAS NMR in the chitin fibres phosphorylated using urea and H3PO4 are obvious indicating that phosphorylation takes place not in the C1 but in the C6 region. Micro-FTIR and 31P MAS NMR suggested that ammonium hydrogen phosphate formed during the phosphorylation procedure. Chitin fibres phosphorylated using urea and H3PO4 and then soaked in saturated Ca(OH)2 solution at ambient temperature, which lead to the formation of thin coatings formed by partial hydrolysis of the PO4 functionalities, were found to stimulate the growth of a calcium phosphate coating on their surfaces after soaking in 1.5xSBF solution for as little as one day. The thin layer after Ca(OH)2 treatment functioned as a nucleation layer for further calcium phosphate deposition after soaking in 1.5xSBF solution. EDX-measured Ca : P ratios of the coatings of Ca(OH)2-treated phosphorylated chitin in 1.5xSBF solution suggested that calcium-deficient apatite was formed. PMID:15348722

Yokogawa, Y; Paz Reyes, J; Mucalo, M R; Toriyama, M; Kawamoto, Y; Suzuki, T; Nishizawa, K; Nagata, F; Kamayama, T

1997-07-01

65

Amorphous calcium phosphate and its application in dentistry  

PubMed Central

Amorphous Calcium Phosphate (ACP) is an essential mineral phase formed in mineralized tissues and the first commercial product as artificial hydroxyapatite. ACP is unique among all forms of calcium phosphates in that it lacks long-range, periodic atomic scale order of crystalline calcium phosphates. The X-ray diffraction pattern is broad and diffuse with a maximum at 25 degree 2 theta, and no other different features compared with well-crystallized hydroxyapatite. Under electron microscopy, its morphological form is shown as small spheroidal particles in the scale of tenths nanometer. In aqueous media, ACP is easily transformed into crystalline phases such as octacalcium phosphate and apatite due to the growing of microcrystalline. It has been demonstrated that ACP has better osteoconductivity and biodegradability than tricalcium phosphate and hydroxyapatite in vivo. Moreover, it can increase alkaline phosphatase activities of mesoblasts, enhance cell proliferation and promote cell adhesion. The unique role of ACP during the formation of mineralized tissues makes it a promising candidate material for tissue repair and regeneration. ACP may also be a potential remineralizing agent in dental applications. Recently developed ACP-filled bioactive composites are believed to be effective anti-demineralizing/remineralizing agents for the preservation and repair of tooth structures. This review provides an overview of the development, structure, chemical composition, morphological characterization, phase transformation and biomedical application of ACP in dentistry. PMID:21740535

2011-01-01

66

Mechanical properties of calcium phosphate scaffolds fabricated by robocasting.  

PubMed

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

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

2008-04-01

67

Prediction of the Setting Properties of Calcium Phosphate Bone Cement  

PubMed Central

Setting properties of bone substitutes are improved using an injectable system. The injectable bone graft substitutes can be molded to the shape of the bone cavity and set in situ when injected. Such system is useful for surgical operation. The powder part of the injectable bone cement is included of ?-tricalcium phosphate, calcium carbonate, and dicalcium phosphate and the liquid part contains poly ethylene glycol solution with different concentrations. In this way, prediction of the mechanical properties, setting times, and injectability helps to optimize the calcium phosphate bone cement properties. The objective of this study is development of three different adaptive neurofuzzy inference systems (ANFISs) for estimation of compression strength, setting time, and injectability using the data generated based on experimental observations. The input parameters of models are polyethylene glycol percent and liquid/powder ratio. Comparison of the predicted values and measured data indicates that the ANFIS model has an acceptable performance to the estimation of calcium phosphate bone cement properties. PMID:22919372

Rabiee, Seyed Mahmud; Baseri, Hamid

2012-01-01

68

Synthesis of amorphous calcium phosphate using various types of cyclodextrins  

SciTech Connect

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.

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

69

Preparation of porous apatite granules from calcium phosphate cement  

E-print Network

Preparation of porous apatite granules from calcium phosphate cement A. C. Tas Received: 30 March and 37 °C. A CaP cement powder, comprising a-Ca3(PO4)2 (61 wt.%), CaH- PO4 (26%), CaCO3 (10 to 1 mm. Cement powder (35 wt.%) and NaCl (65 wt.%) mixture was kneaded with an ethanol­Na2HPO4

Tas, A. Cuneyt

70

Compositional dependence of calcium phosphate layer formation in fluoride Bioglasses.  

PubMed

Bioglasses form a double layer composed of apatite and a silica-rich layer when placed in a simulated physiological solution as well as in living tissue [A.E. Clark, C.G. Pantano, and L. L. Hench, "Auger spectroscopic analysis of bioglass corrosion films," J. Am. Ceram. Soc., 59(1-2), 37-39 (1976).]. In the present work, the mechanisms of the calcium phosphate layer and the silica-rich layer formation of fluoride Bioglasses in Tris-buffer solution are studied as a function of the SiO2 content. Fourier Transform Infrared Reflection Spectroscopy (FTIRS) is used to investigate the mechanism of formation of calcium phosphate and silica-rich layers on the glass surface. Ion concentration in reacted solution and elemental depth profiles are obtained by Induced Coupled Plasma Atomic Emission Spectrometry (ICP) and Auger Electron Spectroscopy (AES), respectively. Si--O bonds with one nonbridging oxygen and Si--O--Si bonds form at the early stage of reaction. Strong phosphorus ion uptake occurs when an amorphous calcium phosphate layer crystallizes. Glasses with high silica content (conventional glass) form the silica-rich layer first followed by a calcium phosphate layer on top. However, glasses with low silica content (invert glass) form both layers simultaneously. The rate of apatite formation decreases with increasing SiO2 content, especially in the region of conventional glass compositions. Ion release rates decreases as SiO2 content increases, with a significant change occurring at the compositional boundary between invert and conventional glasses. PMID:1331116

Kim, C Y; Clark, A E; Hench, L L

1992-09-01

71

Bone regeneration: molecular and cellular interactions with calcium phosphate ceramics  

PubMed Central

Calcium phosphate bioceramics are widely used in orthopedic and dental applications and porous scaffolds made of them are serious candidates in the field of bone tissue engineering. They have superior properties for the stimulation of bone formation and bone bonding, both related to the specific interactions of their surface with the extracellular fluids and cells, ie, ionic exchanges, superficial molecular rearrangement and cellular activity. PMID:17717972

Barrère, Florence; van Blitterswijk, Clemens A; de Groot, Klaas

2006-01-01

72

Growth of calcium phosphate on phosphorylated chitin fibres  

Microsoft Academic Search

Calcium phosphate growth on chitin phosphorylated fibres was studied using scanning electron microscopy and energy dispersive X-ray analysis (SEM, EDX), micro-Fourier transform infrared spectroscopy (FTIR), and solid state magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. The C6 chemical shift positions of 13C MAS NMR in the chitin fibres phosphorylated using urea and H3PO4 are obvious indicating that phosphorylation

Y. YOKOGAWA; J PAZ REYES; M. R MUCALO; M TORIYAMA; Y KAWAMOTO; T SUZUKI; K NISHIZAWA; F NAGATA; T KAMAYAMA

1997-01-01

73

Biomimetic transformations of amorphous calcium phosphate: kinetic and thermodynamic studies.  

PubMed

The biomimetic synthesis and phase transformation of XRD amorphous calcium phosphate were studied by application of kinetic, chemical and spectral (XRD and IR) methods and thermodynamic simulations. Two SBFs (SBFc and SBFr), differing in their HCO(3)(-) and Cl(-) ion contents, were used in the maturation studies. It has been proven that the biomimetic maturation accelerated the phase transformation of less thermodynamically stable amorphous calcium phosphate to poorly crystalline hydroxyapatite. Several regularities have been found: (i) kinetic reasons determined the biomimetic precipitation of XRD-amorphous calcium deficient phosphate (ACP); (ii) the precipitated ACP always contained impurities due to co-precipitation, ion substitution and incorporation phenomena; (iii) the increased content of HCO(3)(-) ions in the surrounding microenvironments increased the rate of phase transformation and the concentration of MeHCO(3)(+) (Me = Ca, Mg) species in the solution, but the solubility of CaCO(3) has only been decreased and its precipitation accelerated, thus playing a crucial role in the process under study. PMID:20532962

Rabadjieva, D; Gergulova, R; Titorenkova, R; Tepavitcharova, S; Dyulgerova, E; Balarew, Chr; Petrov, O

2010-09-01

74

In vitro studies of calcium phosphate silicate bone cements.  

PubMed

A novel calcium phosphate silicate bone cement (CPSC) was synthesized in a process, in which nanocomposite forms in situ between calcium silicate hydrate (C-S-H) gel and hydroxyapatite (HAP). The cement powder consists of tricalcium silicate (C(3)S) and calcium phosphate monobasic (CPM). During cement setting, C(3)S hydrates to produce C-S-H and calcium hydroxide (CH); CPM reacts with the CH to precipitate HAP in situ within C-S-H. This process, largely removing CH from the set cement, enhances its biocompatibility and bioactivity. The testing results of cell culture confirmed that the biocompatibility of CPSC was improved as compared to pure C(3)S. The results of XRD and SEM characterizations showed that CPSC paste induced formation of HAP layer after immersion in simulated body fluid for 7 days, suggesting that CPSC was bioactive in vitro. CPSC cement, which has good biocompatibility and low/no cytotoxicity, could be a promising candidate as biomedical cement. PMID:23114635

Zhou, Shuxin; Ma, Jingzhi; Shen, Ya; Haapasalo, Markus; Ruse, N Dorin; Yang, Quanzu; Troczynski, Tom

2013-02-01

75

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

E-print Network

Comparison study of biomimetic strontium-doped calcium phosphate coatings by electrochemical April 2012 Ã? Springer Science+Business Media, LLC 2012 Abstract In this study, strontium-doped calcium of the strontium-doped calcium phosphate coatings were evaluated using bone cell culture using MC3T3-E1 osteoblast

Meng, Yizhi

76

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

E-print Network

Simulations of Inositol Phosphate Metabolism and Its Interaction with InsP3-Mediated Calcium bisphosphate, triggers numerous cellular processes by regulating calcium release from internal stores. The Ins(1,4,5)P3-mediated calcium release. We find temporal dynamics of most inositol phosphates

Bhalla, Upinder S.

77

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

E-print Network

Synthesis of Calcium Hydroxyapatite­Tricalcium Phosphate (HA­TCP) Composite Bioceramic Powders important inorganic phases of synthetic bone applications--namely, calcium hydroxyapatite (Ca10(PO4)6(OH)2 (HA)) and tri- calcium phosphate (Ca3(PO4)2 (TCP))--were prepared as submicrometer-sized, chemically

Tas, A. Cuneyt

78

Phosphate decreases urine calcium and increases calcium balance: A meta-analysis of the osteoporosis acid-ash diet hypothesis  

PubMed Central

Background The acid-ash hypothesis posits that increased excretion of "acidic" ions derived from the diet, such as phosphate, contributes to net acidic ion excretion, urine calcium excretion, demineralization of bone, and osteoporosis. The public is advised by various media to follow an alkaline diet to lower their acidic ion intakes. The objectives of this meta-analysis were to quantify the contribution of phosphate to bone loss in healthy adult subjects; specifically, a) to assess the effect of supplemental dietary phosphate on urine calcium, calcium balance, and markers of bone metabolism; and to assess whether these affects are altered by the b) level of calcium intake, c) the degree of protonation of the phosphate. Methods Literature was identified through computerized searches regarding phosphate with surrogate and/or direct markers of bone health, and was assessed for methodological quality. Multiple linear regression analyses, weighted for sample size, were used to combine the study results. Tests of interaction included stratification by calcium intake and degree of protonation of the phosphate supplement. Results Twelve studies including 30 intervention arms manipulated 269 subjects' phosphate intakes. Three studies reported net acid excretion. All of the meta-analyses demonstrated significant decreases in urine calcium excretion in response to phosphate supplements whether the calcium intake was high or low, regardless of the degree of protonation of the phosphate supplement. None of the meta-analyses revealed lower calcium balance in response to increased phosphate intakes, whether the calcium intake was high or low, or the composition of the phosphate supplement. Conclusion All of the findings from this meta-analysis were contrary to the acid ash hypothesis. Higher phosphate intakes were associated with decreased urine calcium and increased calcium retention. This meta-analysis did not find evidence that phosphate intake contributes to demineralization of bone or to bone calcium excretion in the urine. Dietary advice that dairy products, meats, and grains are detrimental to bone health due to "acidic" phosphate content needs reassessment. There is no evidence that higher phosphate intakes are detrimental to bone health. PMID:19754972

Fenton, Tanis R; Lyon, Andrew W; Eliasziw, Michael; Tough, Suzanne C; Hanley, David A

2009-01-01

79

Phase Transformation of Calcium Phosphates by Electrodeposition and Heat Treatment  

NASA Astrophysics Data System (ADS)

The effect of heat treatment on the calcium phosphate deposited on Ti-6Al-4V substrate using an electrolytic process is investigated. The calcium phosphate was deposited in a 0.04 M Ca(H2PO4)2·H2O (MCPM) solution on a Ti-6Al-4V substrate at 333 K (60 °C), 10 V, and 80 Torr for 1 hour, and calcined at various temperatures for 4 hours. The X-ray diffraction (XRD) results demonstrate that the phases are dicalcium phosphate (CaHPO4, DCPD) and hydroxyapatile [Ca(PO4)6 (OH)2, HAP] for the as-deposited samples. When the deposited sample was calcined at 873 K (600 °C) for 4 hours, the XRD results show that the transformation of DCPD to HAP occurs. Moreover, HAP converts to ?-TCP, CPP, and CaO. For the sample calcined at 1073 K (800 °C) for 4 hours, the scanning electron microscopy (SEM) micrograph reveals that the crack of the calcined sample propagates with a width of about 3 ?m. This result is due to HAP becoming decomposed and converting to ?-TCP, CPP, CaO, and H2O. The vaporization of H2O within the calcined sample promotes the crack propagation and growth.

Shih, Wei-Jen; Wang, Moo-Chin; Chang, Kuo-Ming; Wang, Cheng-Li; Wang, Szu-Hao; Li, Wang-Long; Huang, Hong-Hsin

2010-12-01

80

Calcium phosphate bone cements for local vancomycin delivery.  

PubMed

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

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

2015-04-01

81

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

Microsoft Academic Search

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

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

2010-01-01

82

Selective laser sintering of calcium phosphate materials for orthopedic implants  

NASA Astrophysics Data System (ADS)

Two technologies, Solid Freeform Fabrication (SFF) and bioceramics are combined in this work to prepare bone replacement implants with complex geometry. SFF has emerged as a crucial technique for rapid prototyping in the last decade. Selective Laser Sintering (SLS) is one of the established SFF manufacturing processes that can build three-dimensional objects directly from computer models without part-specific tooling or human intervention. Meanwhile, there have been great efforts to develop implantable materials that can assist in regeneration of bone defects and injuries. However, little attention has been focused in shaping bones from these materials. The main thrust of this research was to develop a process that can combine those two separate efforts. The specific objective of this research is to develop a process that can construct bone replacement material of complex geometry from synthetic calcium phosphate materials by using the SLS process. The achievement of this goal can have a significant impact on the quality of health care in the sense that complete custom-fit bone and tooth structures suitable for implantation can be prepared within 24--48 hours of receipt of geometric information obtained either from patient Computed Tomographic (CT) data, from Computer Aided Design (CAD) software or from other imaging systems such as Magnetic Resonance Imaging (MRI) and Holographic Laser Range Imaging (HLRI). In this research, two different processes have been developed. First is the SLS fabrication of porous bone implants. In this effort, systematic procedures have been established and calcium phosphate implants were successfully fabricated from various sources of geometric information. These efforts include material selection and preparation, SLS process parameter optimization, and development of post-processing techniques within the 48-hour time frame. Post-processing allows accurate control of geometry and of the chemistry of calcium phosphate, as well as control of micro and macro pore structure, to maximize bone healing and provide sufficient mechanical strength. It also permits the complete removal of the polymeric binders that are resided in the SLS process. In collaboration with the University of Texas Health Science Center at San Antonio and BioMedical Enterprises, Inc., porous implants based on anatomical geometry have been successfully implanted in rabbits and dogs. These histologic animal studies reveal excellent biocompatibility and show its great potential for commercial custom-fit implant manufacture. The second research effort involves fabrication of fully dense bone for application in dental restoration and load-bearing orthopedic functions. Calcium phosphate glass melts, proven to be biocompatible in the first effort, were cast into carbon molds. Processes were developed for preparing the molds. These carbon molds of anatomic shape can be prepared from either Computer Numerical Control (CNC) milling of slab stock or SLS processing of thermoset-coated graphite powder. The CNC milling method provides accurate dimension of the molds in a short period of time, however, the capable geometries are limited; generally two pieces of molds are required for complex shapes. The SLS method provides very complex shape green molds. However, they need to go through pyrolysis of thermoset binder to provide the high temperature capability reached at calcium phosphate melt temperatures (1100°C) and noticeable shrinkage was observed during pyrolysis. The cast glass was annealed to develop polycrystalline calcium phosphate. This process also exhibits great potential.

Lee, Goonhee

83

Interactions of casein micelles with calcium phosphate particles.  

PubMed

Insoluble calcium phosphate particles, such as hydroxyapatite (HA), are often used in calcium-fortified milks as they are considered to be chemically unreactive. However, this study showed that there was an interaction between the casein micelles in milk and HA particles. The caseins in milk were shown to bind to the HA particles, with the relative proportions of bound ?-casein, ?S-casein, and ?-casein different from the proportions of the individual caseins present in milk. Transmission electron microscopy showed no evidence of intact casein micelles on the surface of the HA particles, which suggested that the casein micelles dissociated either before or during binding. The HA particles behaved as ion chelators, with the ability to bind the ions contained in the milk serum phase. Consequently, the depletion of the serum minerals disrupted the milk mineral equilibrium, resulting in dissociation of the casein micelles in milk. PMID:24896851

Tercinier, Lucile; Ye, Aiqian; Anema, Skelte G; Singh, Anne; Singh, Harjinder

2014-06-25

84

Mesoscale crystallization of calcium phosphate nanostructures in protein (casein) micelles  

NASA Astrophysics Data System (ADS)

Aqueous micelles of the multi-protein calcium phosphate complex, casein, were treated at 60 °C and pH 7 over several months. Although partial dissociation of the micelles into 12 nm sized amorphous calcium phosphate (ACP)/protein nanoparticles occurred within a period of 14 days, crystallization of the ACP nanoclusters into bundles of hydroxyapatite (HAP) nanofilaments was not observed until after 12 weeks. The HAP nanofilaments were formed specifically within the partially disrupted protein micelles suggesting a micelle-mediated pathway of mesoscale crystallization. Similar experiments using ACP-containing synthetic micelles prepared from ?-casein protein alone indicated that co-aligned bundles of HAP nanofilaments were produced within the protein micelle interior after 24 hours at temperatures as low as 35 °C. The presence of Mg2+ ions in the casein micelles, as well as a possible synergistic effect associated with the multi-protein nature of the native aggregates, could account for the marked inhibition in mesoscale crystallization observed in the casein micelles compared with the single-component ?-casein constructs.Aqueous micelles of the multi-protein calcium phosphate complex, casein, were treated at 60 °C and pH 7 over several months. Although partial dissociation of the micelles into 12 nm sized amorphous calcium phosphate (ACP)/protein nanoparticles occurred within a period of 14 days, crystallization of the ACP nanoclusters into bundles of hydroxyapatite (HAP) nanofilaments was not observed until after 12 weeks. The HAP nanofilaments were formed specifically within the partially disrupted protein micelles suggesting a micelle-mediated pathway of mesoscale crystallization. Similar experiments using ACP-containing synthetic micelles prepared from ?-casein protein alone indicated that co-aligned bundles of HAP nanofilaments were produced within the protein micelle interior after 24 hours at temperatures as low as 35 °C. The presence of Mg2+ ions in the casein micelles, as well as a possible synergistic effect associated with the multi-protein nature of the native aggregates, could account for the marked inhibition in mesoscale crystallization observed in the casein micelles compared with the single-component ?-casein constructs. Electronic supplementary information (ESI) available: Particle size histograms, TEM, EDX and electron diffraction data. See DOI: 10.1039/c0nr00158a

Thachepan, Surachai; Li, Mei; Mann, Stephen

2010-11-01

85

Preparation of DNA/Gold Nanoparticle Encapsulated in Calcium Phosphate.  

PubMed

Biocompatible DNA/gold nanoparticle complex with a protective calcium phosphate (CaP) coating was prepared by incubating DNA/gold nanoparticle complex coated by hyaluronic acid in SBF (simulated body fluid) with a Ca concentration above 2?mM. The CaP-coated DNA complex was revealed to have high compatibility with cells and resistance against enzymatic degradation. By immersion in acetate buffer (pH 4.5), the CaP capsule released the contained DNA complex. This CaP capsule including a DNA complex is promising as a sustained-release system of DNA complexes for gene therapy. PMID:21773047

Ito, Tomoko; Ibe, Koyuki; Uchino, Tomohiro; Ohshima, Hiroyuki; Otsuka, Makoto

2011-01-01

86

Further studies of calcium phosphate growth on phosphorylated cotton fibres  

Microsoft Academic Search

Further studies using scanning electron microscopy\\/energy dispersive X-ray analysis (SEM\\/EDX), micro-Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and solid state magic angle spinning nuclear magnetic resonance (MAS NMR) techniques of calcium phosphate growth on Ca(OH)2-treated urea\\/H3PO3- and urea\\/H3PO4-modified cotton fibres are reported. In the case of the Ca(OH)2-treated urea\\/H3PO3-modified fibres which have been reported in an earlier paper,

M. R. Mucalo; Y. Yokogawa; T. Suzuki; Y. Kawamoto; F. Nagata; K. Nishizawa

1995-01-01

87

Amorphous calcium phosphate composites with improved mechanical properties  

PubMed Central

Hybridized zirconium amorphous calcium phosphate (ACP)-filled methacrylate composites make good calcium and phosphate releasing materials for anti-demineralizing/remineralizing applications with low mechanical demands. The objective of this study was to assess the effect of the particle size of the filler on the mechanical properties of these composites. Photo-curable resins were formulated from ethoxylated bisphenol A dimethacrylate, triethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate and methacryloxyethyl phthalate. Camphorquinone and ethyl-4-N,N-dimethylaminobenzoate were utilized as components of the photoinitiator system. After 2 h of mechanical milling in isopropanol, an approximate 64 % reduction in the median particle diameter was observed [27.48 ?m vs. 9.98 ?m] for unmilled and milled wet ACP, respectively. Dry ACP showed a 43 % reduction in particle size from pre- to post-milling. As well as dry composites, those that had been immersed in aqueous media were evaluated for their Young’s Modulus, water sorption, biaxial tensile, three-point flexural and diametral tensile strength. Mechanically milling the filler increased the volume of fine particles in the composite specimens, resulting in a more homogeneous intra-composite distribution of ACP and a reduction in voids. In turn, less water diffused into the milled composites upon aqueous exposure, and they showed a marked improvement in biaxial flexure strength and a moderate improvement in flexural strength over composites with unmilled ACP. The demonstrated improvement in the mechanical stability of milled Zr-ACP composites may help in extending their dental applicability. PMID:18688290

O’Donnell, J.N.R.; Antonucci, J.M.; Skrtic, D.

2008-01-01

88

Microporous calcium phosphate ceramics driving osteogenesis through surface architecture.  

PubMed

The presence of micropores in calcium phosphate (CaP) ceramics has shown its important role in initiating inductive bone formation in ectopic sites. To investigate how microporous CaP ceramics trigger osteoinduction, we optimized two biphasic CaP ceramics (i.e., BCP-R and BCP-S) to have the same chemical composition, equivalent surface area per volume, comparable protein adsorption, similar ion (i.e., calcium and phosphate) exchange and the same surface mineralization potential, but different surface architecture. In particular, BCP-R had a surface roughness (Ra) of 325.4 ± 58.9 nm while for BCP-S it was 231.6 ± 35.7 nm. Ceramic blocks with crossing or noncrossing channels of 250, 500, 1000, and 2000 µm were implanted in paraspinal muscle of dogs for 12 weeks. The percentage of bone volume in the channels was not affected by the type of pores (i.e., crossing vs. closed) or their size, but it was greatly influenced by the ceramic type (i.e., BCP-R vs. BCP-S). Significantly, more bone was formed in the channels of BCP-R than in those of BCP-S. Since the two CaP ceramics differed only in their surface architecture, the results hereby demonstrate that microporous CaP ceramics may induce ectopic osteogenesis through surface architecture. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1188-1199, 2015. PMID:25044678

Zhang, Jingwei; Barbieri, Davide; Ten Hoopen, Hetty; de Bruijn, Joost D; van Blitterswijk, Clemens A; Yuan, Huipin

2015-03-01

89

Fully injectable calcium phosphate cement--a promise to dentistry.  

PubMed

Calcium phosphate cements (CPC) are self setting and biocompatible bone substitute materials with potential applications in dentistry. However, its clinical use has been challenged by poor rheological properties. A novel formulation of CPC has been developed, which gives a fully injectable and cohesive paste. This work investigates the suitability of the new "fully injectable calcium phosphate cement" (FI-CPC) for dental applications. The cementing properties, material characteristics, and the rheological properties were tested using a battery of material characteristics methods. The biocompatibility was also evaluated as per ISO 7405. The setting time (20 min) and compressive strength (>11 Mpa) of FI-CPC satisfy the clinical requirements. It underwent setting without any exothermic reaction, keeping good dimensional stability. The cement paste could be extruded through a 18-gauge needle, easily and fully. It showed excellent cohesion when immersed in water. FI-CPC was seen to set into a micro-porous mass of hydroxyapatite, the mineral part of human dentin. It showed good attachment to dentin walls, when filled in tooth perforations. FI-CPC was found non-toxic, non-allergic, non-pyrogenic, and soft-tissue compatible. The study shows that FI-CPC provides a self setting bio-compatible paste with excellent rheological properties for surgical applications. The set cement provides good and stable sealing. The osteoconductive property is an added advantage. FI-CPC proves to be an ideal material for endodontic sealing/filling and periodontic repair. PMID:15915629

Komath, Manoj; Varma, H K

2004-01-01

90

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

PubMed

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

Naidu, Sonia; Scherer, George W

2014-12-01

91

Biocompatibility and resorption of a brushite calcium phosphate cement.  

PubMed

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

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

92

Ethnic differences in urinary calcium and phosphate excretion between Gambian and British older adults.  

PubMed

Ethnic differences in renal calcium and phosphate excretion exist, which may depend on differences in their dietary intakes and regulatory factors. We report highly significant differences in urinary calcium and phosphate excretion between white British and Gambian adults after statistical adjustment for mineral intakes, indicating an independent effect of ethnicity. PMID:25311107

Redmond, J; Palla, L; Yan, L; Jarjou, L M A; Prentice, A; Schoenmakers, I

2014-10-14

93

Reinforcement of calcium phosphate cement by incorporating with high-strength ?-tricalcium phosphate aggregates.  

PubMed

Calcium phosphate cement (CPC) sets to form hydroxyapatite after implantation and has been used in orthopedic and dental procedures. However, the brittleness and low strength of CPC prohibit its use in many stress-bearing locations, and so the improvement of the compressive strength is one of the focuses of research on CPC. In this study, a novel way was used to improve the mechanical performance of CPC by dispersion of high-strength degradable ?-tricalcium phosphate (?-TCP) granules sized between 200 ?m and 450 ?m in the cement as aggregates. Intimate bonding was formed between the aggregates and CPC matrix after hydration. The results showed that, by addition of 20 wt % the as-prepared ?-TCP aggregates, the compressive strength of the calcium phosphate cement was increased by about 70%, while the paste of the CPC concrete still maintained injectable, and the heat release decreased obviously (about 25%) in the hydration process. The high strength or high rigidity of the ?-TCP aggregates and good interfacial bonding between the aggregates and the CPC matrix seemed to contribute to the significant improvement in the mechanical performance. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 350-359, 2012. PMID:22113933

Gu, Tao; Shi, Haishan; Ye, Jiandong

2012-02-01

94

Development of artificial seed crystal for crystallization of calcium phosphate.  

PubMed

An artifical seed crystal material consisting of calcium silicate hydrate (5CaO x 6SiO2 x 5H2O : tobermorite crystals) applicable for phosphorus removal by crystallization was developed. Card-house shaped tobermorite crystals were developed on the seed material where orthophosphate crystallized as a calcium phosphate. The seed material can be manufactured by mixing siliceous and calcareous raw materials, pelletizing and subsequent autoclaving. Laboratory experiments were conducted to apply the new developed seed crystal material in the phosphorus recovery from sludge sidestreams of a wastewater treatment plant. In this crystallization process, the performance the carbon dioxide degassingprocess usually carried out when applying crystallization was not necessary, the hydroxyapatite was able to crystallize at a pH of 8.0 to 8.5 without precipitation of calcium carbonates. In the treatment of a sidestream with orthophosphate concentrations of 50 mgl(-1) and COD concentrations between 200 to 400 mgl(-1), phosphorus removal efficiencies ranging from 75 to 85% were observed. The seed crystal material was collected after the laboratory experiments and the chemical estimation and the germination test for agricultural reuse were performed. As a result, it was shown that the hydroxyapatite precipitated on the seed material had a 100% fusibility to soil and had characteristics to be a good nutrient source as a fertilizer for plants. PMID:11804345

Moriyama, K; Kojima, T; Minawa, Y; Matsumoto, S; Nakamachi, K

2001-11-01

95

Clinical and histologic observation of replacement of biphasic calcium phosphate by bone tissue in monkeys.  

PubMed

Biphasic calcium phosphate, consisting of beta-tricalcium phosphate and hydroxyapatite, was implanted in wide and deep periodontal osseous defects of monkeys in combination with the guided tissue regeneration technique. After 12 weeks, sites treated with a combination of biphasic calcium phosphate and guided tissue regeneration maintained the shape of the ridge, but both guided tissue regeneration and control sites (untreated) showed extreme resorption. A histopathologic investigation revealed that numerous macrophages contained small particles of ceramic within their vesicles and the active bone replacement occurred from the surrounding bone. Biphasic calcium phosphate has osteoconductive potential and this potential may be related to degradation by macrophage phagocytosis. PMID:8593983

Hashimoto-Uoshima, M; Ishikawa, I; Kinoshita, A; Weng, H T; Oda, S

1995-04-01

96

Calcium phosphate and fluorinated calcium phosphate coatings on titanium deposited by Nd:YAG laser at a high fluence.  

PubMed

Calcium phosphate coatings are known to enhance long-term fixation, reliability and promote osteointegration of cementless titanium-based implant devices. This study was aimed at the pulsed laser deposition of calcium phosphate coatings onto titanium using hydroxyapatite and hydroxyapatite-fluorapatite targets. The deposition was carried out at the high laser beam fluence conditions, about 12 J/cm(2). The coatings were characterized with respect to their morphology, phase composition and hardness. X-ray energy dispersive analysis revealed the coatings retain their elemental composition, and fluoride content within the film is the same as in the initial target. However, unlike sintered targets, the deposited films contain no apatite-like phases. The hardness of the films, about 18 GPa, is surprisingly high compared to that of hydroxyapatite and hydroxyapatite-fluorapatite ceramic targets. The deposited coatings of 2.7-2.9 microm thickness have uniform and dense microstructure, containing the solidified droplets of the expulsed from the target phase. The uncommon structure and hardness of the films can be attributed to the melting and phase decomposition of the initial material in the laser plasma. PMID:15350786

Ferro, Daniela; Barinov, Sergey M; Rau, Jiulietta V; Teghil, Roberto; Latini, Alessandro

2005-03-01

97

[Allergy of calcium phosphate cement material following skull reconstruction: a case report].  

PubMed

The paste form of calcium phosphate cement is often used in skull reconstruction because of the biocompatibility and early handling of these cements. Although it had rarely been shown to produce a foreign body reaction, we encountered a patient who experienced an allergic reaction to calcium phosphate cements(Biopex®. A patch test was performed and a positive reaction to magnesium phosphate was obtained. Biopex® contains magnesium phosphate, so we diagnosed this case as allergic reaction. Pathological analysis revealed infiltration of plasmacytes in the bone flap around the calcium phosphate cement. The postoperative course was uneventful 3 years after surgery. Allergy to calcium phosphate cements is rare, but must be considered in differential diagnosis of its side effects. PMID:23542795

Mizowaki, Takashi; Miyake, Shigeru; Yoshimoto, Yuji; Matsuura, Yoshitaka; Akiyama, Sou

2013-04-01

98

Preparation and properties of some magnesium-containing calcium phosphate cements  

Microsoft Academic Search

Attempts were made to prepare magnesium-containing calcium phosphate cements. These were successful at the composition CaMg2(PO4)2xH2O. X-ray diffraction showed that such a compound is not formed but that the cement consists of magnesium phosphate precipitated on the calcium phosphate admixture. The pH of this formulation is around 10 during setting and after. The cement is injectable. Its setting time is

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

1994-01-01

99

The modulation of osteogenesis in vitro by calcium titanium phosphate coatings  

Microsoft Academic Search

Calcium phosphate coated titanium and titanium alloy are widely used as dental and orthopaedic implants. This study examines the effect of novel calcium titanium and calcium titanium zirconium phosphates suitable for plasma-spraying onto titanium substrata on the expression of bone-related genes and proteins by human bone-derived cells (HBDC) and compares this behavior to that on native titanium and hydroxyapatite-coated titanium.

C. Knabe; G. Berger; R. Gildenhaar; F. Klar; H. Zreiqat

2004-01-01

100

Composition and properties of silver-containing calcium carbonate-calcium phosphate bone cement.  

PubMed

The introduction of silver, either in the liquid phase (as silver nitrate solution: Ag(L)) or in the solid phase (as silver phosphate salt: Ag(S)) of calcium carbonate-calcium phosphate (CaCO3-CaP) bone cement, its influence on the composition of the set cement (C-Ag(L) and C-Ag(S) cements with a Ca/Ag atomic ratio equal to 10.3) and its biological properties were investigated. The fine characterisation of the chemical setting of silver-doped and reference cements was performed using FTIR spectroscopy. We showed that the formation of apatite was enhanced from the first hours of maturation of C-Ag(L) cement in comparison with the reference cement, whereas a longer period of maturation (about 10 h) was required to observe this increase for C-Ag(S) cement, although in both cases, silver was present in the set cements mainly as silver phosphate. The role of silver nitrate on the setting chemical reaction is discussed and a chemical scheme is proposed. Antibacterial activity tests (S. aureus and S. epidermidis) and in vitro cytotoxicity tests (human bone marrow stromal cells (HBMSC)) showed that silver-loaded CaCO3-CaP cements had antibacterial properties (anti-adhesion and anti-biofilm formation) without a toxic effect on HBMSC cells, making C-Ag(S) cement a promising candidate for the prevention of bone implant-associated infections. PMID:23892487

Jacquart, Sylvaine; Siadous, Robin; Henocq-Pigasse, Christel; Bareille, Reine; Roques, Christine; Rey, Christian; Combes, Christèle

2013-12-01

101

Bone formation in algae-derived and synthetic calcium phosphates with or without poloxamer.  

PubMed

Calcium phosphate ceramics such as hydroxyapatite (HA) and biphasic calcium phosphates are used clinically to repair bone defects. These calcium phosphate ceramics can differ by composition, structure, and rate of degradation. This study compared 3 calcium phosphate ceramics, 2 of which have similar structure but different composition: 100% HA (algae derived) and HA/?-tricalcium phosphate (?-TCP) 20/80 (algae derived), and 2 with different structure but similar composition: HA/?-TCP 20/80 (algae derived) and HA/?-TCP 15/85 (synthetic). Calcium phosphate ceramics can be difficult to handle and contour during the surgeries. To improve handling, Poloxamer 407 (P407) was added to the 3 ceramics, and its effect on bone healing was also assessed. Bilateral calvarial defects created in the parietal bones of New Zealand white rabbits were left unfilled or were filled with autograft or one of the ceramics, with and without P407. Six weeks after operation, healing was evaluated qualitatively by histology and quantitatively by micro-computed tomography analysis and histomorphometry. All 3 calcium phosphate ceramics demonstrated osteoconductivity and performed similarly in supporting new bone formation, suggesting that the differences in their composition, structure, or degradation did not significantly affect their ability to promote bone healing in this application. Incorporating P407 did not impede osteoconductivity as HA and biphasic calcium phosphate combined with P407 performed similarly as when used alone for craniofacial defect repair. PMID:23524692

Zhou, Aileen Jing-Jing; Clokie, Cameron Malcolm Lang; Peel, Sean Alexander Fitzgerald

2013-03-01

102

Novel microwave synthesis of amorphous calcium phosphate nanospheres.  

PubMed

Amorphous calcium phosphate (ACP) is an important precursor phase in tissue mineralization. It shows high solubility and excellent remineralization ability. Commercially viable techniques for producing ACP are high-cost/low-efficiency process. This article describes a novel microwave (MW)-assisted ACP synthesis route as an alternative to current ACP synthesis methods. An important feature of the process is the use of supersaturated biomimetic fluids (SBFs), which are based on Kokubo-like simulated body fluids. However, our present compositions are substantially different in that they no longer simulate the body fluid compositions. The effects of solution composition and processing parameters were studied. The mechanism of ACP synthesis under MW irradiation process is also discussed. The as-synthesized ACP nanospheres were characterized and showed good reactivity and biocompatibility. These as-synthesized nanoparticles can be potential candidates for biomedical applications and remineralization mechanism study. PMID:22331618

Zhou, Huan; Bhaduri, Sarit

2012-05-01

103

Regulation of calcium phosphate formation by native amelogenins in vitro.  

PubMed

Our previous in vitro studies have shown that recombinant full-length porcine amelogenin rP172 can transiently stabilize amorphous calcium phosphate (ACP) and uniquely guide the formation of well-aligned bundles of hydroxyapatite (HA) crystals, as seen in the secretory stage of amelogenesis. This functional capacity is dependent on the hydrophilic C-terminal domain of full-length amelogenin. However, we have also found that native phosphorylated (single S-16 site) forms of full-length (P173) and C-terminal cleaved (P148) amelogenins can stabilize ACP for >?2?d and prevent HA formation. The present study was carried out to test the hypothesis that, at reduced concentrations, native full-length P173 also has the capacity to guide ordered HA formation. The effect of P148 and P173 concentrations (0.2-2.0?mg/ml) on the rate of spontaneous calcium phosphate precipitation was monitored via changes in solution pH, while mineral phases formed were assessed using TEM. At higher P173 concentrations (1.0-2.0?mg/ml), limited mineral formation occurred and only ACP nanoparticles were observed during a 48?h period. However, at 0.4?mg/ml P173, a predominance of organized bundles of linear, needle-like HA crystals were observed. At 0.2?mg/ml of P173, limited quantities of less organized HA crystals were found. Although P148 similarly stabilized ACP, it did not guide ordered HA formation, like P173. Hence, the establishment of the hierarchical enamel structure during secretory stage amelogenesis may be regulated by the partial removal of full-length amelogenin via MMP20 proteolysis, while predominant amelogenin degradation products, like P148, serve to prevent uncontrolled mineral formation. PMID:25158174

Kwak, Seo-Young; Kim, Sonia; Yamakoshi, Yasuo; Simmer, James P; Beniash, Elia; Margolis, Henry C

2014-08-01

104

On the effect of the injection of potassium phosphate in vivo inducing the precipitation of serum calcium with inorganic phosphate  

PubMed Central

High concentrations of inorganic phosphate (Pi) resulted from the hydrolysis of ATP is strongly associated to the weakness of the contractile mechanism of muscles due to its attractiveness to calcium. The majority of the experiments to study such effect are conducted in vitro. This work investigates the effects of different concentrations of Pi, induced by the injection of potassium phosphate in live animals, in the precipitation with serum calcium and the generation of calcium phosphate composites. The experiments were also designed to find out the ideal amount of potassium phosphate to induce an effective reaction. Potassium phosphate was injected in Wistar rats, randomly separated and distributed into seven groups. Group I was injected with 0.5 ml of saline solution (control) and groups II through VII were injected with 0.5, 1.5, 2.5, 5.0, 7.5 and 10.0 mg/kg of potassium phosphate, respectively. Blood collected from the inferior vena cava was submitted to biochemical analyses to measure the concentrations of calcium, Pi, urea and creatinine. The results showed that Pi, induced by the injection of potassium phosphate in live animals, causes precipitation with serum calcium, with statistically significant differences between the control and the treatment groups for doses up to 5.0 mg/kg. No statistically significant differences were found between the different doses and the concentration of urea and creatinine in the plasma. We conclude that potassium phosphate can be used to induce serum calcium precipitation in-vivo, with minor effects on other physiological variables, and the ideal dose to do so is 5.0 mg/kg. PMID:24379908

Soares, Alcimar B; Ticianeli, José G; Soares, Letícia B M; Amaro, George

2013-01-01

105

Calcium phosphate nanoparticles functionalized with a dimethacrylate monomer.  

PubMed

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

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

2014-12-01

106

Type IIc Sodium–Dependent Phosphate Transporter Regulates Calcium Metabolism  

PubMed Central

Primary renal inorganic phosphate (Pi) wasting leads to hypophosphatemia, which is associated with skeletal mineralization defects. In humans, mutations in the gene encoding the type IIc sodium–dependent phosphate transporter lead to hereditary hypophophatemic rickets with hypercalciuria, but whether Pi wasting directly causes the bone disorder is unknown. Here, we generated Npt2c-null mice to define the contribution of Npt2c to Pi homeostasis and to bone abnormalities. Homozygous mutants (Npt2c?/?) exhibited hypercalcemia, hypercalciuria, and elevated plasma 1,25-dihydroxyvitamin D3 levels, but they did not develop hypophosphatemia, hyperphosphaturia, renal calcification, rickets, or osteomalacia. The increased levels of 1,25-dihydroxyvitamin D3 in Npt2c?/? mice compared with age-matched Npt2c+/+ mice may be the result of reduced catabolism, because we observed significantly reduced expression of renal 25-hydroxyvitamin D–24-hydroxylase mRNA but no change in 1?-hydroxylase mRNA levels. Enhanced intestinal absorption of calcium (Ca) contributed to the hypercalcemia and increased urinary Ca excretion. Furthermore, plasma levels of the phosphaturic protein fibroblast growth factor 23 were significantly decreased in Npt2c?/? mice. Sodium-dependent Pi co-transport at the renal brush border membrane, however, was not different among Npt2c+/+, Npt2c+/?, and Npt2c?/? mice. In summary, these data suggest that Npt2c maintains normal Ca metabolism, in part by modulating the vitamin D/fibroblast growth factor 23 axis. PMID:19056871

Segawa, Hiroko; Onitsuka, Akemi; Kuwahata, Masashi; Hanabusa, Etsuyo; Furutani, Junya; Kaneko, Ichiro; Tomoe, Yuka; Aranami, Fumito; Matsumoto, Natsuki; Ito, Mikiko; Matsumoto, Mitsuru; Li, Minqi; Amizuka, Norio; Miyamoto, Ken-ichi

2009-01-01

107

Investigating calcium polyphosphate addition to a conventional calcium phosphate cement for bone-interfacing applications  

NASA Astrophysics Data System (ADS)

Calcium phosphate cements (CPCs) are of great interest in bone regeneration applications because of their biocompatibility and osteoconductivity, and as delivery vehicles for therapeutics; however, delivery applications have been limited by adverse interactions between therapeutics and the cement setting reaction. Amorphous calcium polyphosphate (CPP) yields a biodegradable material with a demonstrated drug delivery capacity following appropriate processing. The incorporation of drug-loaded CPP into a CPC is under consideration as a method of minimizing adverse interactions and extending drug release. This thesis represents the first investigation into the effects of CPP addition on the properties, setting and antibiotic release profile of a conventional apatitic calcium phosphate cement. As-made, gelled and vancomycin-loaded CPP particulate were added to the powder component of a conventional dicalcium phosphate/tetracalcium phosphate CPC. The setting behaviour, set properties and microstructure of the resulting CPP-CPCs were evaluated with setting time testing (Gilmore needle method), pH testing, mechanical testing, SEM imaging, XRD and FTIR analysis. In vitro degradation and elution behaviour were evaluated by monitoring calcium release (atomic absorbance spectroscopy), mechanical strength and vancomycin release (UV-visual spectrophotometry). CPP addition was found to increase the setting time, reduce the mechanical strength and inhibit the conversion of the CPC starting powders to the set apatitic phase. The most likely mechanism for the observed effect of CPP addition was the adsorption of polyphosphate chains on the particle surfaces, which would inhibit the dissolution of the starting powders and the conversion of apatite precursor phases to apatite, leading to reduced mechanical properties. The detrimental effects of CPP were reduced by limiting the CPP fraction to less than a few weight per cent and increasing the size of the CPP particulate. CPP-containing CPCs were found to degrade more rapidly than the CPP-free controls. The ability of drug-loaded CPP to minimize adverse interactions between drug and cement could not be determined because of the adverse effect of CPP itself and the low vancomycin loads studied, but there was evidence that vancomycin release from apatitic CPCs could be extended through the use of loaded CPP.

Krausher, Jennifer Lynn

108

Autophagy induced by calcium phosphate precipitates targets damaged endosomes.  

PubMed

Calcium phosphate precipitates (CPPs) form complexes with DNA, which enter cells via endocytosis. Under this condition CPPs induce autophagy via the canonic autophagy machinery. Here we showed that CPP-induced autophagy was also dependent on endocytosis as the process was significantly inhibited by methyl-?-cyclodextrin and dynasore, which suppress clathrin-dependent endocytosis. Consistently, CPP treatment triggered the formation of filipin-positive intracellular vesicles whose membranes are rich in cholesterol. Unexpectedly, these vesicles were also positive for galectin 3, suggesting that they were damaged and the membrane glycans became accessible to galectins to bind. Endosome damage was caused by endocytosis of CPPs and was reversed by calcium chelators or by endocytosis inhibitors. Notably, CPP-induced LC3-positive autophagosomes were colocalized with galectin 3, ubiquitin, and p62/SQSTM1. Inhibition of galectin 3 reduced p62 puncta and autophagosome formation. Knockdown of p62 additionally inhibited the colocalization of autophagosomes with galectins. Furthermore, most of the galectin 3-positive vesicles were colocalized with Rab7 or LAMP1. Agents that affect endosome/lysosome maturation and function, such as bafilomycin A1, also significantly affected CPP-induced tubulovesicular autophagosome formation. These findings thus indicate that endocytosed CPPs caused endosome damage and recruitment of galectins, particularly at the later endosome stage, which led to the interaction of the autophagosomal membranes with the damaged endosome in the presence of p62. PMID:24619419

Chen, Xi; Khambu, Bilon; Zhang, Hao; Gao, Wentao; Li, Min; Chen, Xiaoyun; Yoshimori, Tamotsu; Yin, Xiao-Ming

2014-04-18

109

Precipitation of calcium carbonate and calcium phosphate under diffusion controlled mixing  

SciTech Connect

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.

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

2014-07-01

110

Low temperature solution deposition of calcium phosphate coatings for orthopedic implants  

SciTech Connect

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.

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

1994-04-01

111

Effect of calcium carbonate on the compliance of an apatitic calcium phosphate bone cement.  

PubMed

Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time and the ultimate compressive strength. Three cement formulations were tested. The previously developed Biocement H was made of a powder containing alpha-tertiary calcium phosphate and precipitated hydroxyapatite. Biocement B2 powder was made by adding some CaCO3 to Biocement H, whereas Biocement B1 was made by adding some CaCO3 but with simultaneous adjustment of the amount of precipitated hydroxyapatite.The liquid/ powder ratio of the cement paste and the accelerator concentrations (percentage Na2HPO4) in cement liquid were varied. For Biocement H there was no combination of L/P ratio and percentage Na2HPO4 for which all clinical requirements were satisfied. However, there was an area of full compliance for Biocements B1 and B2, of which that for B1 was the largest. Therefore, Biocement B1 may be applied in clinical situations as those in orthopaedics, plastic and reconstructive surgery and oral and maxillofacial surgery, even when early contact with blood is inevitable. PMID:9430336

Khairoun, I; Boltong, M G; Driessens, F C; Planell, J A

1997-12-01

112

Preparation of in situ hardening composite microcarriers: Calcium phosphate cement combined with alginate for bone regeneration  

PubMed Central

Novel microcarriers consisting of calcium phosphate cement and alginate were prepared for use as three-dimensional scaffolds for the culture and expansion of cells that are effective for bone tissue engineering. The calcium phosphate cement-alginate composite microcarriers were produced by an emulsification of the composite aqueous solutions mixed at varying ratios (calcium phosphate cement powder/alginate solution?=?0.8–1.2) in an oil bath and the subsequent in situ hardening of the compositions during spherodization. Moreover, a porous structure could be easily created in the solid microcarriers by soaking the produced microcarriers in water and a subsequent freeze-drying process. Bone mineral-like apatite nanocrystallites were shown to rapidly develop on the calcium phosphate cement–alginate microcarriers under moist conditions due to the conversion of the ?-tricalcium phosphate phase in the calcium phosphate cement into a carbonate–hydroxyapatite. Osteoblastic cells cultured on the microspherical scaffolds were proven to be viable, with an active proliferative potential during 14 days of culture, and their osteogenic differentiation was confirmed by the determination of alkaline phosphatase activity. The in situ hardening calcium phosphate cement–alginate microcarriers developed herein may be used as potential three-dimensional scaffolds for cell delivery and tissue engineering of bone. PMID:23836845

Park, Jung-Hui; Lee, Eun-Jung; Knowles, Jonathan C

2014-01-01

113

Synthesis of spherical calcium phosphate particles for dental and orthopedic applications  

PubMed Central

Calcium phosphate materials have been used increasingly in the past 40 years as bone graft substitutes in the dental and orthopedic fields. Accordingly, numerous fabrication methods have been proposed and used. However, the controlled production of spherical calcium phosphate particles remains a challenge. Since such particles are essential for the synthesis of pastes and cements delivered into the host bone by minimally-invasive approaches, the aim of the present document is to review their synthesis and applications. For that purpose, production methods were classified according to the used reagents (solutions, slurries, pastes, powders), dispersion media (gas, liquid, solid), dispersion tools (nozzle, propeller, sieve, mold), particle diameters of the end product (from 10 nm to 10 mm), and calcium phosphate phases. Low-temperature calcium phosphates such as monetite, brushite or octacalcium phosphate, as well as high-temperature calcium phosphates, such as hydroxyapatite, ?-tricalcium phosphate or tetracalcium phosphate, were considered. More than a dozen production methods and over hundred scientific publications were discussed. PMID:23719177

Bohner, Marc; Tadier, Solène; van Garderen, Noémie; de Gasparo, Alex; Döbelin, Nicola; Baroud, Gamal

2013-01-01

114

Mechanical and fracture behavior of calcium phosphate cements  

NASA Astrophysics Data System (ADS)

Apatite-based calcium phosphate cements are currently employed to a limited extent in the biomedical and dental fields. They present significant potential for a much broader range of applications, particularly as a bone mineral substitute for fracture fixation. Specifically, hydroxyapatite (HA) is known for its biocompatibility and non-immunogenicity, attributed to its similarity to the mineral phase of natural bone. The advantages of a cement-based HA include injectability, greater resorbability and osteoconductivity compared to sintered HA, and an isothermal cement-forming reaction that avoids necrosis during cement setting. Although apatite cements demonstrate good compressive strength, tensile properties are very weak compared to natural bone. Applications involving normal weight-bearing require better structural integrity than apatite cements currently provide. A more thorough understanding of fracture behavior can elucidate failure mechanisms and is essential for the design of targeted strengthening methods. This study investigated a hydroxyapatite cement using a fracture mechanics approach, focusing on subcritical crack growth properties. Subcritical crack growth can lead to much lower load-bearing ability than critical strength values predict. Experiments show that HA cement is susceptible to crack growth under both cyclic fatigue-crack growth and stress corrosion cracking conditions, but only environmental, not mechanical, mechanisms contribute to crack extension. This appears to be the first evidence ever presented of stress corrosion crack growth behavior in calcium phosphate cements. Stress corrosion cracking was examined for a range of environmental conditions. Variations in pH have surprisingly little effect. Behavior in water at elevated temperature (50°C) is altered compared to water at ambient temperature (22°C), but only for crack-growth velocities below 10-7 m/s. However, fracture resistance of dried HA cement in air increases significantly compared to in water. Based on observed trends, mechanisms of stress corrosion cracking are considered. Strengthening methods using proteins as second phase additions to HA cement were also investigated. Critical flexure strength of these composites increases to a limited extent, primarily due to bridging of the fracture surfaces by organic phases. Despite the increase for critical values, stress corrosion crack growth of cement-albumin composites remains similar to unreinforced cement. This discrepancy between critical and subcritical behavior is discussed.

Jew, Victoria Chou

115

Premixed rapid-setting calcium phosphate composites for bone repair?  

PubMed Central

Although calcium phosphate cement (CPC) is promising for bone repair, its clinical use requires on site powder–liquid mixing. To shorten surgical time and improve graft properties, it is desirable to develop premixed CPC in which the paste remains stable during storage and hardens only after placement into the defect. The objective of this study was to develop premixed CPC with rapid setting when immersed in a physiological solution. Premixed CPCs were formulated using the following approach: Premixed CPC = CPC powder+nonaqueous liquid+gelling agent+hardening accelerator. Three premixed CPCs were developed: CPC–monocalcium phosphate monohydrate (MCPM), CPC–chitosan, and CPC–tartaric. Setting time for these new premixed CPCs ranged from 5.3 to 7.9 min, significantly faster than 61.7 min for a premixed control CPC reported previously (p<05). SEM revealed the formation of nano-sized needle-like hydroxyapatite crystals after 1 d immersion and crystal growth after 7 d. Diametral tensile strength for premixed CPCs at 7 d ranged from 2.8 to 6.4 MPa, comparable to reported strengths for cancellous bone and sintered porous hydroxyapatite implants. Osteoblast cells attained a normal polygonal morphology on CPC–MCPM and CPC–chitosan with cytoplasmic extensions adhering to the nano-hydroxyapatite crystals. In summary, fast-setting premixed CPCs were developed to avoid the powder–liquid mixing in surgery. The pastes hardened rapidly once immersed in physiological solution and formed hydroxyapatite. The cements had strengths matching those of cancellous bone and sintered porous hydroxyapatite and non-cytotoxicity similar to conventional non-premixed CPC. PMID:15769536

Carey, Lisa E.; Xu, Hockin H.K.; Simon, Carl G.; Takagi, Shozo; Chow, Laurence C.

2009-01-01

116

Polyelectrolyte multilayer-calcium phosphate composite coatings for metal implants.  

PubMed

The preparation of organic-inorganic composite coatings with the purpose to increase the bioactivity of bioinert metal implants was investigated. As substrates, glass plates and rough titanium surfaces (Ti-SLA) were employed. The method comprises the deposition of polyelectrolyte multilayers (PEMLs) followed by immersion of the coated substrate into a calcifying solution of low supersaturation (MCS). Single or mixed PEMLs were constructed from poly-L-lysine (PLL) alternating with poly-L-glutamate, (PGA), poly-L-aspartate (PAA), and/or chondroitin sulfate (CS). ATR-FTIR spectra reveal that (PLL/PGA)10 multilayers and mixed multilayers with a (PLL/PGA)5 base contain intermolecular ?-sheet structures, which are absent in pure (PLL/PAA)10 and (PLL/CS)10 assemblies. All PEML coatings had a grainy topography with aggregate sizes and size distributions increasing in the order: (PLL/PGA)n < (PLL/PAA)n < (PLL/CS)n. In mixed multilayers with a (PLL/PGA)n base and a (PLL/PAA)n or (PLL/CS)n top, the aggregate sizes were greatly reduced. The PEMLs promoted calcium phosphate nucleation and early crystal growth, the intensity of the effect depending on the composition of the terminal layer(s) of the polymer. In contrast, crystal morphology and structure depended on the supersaturation, pH, and ionic strength of the MCS, rather than on the composition of the organic matrix. Crystals grown on both uncoated and coated substrates were mostly platelets of calcium deficient carbonate apatite, with the Ca/P ratio depending on the precipitation conditions. PMID:25105729

Elyada, Alon; Garti, Nissim; Füredi-Milhofer, Helga

2014-10-13

117

Characterization of a silver-incorporated calcium phosphate film by RBS and its antimicrobial effects  

NASA Astrophysics Data System (ADS)

A thin calcium phosphate film was synthesized on both commercially pure Ti and Si wafers by electron beam evaporation of hydroxyapatite as an evaporant with simultaneous Ar ion beam bombardments. Silver was introduced into an ion-beam-assisted deposition of a calcium phosphate thin film for antimicrobial effect. The amount of incorporated silver ions was controlled by immersing calcium-phosphate-coated samples in different AgNO3 concentrations, and Rutherford backscattering spectrometry (RBS) was employed to measure the amounts of substituted silver. The higher concentration of silver in the calcium phosphate film was more effective in reducing the bacteria of Escherichia coli ATCC 8739 and Streptococcus mutans OMZ 65 on contact with respect to controls.

Han, I.-H.; Lee, I.-S.; Song, J.-H.; Lee, M.-H.; Park, J.-C.; Lee, G.-H.; Sun, X.-D.; Chung, S.-M.

2007-09-01

118

Calcium phosphate: an alternative calcium compound for dietary prevention of colon cancer? A study on intestinal and faecal parameters in healthy volunteers.  

PubMed

In an effort to reduce the risk of colorectal cancer development, oral calcium carbonate supplementation has been used in previous studies for the precipitation of cytotoxic bile acids and fatty acids. In human intervention trials its effect on mucosal hyperproliferation in the colorectum has not always been satisfactory. Because the complexation of calcium and bile acids requires the formation of calcium phosphate, we performed an intervention study in 14 healthy volunteers, giving them 1,500 mg calcium as Ca3(PO4)2 for 1 week. The effects of tricalcium phosphate on luminal and faecal parameters of cytolytic activity were evaluated before, during, and after calcium phosphate supplementation. The cytolytic activity of faecal water and intestinal alkaline phosphatase activity in faecal water were not affected by supplemental calcium phosphate. In duodenal bile, the proportion of cholic acid tended to increase, whereas that of chenodeoxycholic acid tended to decrease during calcium phosphate supplementation. Neither concentrations of total and individual faecal bile acids, nor that of faecal fat were affected during calcium phosphate supplementation. It is suggested that, although phosphate is involved in bile acid precipitation, phosphate competes for calcium in the binding of fatty acids. This might possibly explain the unchanged cytolytic potency of faecal water, and therefore does not make tricalcium phosphate a suitable calcium compound for dietary intervention. PMID:8401176

Cats, A; Mulder, N H; de Vries, E G; Oremus, E T; Kreumer, W M; Kleibeuker, J H

1993-09-01

119

Ethoxylated Bisphenol Dimethacrylate-based Amorphous Calcium Phosphate Composites  

PubMed Central

Improving the anti-demineralizing/remineralizing and mechanical properties of amorphous calcium phosphate (ACP) composites has been the focus of our recent research. In this study, an ethoxylated bisphenol A dimethacrylate (EBPADMA) was blended with triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA) and methacryloxyethyl phthalate (MEP) to form three experimental resins. The resins were formulated to have 3 different EBPADMA/TEGDMA molar ratios (0.50, 0.85 and 1.35) and a constant HEMA/MEP molar ratio (8.26 ± 0.33). The resins were photo-activated for visible light polymerization and composites were prepared by admixture of either unmilled or milled zirconia-ACP filler (40 % by mass). One aim of the study was to test if improved ion release can be achieved by elevating the EBPADMA/TEGDMA ratio while lowering the level of surface active methacryloxyethyl phthalate in the resin without adversely affecting the strength, degree of vinyl conversion and water sorption of composites. A second aim was to assess the effect of using milled vs. unmilled ACP on these properties of the various composites. Both copolymers blends and composites were assessed for the biaxial flexure strength, degree of vinyl conversion and water sorption, and the composites were evaluated for the mineral ion release as well. Overall ion release of all composites was significantly above the theoretical minimum necessary for remineralization and calcium ion release was not impeded by calcium binding with the carboxylic acid groups of methacryloxyethyl phthalate. Increased supersaturation was attained with increasing EBPADMA/TEGDMA ratio in the resin. Variations in resin composition had no effect on the biaxial flexure strength or degree of vinyl conversion of composites. The biaxial flexure strength values of the milled ACP composites were higher than the biaxial flexure strength values of unmilled ACP composites (56 % and 79 %, respectively for dry and wet specimens). Degree of vinyl conversion of composites was only moderately reduced (13.6 % and 7.3 %, for unmilled and milled ACP, respectively) compared to unfilled resins [(80.2 ± 3.1) %]. Water sorption decreased in the following order: unmilled ACP composites > milled ACP composites ? copolymer blends. Fine-tuning of the resin and utilizing milled ACP filler improved the remineralizing potential of ACP composites without impeding their vinyl conversion, mechanical strength or water sorption. PMID:16701862

Skrtic, D.; Antonucci, J.M.; Liu, D.W.

2006-01-01

120

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

Microsoft Academic Search

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

Martin Jordan; Annette Schallhorn; Florian M. Wurm

1996-01-01

121

Study of controlled tetracycline release from porous calcium phosphate\\/polyhydroxybutyrate composites  

Microsoft Academic Search

Porous calcium phosphate ceramics were prepared by sintering of mixtures of nanocrystalline apatitic calcium phosphate and\\u000a fibrous natural cotton cellulose after pressing at temperatures of 1150 ?C and 1250 ?C. Micro-and macropores were present\\u000a in microstructures of ceramic samples. The microstructures of porous ceramics were similar to those observed in bone tissues\\u000a and fiber-like randomly oriented texture was observed in

L’ Medvecký; R. Štulajterová; J. Brian?in

2007-01-01

122

Effects of adding resorbable phosphate glass fibres and PLA to calcium phosphate bone cements.  

PubMed

ABSTRACTBackground: Calcium phosphate cements (CPCs), due to their biocompatibility and degradation properties, are being widely investigated as a replacement to more commonly used polymethylmethacrylate (PMMA) for vertebroplasty. CPCs have shown the potential to be replaced by host bone tissue during the healing/remodelling process. However, brittleness and comparatively low strength restrict the use of CPC in load-bearing applications. Although porous CPC can integrate with bone over time, slow degradation profiles and poor interconnectivity between pores restricts osseointegration to the top layer of CPC only.Methods: Polylactic acid (PLA) and phosphate glass fibres (PGFs) were incorporated in a CPC matrix to overcome the problem of inherent brittleness and limited osseointegration.Results: Incorporation of PLA and PGFs within CPC was successful in achieving a much less brittle CPC matrix without affecting the mechanical properties of CPC. The area under the stress-strain curve showed that the total energy to failure of the CPC hybrid was significantly greater than that of the CPC control.Conclusions: The methodology adopted here to add PLA within the CPC matrix may also allow for incorporation of PLA cross-linked biochemicals. Micrographic studies revealed that it was possible to confer control over pore size, shape and interconnectivity without negatively affecting the mechanical properties of the cement. This tailorable porosity could potentially lead to better osseointegration within CPC. PMID:24744228

Hasan, Muhammad Sami; Carpenter, Nicholas; Wei, Teo Ling; McNally, Donal; Ahmed, Ifty; Boszczyk, Bronek M

2014-04-01

123

RANKL delivery from calcium phosphate containing PLGA microspheres.  

PubMed

Ideally, bone substitute materials would undergo cell-mediated degradation during the remodeling process of the host bone tissue while being replaced by newly formed bone. In an attempt to exploit the capacity of Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL) to stimulate osteoclast-like cells formation, this study explored different loading methods for RANKL in injectable calcium phosphate cement (CPC) and the effect on release and biological activity. RANKL was loaded via the liquid phase of CPC by adsorption onto or incorporation into poly(lactic-co-glycolic acid) (PLGA) microspheres with two different morphologies (i.e., hollow and dense), which were subsequently embedded in CPC. As controls nonembedded PLGA-microspheres were used as well as plain CPC scaffolds with RANKL adsorbed onto the surface. RANKL release and activity were evaluated by Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) and osteoclast-like cells formation in cell culture experiments. Results indicated that sustained release of active RANKL can be achieved upon RANKL adsorption to PLGA microspheres, whereas inactive RANKL was released from CPC-PLGA formulations with RANKL incorporated within the microspheres or within the liquid phase of the CPC. These results demonstrate that effective loading of RANKL in injectable CPC is only possible via adsorption to PLGA microspheres, which are subsequently embedded within the CPC-matrix. PMID:23529979

Félix Lanao, Rosa P; Bosco, Ruggero; Leeuwenburgh, Sander C G; Kersten-Niessen, Monique J F; Wolke, Joop G C; van den Beucken, Jeroen J J P; Jansen, John A

2013-11-01

124

Interaction of light with dye-doped calcium phosphate nanoparticles  

NASA Astrophysics Data System (ADS)

In this work we present work on a novel amorphous calcium phosphate nanoparticle system for use in bioimaging and drug delivery applications. The system, by virtue of its synthesis, can be made to encapsulate and protect any number of molecules that are not suitable for biological applications on their own; for example, medication that is poorly soluble in aqueous solution can be encapsulated for delivery, or fragile optical molecules can be encapsulated to protect them from the local environment. We have encapsulated the near-infrared dye indocyanine green, which has beneficial properties for optical imaging (low biotoxicity, absorption and emission at a minimum of tissue absorption). There are two original works presented in this thesis. The first describes the measurement of the quantum yield of the indocyanine green-doped nanoparticles, as well as the development of a theoretical method to extract the molecular quantum yield of a fluorophore encapsulated in a dielectric sphere from effective quantum yield measurements of nanoparticle dispersions in solution. The second work is an application of diffuse scattering theory to the problem of light propagation in biological tissue; specifically, the limits on penetration depth for photodynamic therapy and bioimaging.

Russin, Timothy John

125

Hydrothermal-electrochemical deposition of calcium phosphates on various metals.  

PubMed

Calcium phosphates were formed on five kinds of substrate metals using a hydrothermal-electrochemical method in an autoclave with two electrodes. The electrolyte dissolving NaCl, K2HPO4, CaCl2.2H2O, tris (hydroxymethyl) aminomethane, and hydrochloric acid was maintained at 100 degrees C, 150 degrees C and 200 degrees C. The counter electrode, the anode, was platinum plate, 20 x 20 x 0.5 mm, and the working electrodes as cathode were pure titanium, pure zinc, pure nickel, pure iron, and stainless steel plates. A constant direct current at 12.5 mA/cm2 was loaded for 1 hr. Hydroxyapatite [Ca10(PO4)6(OH)2] only deposited at three temperatures on pure titanium plate. On pure zinc plate, both parascholzite [CaZn2(PO4)2.2H2O] and hydroxyapatite were formed at 150 degrees C and both parascholzite and ZnO were formed at 200 degrees C. Both hydroxyapatite and beta-TCP [beta-Ca3(PO4)2] were formed on pure nickel, pure iron, and stainless steel plates at 200 degrees C. It seems that the incorporation of the metal ions released from the electrode decreased the Ca/P ratio of the deposit due to the formation of other compounds except hydroxyapatite. PMID:10786136

Ban, S; Matsuo, K; Mizutani, N; Hasegawa, J

1999-09-01

126

Antibacterial Property Expressed by a Novel Calcium Phosphate Glass  

PubMed Central

We have developed a calcium phosphate glass (CPG) doped with Zn2+ or F? or combined Zn2+ and F? ions, which are naturally found in the human body and play a dual role in bone formation and antibacterial activity. Previously, we have demonstrated that this family of CPGs has superior osteoconductive and resorbable properties in vivo. This study aimed to investigate the antibacterial property of CPGs incorporating Zn2+ and/or F?. We used Streptococcus mutans as a model organism because it is one of the major human oral pathogens and an early colonizer, and it has been associated with several oral infections, such as dental caries, periodontitis, and peri-implantitis. 0.01g and 0.05g of CPGs were incubated with Streptococcus mutans for 0, 2, 4, and 6 h. Serial dilutions were plated in triplicate and colony forming units were determined. The antimicrobial effect of CPG incorporating Zn2+ or F? was greater than CPG incorporating both these ions. CPG without doping produced a moderate antimicrobial effect. This family of CPGs, previously shown to promote new bone formation in vivo, is demonstrated to have superior bactericidal properties. PMID:24039127

Liu, Lela; Pushalkar, Smruti; Saxena, Deepak; LeGeros, Racquel Z.; Zhang, Yu

2014-01-01

127

Stem Cell-Calcium Phosphate Constructs for Bone Engineering  

PubMed Central

While human bone-marrow-derived mesenchymal stem cells (hBMSCs) have been investigated, human umbilical cord mesenchymal stem cells (hUCMSCs) are a relatively new cell source. Little has been reported on hUCMSC encapsulation in scaffolds for bone tissue engineering. The objective of this study was to encapsulate hBMSCs and hUCMSCs in calcium phosphate cement (CPC) scaffolds for dental, craniofacial, and orthopedic applications. Stem-cell-encapsulating CPC construct with chitosan and fiber reinforcement reached the strength of cancellous bone, which was much stronger than previous injectable carriers for cell delivery. hUCMSCs and hBMSCs inside the constructs showed excellent viability and osteo-differentiation. The encapsulated hUCMSCs synthesized nearly three-fold more bone minerals than the hBMSCs in vitro. Hence, stem-cell-encapsulating CPC-chitosan-fiber construct may be promising for dental and orthopedic applications. This study indicated that the hUCMSCs were a potent alternative to the gold-standard hBMSCs, which may have a broad impact on regenerative medicine and dental tissue engineering. PMID:20929721

Xu, H.H.K.; Zhao, L.; Weir, M.D.

2010-01-01

128

Remineralization of demineralized enamel via calcium phosphate nanocomposite.  

PubMed

Secondary caries remains the main problem limiting the longevity of composite restorations. The objective of this study was to investigate the remineralization of demineralized human enamel in vitro via a nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP). NACP were synthesized by a spray-drying technique and incorporated into a dental resin. First, caries-like subsurface enamel lesions were created via an acidic solution. Then, NACP nanocomposite or a commercial fluoride-releasing control composite was placed on the demineralized enamel, along with control enamel without a composite. These specimens were then treated with a cyclic demineralization/remineralization regimen for 30 days. Quantitative microradiography showed typical enamel subsurface demineralization before cyclic demineralization/remineralization treatment, and significant remineralization in enamel under the NACP nanocomposite after the demineralization/remineralization treatment. The NACP nanocomposite had the highest enamel remineralization (mean ± SD; n = 6) of 21.8 ± 3.7%, significantly higher than the 5.7 ± 6.9% for fluoride-releasing composite (p < 0.05). The enamel group without composite had further demineralization of -26.1 ± 16.2%. In conclusion, a novel NACP nanocomposite was effective in remineralizing enamel lesions in vitro. Its enamel remineralization was 4-fold that of a fluoride-releasing composite control. Combined with the good mechanical and acid-neutralization properties reported earlier, the new NACP nanocomposite is promising for remineralization of demineralized tooth structures. PMID:22933607

Weir, M D; Chow, L C; Xu, H H K

2012-10-01

129

Genetic Responses to Nanostructured Calcium-phosphate-coated Implants  

PubMed Central

Nanostructured calcium phosphate (CaP) has been histologically and biomechanically proven to enhance osseointegration of implants; however, conventional techniques were not sufficiently sensitive to capture its biological effects fully. Here, we compared the conventional removal torque (RTQ) evaluation and gene expression in tissues around nanostructured CaP-coated implants, using real-time RT-PCR, with those of uncoated implants, in a rabbit model. At 2 wks, RTQ values were significantly higher, alkaline phosphatase (ALP) expression was significantly higher, and runt-related transcription factor 2 and tumor necrosis factor-? expressions were significantly lower in the coated than in the uncoated implants. This indicates that inflammatory responses were suppressed and osteoprogenitor activity increased around the CaP-coated surface. At 4 wks, although RTQ values did not significantly differ between the 2 groups, ALP and osteocalcin (OCN) were significantly up-regulated in the coated group, indicating progressive mineralization of the bone around the implant. Moreover, an osteoclast marker, adenosine triphosphatase, which indicates acidification of the resorption lacunae, was significantly higher for the coated implants, suggesting gradual resorption of the CaP coating. This study reveals detailed genetic responses to nanostructured CaP-coated implants and provides evidence that the effect of nanotopography is significant during the osseointegration cascade. PMID:21933935

Jimbo, R.; Xue, Y.; Hayashi, M.; Schwartz-Filho, H.O.; Andersson, M.; Mustafa, K.; Wennerberg, A.

2011-01-01

130

Current perspectives: calcium phosphate nanocoatings and nanocomposite coatings in dentistry.  

PubMed

The purpose of coatings on implants is to achieve some or all of the improvements in biocompatibility, bioactivity, and increased protection from the release of harmful or unnecessary metal ions. During the last decade, there has been substantially increased interest in nanomaterials in biomedical science and dentistry. Nanocomposites can be described as a combination of two or more nanomaterials. By this approach, it is possible to manipulate mechanical properties, such as strength and modulus of the composites, to become closer to those of natural bone. This is feasible with the help of secondary substitution phases. Currently, the most common composite materials used for clinical applications are those selected from a handful of available and well-characterized biocompatible ceramics and natural and synthetic polymers. This approach is currently being explored in the development of a new generation of nanocomposite coatings with a wider range of oral and dental applications to promote osseointegration. The aim of this review is to give a brief introduction into the new advances in calcium phosphate nanocoatings and their composites, with a range of materials such as bioglass, carbon nanotubes, silica, ceramic oxide, and other nanoparticles being investigated or used in dentistry. PMID:23857642

Choi, A H; Ben-Nissan, B; Matinlinna, J P; Conway, R C

2013-10-01

131

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

Microsoft Academic Search

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

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

132

Calcium-phosphate microprecipitates mimic microparticles when examined with flow cytometry.  

PubMed

There are increased levels of circulating microparticles (MPs) in several disease states. Flow cytometry is a common method to examine MPs, but their small size necessitates the use of markers to distinguish specifically MPs from artifact. Annexin V, which binds phosphatidylserine, is a commonly used marker for MP detection. Annexin V requires millimolar calcium ion for optimum binding. Ca(++) can precipitate with phosphate in phosphate-buffered saline (PBS). Calcium-phosphate microprecipitates were formed by titrating Ca(++) into PBS and examined using flow cytometry. Calcium-phosphate microprecipitates were compared with MPs derived from aged donor blood units. Microprecipitates were ?0.7-0.9 ?m in diameter compared with standard beads of known size. The microprecipitates disappeared with the addition of Ca(++) chelator. When we added fluorescently labeled antibodies to microprecipitates, the median fluorescent signal increased with increasing Ca(++) concentration regardless of specificity of the antibody. When repeated with a biological sample, there was an apparent increase in the fluorescent signal that returned to baseline after Ca(++) chelation. The flow cytometry signal of calcium-phosphate microprecipitates overlaps with the MP signal. Since Ca(++) is essential for annexin V binding, it is essential to avoid artifacts from calcium-phosphate microprecipitates when using any buffer or biological fluid containing phosphate. This also highlights the potential utility of flow cytometry for the analysis of crystals in biological fluids. PMID:23125136

Larson, Michael C; Luthi, Maia R; Hogg, Neil; Hillery, Cheryl A

2013-02-01

133

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

E-print Network

Calcium Phosphate Nanoparticles Synthesis Procedure: · Make sure the hood is clean and free of all 10-2 M calcium chloride solution in the above degassed water (make sure to sonicate for 10 min to dissolve calcium chloride completely). · Likewise prepare 6 x 10-3 M disodium phosphate solution from

Burgess, Kevin

134

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...

135

Casein Micelle Substructure and Calcium Phosphate Interactions Studied by Sephacryl Column Chromatography  

Microsoft Academic Search

Experiments were designed to manipulate only one of the factors known to be important in maintaining the integrity of casein micelles while holding all of the other factors constant. Casein micelles were dis- sociated either by reducing the content of colloidal calcium phosphate or by adding k-casein at a constant free calcium ion concentration, pH, and ionic strength and, in

Carl Holt

1998-01-01

136

Effects of calcium phosphate/chitosan composite on bone healing in rats: calcium phosphate induces osteon formation.  

PubMed

Vascularization of an artificial graft represents one of the most significant challenges facing the field of bone tissue engineering. Over the past decade, strategies to vascularize artificial scaffolds have been intensively evaluated using osteoinductive calcium phosphate (CaP) biomaterials in animal models. In this work, we observed that CaP-based biomaterials implanted into rat calvarial defects showed remarkably accelerated formation and mineralization of new woven bone in defects in the initial stages, at a rate of ?60??m/day (0.8?mg/day), which was considerably higher than normal bone growth rates (several ?m/day, 0.1?mg/day) in implant-free controls of the same age. Surprisingly, we also observed histological evidence of primary osteon formation, indicated by blood vessels in early-region fibrous tissue, which was encapsulated by lamellar osteocyte structures. These were later fully replaced by compact bone, indicating complete regeneration of calvarial bone. Thus, the CaP biomaterial used here is not only osteoinductive, but vasculogenic, and it may have contributed to the bone regeneration, despite an absence of osteons in normal rat calvaria. Further investigation will involve how this strategy can regulate formation of vascularized cortical bone such as by control of degradation rate, and use of models of long, dense bones, to more closely approximate repair of human cortical bone. PMID:24460696

Fernández, Tulio; Olave, Gilberto; Valencia, Carlos H; Arce, Sandra; Quinn, Julian M W; Thouas, George A; Chen, Qi-Zhi

2014-07-01

137

Calcium phosphate coating on titanium using laser and plasma spray  

NASA Astrophysics Data System (ADS)

Though calcium phosphate (CaP) coated implants are commercially available, its acceptance is still not wide spread due to challenges related to weaker interfacial bonding between metal and ceramic, and low crystallinity of hydroxyapatite (HA). The objectives of this research are to improve interfacial strength, crystallinity, phase purity and bioactivity of CaP coated metallic implants for orthopaedic applications. The rationale is that forming a diffuse and gradient metal-ceramic interface will improve the interfacial strength. Moreover, reducing CaP particles exposure to high temperature during coating preparation, can lead to improvement in both crystallinity and phase purity of CaP. In this study, laser engineered net shaping (LENS(TM)) was used to coat Ti metal with CaP. LENS(TM) processing enabled generation of Ti+TCP (tricalcium phosphate) composite coating with diffused interface, that also increased the coating hardness to 1049+/-112 Hv compared to a substrate hardness of 200+/-15 Hv. In vitro bone cell-material interaction studies confirmed the bioactivity of TCP coatings. Antimicrobial properties of the TCP coatings were improved by silver (Ag) electrodeposition. Along with LENS(TM), radio frequency induction plasma spray, equipped with supersonic plasma nozzle, was used to prepare HA coatings on Ti with improved crystallinity and phase purity. The coating was made of multigrain HA particles of ˜200 nm in size, which consisted of 15--20 nm HA grains. In vitro bone cell-material interaction and in vivo rat model studies confirmed the HA coatings to be bioactive. Furthermore, incorporation of Sr2+ improved bone cell of HA coatings interaction. A combination of LENS(TM) and plasma spray was used to fabricate a compositionally graded HA coatings on Ti where the microstructure varied from pure HA at the surface to pure Ti substrate with a diffused Ti+TCP composite region in between. The plasma spray system was used to synthesize spherical HA nano powder from HA sol, where the production rate was 20 g/h, which is only 16% of the total powder produced. The effects of Sr2+ and Mg2+ doping on bone cell-CaP interaction was further studied with osteoclast cells. Mg2+ doing was found to be an effective way of controlling osteoclast differentiation.

Roy, Mangal

138

Low temperature method for the production of calcium phosphate fillers  

PubMed Central

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

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

2004-01-01

139

Reinforcement of calcium phosphate cement with multi-walled carbon nanotubes and bovine serum albumin for injectable bone substitute applications  

Microsoft Academic Search

This paper presents the development of novel alternative injectable calcium phosphate cement (CPC) composites for orthopaedic applications. The new CPC composites comprise ?-tri-calcium phosphate (?-TCP) and di-calcium phosphate anhydrous (DCPA) mixed with bovine serum albumin (BSA) and incorporated with multi-walled carbon nanotubes (MWCNTs) or functionalized MWCNTs (MWCNTs–OH and MWCNTs–COOH). Scanning electron microscopy (SEM), compressive strength tests, injectability tests, Fourier transform

Kean-Khoon Chew; Kah-Ling Low; Sharif Hussein Sharif Zein; David S. McPhail; Lutz-Christian Gerhardt; Judith A. Roether; Aldo R. Boccaccini

2011-01-01

140

Premixed calcium phosphate cements: Synthesis, physical properties, and cell cytotoxicity  

PubMed Central

Objectives Calcium phosphate cement (CPC) is a promising material for dental, periodontal, and craniofacial repairs. However, its use requires on-site powder–liquid mixing that increases the surgical placement time and raises concerns of insufficient and inhomogeneous mixing. The objective of this study was to determine a formulation of premixed CPC (PCPC) with rapid setting, high strength, and good in vitro cell viability. Methods PCPCs were formulated from CPC powder + non-aqueous liquid + gelling agent + hardening accelerator. Five PCPCs were thus developed: PCPC-Tartaric, PCPC-Malonic, PCPC-Citric, PCPC-Glycolic, and PCPC-Malic. Formulations and controls were compared for setting time, diametral tensile strength, and osteoblast cell compatibility. Results Setting time (mean ± S.D.; n = 4) for PCPC-Tartaric was 8.2 ± 0.8 min, significantly less than the 61.7 ± 1.5 min for the Premixed Control developed previously (p < 0.001). On 7th day immersion, the diametral tensile strength of PCPC-Tartaric reached 6.5 ± 0.8 MPa, higher than 4.5 ± 0.8 MPa of Premixed Control (p = 0.036). Osteoblast cells displayed a polygonal morphology and attached to the nano-hydroxyapatite crystals in the PCPCs. All cements had similar live cell density values (p = 0.126), indicating that the new PCPCs were as cell compatible as a non-premixed CPC control known to be biocompatible. Each of the new PCPCs had a cell viability that was not significantly different (p > 0.1) from that of the non-premixed CPC control. Significance PCPCs will eliminate the powder–liquid mixing during surgery and may also improve the cement performance. The new PCPCs supported cell attachment and yielded a high cell density and viability. Their mechanical strengths approached the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. These nano-crystalline hydroxyapatite cements may be useful in dental, periodontal, and craniofacial repairs. PMID:16678895

Xu, Hockin H.K.; Carey, Lisa E.; Simon, Carl G.; Takagi, Shozo; Chow, Laurence C.

2009-01-01

141

Treatment of a Lateral Tibial Plateau Osteochondritis Dissecans Lesion With Subchondral Injection of Calcium Phosphate  

PubMed Central

Osteochondritis dissecans lesions occur frequently in children and adolescents. Treatment can be challenging and depends on the status of the articular cartilage and subchondral bone. Injection of calcium phosphate bone substitute into the area of subchondral bone edema (Subchondroplasty; Knee Creations, West Chester, PA) may be an option. We present a case of a lateral tibial plateau osteochondritis dissecans lesion treated with subchondral injection of nanocrystalline calcium phosphate. Preoperative magnetic resonance imaging is used to determine the area of subchondral edema, and intraoperative fluoroscopy is used to localize this area with the injection cannula. Calcium phosphate is injected by use of a series of syringes until the appropriate fill is obtained. Treatment of concomitant cartilage defects may also be carried out at this time. PMID:24265997

Abrams, Geoffrey D.; Alentorn-Geli, Eduard; Harris, Joshua D.; Cole, Brian J.

2013-01-01

142

Preliminary characterization of calcium chemical environment in apatitic and non-apatitic calcium phosphates of biological interest by X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Several reports have mentioned the existence of non-apatitic environments of phosphate and carbonate ions in synthetic and biological poorly crystalline apatites. However there were no direct spectroscopic evidences for the existence of non-apatitic environment of calcium ions. X-ray Absorption Spectroscopy, at the K-edge of calcium, allows the discrimination between different calcium phosphates of biological interest despite great spectral similarities. A primary analysis of the spectra reveals the existence, in synthetic poorly crystalline apatites, of variable features related to the maturation stage of the sample and corresponding to the existence of non-apatitic environments of calcium ions. Although these features can also be found in several other calcium phosphate salts, and do not allow a clear identification of the ionic environments of calcium ions, they give a possibility to directly determine the maturity of poorly crystalline apatite from calcium X-ray Absorption Near Edge Structure spectra.

Eichert, D.; Salomé, M.; Banu, M.; Susini, J.; Rey, C.

2005-07-01

143

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

PubMed Central

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

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

2012-01-01

144

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

SciTech Connect

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.

Drew Lenzen Enlow

2006-08-09

145

Recent studies of bone mineral: Is the amorphous calcium phosphate theory valid?  

NASA Astrophysics Data System (ADS)

Recent studies on bone mineral are reviewed, with particular emphasis on the nature of the initial mineral deposited and the changes occuring during further mineralization and maturation. It is shown that amorphous calcium phosphate, which has been proposed as the precursor of hydroxyapatite in bone mineral, cannot be detected in significant quantity in the earliest bone mineral formed, and furthermore that there is evidence that no progressive decrease in amount of any amorphous phase occurs with bone maturation. We conclude in general that the X-ray difraction pattern and non-stoichiometric composition of bone mineral, and the changes in these characteristic observed with age and maturation cannot be explained by the presence of a second phase in progressively decreasing proportion whether it be amorphous calcium phosphate, octacalcium phosphate, brushite or some other distinct phase. The structural and compositional changes observed with age and maturation in bone mineral are consistent with a general increase in the degree of crystal perfection of a calcium phosphate phase best described as a poorly crystalline hydroxyapatite, although the exact details of the stuctural and compositional modification taking place with maturation must await further research. The role of brushite, which has been proposed as the earliest solid calcium phosphate phase deposited in at least one species, is reviewed.

Glimcher, Melvin J.; Bonar, Laurence C.; Grynpas, Marc D.; Landis, William J.; Roufosse, Albert H.

1981-05-01

146

The fabrication and biochemical evaluation of alumina reinforced calcium phosphate porous implants.  

PubMed

Alumina reinforced calcium phosphate porous implants were manufactured to improve the mechanical strength while maintaining the bioactivity of calcium phosphate ceramics. The alumina porous bodies, which provided the mechanical strength, were fabricated by a polyurethane sponge method and multiple coating techniques resulted in the porous bodies with a 90-75% porosity and a compressive strength of up to approximately 6MPa. The coating of hydroxyapatite (HAp) or tricalcium phosphate (beta-TCP) was performed by dipping the alumina porous bodies into calcium phosphate ceramic slurries and sintering the specimens. The fairly strong bonding between the HAp or TCP coating layer and the alumina substrate was obtained by repeating the coating and sintering processes. The biochemical evaluations of the porous implants were conducted by in vitro and in vivo tests. For in vitro test, the implants were immersed in Ringer's solution and the release of Ca and P ions were detected and compared with those of calcium phosphate powders. For in vivo test, the porous bodies were implanted into mixed breed dogs and bone mineral density measurements and histological studies were conducted. The alumina reinforced HAp porous implants had a higher strength than the HAp porous implants and exhibited a similar bioactivity and osteoconduction property to the HAp porous implants. PMID:12818545

Jun, Youn Ki; Kim, Wan Hee; Kweon, Oh Kyeong; Hong, Seong Hyeon

2003-09-01

147

Simulations of inositol phosphate metabolism and its interaction with InsP(3)-mediated calcium release.  

PubMed Central

Inositol phosphates function as second messengers for a variety of extracellular signals. Ins(1,4,5)P(3) generated by phospholipase C-mediated hydrolysis of phosphatidylinositol bisphosphate, triggers numerous cellular processes by regulating calcium release from internal stores. The Ins(1,4,5)P(3) signal is coupled to a complex metabolic cascade involving a series of phosphatases and kinases. These enzymes generate a range of inositol phosphate derivatives, many of which have signaling roles of their own. We have integrated published biochemical data to build a mass action model for InsP(3) metabolism. The model includes most inositol phosphates that are currently known to interact with each other. We have used this model to study the effects of a G-protein coupled receptor stimulus that activates phospholipase C on the inositol phosphates. We have also monitored how the metabolic cascade interacts with Ins(1,4,5)P(3)-mediated calcium release. We find temporal dynamics of most inositol phosphates to be strongly influenced by the elaborate networking. We also show that Ins(1,3,4,5)P(4) plays a key role in InsP(3) dynamics and allows for paired pulse facilitation of calcium release. Calcium oscillations produce oscillatory responses in parts of the metabolic network and are in turn temporally modulated by the metabolism of InsP(3). PMID:12202356

Mishra, Jyoti; Bhalla, Upinder S

2002-01-01

148

Phase composition, mechanical performance and in vitro biocompatibility of hydraulic setting calcium magnesium phosphate cement  

Microsoft Academic Search

Brushite (CaHPO4·2H2O)-forming calcium phosphate cements are of great interest as bone replacement materials because they are resorbable in physiological conditions. However, their short setting times and low mechanical strengths limit broad clinical application. In this study, we showed that a significant improvement of these properties of brushite cement could be achieved by the use of magnesium-substituted ?-tricalcium phosphate with the

Uwe Klammert; Tobias Reuther; Melanie Blank; Isabelle Reske; Jake E. Barralet; Liam M. Grover; Alexander C. Kübler; Uwe Gbureck

2010-01-01

149

Mechanical and Biological Performance of Calcium Phosphate Coatings on Porous Bone Scaffold  

Microsoft Academic Search

Composite coatings, consisting of calcium phosphate (CaP) ceramics and phosphate-based glass (P-glass), were obtained on a strong ZrO2 porous scaffold to improve biocompatibility by combining mechanical properties and biological activity. Powder mixtures of hydroxyapatite (HA) and P-glass in vary- ing composition and content were dip-coated on a ZrO2 porous scaffold and heat-treated above 800°C fo r2hi nair. During thermal treatment,

Hae-Won Kim; Jonathan C. Knowles; Hyoun-Ee Kim

2004-01-01

150

Calcium phosphate thin films synthesized by pulsed laser deposition: Physicochemical characterization and in vitro cell response  

Microsoft Academic Search

We review the progress made by us using pulsed laser deposition (PLD) of two bioactive calcium phosphates: octacalcium phosphate (OCP) and Mn doped carbonated hydroxyapatite (Mn-CHA). Coatings of these materials well suited for biomimetic medical prostheses and pivots were synthesized on titanium substrates with a pulsed KrF* UV laser source.The best deposition conditions for Mn-CHA thin films were 13Pa O2,

I. N. Mihailescu; P. Torricelli; A. Bigi; I. Mayer; M. Iliescu; J. Werckmann; G. Socol; F. Miroiu; F. Cuisinier; R. Elkaim; G. Hildebrand

2005-01-01

151

Self-setting bioactive calcium–magnesium phosphate cement with high strength and degradability for bone regeneration  

Microsoft Academic Search

Calcium phosphate cement (CPC) has been successfully used in clinics as bone repair biomaterial for many years. However, poor mechanical properties and a low biodegradation rate limit any further applications. Magnesium phosphate cement (MPC) is characterized by fast setting, high initial strength and relatively rapid degradation in vivo. In this study, MPC was combined with CPC to develop novel calcium–magnesium

Fan Wu; Jie Wei; Han Guo; Fangping Chen; Hua Hong; Changsheng Liu

2008-01-01

152

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

E-print Network

Porous, Biphasic CaCO3-Calcium Phosphate Biomedical Cement Scaffolds from Calcite (CaCO3) Powder A. Cuneyt Tas* Department of Biomedical Engineering, Yeditepe University, Istanbul 34755, Turkey Calcite (CaH 3.2 by adding NaOH, to form biphasic, micro-, and macroporous calcite-apatitic calcium phosphate (Ap

Tas, A. Cuneyt

153

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

E-print Network

45S5 Bioactive glass surface charge variations and the formation of a surface calcium phosphate- phate (Ca-P) layer formation kinetics on the surface of 45S5 bioactive glass (BG). We hypothesize a surface calcium phosphate layer in vivo, bioactive materials, such as 45S5 bioactive glass (BG), are able

Lu, Helen H.

154

Histological analysis of calcium phosphate bone grafts for surgically created periodontal bone defects in dogs  

PubMed Central

A calcium phosphate cement (CPC-1), prepared by mixing an equimolar mixture of tetracalcium phosphate and dicalcium phosphate anhydrous with water, has been shown to be highly biocompatible and osteoconductive. A new type of calcium phosphate cement (CPC-2), prepared by mixing a mixture of ?-tricalcium phosphate and calcium carbonate with pH 7.4 sodium phosphate solution, was also reported to be highly biocompatible. The objective of the present study was to compare the osteoconductivities of CPC-1 and CPC-2 when implanted in surgically created defects in the jaw bones of dogs. At 1 month after surgery, implanted CPC-1 was partially replaced by new bone and converted to bone within 6 months. In comparison, at 1 month after surgery, the defect filled with CPC-2 was mostly replaced by new bone. Therefore, bone formation in CPC-2-filled pocket was more rapid than in CPC-1-filled pocket. These findings supported the hypothesis that CPC-2 converted to bone more rapidly than CPC-1. PMID:19241686

SUGAWARA, Akiyoshi; FUJIKAWA, Kenji; TAKAGI, Shozo; CHOW, Laurence C.

2009-01-01

155

Effect of rapidly resorbable calcium phosphates and a calcium phosphate bone cement on the expression of bone-related genes and proteins in vitro.  

PubMed

The use of biodegradable bone substitutes is advantageous for alveolar ridge augmentation because it avoids second-site surgery for autograft harvesting. This study examines the effect of novel, rapidly resorbable calcium phosphates and a calcium phosphate bone cement on the expression of bone-related genes and proteins by human bone-derived cells (HBDCs) and compares this behavior to that of tricalciumphosphate (TCP). Test materials were alpha-TCP, two materials with a crystalline phase Ca(2)KNa(PO(4))(2) and with a small amorphous portion containing either magnesium potassium phosphate (material denominated GB14) or silica phosphate (material denominated GB9), and a calcium phosphate bone cement (material denominated Biocement D). HBDCs were grown on the substrata for 3, 7, 14, and 21 days, counted, and probed for various mRNAs and proteins (type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase, and bone sialoprotein). All substrates supported continuous cellular growth for 21 days. In the presence of GB14 and Biocement D specimens cell proliferation was reduced and cell differentiation increased. At day 21, the greatest number of cells was found on GB9 expressing significantly higher levels of bone-related proteins than cells grown on all other surfaces. Because all novel materials facilitated the expression of the osteoblastic phenotype at least as much as TCP and the polystyrene control, these biomaterials can be regarded as excellent candidate bone substitute materials. GB9 induced the highest proliferation and cellular differentiation after 21 days of incubation, suggesting that this material may possess a higher potency for enhancing osteogenesis than TCP. PMID:14999762

Knabe, C; Berger, G; Gildenhaar, R; Meyer, J; Howlett, C R; Markovic, B; Zreiqat, H

2004-04-01

156

Evidence of calcium phosphate depositions in stenotic arteriovenous fistulas  

Microsoft Academic Search

This study investigates vascular samples from patients with and without end-stage renal disease (ESRD) to determine the occurrence of calcium depositions. Findings in stenotic arteriovenous (AV)-fistula veins were compared with those of nonstenotic AV-fistula veins, non[ndash ]AV-fistula veins, and atherosclerotic vessels. Calcium and phosphorus content was measured by means of scanning electron microscopy and its built-in method of energy-dispersive spectrometry

Lars-Fride Olsson; Rolf Odselius; Else Ribbe

2001-01-01

157

Competitive adsorption of bovine serum albumin and lysozyme on characterized calcium phosphates by polyacrylamide gel electrophoresis method.  

PubMed

Characterizations of hydroxyapatite (HA), biphasic calcium phosphate (BCP) and beta tricalcium phosphate (beta-TCP) ceramic particles were carried out using X-ray diffusion (XRD), Scanning electron micrograph (SEM), Particle Sizer and Zeta potential analyzer. Competitive adsorption of bovine serum albumin (BSA) and lysozyme (LSZ) on the three calcium phosphates were investigated by polyacrylamide gel electrophoresis (PAGE) method. The results showed that HA, BCP and beta-TCP ceramic particles with irregular shapes and similar size distributions all had negative surface net charges in pH7.4 phosphate buffered saline (PBS) solution and exhibited alike behaviors of BSA and LSZ adsorption. LSZ had higher affinity for calcium phosphate ceramics than BSA and its adsorption on them didn't be almost influenced by the increasing of BSA concentration in the solution. Electrostatic interaction played an important role on the competitive adsorption of BSA and LSZ on the surface of calcium phosphate ceramic particles. PMID:17619993

Zhu, X D; Fan, H S; Zhao, C Y; Lu, J; Ikoma, T; Tanaka, J; Zhang, X D

2007-11-01

158

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

Microsoft Academic Search

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

EDUARDO A SLATOPOLSKY; STEVEN K BURKE; MAUREEN A DILLON

1999-01-01

159

Phase development in the hardening process of two calcium phosphate bone cements: an energy dispersive X-ray diffraction study  

Microsoft Academic Search

This work was aimed at the application of an energy dispersive X-ray diffraction technique to study the kinetics of phase development during the setting and hardening reactions in two calcium phosphate bone cements. The cements under study are based on either tricalcium phosphate or tetracalcium phosphate initial solid phase, and a magnesium carbonate–phosphoric acid liquid phase as the hardening liquid.

A. Generosi; V. V. Smirnov; J. V. Rau; V. Rossi Albertini; D. Ferro; S. M. Barinov

2008-01-01

160

Casein precipitation equilibria in the presence of calcium ions and phosphates  

E-print Network

. These crystals provide a substrate for protein adsorption, with subsequent cross-binding of the casein micelles has not been clarified. In milk, casein micelles exist as colloidal parti- cles 100Á/300 nm consti- tuent of casein micelles is `micellar' or `colloidal' calcium phosphate [3,7]. The presence

Velev, Orlin D.

161

Synthesis of nanocrystalline calcium phosphate in microemulsion--effect of nature of surfactants.  

PubMed

Nanosized calcium phosphate (CP) powders have been synthesized by an inverse microemulsion system using kerosene as the oil phase, a cationic surfactant Aliquat 336, a non-ionic surfactant Tween 20 and their mixture and aqueous solutions of calcium nitrate tetrahydrate and biammonium hydrogen phosphate as the water phase. It has been found that the nature of surfactants played an important role to regulate the size and morphologies of the calcium phosphate nanoparticles. The cationic surfactant Aliquat 336 has been found to regulate the nucleation and crystal growth. The synthesized powders have been comprehensively characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Our results show that the brushite (DCPD) is the major phase comprising the calcium phosphate nanoparticles. In mixed surfactants mediated system a morphological controlled highly crystalline particles have been synthesized. Further, the role of Aliquat 336 has been established and a plausible synthetic mechanism has been proposed. PMID:18083184

Singh, Sujata; Bhardwaj, Pallavi; Singh, V; Aggarwal, S; Mandal, U K

2008-03-01

162

Influence of polymer addition on the mechanical properties of a premixed calcium phosphate cement  

PubMed Central

Premixed calcium phosphate cements can reduce handling complications that are associated with the mixing of cements in the operating room. However, to extend the clinical indication of ceramic cements their mechanical properties need to be further improved. The incorporation of a polymeric material with intrinsically high tensile properties could possibly assist in increasing the mechanical properties of calcium phosphate cement. In this study polymer microparticles made from poly(lactid-co-glycolide) plasticised with poly(ethylene glycol) 400 (PLGA/PEG microparticles) were added in amounts of up to 5 wt% to a premixed acidic calcium phosphate cement. The PLGA/PEG microparticles added undergo a shape transformation at 37 °C, which could give a better integration between polymer microparticles and ceramic cement compared with polymer microparticles lacking this property. The results showed that the incorporation of 1.25 wt% PLGA/PEG microparticles increased the compressive strength by approximately 20% up to 15.1 MPa while the diametral tensile strength was kept constant. The incorporation of PLGA/PEG microparticles increased the brushite to monetite ratio after setting compared with pure ceramic cements. In conclusion, small amounts of PLGA/PEG microparticles can be incorporated into premixed acidic calcium phosphate cement and increase their mechanical properties, which could lead to increased future applications. PMID:24270588

Engstrand, Johanna; Persson, Cecilia; Engqvist, Håkan

2013-01-01

163

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

NASA Astrophysics Data System (ADS)

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.

Lowenstam, H. A.; Weiner, S.

1985-01-01

164

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

Microsoft Academic Search

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

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

2011-01-01

165

Bond between reinforcing steel fibres and magnesium phosphate\\/calcium aluminate binders  

Microsoft Academic Search

The work reported provides new information on the bond between two types of steel fibres and two different rapid strengthening matrices, magnesia phosphate and accelerated calcium aluminate. Two new methods have been developed in order to investigate:•the tensile chemical (or adhesive) bond strength between steel fibres and a cement matrix;•the durability of the steel fibre cement matrix bond when exposed

P Frantzis; R Baggott

2000-01-01

166

Effect of various additives and temperature on some properties of an apatitic calcium phosphate cement  

Microsoft Academic Search

The effect of additives and temperature on setting time, swelling time and compressive strength of a previously developed apatitic calcium phosphate cement was investigated. Setting was faster at body temperature than at room temperature. Early contact with aqueous solutions resembling blood and other body fluids had no effect. Deliberate additions of soluble carbonates, pyrophosphate or magnesium salts to the cement

M. P. Ginebra; M. G. Boltong; E. FernÁndez; J. A. Planell; F. C. M. Driessens

1995-01-01

167

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

E-print Network

Self-Assembly of Filamentous Amelogenin Requires Calcium and Phosphate: From Dimers via Nanoribbons, San Francisco, California 94143, United States *S Supporting Information ABSTRACT: Enamel matrix self-assembly tested if amelogenin, the main enamel matrix protein, can self-assemble into ribbon-like structures

Sali, Andrej

168

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

E-print Network

Osteoblast proliferation on neat and apatite-like calcium phosphate-coated titanium foam scaffolds-bearing ability of lightweight titanium made it possible to be used as a biomaterial, especially in hip revision and fixation surgery. It was initially shown that sand-blasted or surface-roughened titanium implants had

Tas, A. Cuneyt

169

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

E-print Network

Note Effect of milk solids concentration on the pH, soluble calcium and soluble phosphate levels of milk during heating Skelte G. ANEMA* Fonterra Research Centre, Private Bag 11029, Palmerston North, New 2009 Abstract ­ When milk is processed to dairy products, the concentration of the milk

Boyer, Edmond

170

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

E-print Network

Formation of Biomimetic Porous Calcium Phosphate Coatings on Surfaces of Polyethylene/Zinc Stearate of using polyethylene-stearate blends having CaP coatings include: increased surface porosity that can in terms of uniform surface coverage and coating thickness [1]. The temperatures used for plasma spray

Drelich, Jaroslaw W.

171

Inhomogeneity of calcium phosphate coatings deposited by laser ablation at high deposition rate  

Microsoft Academic Search

Calcium phosphate coatings were deposited with a KrF excimer laser onto titanium alloy to study their homogeneity. Deposition was performed at a high deposition rate under a water vapour atmosphere of 45 Pa and at a substrate temperature of 575 °C. Samples were also submitted to annealing under the same conditions of deposition for different times just after deposition. The

J. M. Fernández-Pradas; G. Sardin; J. L. Morenza

2003-01-01

172

Adjuvant effects of chitosan and calcium phosphate particles in an inactivated Newcastle disease vaccine  

Technology Transfer Automated Retrieval System (TEKTRAN)

The adjuvant activity of chitosan and calcium phosphate-particles (CAP) was studied following intranasal coadministration of commercial chickens with inactivated Newcastle disease virus (NDV) vaccine. After three vaccinations with inactivated NDV in combination with chitosan or CAP an increase in an...

173

Juvenile osteopetrosis: effects on blood and bone of prednisone and a low calcium, high phosphate diet  

Microsoft Academic Search

Four children with juvenile osteopetrosis are described who were treated with a combination of prednisone and a low calcium, high phosphate diet. One of the children, treated as a neonate, achieved complete clinical and radiological remission from the disease after nine months, at which point treatment was stopped. There have been no signs of recurrence for two years. Two who

L M Dorantes; A M Mejia; S Dorantes

1986-01-01

174

Influence of annealing temperature on RF magnetron sputtered calcium phosphate coatings  

Microsoft Academic Search

The effect of different annealing temperatures on the characteristics of thin calcium phosphate coatings fabricated by radiofrequency magnetron sputtering was studied. Annealing of the as-sputtered films was necessary to change the amorphous coating to a crystalline coating. The films were annealed for 2 and 4 h at 400, 600, 800,1000 and 1200 °C under dry argon or argon and water

K. van Dijk; H. G. Schaeken; J. G. C. Wolke; J. A. Jansen

1996-01-01

175

Effect of different calcium phosphate scaffold ratios on odontogenic differentiation of human dental pulp cells.  

PubMed

Calcium phosphate (CaP) scaffolds have been widely and successfully used with osteoblast cells for bone tissue regeneration. However, it is necessary to investigate the effects of these scaffolds on odontoblast cells' proliferation and differentiation for dentin tissue regeneration. In this study, three different hydroxyapatite (HA) to beta tricalcium phosphate (?-TCP) ratios of biphasic calcium phosphate (BCP) scaffolds, BCP20, BCP50, and BCP80, with a mean pore size of 300?m and 65% porosity were prepared from phosphoric acid (H2PO4) and calcium carbonate (CaCO3) sintered at 1000°C for 2h. The extracts of these scaffolds were assessed with regard to cell viability and differentiation of odontoblasts. The high alkalinity, more calcium, and phosphate ions released that were exhibited by BCP20 decreased the viability of human dental pulp cells (HDPCs) as compared to BCP50 and BCP80. However, the cells cultured with BCP20 extract expressed high alkaline phosphatase activity and high expression level of bone sialoprotein (BSP), dental matrix protein-1 (DMP-1), and dentin sialophosphoprotein (DSPP) genes as compared to that cultured with BCP50 and BCP80 extracts. The results highlighted the effect of different scaffold ratios on the cell microenvironment and demonstrated that BCP20 scaffold can support HDPC differentiation for dentin tissue regeneration. PMID:25686943

AbdulQader, Sarah Talib; Kannan, Thirumulu Ponnuraj; Rahman, Ismail Ab; Ismail, Hanafi; Mahmood, Zuliani

2015-04-01

176

Inflammatory cytokine response to titanium chemical composition and nanoscale calcium phosphate surface modification  

Microsoft Academic Search

Nanoscale surface modification of titanium dental implants with calcium phosphate (CaP) has been shown to achieve superior bone wound healing and osseointegration compared with smooth or microrough titanium surfaces alone. As bone healing has been shown to be influenced by the action of cytokines, this study examined whether changes in cytokine gene expression from RAW 264.7 cells cultured on commercially

Stephen Hamlet; Saso Ivanovski

2011-01-01

177

Strontium enhances osseointegration of calcium phosphate cement: a histomorphometric pilot study in ovariectomized rats  

PubMed Central

Background Calcium phosphate cements are used frequently in orthopedic and dental surgeries. Strontium-containing drugs serve as systemic osteoblast-activating medication in various clinical settings promoting mechanical stability of the osteoporotic bone. Methods Strontium-containing calcium phosphate cement (SPC) and calcium phosphate cement (CPC) were compared regarding their local and systemic effects on bone tissue in a standard animal model for osteoporotic bone. A bone defect was created in the distal femoral metaphysis of 60 ovariectomized Sprague-Dawley rats. CPC and SPC were used to fill the defects in 30 rats in each group. Local effects were assessed by histomorphometry at the implant site. Systemic effects were assessed by bone mineral density (BMD) measurements at the contralateral femur and the spine. Results Faster osseointegration and more new bone formation were found for SPC as compared to CPC implant sites. SPC implants exhibited more cracks than CPC implants, allowing more bone formation within the implant. Contralateral femur BMD and spine BMD did not differ significantly between the groups. Conclusions The addition of strontium to calcium phosphate stimulates bone formation in and around the implant. Systemic release of strontium from the SPC implants did not lead to sufficiently high serum strontium levels to induce significant systemic effects on bone mass in this rat model. PMID:23758869

2013-01-01

178

Phosphorus-31 NMR Studies of Cell Wall-Associated Calcium-Phosphates in Ulva lactuca1  

PubMed Central

Phosphate concentrations in the range 0.1 to 2.0 millimolar induced the formation of extracellular amorphous calcium-phosphates in the cell wall of the marine macro algae Ulva lactuca when they were cultivated in light in seawater at 20°C. A broad resonance representing these compounds as well as resonances for extracellular orthophosphate and polyphosphates could be followed by 31P-nuclear magnetic resonance spectroscopy. The presence of the calcium-phosphate made the cells brittle and it inhibited the growth of the macro algae and caused mortality within 1 week. The formation of the calcium-phosphates was influenced by the external phosphate concentration, the extracellular pH and the nature and concentration of the external nitrogen source. Furthermore, no formation of these compounds was observed when Ulva lactuca was cultivated in the dark, at low temperatures (5°C) or in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The complex could be removed through washes with ethylenediaminetetraacetate; this treatment did not alter the intracellular pH or the orthophosphate and polyphosphate pools and it restored growth. Images Figure 2 PMID:16666741

Weich, Rainer G.; Lundberg, Peter; Vogel, Hans J.; Jensén, Paul

1989-01-01

179

Gas phase laser synthesis and processing of calcium phosphate nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

Biochemical processes make pervasive use of calcium and phosphate ions. Calcium phosphate salts that are naturally nontoxic and bioactive have been used for several medical applications in form of coatings and micropowders. Nanoparticle-based calcium phosphates have been shown to be internalized by living cells and be effective in DNA transfection, drug delivery, and transport of fluorophores for imaging of intracellular processes. They are also expected to interact strongly with cell adhesive proteins and are therefore promising elements in approaches to mimic the complex environment of the extra cellular matrix of bone. Harnessing this biomedical potential requires the ability to control the numerous characteristics of nanophase calcium phosphates that affect biological response, including nanoparticle chemical composition, crystal phase, crystallinity, crystallographic orientation of exposed faces, size, shape, surface area, number concentration, and degree of aggregation. This dissertation focuses on the use of laser-induced gas-phase synthesis for creation of calcium phosphate nanoparticles, and corresponding nanoparticle-based substrates that could offer new opportunities for guiding biological responses through well-controlled biochemical and topological cues. Gas-phase synthesis of nanoparticles has several characteristics that could enhance control over particle morphology, crystallinity, and surface area, compared to liquid-phase techniques. Synthesis from gas-phase precursors can be carried out at high temperatures and in high-purity inert or reactive gas backgrounds, enabling good control of chemistry, crystal structure, and purity. Moreover, the particle mean free path and number concentration can be controlled independently. This allows regulation of interparticle collision rates, which can be adjusted to limit aggregation. High-temperature synthesis of well-separated particles is therefore possible. In this work high power lasers are employed to vaporize microcrystalline calcium phosphate materials to generate an aerosol of nanoparticles which is further processed and deposited using principles of aerosol mechanics. Particles and resulting particle-based systems are analyzed by transmission electron microscopy, atomic force microscopy, X-ray diffraction, and optical absorption. Obtained substrates are functionalized with cell adhesive peptides. Findings show that laser-induced gas-phase synthesis provides attractive new dimensions in the controlled fabrication of calcium phosphate nanoparticles, including manipulation not only of size and chemical composition, but also crystal phase make-up, fractal structure, and nanotopography of derived substrates.

Bapat, Parimal V.

180

The role of intracellular calcium phosphate in osteoblast-mediated bone apatite formation  

PubMed Central

Mineralization is a ubiquitous process in the animal kingdom and is fundamental to human development and health. Dysfunctional or aberrant mineralization leads to a variety of medical problems, and so an understanding of these processes is essential to their mitigation. Osteoblasts create the nano-composite structure of bone by secreting a collagenous extracellular matrix (ECM) on which apatite crystals subsequently form. However, despite their requisite function in building bone and decades of observations describing intracellular calcium phosphate, the precise role osteoblasts play in mediating bone apatite formation remains largely unknown. To better understand the relationship between intracellular and extracellular mineralization, we combined a sample-preparation method that simultaneously preserved mineral, ions, and ECM with nano-analytical electron microscopy techniques to examine osteoblasts in an in vitro model of bone formation. We identified calcium phosphate both within osteoblast mitochondrial granules and intracellular vesicles that transported material to the ECM. Moreover, we observed calcium-containing vesicles conjoining mitochondria, which also contained calcium, suggesting a storage and transport mechanism. Our observations further highlight the important relationship between intracellular calcium phosphate in osteoblasts and their role in mineralizing the ECM. These observations may have important implications in deciphering both how normal bone forms and in understanding pathological mineralization. PMID:22879397

Boonrungsiman, Suwimon; Gentleman, Eileen; Carzaniga, Raffaella; Evans, Nicholas D.; McComb, David W.; Porter, Alexandra E.; Stevens, Molly M.

2012-01-01

181

A construction of novel iron-foam-based calcium phosphate/chitosan coating biodegradable scaffold material.  

PubMed

Slow corrosion rate and poor bioactivity restrict iron-based implants in biomedical application. In this study, we design a new iron-foam-based calcium phosphate/chitosan coating biodegradable composites offering a priority mechanical and bioactive property for bone tissue engineering through electrophoretic deposition (EPD) followed by a conversion process into a phosphate buffer solution (PBS). Tensile test results showed that the mechanical property of iron foam could be regulated through altering the construction of polyurethane foam. The priority coatings were deposited from 40% nano hydroxyapatite (nHA)/ethanol suspension mixed with 60% nHA/chitosan-acetic acid aqueous solution. In vitro immersion test showed that oxidation-iron foam as the matrix decreased the amount of iron implanted and had not influence on the bioactivity of this implant, obviously. So, this method could also be a promising method for the preparation of a new calcium phosphate/chitosan coating on foam construction. PMID:23827538

Wen, Zhaohui; Zhang, Liming; Chen, Chao; Liu, Yibo; Wu, Changjun; Dai, Changsong

2013-04-01

182

Nanocrystalline biphasic resorbable calcium phosphate (HAp/?-TCP) thin film prepared by electron beam evaporation technique  

NASA Astrophysics Data System (ADS)

Biphasic calcium phosphate (BCP) thin film having resorbable ?-tricalcium phosphate (?-TCP) and non-resorbable hydroxyapatite (HAp) phases having enhanced bioactivity was synthesized by electron beam evaporation technique. Nanosized BCP was deposited as a layer (500 nm) on (0 0 1) silicon substrate by electron beam evaporation and crystalline phase of samples were found to improve on annealing at 700 °C. Uniform deposition of calcium phosphate on silicon substrate was verified from elemental mapping using scanning electron microscope (SEM-EDX). Annealing of the samples led to a decrease in surface roughness, hydrophobicity and dissolution of the coating layer. Amoxicillin loaded thin films exhibited significant bacterial resistance. In addition, BCP thin films did not exhibit any cytotoxicity. Antibiotics incorporated BCP coated implants might prevent the post-surgical infections and could promote bone-bonding of orthopedic devices.

Elayaraja, K.; Chandra, V. Sarath; Joshy, M. I. Ahymah; Suganthi, R. V.; Asokan, K.; Kalkura, S. Narayana

2013-06-01

183

31P NMR as a spectroscopic monitor of the spontaneous precipitation of calcium phosphates.  

PubMed

High-resolution 31P NMR spectroscopy is shown to be a potentially valuable new method for monitoring the spontaneous precipitation of calcium phosphates from metastable supersaturated solutions. An apparatus capable of pH-statting the sample in a spinning 20 mm NMR sample tube is briefly described. The spontaneous precipitation of dicalcium phosphate dihydrate, CaHPO4 X 2H2O, pH-statted at pH 5, is characterized by a base-uptake curve which follows the decrease in the intensity of the solution 31P resonance. The precipitation of amorphous calcium phosphate at neutral pH, which exhibited an induction period of approximately 10 min, was also studied. No evidence of NMR peaks from transient clusters or the initial colloidal solid phase has been seen. PMID:6871759

Yesinowski, J P; Benedict, J J

1983-05-01

184

Modelling biological and chemically induced precipitation of calcium phosphate in enhanced biological phosphorus removal systems.  

PubMed

The biologically induced precipitation processes can be important in wastewater treatment, in particular treating raw wastewater with high calcium concentration combined with Enhanced Biological Phosphorus Removal. Currently, there is little information and experience in modelling jointly biological and chemical processes. This paper presents a calcium phosphate precipitation model and its inclusion in the Activated Sludge Model No 2d (ASM2d). The proposed precipitation model considers that aqueous phase reactions quickly achieve the chemical equilibrium and that aqueous-solid change is kinetically governed. The model was calibrated using data from four experiments in a Sequencing Batch Reactor (SBR) operated for EBPR and finally validated with two experiments. The precipitation model proposed was able to reproduce the dynamics of amorphous calcium phosphate (ACP) formation and later crystallization to hydroxyapatite (HAP) under different scenarios. The model successfully characterised the EBPR performance of the SBR, including the biological, physical and chemical processes. PMID:21565382

Barat, R; Montoya, T; Seco, A; Ferrer, J

2011-06-01

185

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

NASA Astrophysics Data System (ADS)

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.

Tarasevich, Barbara J.

186

Structure and properties of calcium iron phosphate glasses  

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

187

Growth of calcium phosphate on ion-exchange resins pre-saturated with calcium or hydrogenphosphate ions: an SEM\\/EDX and XPS study  

Microsoft Academic Search

Calcium phosphate formed on the surfaces of ion-exchange resins pre-saturated with either Ca2+ or HPO42- ions has been studied using a combination of scanning electron microscopy (SEM)\\/energy dispersive X-ray (EDX) analysis and X-ray photoelectron spectroscopy (XPS). Calcium phosphate was formed at a temperature of 36.5°C via two methods. On Ca2+ or HPO42--saturated resins, 1.5xSBF (simulated body fluid) solution was used

M. R. Mucalo; M. Toriyama; Y. Yokogawa; T. Suzuki; Y. Kawamoto; F. Nagata; K. Nishizawa

1995-01-01

188

Ectopic bone formation by microporous calcium phosphate ceramic particles in sheep muscles.  

PubMed

Calcium phosphate ceramics are widely used in bone reconstructive surgery because of their osteconductive properties. However, these materials generally lack osteoinductive properties required to support bone healing in large defects. In this article, we study the osteoinductive potential of calcium phosphate ceramic particles implanted for 6 months into the dorsal muscles of eight adult female sheep. Microporous biphasic calcium phosphate (MBCP) granules of 1-2 mm composed of hydroxyapatite and beta-tricalcium phosphate (60/40) had macropores of 450 microm, micropores of 0.43 microm, and a specific surface area of 1.8 m(2)/g. After 6 months in the back muscles of sheep, the explants composed of MBCP granules were hard and encapsulated by normal muscle tissue. Ectopic bone formation with Haversian structures was observed in close contact with the MBCP granules in histological sections. Back-scattered electron microscopy and micro-computed tomography indicated that approximately 10% of well-mineralized bone with mature osteocytes had formed between or upon the granules. The ectopic bone showed trabeculae bridging the MBCP granules. Both the number and thickness of the trabeculae formed between the MBCP particles were comparable to those measured in spongious bone. The overall results therefore confirmed the presence of mature bone after intramuscular implantation of MBCP granules. The different hypotheses explaining ectopic bone formation induced by MBCP granules are discussed. Synthetic bone substitutes with osteoinductive properties could be used in bone reconstructive surgery. PMID:15869915

Le Nihouannen, Damien; Daculsi, Guy; Saffarzadeh, Afchine; Gauthier, Olivier; Delplace, Séverine; Pilet, Paul; Layrolle, Pierre

2005-06-01

189

Ectopic osteoid and bone formation by three calcium-phosphate ceramics in rats, rabbits and dogs.  

PubMed

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

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

2014-01-01

190

FGF23 and Klotho: the new cornerstones of phosphate/calcium metabolism  

PubMed Central

Since its first description as a phosphaturic agent in the early 2000’s, the Fibroblast Growth Factor 23 (FGF23) has rapidly become the third key player of phosphate/calcium metabolism with the two ‘old’ PTH and vitamin D. FGF23 is a protein synthesized by osteocytes that acts mainly as a phosphaturic factor and a suppressor of 1? hydroxylase activity in the kidney. It inhibits the expression of type IIa and IIc sodium-phosphate cotransporters on the apical membrane of proximal tubular cells, thus leading to an inhibition of phosphate reabsorption. Moreover, it also inhibits the 1? hydroxylase activity. These two renal pathways account together for the hypophosphatemic effect of FGF23, but FGF23 has also been recently described as an inhibiting factor for PTH synthesis. Its exact role in bone remains to be defined. A transmembrane protein, Klotho, is an essential cofactor for FGF23 biological activity, but it can also act by itself for calcium and PTH regulation. This paper gives an overview of these recent data of phosphate/calcium physiology, as well as a description of clinical conditions associated with FGF23 deregulation (genetic diseases and chronic kidney disease). As a conclusion, future therapeutic consequences of the FGF23/Klotho axis are discussed. PMID:21497493

Bacchetta, Justine; Cochat, Pierre; Salusky, Isidro B

2014-01-01

191

Laminin Coating Promotes Calcium Phosphate Precipitation on Titanium Discs in vitro  

PubMed Central

ABSTRACT Objectives The objective of this study was to investigate the effect of a laminin coating on calcium phosphate precipitation on three potentially bioactive titanium surfaces in simulated body fluid. Material and Methods Blasted titanium discs were prepared by alkali and heat treatment (AH), anodic oxidation (AO) or hydroxyapatite coating (HA) and subsequently coated with laminin. A laminin coated blasted surface (B) served as a positive control while a blasted non coated (B-) served as a negative control. Surface morphology was examined by Scanning Electron Microscopy (SEM). The analysis of the precipitated calcium and phosphorous was performed by Energy Dispersive X-ray Spectroscopy (EDX). Results The thickness of the laminin coating was estimated at 26 Å by ellipsometry. Interferometry revealed that the coating process did not affect any of the tested topographical parameters on µm level when comparing B to B-. After 2 weeks of incubation in SBF, the alkali-heat treated discs displayed the highest calcium phosphate deposition and the B group showed higher levels of calcium phosphate than the B- group. Conclusions Our results suggest that laminin may have the potential to be used as a coating agent in order to enhance the osseoinductive performance of biomaterial surfaces, with the protein molecules possibly functioning as nucleation centres for apatite formation. Nevertheless, in vivo studies are required in order to clarify the longevity of the coating and its performance in the complex biological environment. PMID:24422002

Stenport, Victoria Franke; Currie, Fredrik; Wennerberg, Ann

2011-01-01

192

Effects of a calcium phosphate cement on mineralized nodule formation compared with endodontic cements.  

PubMed

The aim of this study was to investigate mineralizing ability of a premixed calcium phosphate cement (premixed-CPC) compared to mineral trioxide aggregate (MTA) and zinc oxide eugenol cement (SuperEBA) in ROS17/2.8 cells. The measurements of cell proliferation, alkaline phosphatase (ALPase) activity and mineralized nodule formation in the presence or absence (control) of the test materials were performed using a cell culture insert method with the test materials placed on a porous membrane of culture plate insert. Mineralized nodules were detected by staining with alizarin red, and the calcium content of the mineralized nodules was determined quantitatively using a calcium assay kit. Premixed-CPC and MTA indicated significantly higher cell proliferation, ALPase activity, mineralized nodule formation, and calcium content in nodules than those of SuperEBA (p<0.05). The present results suggest that premixed-CPC has the same mineralizing ability as MTA. PMID:22277611

Ogata, Hidehiro; Hayashi, Makoto; Tsuda, Hiromasa; Suzuki, Naoto; Maeno, Masao; Sugawara, Akiyoshi; Ogiso, Bunnai

2012-02-01

193

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

PubMed

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

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

2013-07-01

194

Surface-engineered bacterial cellulose as template for crystallization of calcium phosphate.  

PubMed

Bacterial cellulose (BC), produced by Acetobacter xylinum, and cotton linters as reference were surface modified by ozone-induced graft polymerization of acrylic acid and used as a template for crystallization of calcium phosphate. The grafting was verified using attenuated total reflection-infrared radiation (ATR-IR) and electron spectroscopy for chemical analysis (ESCA). ATR-IR revealed an additional absorption band at 1700 cm(-1), corresponding to the carbonyl group in polyacrylic acid. ESCA figures show, apart from the characteristic peaks for cellulose, additional peaks at 285 eV and 289 eV that correspond to groups in acrylic acid. The grafting yield is higher on cotton linters compared with BC, which most likely has to do with differences in crystallinity and reactivity of the different cellulose materials. No morphology difference directly caused by grafting could be seen with scanning electron microscopy (SEM), which might indicate that acrylic acid was grafted as a thin film on the surface of the cellulose micro fibrils. Calcium phosphate was formed on the surface-modified cellulose by first pre-soaking the materials in a saturated Ca(OH)2 and later in simulated body fluid (SBF). The atomic ratio of calcium phosphate was determined by ESCA to be about 1.5 for the different materials. Energy dispersive spectroscopy (EDS) was used to map and verify that the crystals were calcium phosphate. Secondary ion mass spectroscopy (SIMS) was also used to verify the presence of calcium phosphate complex onto BC. SEM images showed the difference in dimension, distribution and morphology of the crystals depending on the materials. Smaller and a greater number of crystals were obtained on the surface-modified BC and larger and fewer crystals on surface-modified cotton linters. Structural and grafting differences between the celluloses may lead to differences in nucleation sites and possibly differences in the morphology of the Ca-P crystals. The BC-calcium phosphate composite is expected to be useful as a scaffold for bone tissue regeneration. PMID:16768294

Bodin, Aase; Gustafsson, Lena; Gatenholm, Paul

2006-01-01

195

Hierarchically microporous\\/macroporous scaffold of magnesium–calcium phosphate for bone tissue regeneration  

Microsoft Academic Search

Hierarchically 3D microporous\\/macroporous magnesium–calcium phosphate (micro\\/ma-MCP) scaffolds containing magnesium ammonium phosphate hexahydrate [NH4MgPO4·6H2O] and hydroxyapatite [Ca10(PO4)6(OH)2] were fabricated from cement utilizing leaching method in the presence of sodium chloride (NaCl) particles and NaCl saturated water solution. NaCl particles produced macropororosity, and NaCl solution acted as both cement liquid and porogens, inducing the formation of microporosity. The micro\\/ma-MCP scaffolds with porosities

Jie Wei; Junfeng Jia; Fan Wu; Shicheng Wei; Huanjun Zhou; Hongbo Zhang; Jung-Woog Shin; Changsheng Liu

2010-01-01

196

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

Microsoft Academic Search

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.

Y Zhang; Miqin Zhang

2001-01-01

197

[Cognitive Function and Calcium. The relationship between inositol phosphates and brain function].  

PubMed

Inositol phosphates are produced depending on the numbers of the phosphate group which is added to the inositol ring which is 6 membered ring derived from a component of a biological membrane. Inositol 1, 4, 5 trisphosphate (IP3) operates on IP3 receptor on the endoplasmic reticulum, and is related to a release of calcium in the cell. IP3 is associated with various brain functions and neurodegenerative disorders. Moreover, there are IP4, IP5, IP6 and IP7 such as inositol polyphosphates in mammals. Notably, inositol hexakisphoshate kinase (IP6) which phosphorylates IP6 to IP7 plays important roles in the pathophysiology of various neurodegenerative disorders. PMID:25634048

Nagata, Eiichiro

2015-01-01

198

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

NASA Astrophysics Data System (ADS)

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.

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

2006-08-01

199

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

Microsoft Academic Search

The effects of solid state synthesis process parameters and primary calcium precursor on the cement-type hydration efficiency\\u000a (at 37°C) of ?-tricalcium phosphate (Ca3(PO4)2 or ?-TCP) into hydroxyapatite (Ca10?xHPO4(PO4)6?x(OH)2?x x = 0–1, or HAp) have been investigated. ?-TCP was synthesized by firing of stoichiometric amount of calcium carbonate (CaCO3) and monetite (CaHPO4) at 1150–1350°C for 2 h. Three commercial grade CaCO3 powders of different

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

2011-01-01

200

Osteotomy of distal radius fracture malunion using a fast remodeling bone substitute consisting of calcium sulphate and calcium phosphate.  

PubMed

Malunion after a distal radius fracture can be treated with an osteotomy of the distal radius. Autologous iliac crest bone graft is often used to fill the gap, but the procedure is associated with donor site morbidity. In this study a novel fast resorbing biphasic bone substitute consisting of a mixture of calcium sulphate and calcium phosphate is used (Cerament BoneSupport AB, Sweden). Fifteen consecutive patients, with a mean age of 52 (27-71) years were included. All had a malunion after a distal radius fracture and underwent an osteotomy. A fragment specific fixation system, TriMed (TriMed, Valencia, CA), consisting of a Buttress Pin and a Radial Pin Plate were used for fixation and a calcium sulphate and calcium phosphate mixture as bone substitute. The patients were followed for 1 year. Grip strength increased from 61 (28-93)% of the contralateral hand to 85 (58-109)%, p < 0.001. DASH scores decreased from 37 (22-61) to 24 (2-49) p = 0.003. Radiographically all osteotomies healed. An increase of ulnar variance was noted during healing from 1.8 mm immediately postoperatively to 2.6 mm at final follow up. Osteotomy can increase grip strength and decease disability after a malunited fracture. In the present series the bone substitute was replaced by bone, but a minor loss of the achieved radiographic correction was noted in some patients during osteotomy healing. A more rigid fixation may improve the radiographic outcome with this kind of bone substitute. PMID:19904822

Abramo, Antonio; Geijer, Mats; Kopylov, Philippe; Tägil, Magnus

2010-01-01

201

Synergistic acceleration in the osteogenesis of human mesenchymal stem cells by graphene oxide-calcium phosphate nanocomposites.  

PubMed

Nanocomposites consisting of oblong ultrathin plate shaped calcium phosphate nanoparticles and graphene oxide microflakes were synthesized and have demonstrated markedly synergistic effect in accelerating stem cell differentiation to osteoblasts. PMID:24891127

Tatavarty, Rameshwar; Ding, Hao; Lu, Guijin; Taylor, Robert J; Bi, Xiaohong

2014-08-11

202

Engineering of polarized tubular structures in a microfluidic device to study calcium phosphate stone formation.  

PubMed

This communication describes the formation of tubular structures with a circular cross-section by growing epithelial cells in a microfluidic (MF) device. Here we show for the first time that it is possible to form a monolayer of polarized cells, embedded within the MF device which can function as an in vivo epithelia. We showed: i) the overexpression of specific protein(s) of interest (i.e., ion channel and transport proteins) is feasible inside tubular structures in MFs; ii) the functional kinetic information of Ca(2+) in cells can be measured by microflurometry using cell permeable Ca(2+) probe under confocal microscope; and iii) calcium phosphate stones can be produced in real time in MFs with Ca(2+) transporting epithelia. These data suggest that tubular structures inside this MF platform can be used as a suitable model to understand the molecular and pharmacological basis of calcium phosphate stone formation in the epithelial or other similar cellular micro environments. PMID:22960772

Wei, Zengjiang; Amponsah, Prince K; Al-Shatti, Mariyam; Nie, Zhihong; Bandyopadhyay, Bidhan C

2012-10-21

203

Advances in calcium phosphate coatings--anodic spark deposition: a review.  

PubMed

High voltage anodization of titanium in the presence of an electrolytic medium containing calcium and phosphate ions has shown improved osteointegration and biocompatibility compared to untreated titanium. Processing parameters influence the unique porous microstructure developed during anodization. These parameters tailor the specific properties of the surface to achieve improved osseointegration of an implant. In addition, subsequent treatment following anodization further alters the microstructure. Numerous studies have examined the influence of these properties on the cellular response and the mechanical properties in terms of coating adhesion and pull-out strength in bone; however, there are conflicting reports on the cellular responses. This review examines those processing parameters and the related influence on cellular responses and mechanical properties. In addition, this review provides a summary of published reports regarding the work related to the advancement of calcium phosphate coatings achieved through high voltage anodization. PMID:24389196

Calvert, Kayla L; Desai, Tejal; Webster, Thomas J

2014-01-01

204

Vertebral body recollapse without trauma after kyphoplasty with calcium phosphate cement.  

PubMed

Traditionally, immobilization and external bracing has been recommended for patients with type A traumatic and non-osteoporotic fractures that do not present neurological deficits or significant instability. Nevertheless, several authors have recently suggested the possibility to treat thoraco-lumbar and lumbar vertebral compression post-traumatic fractures using standalone balloon kyphoplasty with osteoconductive filler materials, such as calcium phosphate (CPC). Maestretti and Huang have demonstrated the advantages of this technique showing an almost immediate return to daily activities without the inconvenience of wearing a brace, pain reduction, minimal operative risks and maintenance of stability, therefore proposing this as a first-choice technique in young patient needing rapid spine stability. The authors present a case of vertebral body recollapse after kyphoplasty with calcium phosphate cement (CPC) in a 47-year-old man with an A1.2 post-traumatic L1 compression fracture. PMID:21468725

Piazzolla, Andrea; De Giorgi, Giuseppe; Solarino, Giuseppe

2011-08-01

205

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

PubMed Central

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

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

206

Recurrent calcium phosphate urolithiasis in a black-and-white ruffed lemur (Varecia variegata).  

PubMed

An adult intact male black-and-white ruffed lemur (Varecia variegata) suffered recurrent bouts of urethral blockage over a 3-yr period caused by calcium phosphate (apatite form) uroliths. Surgical intervention was required in two of the three instances. Various attempts at medical management failed to control formation of the stones, and the underlying etiology remains unclear. In addition, there have been consistent, multiple, unchanging renal mineralizations over the course of the case. Medical management failed to significantly alter the urinary pH; although, to date, no further problems have been noted. To the authors' knowledge, this is the first known report of calcium phosphate stones in a prosimian species. PMID:24712174

Cushing, Andrew C; Kollias, George; Knafo, S Emmanuelle; Streeter, Renee; Ahou-Madi, Noha

2014-03-01

207

Interactions between inositol phosphates and cytosolic free calcium following bradykinin stimulation in cultured human skin fibroblasts.  

PubMed

The inositol triphosphate (IP3) that results from hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) is generally accepted to be responsible for the mobilization of intracellular calcium. However, some studies suggest that low concentrations of agonists elevate cytosolic free calcium concentration ([Ca2+]i) without IP3 formation. Thus, in the present studies, a comparison of the temporal response of inositol phosphates (IP3, IP2 and IP) and [Ca2+]i to a wide range of bradykinin concentrations was used to examine the relation of these two signal transduction events in cultured human skin fibroblasts (GM3652). In addition, the effects of alterations in internal or external calcium on the response of these second messengers to bradykinin were determined. Bradykinin stimulated accumulation of inositol phosphates and a rise of [Ca2+]i in a time- and dose-dependent manner. Decreasing the bradykinin concentration from 1 microM to 0.1 microM increased the time until the IP3 peak, and when the bradykinin concentration was reduced to 0.01 microM IP3 was not detected. [Ca2+]i was examined under parallel conditions. As the bradykinin concentration was reduced from 1 microM to 0.01 microM, the time to reach the peak of [Ca2+]i increased progressively, but the magnitude of the peak was unaltered. These two second messengers were variably dependent on external calcium. Although the bradykinin-stimulated initial spike of [Ca2+]i did not depend on extracellular calcium, the subsequent sustained levels of [Ca2+]i were abolished in calcium free medium. The bradykinin-stimulated inositol phosphate formation was not dependent on the extracellular calcium nor on the elevation of [Ca2+]i that was produced with Br-A23187. These results demonstrate that bradykinin-induced IP3 formation can be independent of [Ca2+]i and of external calcium, whereas changes in [Ca2+]i are partially dependent on external calcium. PMID:2001422

Huang, H M; Toral-Barza, L; Gibson, G E

1991-02-19

208

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

SciTech Connect

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.

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

2008-01-01

209

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

Microsoft Academic Search

The biocompatibility and the load-bearing ability of lightweight titanium made it possible to be used as a biomaterial, especially in hip revision and fixation surgery. It was initially shown that sand-blasted or surface-roughened titanium implants had an improved bone-bonding ability over the bioinert metallic surfaces. Plasma-spraying of a phase mixture of loosely-attached calcium phosphates on titanium implants further improved their

Sahil Jalota; Sarit B. Bhaduri; A. Cuneyt Tas

2007-01-01

210

Osteoinductive Calcium Phosphate clay nanoparticle bone cements (CPCs) with enhanced mechanical properties.  

PubMed

Calcium Phosphate Cements (CPCs) with osteoconductive properties are limited in their applications because of their poor mechanical properties. This study investigated the additive effect of Dexamethasone-doped Halloysite Nanotubes (HNTs on the mechanical properties of CPCs. HNTs are nanosized tubes with alumino-silicate composition. Physico-chemical properties, cytocompatability and cellular functionality of the nanocomposites were assayed. Results suggest that these nanoenhanced composites have a huge potential to broaden the applications of CPCs. PMID:25570848

Jammalamadaka, Udayabhanu; Tappa, Karthik; Mills, David

2014-08-01

211

Inhomogeneity of calcium phosphate coatings deposited by laser ablation at high deposition rate  

Microsoft Academic Search

.   Calcium phosphate coatings were deposited with a KrF excimer laser onto titanium alloy to study their homogeneity. Deposition\\u000a was performed at a high deposition rate under a water vapour atmosphere of 45 Pa and at a substrate temperature of 575 C.\\u000a Samples were also submitted to annealing under the same conditions of deposition for different times just after deposition.\\u000a The effects

J. M. Fernández-Pradas; G. Sardin; J. L. Morenza

2003-01-01

212

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

Microsoft Academic Search

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.

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

1969-01-01

213

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

Microsoft Academic Search

Studies were undertaken investigating improvements to the biological interaction of polymeric implant materials through their coating with an osteoinductive calcium phosphate (CaP)-type film using biomimetic deposition technology. Past research indicates that CaP coatings on implant materials increase bone growth and remodeling rates as well as enhance the stability of the bone-implant interface. This is due to the highly biocompatible nature

Jaroslaw Drelich; Kevin G. Field

214

The functional expression of human bone-derived cells grown on rapidly resorbable calcium phosphate ceramics  

Microsoft Academic Search

The use of biodegradable bone substitutes is advantageous for alveolar ridge augmentation, since it avoids second-site surgery for autograft harvesting. This study examines the effect of novel, rapidly resorbable calcium phosphates on the expression of bone-related genes and proteins by human bone-derived cells (HBDC) and compares this behavior to that of tricalciumphosphate (TCP). Test materials were ?-TCP, and four materials

C. Knabe; G. Berger; R. Gildenhaar; C. R. Howlett; B. Markovic; H. Zreiqat

2004-01-01

215

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

E-print Network

hydroxyapatite is the least soluble and the most stable calcium phosphate phase in aqueous solutions at pH values the human blood plasma, was ®rst used by Kokubo and his co-workers,12�14 to prove the similarity between nanosized HA powders, under the biomimetic conditions of 37 C and pH=7.4, by using synthetic body ¯uids (SBF

Tas, A. Cuneyt

216

Effect of increasing the colloidal calcium phosphate of milk on the texture and microstructure of yogurt  

Microsoft Academic Search

The effect of increasing the colloidal calcium phosphate (CCP) content on the physical, rheological, and microstructural properties of yogurt was investigated. The CCP content of heated (85°C for 30min) milk was increased by increasing the pH by the addition of alkali (NaOH). Alkalized milk was dialyzed against pasteurized skim milk at approximately 4°C for 72h to attempt to restore the

T. Ozcan; D. Horne; J. A. Lucey

2011-01-01

217

Demineralized bone matrix and hydroxyapatite\\/tri-calcium phosphate mixture for bone healing in rats  

Microsoft Academic Search

Purpose: Hydroxyapatite\\/tri-calcium phosphate (HA\\/TCP) mixture is an osteoconductive material used as a bone graft substitute, and demineralised bone matrix (DBM) is an osteoinductive material. A combination of DBM and HA\\/TCP mixture would probably create a composite with both osteoconductive and osteoinductive properties. The purpose of this study was to determine the effect of the combination of DBM and HA\\/TCP mixture

Ali Öztürk; H. Yetkin; L. Memis; E. Cila; S. Bolukbasi; C. Gemalmaz

2006-01-01

218

Investigation of nanocomposites based on hydrated calcium phosphates and cellulose Acetobacter xylinum  

Microsoft Academic Search

Composites based on two biocompatible compounds, namely, inorganic hydrated calcium phosphates and organic microfibrillar\\u000a ribbons of cellulose Acetobacter xylinum, are prepared by aggregation in an aqueous suspension. The influence of the structural organization of the hydroxyapatite\\u000a and temperature-time conditions on the formation of the composite materials of different compositions is investigated. It\\u000a is revealed that the composite materials are textured

A. K. Khripunov; Yu. G. Baklagina; V. A. Sinyaev; E. S. Shustikova; B. A. Paramanov; D. P. Romanov; R. Yu. Smyslov; A. A. Tkachenko

2008-01-01

219

Perfusion electrodeposition of calcium phosphate on additive manufactured titanium scaffolds for bone engineering  

Microsoft Academic Search

A perfusion electrodeposition (P-ELD) system was reported to functionalize additive manufactured Ti6Al4V scaffolds with a calcium phosphate (CaP) coating in a controlled and reproducible manner. The effects and interactions of four main process parameters – current density (I), deposition time (t), flow rate (f) and process temperature (T) – on the properties of the CaP coating were investigated. The results

Yoke Chin Chai; Silvia Truscello; Simon Van Bael; Frank P. Luyten; Jozef Vleugels; Jan Schrooten

2011-01-01

220

Factors modulating the pH at which calcium and magnesium phosphates precipitate from human urine  

Microsoft Academic Search

The factors controlling the rate at which crystalline bacterial biofilms develop on indwelling bladder catheters are poorly understood. It is known that normally the pH of voided urine (pHv) is lower than the pH at which calcium and magnesium phosphates come out of urine solution (pHn). In patients who develop infections with urease producing bacteria, however, the pHv rises above

M. T. E. Suller; V. J. Anthony; S. Mathur; R. C. L. Feneley; J. Greenman; D. J. Stickler

2005-01-01

221

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

Microsoft Academic Search

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

James H. Adair

2008-01-01

222

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

Microsoft Academic Search

Summary Jaws of large individuals, over 2 m in total length, of the shark speciesCarcharodon carcharias (great white shark) andIsurus oxyrinchus (mako shark) of the family Lamnidae, andGaleocerdo cuvieri (tiger shark) andCarcharhinus 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

G. Dingerkus; B. Séret; E. Guilbert

1991-01-01

223

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)

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.

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

2011-10-01

224

ADRF-CP Surface-Coil Spectroscopy of Synthetic Calcium Phosphates and Bone Mineral  

NASA Astrophysics Data System (ADS)

Proton to phosphorus-31 cross polarization via adiabatic demagnetization in the rotating frame (ADRF-CP) has been used, in conjunction with a surface coil, to detect monohydrogen phosphate (acid phosphate) ions in the presence of a large background of nonprotonated phosphate (orthophosphate) ions in porcine bone and synthetic calcium phosphates. Transient oscillations were observed in the transfer of polarization between the proton dipolar and phosphorus Zeeman nuclear-spin reservoirs at short times after the initiation of thermal contact. The oscillations were observed in all samples, including bone. Orthophosphate suppression was achieved by detecting the signal when the orthophosphate oscillation was passing through zero, and by adjusting the phosphorus RF field to achieve optimal cross polarization with the proton local fields of the acid phosphate ions. ADRF-CP techniques deposit less RF power than traditional spin-lock CP techniques, and are hence compatible with in vivoapplication. As the ratio of the protonated to nonprotonated phosphate can be used as a marker for bone-mineral maturity, ADRF-CP spectroscopy creates the possibility of characterizing bone-mineral dynamics in vivoby solid-state NMR.

Ramanathan, Chandrasekhar; Wu, Yaotang; Pfleiderer, Bettina; Lizak, Martin J.; Garrido, Leoncio; Ackerman, Jerome L.

225

Calcium phosphate-bearing matrices induce osteogenic differentiation of stem cells through adenosine signaling.  

PubMed

Synthetic matrices emulating the physicochemical properties of tissue-specific ECMs are being developed at a rapid pace to regulate stem cell fate. Biomaterials containing calcium phosphate (CaP) moieties have been shown to support osteogenic differentiation of stem and progenitor cells and bone tissue formation. By using a mineralized synthetic matrix mimicking a CaP-rich bone microenvironment, we examine a molecular mechanism through which CaP minerals induce osteogenesis of human mesenchymal stem cells with an emphasis on phosphate metabolism. Our studies show that extracellular phosphate uptake through solute carrier family 20 (phosphate transporter), member 1 (SLC20a1) supports osteogenic differentiation of human mesenchymal stem cells via adenosine, an ATP metabolite, which acts as an autocrine/paracrine signaling molecule through A2b adenosine receptor. Perturbation of SLC20a1 abrogates osteogenic differentiation by decreasing intramitochondrial phosphate and ATP synthesis. Collectively, this study offers the demonstration of a previously unknown mechanism for the beneficial role of CaP biomaterials in bone repair and the role of phosphate ions in bone physiology and regeneration. These findings also begin to shed light on the role of ATP metabolism in bone homeostasis, which may be exploited to treat bone metabolic diseases. PMID:24395775

Shih, Yu-Ru V; Hwang, YongSung; Phadke, Ameya; Kang, Heemin; Hwang, Nathaniel S; Caro, Eduardo J; Nguyen, Steven; Siu, Michael; Theodorakis, Emmanuel A; Gianneschi, Nathan C; Vecchio, Kenneth S; Chien, Shu; Lee, Oscar K; Varghese, Shyni

2014-01-21

226

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

PubMed Central

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

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

2014-01-01

227

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

PubMed

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

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

228

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

229

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

PubMed

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

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

2015-01-15

230

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

PubMed Central

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

Wei, Mei

2013-01-01

231

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

SciTech Connect

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.

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

232

Microstructure and chemistry affects apatite nucleation on calcium phosphate bone graft substitutes.  

PubMed

The bioactivity of calcium phosphate bone grafts of varying chemistry and strut-porosity was compared by determining the rate of formation of hydroxycarbonate apatite crystals on the material surface after being soaked in simulated body fluid for up to 30 days. Three groups of silicate-substituted hydroxyapatite material were tested, with each group comprising a different quantity of strut-porosity (23, 32, and 46 % volume). A commercially available porous ?-tricalcium phosphate bone graft substitute was tested for comparison. Results indicate that strut-porosity of a material affects the potential for formation of a precursor to bone-like apatite and further confirms previous findings that ?-tricalcium phosphate is less bioactive than hydroxyapatite. PMID:23242766

Campion, Charlie R; Ball, Sara L; Clarke, Daniel L; Hing, Karin A

2013-03-01

233

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

PubMed

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

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

2015-04-01

234

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

PubMed Central

Enamel matrix self-assembly has long been suggested as the driving force behind aligned nanofibrous hydroxyapatite formation. We tested if amelogenin, the main enamel matrix protein, can self-assemble into ribbon-like structures in physiologic solutions. Ribbons 17nm wide were observed to grow several microns in length, requiring calcium, phosphate, and pH 4.0–6.0. The pH range suggests that the formation of ion bridges through protonated histidine residues is essential to self-assembly, supported by a statistical analysis of 212 phosphate-binding proteins predicting twelve phosphate-binding histidines. Thermophoretic analysis verified the importance of calcium and phosphate in self-assembly. X-ray scattering characterized amelogenin dimers with dimensions fitting the cross-section of the amelogenin ribbon, leading to the hypothesis that antiparallel dimers are the building blocks of the ribbons. Over 5–7 days, ribbons self-organized into bundles composed of aligned ribbons mimicking the structure of enamel crystallites in enamel rods. These observations confirm reports of filamentous organic components in developing enamel and provide a new model for matrix-templated enamel mineralization. PMID:22974364

Martinez-Avila, Olga; Wu, Shenping; Kim, Seung Joong; Cheng, Yifan; Khan, Feroz; Samudrala, Ram; Sali, Andrej; Horst, Jeremy A.; Habelitz, Stefan

2012-01-01

235

Mechanical characterization of dense calcium phosphate bioceramics with interconnected porosity.  

PubMed

Porous hydroxyapatite/tricalcium phosphate (HA/TCP) bioceramics were fabricated by a novel technique of vacuum impregnation of reticulated polymeric foams with ceramic slip. The samples had approximately 5-10% interconnected porosity and controlled pore sizes appropriate to allow bone ingrowth, combined with good mechanical properties. A range of polyurethane foams with 20, 30 and 45 pores per inch (ppi) were used as templates to produce samples for testing. The foams were inpregnated with solid loadings in the range of 60-140 wt%. The results indicated that the average apparent density of the HA/TCP samples was 2.48 g/cm(3), the four-point bending strength averaged 16.98 MPa, the work of fracture averaged 15.46 J/m(2) and the average compressive strength was 105.56 MPa. A range of mechanical properties resulted from the various combinations of different grades of PU foam and the solid loading of slips. The results indicated that it is possible to manufacture open pore HA/TCP bioceramics, with compressive strengths comparable to human bone, which could be of significant clinical interest. PMID:17569009

Hsu, Y H; Turner, I G; Miles, A W

2007-12-01

236

Fabrication of calcium phosphate-calcium sulfate injectable bone substitute using hydroxy-propyl-methyl-cellulose and citric acid.  

PubMed

In this study, an injectable bone substitute (IBS) consisting of citric acid, chitosan, and hydroxyl propyl methyl cellulose (HPMC) as the liquid phase and tetra calcium phosphate (TTCP), dicalcium phosphate dihydrate (DCPD) and calcium sulfate dehydrate (CSD, CaSO4 x 2H2O) powders as the solid phase, were fabricated. Two groups were classified based on the percent of citric acid in the liquid phase (20, 40 wt%). In each groups, the HPMC percentage was 0, 2, and 4 wt%. An increase in compressive strength due to changes in morphology was confirmed by scanning electron microscopy images. A good conversion rate of HAp at 20% citric acid was observed in the XRD profiles. In addition, HPMC was not obviously affected by apatite formation. However, both HPMC and citric acid increased the compressive strength of IBS. The maximum compressive strength for IBS was with 40% citric acid and 4% HPMC after 14 days of incubation in 100% humidity at 37 degrees C. PMID:20333539

Thai, Van Viet; Lee, Byong-Taek

2010-06-01

237

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

Microsoft Academic Search

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

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

1998-01-01

238

Phase composition, mechanical performance and in vitro biocompatibility of hydraulic setting calcium magnesium phosphate cement.  

PubMed

Brushite (CaHPO(4) x 2H(2)O)-forming calcium phosphate cements are of great interest as bone replacement materials because they are resorbable in physiological conditions. However, their short setting times and low mechanical strengths limit broad clinical application. In this study, we showed that a significant improvement of these properties of brushite cement could be achieved by the use of magnesium-substituted beta-tricalcium phosphate with the general formula Mg(x)Ca((3-x))((PO(4))(2) with 0 < x < 3 as cement reactants. The incorporation of magnesium ions increased the setting times of cements from 2 min for a magnesium-free matrix to 8-11 min for Mg(2.25)Ca(0.75)(PO(4))(2) as reactant. At the same time, the compressive strength of set cements was doubled from 19 MPa to more than 40 MPa after 24h wet storage. Magnesium ions were not only retarding the setting reaction to brushite but were also forming newberyite (MgHPO(4) x 3H(2)O) as a second setting product. The biocompatibility of the material was investigated in vitro using the osteoblast-like cell line MC3T3-E1. A considerable increase of cell proliferation and expression of alkaline phosphatase, indicating an osteoblastic differentiation, could be noticed. Scanning electron microscopy analysis revealed an obvious cell growth on the surface of the scaffolds. Analysis of the culture medium showed minor alterations of pH value within the physiological range. The concentrations of free calcium, magnesium and phosphate ions were altered markedly due to the chemical solubility of the scaffolds. We conclude that the calcium magnesium phosphate (newberyite) cements have a promising potential for their use as bone replacement material since they provide a suitable biocompatibility, an extended workability and improved mechanical performance compared with brushite cements. PMID:19837194

Klammert, Uwe; Reuther, Tobias; Blank, Melanie; Reske, Isabelle; Barralet, Jake E; Grover, Liam M; Kübler, Alexander C; Gbureck, Uwe

2010-04-01

239

Calcium phosphate flocs and the clarification of sugar cane juice from whole of crop harvesting.  

PubMed

Sugar cane biomass is one of the most viable feedstocks for the production of renewable fuels and chemicals. Therefore, processing the whole of crop (WC) (i.e., stalk and trash, instead of stalk only) will increase the amount of available biomass for this purpose. However, effective clarification of juice expressed from WC for raw sugar manufacture is a major challenge because of the amounts and types of non-sucrose impurities (e.g., polysaccharides, inorganics, proteins, etc.) present. Calcium phosphate flocs are important during sugar cane juice clarification because they are responsible for the removal of impurities. Therefore, to gain a better understanding of the role of calcium phosphate flocs during the juice clarification process, the effects of impurities on the physicochemical properties of calcium phosphate flocs were examined using small-angle laser light scattering technique, attenuated total reflectance Fourier transformed infrared spectroscopy, and X-ray powder diffraction. Results on synthetic sugar juice solutions showed that the presence of SiO2 and Na(+) ions affected floc size and floc structure. Starch and phosphate ions did not affect the floc structure; however, the former reduced the floc size, whereas the latter increased the floc size. The study revealed that high levels of Na(+) ions would negatively affect the clarification process the most, as they would reduce the amount of suspended particles trapped by the flocs. A complementary study on prepared WC juice using cold and cold/intermediate liming techniques was conducted. The study demonstrated that, in comparison to the one-stage (i.e., conventional) clarification process, a two-stage clarification process using cold liming removed more polysaccharides (?19%), proteins (?82%), phosphorus (?53%), and SiO2 (?23%) in WC juice but increased Ca(2+) (?136%) and sulfur (?200%). PMID:25574835

Thai, Caroline C D; Moghaddam, Lalehvash; Doherty, William O S

2015-02-11

240

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

PubMed Central

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

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

2010-01-01

241

Molecular mechanism of crystallization impacting calcium phosphate cements  

SciTech Connect

In summary, SPM data has shown that (1) Mg inhibits growth on all steps but relatively high Mg/Ca ratios are needed. Extracting the mechanism of interaction requires more modeling of the kinetic data, but step morphology is consistent with incorporation. (2) Citrate has several effects depending on the citrate/Ca ratio. At the lowest concentrations, citrate increases the step free energy without altering the step kinetics; at higher concentrations, the polar step is slowed. (3) Oxalate also slows the polar step but additionally stabilizes a new facet, with a [100]{sub Cc} step. (4) Etidronate has the greatest kinetic impact of the molecules studied. At 7{micro}M concentrations, the polar step slows by 60% and a new polar step appears. However, at the same time the [10-1]{sub Cc} increases by 67%. It should be noted that all of these molecules complex calcium and can effect kinetics by altering the solution supersaturation or the Ca to HPO{sub 4}{sup 2-} ratio. For the SPM data shown, this effect was corrected for to distinguish the effect of the molecule at the crystal surface from the effect of the molecule on the solution speciation. The goal of this paper is to draw connections between fundamental studies of atomic step motion and potential strategies for materials processing. It is not our intent to promote the utility of SPM for investigating processes in cement dynamics. The conditions are spectacularly different in many ways. The data shown in this paper are fairly close to equilibrium (S=1.6) whereas the nucleation of cements is initiated at supersaturation ratios in the thousands to millions. Of course, after the initial nucleation phase, the growth will occur at more modest supersaturations and as the cement evolves towards equilibrium certainly some of the growth will occur in regimes such as shown here. In addition to the difference in supersaturation, cements tend to have lower additive to calcium ratios. As an example, the additive to Ca ratio is {approx}10{sup -3} to 10{sup -4} for a pyrophosphate based cement (Grover et al., 2006). Where the in situ SPM approach provides unique insights is in providing details of where and how molecules inhibit or accelerate kinetics. This has the potential to aid in designing molecules to target specific steps and to guide synergistic combinations of additives. For example, it is unlikely that bulk techniques could deduce the simultaneous acceleration and inhibition effects of etidronate; or that citrate reduced growth rate by altering step density rather than step speed. In addition, SPM data translates to tractable questions for modelers. The questions changes from 'How does etidronate inhibit brushite growth?' to 'Why does etidronate bind strongly to the [101]{sub Cc} step while it doesn't to the [10-1]{sub Cc} step?' This is still a challenging question but it is far better defined. Given that step chemistries are generally different, it seems reasonable to expect that the greatest inhibition will be achieved not with one, but with several synergistically chosen additives. For example, the most effective growth inhibitors for brushite would target the two fast steps, namely the non-polar, [10-1]{sub Cc} and the polar, [101]{sub Cc} steps. Several molecules have been shown to slow the polar step, with etidronate as the most dramatic example. By contrast, only Mg was observed to slow the [10-1]{sub Cc} step. Thus, a combination of high concentrations of Mg to target the [10-1]{sub Cc} step with low concentrations of etidronate to target the polar steps, should be a more effective combination than either alone. However Mg is not a particularly good inhibitor in the sense that high concentrations are needed, and it is not specific. More ideally, an inhibitor would be designed to interact specifically with the [10-1] step, which would allow the two steps to be independently modified. Again, this provides an opportunity for tighter coupling with theoretical modeling. The question changes from 'What types of molecules will inhibit brushite growth' to 'What type of molecule

Giocondi, J L; El-Dasher, B S; Nancollas, G H; Orme, C A

2009-05-31

242

Cooperation of phosphates and carboxylates controls calcium oxalate crystallization in ultrafiltered urine.  

PubMed

Osteopontin (OPN) is one of a group of proteins found in urine that are believed to limit the formation of kidney stones. In the present study, we investigate the roles of phosphate and carboxylate groups in the OPN-mediated modulation of calcium oxalate (CaOx), the principal mineral phase found in kidney stones. To this end, crystallization was induced by addition of CaOx solution to ultrafiltered human urine containing either human kidney OPN (kOPN; 7 consecutive carboxylates, 8 phosphates) or synthesized peptides corresponding to residues 65-80 (pSHDHMDDDDDDDDDGD; pOPAR) or 220-235 (pSHEpSTEQSDAIDpSAEK; P3) of rat bone OPN. Sequence 65-80 was also synthesized without the phosphate group (OPAR). Effects on calcium oxalate monohydrate (COM) and dihydrate (COD) formation were studied by scanning electron microscopy. We found that controls form large, partly intergrown COM platelets; COD was never observed. Adding any of the polyelectrolytes was sufficient to prevent intergrowth of COM platelets entirely, inhibiting formation of these platelets strongly, and inducing formation of the COD phase. Strongest effects on COM formation were found for pOPAR and OPAR followed by kOPN and then P3, showing that acidity and hydrophilicity are crucial in polyelectrolyte-affected COM crystallization. At higher concentrations, OPAR also inhibited COD formation, while P3, kOPN and, in particular, pOPAR promoted COD, a difference explainable by the variations of carboxylate and phosphate groups present in the molecules. Thus, we conclude that carboxylate groups play a primary role in inhibiting COM formation, but phosphate and carboxylate groups are both important in initiating and promoting COD formation. PMID:21234554

Grohe, Bernd; Chan, Brian P H; Sørensen, Esben S; Lajoie, Gilles; Goldberg, Harvey A; Hunter, Graeme K

2011-10-01

243

Plasma Calcium, Inorganic Phosphate and Magnesium During Hypocalcaemia Induced by a Standardized EDTA Infusion in Cows  

PubMed Central

The intravenous Na2EDTA infusion technique allows effective specific chelation of circulating Ca2+ leading to a progressive hypocalcaemia. Methods previously used were not described in detail and results obtained by monitoring total and free ionic calcium were not comparable due to differences in sampling and analysis. This paper describes a standardized EDTA infusion technique that allowed comparison of the response of calcium, phosphorus and magnesium between 2 groups of experimental cows. The concentration of the Na2EDTA solution was 0.134 mol/l and the flow rate was standardized at 1.2 ml/kg per hour. Involuntary recumbency occurred when ionised calcium dropped to 0.39 – 0.52 mmol/l due to chelation. An initial fast drop of ionized calcium was observed during the first 20 min of infusion followed by a fluctuation leading to a further drop until recumbency. Pre-infusion [Ca2+] between tests does not correlate with the amount of EDTA required to induce involuntary recumbence. Total calcium concentration measured by atomic absorption remained almost constant during the first 100 min of infusion but declined gradually when the infusion was prolonged. The concentration of inorganic phosphate declined gradually in a fluctuating manner until recumbency. Magnesium concentration remained constant during infusion. Such electrolyte responses during infusion were comparable to those in spontaneous milk fever. The standardized infusion technique might be useful in future experimental studies. PMID:11503370

Mellau, LSB; Jørgensen, RJ; Enemark, JMD

2001-01-01

244

Effects of 1,25-dihydroxicolecalciferol and dietary calcium-phosphate on distribution of lead to tissues during growth  

SciTech Connect

The susceptibility to the toxic effects of lead (Pb) is mainly mediated by age and nutritional and hormonal status, and children are among the most vulnerable to them. During growth, an increase in calcium, phosphate and vitamin D in diet is recommended to enhance calcium and phosphate intestinal absorption and bone deposit. Calcium and phosphate reduce lead intestinal absorption, and 1,25-dihydroxicolecalciferol (1,25(OH){sub 2}D{sub 3}) (active metabolite of vitamin D) increases both lead and calcium intestinal absorption. However, the effects of 1,25(OH){sub 2}D{sub 3} on lead bone deposit and redistribution to soft tissues are not well known. In this study, we examined the effects of calcium-phosphate diet supplementation and the administration of 1,25(OH){sub 2}D{sub 3} on Pb distribution to soft tissue and bone in growing rats exposed to Pb. Rats (21 days old) were exposed for 28 days to 100 ppm of Pb solution in drinking water. Calcium and phosphate in diet were increased from 1 to 2.5% and from 0.65 to 1.8%, respectively, and 1,25(OH){sub 2}D{sub 3} was administrated by intraperitoneal injection of 7.2 ng/kg every 7 days. Between 21 and 49 days, the body weight increased about 5 times. The results showed that high calcium-phosphate diet led to lower Pb concentration in blood and in bone, but Pb liver and kidney concentrations increased, which indicates that absorption and bone deposit redistribution of Pb decreased. On the other hand, no effect of this diet rich in calcium-phosphate in Pb concentration was observed in brain. Blood and bone Pb concentrations increased even more when the high calcium-phosphate diet included 1,25(OH){sub 2}D{sub 3}. In the rats treated only with 1,25(OH){sub 2}D{sub 3}, blood and bone Pb concentrations were lower. Higher concentrations of lead in the soft organs were observed also in rats treated under a high calcium-phosphate diet plus 1,25(OH){sub 2}D{sub 3} administration. The above mentioned results suggested that 1,25(OH){sub 2}D{sub 3} induces an increased absorption and redistribution of Pb, and therefore, it may enhance systemic damage in Pb-exposed growing animals.

Cortina-Ramirez, G.E. [Department of Biochemistry, Centro de Investigacion y de Estudios Avanzados del IPN, PO Box 14-740, Mexico City 07000 (Mexico); Cerbon-Solorzano, J. [Department of Biochemistry, Centro de Investigacion y de Estudios Avanzados del IPN, PO Box 14-740, Mexico City 07000 (Mexico); Calderon-Salinas, J.V. [Department of Biochemistry, Centro de Investigacion y de Estudios Avanzados del IPN, PO Box 14-740, Mexico City 07000 (Mexico)]. E-mail: jcalder@cinvestav.mx

2006-01-15

245

Effect of casein phosphopeptide-amorphous calcium phosphate and acidulated phosphate fluoride gel on erosive enamel wear  

PubMed Central

Background: Some studies have shown that casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and acidulated phosphate fluoride (APF) gel can protect teeth against erosion. The aim of this study was to assess whether CPP-ACP and fluoride could reduce enamel wear rates under erosive conditions simulating abrasion and acidic diet regimen. Materials and Methods: Enamel specimens consisted of 3 experimental groups (receiving CPP-ACP, APF or both) and a control group. Specimens were subjected to 5,000 wear cycles at a load of 30 N and a pH of 3 in a tooth wear machine. The amount of wear was determined by stereomicroscope. Data were analyzed using one-way analysis of variance and Tukey post hoc tests (? = 0.05). Results: Mean wear rate (mean±SD) was 194.6±49.2 micrometers in CPP-ACP group, 197.6±39.5 in APF group, 134.6±44.7 in combination group and 266.2± 22.7 in the control group. Statistical analysis indicated significantly higher wear rate in the control group than the experimental groups and also in the CPP-ACP and APF group than the combination group (P<0.05). Conclusions: We concluded that although either CPP-ACP or APF can protect enamel against wear, their combination provides significant enamel wear reduction. These findings would lead to new strategies for the clinical management of tooth wear. PMID:23372598

Tehrani, Maryam HajeNorouz Ali; Ghafournia, Maryam; Samimi, Pouran; Savabi, Omid; Parisay, Iman; Askari, Navid; Abtahi, Seyed-Hossein

2011-01-01

246

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

PubMed Central

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

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

2015-01-01

247

Porous hydroxyapatite and biphasic calcium phosphate ceramics promote ectopic osteoblast differentiation from mesenchymal stem cells  

NASA Astrophysics Data System (ADS)

Because calcium phosphate (Ca-P) ceramics have been used as bone substitutes, it is necessary to investigate what effects the ceramics have on osteoblast maturation. We prepared three types of Ca-P ceramics with different Ca-P ratios, i.e. hydroxyapatite (HA), beta-tricalcium phosphate (?-TCP), and biphasic calcium phosphate (BCP) ceramics with dense-smooth and porous structures. Comprehensive gene expression microarray analysis of mouse osteoblast-like cells cultured on these ceramics revealed that porous Ca-P ceramics considerably affected the gene expression profiles, having a higher potential for osteoblast maturation. In the in vivo study that followed, porous Ca-P ceramics were implanted into rat skeletal muscle. Sixteen weeks after the implantation, more alkaline-phosphatase-positive cells were observed in the pores of hydroxyapatite and BCP, and the expression of the osteocalcin gene (an osteoblast-specific marker) in tissue grown in pores was also higher in hydroxyapatite and BCP than in ?-TCP. In the pores of any Ca-P ceramics, 16 weeks after the implantation, we detected the expressions of marker genes of the early differentiation stage of chondrocytes and the complete differentiation stage of adipocytes, which originate from mesenchymal stem cells, as well as osteoblasts. These marker gene expressions were not observed in the muscle tissue surrounding the implanted Ca-P ceramics. These observations indicate that porous hydroxyapatite and BCP had a greater potential for promoting the differentiation of mesenchymal stem cells into osteoblasts than ?-TCP.

Zhang, Lingli; Hanagata, Nobutaka; Maeda, Megumi; Minowa, Takashi; Ikoma, Toshiyuki; Fan, Hongsong; Zhang, Xingdong

2009-04-01

248

Cytocompatibility evaluation of microwave sintered biphasic calcium phosphate scaffolds synthesized using pH control.  

PubMed

Compounds belonging to the calcium phosphate (CaP) system are known to be major constituents of bone and are bioactive to different extents in vitro and in vivo. Their chemical similarity makes them prime candidates for implants and bone tissue engineering scaffolds. CaP nanoparticles of amorphous hydroxyapatite (aHA) and dicalcium phosphate dihydrate (DCPD) were synthesized using chemical precipitation. Uniaxially pressed aHA and DCPD powders were subjected to microwave radiation to promote solid state phase transformations resulting in crystalline hydroxyapatite (HA), tricalcium phosphate (TCP) and biphasic compositions: HA/TCP and TCP/calcium pyrophosphate (CPP) and their subsequent densification. Phase composition of microwave sintered compacts was confirmed via X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Solution pH during crystal growth was found to have a profound effect on particle morphology and post-sintered phases, despite constant sintering temperature. Cytocompatibility assessment using 7F2 cells, corresponding to adult mouse osteoblasts, on microwave and conventional, furnace sintered samples demonstrated that manufacturing method does not impact cellular viability after 24 h or proliferation over 7 days. New CaP deposition and extracellular matrix components were observed in vitro via scanning electron microscopy (SEM). PMID:23827628

Wagner, Darcy E; Jones, Andrew D; Zhou, Huan; Bhaduri, Sarit B

2013-04-01

249

Biomineralization and Size Control of Stable Calcium Phosphate Core Protein Shell Nanoparticles: Potential for Vaccine Applications  

PubMed Central

Calcium phosphate (CaP) polymorphs are nontoxic, biocompatible and hold promise in applications ranging from hard tissue regeneration to drug delivery and vaccine design. Yet, simple and robust routes for the synthesis of protein-coated CaP nanoparticles in the sub-100 nm size range remain elusive. Here, we used cell surface display to identify disulfide-constrained CaP binding peptides that, when inserted within the active site loop of E. coli Thioredoxin 1 (TrxA), readily and reproducibly drive the production of nanoparticles that are 50–70 nm in hydrodynamic diameter and consist of an approximately 25 nm amorphous calcium phosphate (ACP) core stabilized by the protein shell. Like bone and enamel proteins implicated in biological apatite formation, peptides supporting nanoparticle production were acidic. They also required presentation in a loop for high affinity ACP binding since elimination of the disulfide bridge caused a nearly 3-fold increase in hydrodynamic diameters. When compared to a commercial aluminum phosphate adjuvant, the small core-shell assemblies led to a 3-fold increase in mice anti-TrxA titers three weeks post-injection, suggesting that they might be useful vehicles for adjuvanted antigen delivery to dendritic cells. PMID:22263898

Chiu, David; Zhou, Weibin; Kitayaporn, Sathana; Schwartz, Daniel T.; Murali-Krishna, Kaja; Kavanagh, Terrance J.; Baneyx, François

2012-01-01

250

Preparation of spherical calcium phosphate granulates suitable for the biofunctionalization of active brazed titanium alloy coatings.  

PubMed

Abstract Titanium-based alloys can be actively brazed onto bio-inert ceramics and potentially be used as biocompatible coatings. To further improve their bioactivity in vivo, introduction of calcium phosphate (CaP)-based granulates onto their surface layer is possible. For this, mechanically stable CaP-based granulates need to be able to withstand the demand of the brazing process. In this study, spherical granulates, made of a calcium phosphate composite composed primarily of ?-tricalcium phosphate and hydroxyapatite, a bioactive glass, and a mixture of the previous two, were manufactured by spray drying. The influence of organic additives (Dolapix CE64, trisodium citrate) and solids content (30-80 wt%) in the slurry on the physical characteristics of granulates was investigated. X-ray diffraction, Brunauer, Emmett, Teller specific surface area standard method, scanning electron microscopy, granulate size analysis, and single granule strength were performed. Our results showed that trisodium citrate permitted the production of granulates with regular morphology, high density, and increased failure stress values. The strong granules also withstood the brazing process. These results show that CaP bioactive agents can be generated and be integrated during the demanding metallurgical processes, allowing for one-step bioactivation of metal brazes. PMID:25389977

Schickle, Karolina; Gerardo-Nava, Jose L; Puidokas, Sabrina; Anavar, Sharareh Samadian; Bergmann, Christian; Gingter, Philipp; Schickle, Benjamin; Bobzin, Kirsten; Fischer, Horst

2014-11-01

251

Flow perfusion culture of marrow stromal cells seeded on porous biphasic calcium phosphate ceramics.  

PubMed

Calcium phosphate ceramics have been widely used for filling bone defects to aid in the regeneration of new bone tissue. Addition of osteogenic cells to porous ceramic scaffolds may accelerate the bone repair process. This study demonstrates the feasibility of culturing marrow stromal cells (MSCs) on porous biphasic calcium phosphate ceramic scaffolds in a flow perfusion bioreactor. The flow of medium through the scaffold porosity benefits cell differentiation by enhancing nutrient transport to the scaffold interior and by providing mechanical stimulation to cells in the form of fluid shear. Primary rat MSCs were seeded onto porous ceramic (60% hydroxyapatite, 40% beta-tricalcium phosphate) scaffolds, cultured for up to 16 days in static or flow perfusion conditions, and assessed for osteoblastic differentiation. Cells were distributed throughout the entire scaffold by 16 days of flow perfusion culture whereas they were located only along the scaffold perimeter in static culture. At all culture times, flow perfused constructs demonstrated greater osteoblastic differentiation than statically cultured constructs as evidenced by alkaline phosphatase activity, osteopontin secretion into the culture medium, and histological evaluation. These results demonstrate the feasibility and benefit of culturing cell/ceramic constructs in a flow perfusion bioreactor for bone tissue engineering applications. PMID:16133930

Holtorf, Heidi L; Sheffield, Tiffany L; Ambrose, Catherine G; Jansen, John A; Mikos, Antonios G

2005-09-01

252

Microencapsulated rBMMSCs/calcium phosphate cement for bone formation in vivo.  

PubMed

As an injectable scaffold material for bone tissue engineering, calcium phosphate cement (CPC) has good biocompatibility, self-setting, and osteoconduction properties. Alginate-microencapsulated seed cells can pick up the degradation speed and bioactivity of CPC. The aim of this study was to explore the osteogenic ability of a composite of microencapsulated rabbit bone marrow mesenchymal stem cells (rBMMSCs) with ?-tricalcium phosphate/calcium phosphate cement (?-TCP/CPC) in vivo. Cavity defects were created in both femoral condylar regions of New Zealand White rabbits. ?-TCP/CPC (control group) and alginate microencapsulated rBMMSCs/?-TCP/CPC composite (composite group) were implanted separately into the bone defects of both femurs. Bone substitute degradation and new bone formation were evaluated by CBCT, and the defects were examined histologically 8, 16, and 24 weeks after implantation. In addition, fluorescent carbocyanine CM-Dil was used to track the rBMMSCs in vivo after implantation. The results showed that far more new bone and bone marrow grew into the bone defects in the composite group. Few CM-Dil labeled positive cells were observed postoperatively. However more native cells were detected in the graft areas of the composite group than those of the control group. The study indicates that a composite of microencapsulated seed cells/?-TCP/CPC might be considered as a promising injectable material for the generation of new bone tissue. PMID:24211970

Wang, Juan; Qiao, Pengyan; Dong, Limin; Li, Fangfang; Xu, Tao; Xie, Qiufei

2014-01-01

253

Silicon calcium phosphate ceramic as novel biomaterial to simulate the bone regenerative properties of autologous bone.  

PubMed

This study was conducted to develop novel ceramic bone substitute that resembles the autologous bone behavior when used as graft material. Solid-state reaction at 1100°C was performed to synthesize ?-tricalcium phosphate (?-TCP) and biphasic calcium phosphate (BCP). The ceramics were further analyzed to characterize phase composition, microstructural properties, cytocompatability and then challenged to regenerate critical bone defects in the parietal bone of rabbits. X-ray diffraction analysis confirmed the production of ?-TCP and indicated the synthesis of novel BCP composed of ?-TCP and silicocarnotite (calcium phosphate silicate mineral). The cytocompatibility test with human osteoblast cell line revealed enhanced cell proliferation on the BCP ceramic. The novel BCP induced the filling of about 73% of the bone defect with a newly formed bone tissue and an almost complete degradation after 12 weeks of healing. This novel ceramic resembles the autologous bone properties of complete degradation and efficient enhancement of bone formation, making it promising as bone graft material. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2014. PMID:24737706

Manchón, A; Alkhraisat, M; Rueda-Rodriguez, C; Torres, J; Prados-Frutos, J C; Ewald, A; Gbureck, U; Cabrejos-Azama, J; Rodriguez-González, A; López-Cabarcos, E

2014-04-15

254

Calcium phosphate-based particles influence osteogenic maturation of human mesenchymal stem cells.  

PubMed

Biphasic calcium phosphates (BCPs) consist of a mixture of hydroxyapatite and beta-tricalcium phosphate and are recommended as alternatives or additives to autogenous bone for orthopaedic and dental applications. There is clinical evidence showing particle release from bioceramics, which might impair the ability of human mesenchymal stem cells (hMSC) from bone marrow to proliferate or mature into a functional osteoblast phenotype. This study analyses the influence of BCP particles and their precursors, calcium-deficient apatite (CDA) particles, on in vitro hMSC behaviour. Both types of particles were efficiently internalized by hMSC. Cell viability, morphology and actin cytoskeleton reorganization were unaffected by exposure of hMSC to BCP or CDA particles. Direct exposure to BCP particles impaired hMSC osteogenic differentiation and bone matrix mineralization to a lesser extent than CDA, as assayed by evaluation of alkaline phosphatase activity, osteopontin secretion and mineralized nodule formation. The ability of bioceramic particles to affect osteogenic maturation through modification of soluble factors in media was assayed in an in vitro system that avoids direct cell-particle contact. Indirect exposure to CDA particles severely impaired hMSC osteogenic maturation owing to the uptake of Ca2+ from the culture media. Lower textural properties of BCP and the lack of calcium deficiency in its composition prevented Ca2+ uptake, allowing the development of a functional osteoblast phenotype. PMID:19114315

Saldaña, L; Sánchez-Salcedo, S; Izquierdo-Barba, I; Bensiamar, F; Munuera, L; Vallet-Regí, M; Vilaboa, N

2009-05-01

255

Influence of the use of phosphate binders on serum levels of calcium phosphate in patients with chronic kidney disease undergoing hemodialysis: A retrospective and prospective study  

PubMed Central

Hypercalcemia–hyperphosphatemia is an unavoidable consequence of end-stage chronic kidney disease and common in hemodialytic patients. Calcium carbonate (CaCO3) is one type of phosphate binder used widely and prescribed in patients undergoing hemodialysis, aiming to control the levels of calcium and phosphate. These drugs are most effective if taken with meals. This study aimed to evaluate the use of phosphate binders in hemodialysis patients and the factors that influence the success of phosphate binder therapy by experimental studies with retrospective data collection through the medical records and prospectively through the questionnaire and interviews with patients. The research was conducted in the Unit Hemodialysis building floor 8 of Cipto Mangunkusumo Hospital, Jakarta. The data were collected in a retrospective way for two months (January–February 2013) and a prospective study in March–April 2013. Patients included were stage 5 chronic kidney disease patients who underwent hemodialysis in hemodialysis ward of Cipto Mangunkusumo Hospital. Patients who had data of serum levels at the beginning of the use of calcium phosphate and the final data in 2013 got the phosphate binder therapy. Results Ninety six patients with stage 5 chronic kidney disease who underwent hemodialysis had been using phosphate binder for 3 years in average. Patient evaluation showed that hypocalcemia was obtained in 23%; normokalemia in 42.7% and hypercalcemia in 34.3%. While the percentage of patients with hipofosfatemia14, 6%, normofosfatemia 32.3% and 53.1% hyperphosphatemia. Results obtained by the prospective analysis of factors that affect the success of the use of phosphate binder therapy are related to how the routine use of phosphate binders is made by the patient. Chi square test showed a significance of 0.000 (p < 0.05), the effect of 54%. Conclusion We can conclude there are many events happening such as hyperphosphatemia in hemodialysis patients that use phosphate binders. Monitoring of serum levels of calcium phosphate in patients with chronic kidney disease undergoing hemodialysis should be performed every month. Education and the role of clinical staff required to assist compliance and therapeutic efficacy of phosphate binder are necessary. PMID:25161377

Setiani Agus, Lusi; Effendi, Imam; Abdillah, Syamsudin

2013-01-01

256

[Discovery of alpha-Klotho and FGF23 unveiled new insight into calcium and phosphate homeostasis].  

PubMed

Recent advances that have given rise to marked progress in clarifying actions of alpha-Klotho (alpha-Kl) and FGf23 can be summarized as follows ; (i) alpha-Kl binds to Na(+), K(+)-ATPase, and Na(+), K(+)-ATPase is recruited to the plasma membrane by a novelalpha-Kl dependent pathway in correlation with cleavage and secretion ofalpha-Kl in response to extracellular Ca(2+) fluctuation. (ii) The increased Na(+) gradient created by Na(+), K(+)-ATPase activity drives the transepithelial transport of Ca(2+) in the choroid plexus and the kidney, this is defective in alpha-kl(-/-) mice. (iii) The regulated PTH secretion in the parathyroid glands is triggered via recruitment of Na(+), K(+)-ATPase to the cell surface in response to extracellular Ca(2+) concentrations. (iv) alpha-Kl, in combination with FGF23, regulates the production of 1,25 (OH) (2)D in the kidney. In this pathway, alpha-Kl binds to FGF23, andalpha-Kl converts the canonical FGF receptor 1c to a specific receptor for FGF23, enabling the high affinity binding of FGF23 to the cell surface of the distal convoluted tubule where alpha-Kl is expressed. (v) FGF23 signal down-regulates serum phosphate levels, due to decreased NaPi-IIa abundance in the apical membrane of the kidney proximal tubule cells. (vi) alpha-Kl in urine increases TRPV5 channel abundance at the luminal cell surface by hydrolyzing the N-linked extracellular sugar residues of TRPV5, resulting in increased Ca(2+) influx from the lumen. These findings revealed a comprehensive regulatory scheme of mineral homeostasis that is illustrated by the mutually regulated positive/negative feedback actions of alpha-Kl, FGF23, PTH and 1,25 (OH) (2)D. In this regard, alpha-Kl and FGF23 might play pivotal roles in mineral metabolism as regulators that integrate calcium and phosphate homeostasis, although this concept requires further verification in the light of related findings. Here, the unveiling of the molecular functions of alpha-Klotho and FGF23 has recently given new insight into the field of calcium and phosphate homeostasis. Unveiled molecular functions of alpha-Kl and FGF23 provided answers for several important questions regarding the mechanisms of calcium and phosphate homeostasis that remained to be solved, such as : (i) what is the non-hormonal regulatory system that directly responds to the fluctuation of extracellular Ca(2+), (ii) how is Na(+), K(+)-ATPase activity enhanced in response to low calcium stimuli in the parathyroid glands, (iii) what is the exact role of FGF23 in calcium and phosphorus metabolism, (iv) how is Ca(2+) influx through TRPV5 controlled in the DCT nephron, and finally (v) how is calcium homeostasis regulated in cerebrospinal fluid. However, several critical questions still remain to be solved. So far reported,alpha-Kl binds to Na(+), K(+)-ATPase, FGF receptors and FGF23, and alpha-Kl hydrolyzes the sugar moieties of TRPV5. Does alpha-Kl recognize these proteins directly or indirectly?Is there any common mechanism?How can we reconcile such diverse functions of alpha-Kl?What is the Ca(2+) sensor machinery and how can we isolate it?How do hypervitaminosis D and the subsequently altered mineral-ion balance lead to the multiple phenotypes?What is the phosphate sensor machinery and how can we isolate it? How does the Fgf23/alpha-Kl system regulate phosphorus homeostasis?How are serum concentrations of Ca(2 + ) and phosphate mutually regulated? PMID:18591743

Nabeshima, Yo-ichi

2008-07-01

257

Calcification mechanism and bony bonding studies of calcium carbonate and composite aluminosilicate\\/calcium phosphate applied as biomaterials by using radioactivation methods  

Microsoft Academic Search

Bony grafts are used as a filling biomaterial for defective bone. The introduction of new range of synthetic materials offers\\u000a to surgeons additional possibilities to avoid virus transmission risks by using natural grafts in bony surgery. In this work,\\u000a two materials, synthetic calcium carbonate and composite aluminosilicate\\/calcium phosphate were synthesized by an original\\u000a method and experimented “in vivo” as biomaterials

H. Oudadesse; A. C. Derrien; A. Lucas-Girot; S. Martin; G. Cathelieau

2007-01-01

258

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

PubMed

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

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

2014-01-01

259

MICROINCINERATION, ELECTRON MICROSCOPY, AND ELECTRON DIFFRACTION OF CALCIUM PHOSPHATE-LOADED MITOCHONDRIA  

PubMed Central

Isolated rat liver mitochondria were incubated in vitro under conditions supporting the massive accumulation of calcium and phosphate. Samples were embedded, thin sectioned, and examined in the electron microscope. The intramitochondrial distribution of insoluble or structure-bound mineral substances was studied by electron microscopy coupled with recently developed techniques of high resolution microincineration. As shown previously, the ion-loaded mitochondria acquire large, internal granules which have inherent electron opacity indicative of high mineral content. Study of ash patterns in preselected areas of sections directly confirmed the high mineral content of the granules, and the appearance of the residues was consistent with the copresence in the granules of some organic material. Other mitochondrial structures were almost devoid of mineral. Thin sections of unincubated control mitochondria also were incinerated. They were found to contain appreciable amounts of intrinsic mineral, seemingly associated with membranes. The normal, dense matrix granules commonly seen in unaltered mitochondria could be seen in intact sections of these control preparations, but after burning no definite correspondence of any ash to the granules could be demonstrated. The normal granules perhaps do not contain mineral. Heating experiments on ash patterns of all the preparations demonstrated the thermal stability and crystallizability of the ash. The crystallized ash of the in vitro-produced dense granules was tentatively shown by electron diffraction to be ?-tricalcium phosphate (whitlockite). This, together with evidence from the literature, suggests that the original, noncrystalline mineral may be a colloidal, subcrystalline precursor of calcium-deficient hydroxyapatite. Experiments were performed on synthetic calcium phosphates for comparison. Other possible applications of the microincineration techniques are briefly discussed. PMID:4878171

Thomas, Richard S.; Greenawalt, John W.

1968-01-01

260

The Properties of Sintered Calcium Phosphate with [Ca]/[P] = 1.50  

PubMed Central

In order to obtain the properties of the sintered as-dried calcium phosphate with [Ca]/[P] = 1.50, the characteristics of sintered pellets have been investigated using X-ray diffraction (XRD), inductively coupled plasma-mass spectrometry (ICP-MS), Fourier-transform infrared (FT-IR) spectra, Vickers hardness indentation and scanning electron microscopy (SEM). When the pellet samples were sintered between 700 °C and 1200 °C for 4 h, the hydroxyapatite (Ca10(PO4)6(OH)2, HA) still maintained the major phase, accompanied with the rhenanite (NaCaPO4) as the secondary phase and ?-tricalcium phosphate (?-Ca3(PO4)2, ?-TCP) as the minor phases. In addition, the HA partially transformed to ?-tricalcium phosphate (?-Ca3(PO4)2, ?-TCP) and tetracalcium phosphate (Ca4(PO4)2O, TTCP), when the pellet samples were sintered at 1300 °C and 1400 °C, respectively, for 4 h. The maximum density and Vickers Hardness (HV) of sintered pellet samples were 2.85 g/cm3 (90.18% theoretical density (T.D.)) and 407, which appeared at 1200 °C and 900 °C, respectively. PMID:23202968

Hung, I-Ming; Shih, Wei-Jen; Hon, Min-Hsiung; Wang, Moo-Chin

2012-01-01

261

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

E-print Network

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...

Chang, Joshua C

2015-01-01

262

Bioactivity and Surface Reactivity of RF-sputtered Calcium Phosphate Thin Films  

Microsoft Academic Search

Calcium phosphates (CaP) are known to be bioactive, i.e. able to bond\\u000ato bone. This makes CaPs very suitable to be aplied as thin coatings\\u000aon bone-implants. In this work we studied the physicochemical\\u000abehaviour of CaP coatings applied with radio frequency (RF) magnetron\\u000asputtering, a deposition technique that can produce thin (~100 nm),\\u000ahomogeneous, and well-adhereing coatings. As-deposited CaP

Edwin van der Wal

2003-01-01

263

Microstructure of yttric calcium phosphate bioceramic coatings synthesized by laser cladding  

NASA Astrophysics Data System (ADS)

The yttric calcium phosphate (CaP) coatings were in situ prepared on pure titanium substrate by laser cladding. The morphologies and phases constitution of CaP coatings were studied by electron probe microanalysis, X-ray diffraction and so on. The bonding state between the coating and the substrate is fine metallurgical combination, and the addition of yttria can fine the structure and increase the tensile strength of the coatings. The X-ray result shows that the coating is composed of the phases of HA, ?-Ca 2P 2O 7, ?-Ca 2P 2O 7 and CaTiO 3.

Wang, Diangang; Chen, Chuanzhong; Ma, Jie; Lei, Tingquan

2007-02-01

264

VS-501: a novel, nonabsorbed, calcium- and aluminum-free, highly effective phosphate binder derived from natural plant polymer  

PubMed Central

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 (GI) discomfort. VS-501 is a nonabsorbed, 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 fibroblast growth factor-23 and parathyroid hormone in 5/6 NX rats that 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 GI side effects. PMID:25197556

Wu-Wong, J Ruth; Chen, Yung-wu; Gaffin, Robert; Hall, Andy; Wong, Jonathan T; Xiong, Joseph; Wessale, Jerry L

2014-01-01

265

Effects of phosphates on microstructure and bioactivity of micro-arc oxidized calcium phosphate coatings on Mg-Zn-Zr magnesium alloy.  

PubMed

Calcium phosphate (CaP) coatings were prepared on Mg-Zn-Zr magnesium alloy by micro-arc oxidation (MAO) in electrolyte containing calcium acetate monohydrate (CH3COO)2Ca·H2O) and different phosphates (i.e. disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O), sodium phosphate (Na3PO4·H2O) and sodium hexametaphosphate((NaPO3)6)). Scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray diffractometer (XRD) were employed to characterize the microstructure, elemental distribution and phase composition of the CaP coatings. Simulated body fluid (SBF) immersion test was used to evaluate the coating bioactivity and degradability. Systemic toxicity test was used to evaluate the coating biocompatibility. Fluoride ion selective electrode (ISE) was used to measure F(-) ions concentration during 30 days SBF immersion. The CaP coatings effectively reduced the corrosion rate and the surfaces of CaP coatings were covered by a new layer formed of numerous needle-like and scale-like apatites. The formation of these calcium phosphate apatites indicates that the coatings have excellent bioactivity. The coatings formed in (NaPO3)6-containging electrolyte exhibit thicker thickness, higher adhesive strength, slower degradation rate, better apatite-inducing ability and biocompatibility. PMID:23603036

Pan, Y K; Chen, C Z; Wang, D G; Zhao, T G

2013-09-01

266

Evaluating mechanical adhesion of sol-gel titanium dioxide coatings containing calcium phosphate for metal implant application.  

PubMed

The adhesion of thin (< 10 microm) sol-gel calcium phosphate-titanium dioxide films bonded to a titanium substrate was studied using two different tests: a rotating-bending test and a tensile bond test. The former evaluates the impact of both the coating procedure and the surface pre-treatment on the resistance to fatigue of the substrate as well as the adhesion of the coating; the latter measures the tensile adhesion strength of the coating. Both tests gave similar results. A reduction of the thickness of the coating or an increase of the roughness of the substrate improves the quality of the interface. A comparison of the adhesion of the calcium phosphate-titanium dioxide film with that of a pure calcium phosphate coating obtained by a similar route suggests the involvement of a chemical component in the binding. PMID:10985493

Piveteau, L D; Gasser, B; Schlapbach, L

2000-11-01

267

Structural, morphological and surface characteristics of two types of octacalcium phosphate-derived fluoride-containing apatitic calcium phosphates.  

PubMed

Octacalcium phosphate (OCP) has been reported to stimulate bone regeneration during hydrolysis into hydroxyapatite (HA). The present study was designed to characterize structural, morphological and surface properties of fluoride-containing apatitic calcium phosphates (CaP) obtained through OCP hydrolysis or direct precipitation of OCP in the presence of 12-230ppm of fluoride (F). The products were characterized by chemical analysis, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Fourier transform infrared spectroscopy (FTIR) as well as measurements of surface area, solubility, osteoblastic activities and bovine serum albumin (BSA) adsorption. XRD analysis re-confirmed that both preparations yielded more apatitic CaP with a higher concentration of F. However, the co-precipitated products (CF-CaP) maintained the properties of OCP, in particular the solubility, whereas the hydrolysis products (HF-CaP) had the characteristics of fluoridated apatite. The crystals of plate-like OCP were changed to the crystals of rod-like CF-CaP and small irregular HF-CaP with the advance of the hydrolysis. The SAED analysis detected both OCP and apatite crystals even in the most hydrolyzed CF-CaP. Mouse bone marrow stromal ST-2 cells grew better on CF-CaP compared with HF-CaP. BSA adsorption was inhibited on HF-CaP more than on CF-CaP. These results show that OCP produces physicochemically distinct apatitic fluoridated CaP during hydrolysis, regarding the structure, the crystal morphology and the protein adsorption, depending on the fluoride introduction route, which provides biologically interesting material. PMID:22868193

Shiwaku, Y; Anada, T; Yamazaki, H; Honda, Y; Morimoto, S; Sasaki, K; Suzuki, O

2012-12-01

268

Multifunctional calcium phosphate nanoparticles for combining near-infrared fluorescence imaging and photodynamic therapy.  

PubMed

Photodynamic therapy (PDT) of tumors causes skin photosensitivity as a result of unspecific accumulation behavior of the photosensitizers. PDT of tumors was improved by calcium phosphate nanoparticles conjugated with (i) Temoporfin as a photosensitizer, (ii) the RGDfK peptide for favored tumor targeting and (iii) the fluorescent dye molecule DY682-NHS for enabling near-infrared fluorescence (NIRF) optical imaging in vivo. The nanoparticles were characterized with regard to size, spectroscopic properties and uptake into CAL-27 cells. The nanoparticles had a hydrodynamic diameter of approximately 200nm and a zeta potential of around +22mV. Their biodistribution at 24h after injection was investigated via NIRF optical imaging. After treating tumor-bearing CAL-27 mice with nanoparticle-PDT, the therapeutic efficacy was assessed by a fluorescent DY-734-annexin V probe at 2days and 2weeks after treatment to detect apoptosis. Additionally, the contrast agent IRDye® 800CW RGD was used to assess tumor vascularization (up to 4weeks after PDT). After nanoparticle-PDT in mice, apoptosis in the tumor was detected after 2days. Decreases in tumor vascularization and tumor volume were detected in the next few days. Calcium phosphate nanoparticles can be used as multifunctional tools for NIRF optical imaging, PDT and tumor targeting as they exhibited a high therapeutic efficacy, being capable of inducing apoptosis and destroying tumor vascularization. PMID:25529187

Haedicke, Katja; Kozlova, Diana; Gräfe, Susanna; Teichgräber, Ulf; Epple, Matthias; Hilger, Ingrid

2015-03-01

269

Association of calcium and phosphate ions with collagen in the mineralization of vertebrate tissues.  

PubMed

Among the vertebrate species, collagen is the most abundant protein and is associated with mineralization of their skeleton and dentition in all tissues except enamel. In such tissues, bones, calcifying tendon, dentin, and cementum are comprised principally of type I collagen, which has been proposed as a template for apatite mineral formation. Recent considerations of the interaction between type I collagen and calcium and phosphate ions as the major constituents of apatite have suggested that collagen polypeptide stereochemistry underlies binding of these ions at sites within collagen hole and overlap regions and leads to nucleation of crystals. The concept is fundamental to understanding both normal and abnormal mineralization, and it is reviewed in this article. Given this background, avenues for additional research studies in vertebrate mineralization will also be described. The latter include, for instance, how mineralization events subsequent to nucleation, that is, crystal growth and development, occur and whether they, too, are directed by collagen stereochemical parameters; whether mineralization can be expected in all spaces between collagen molecules; whether the side chains of charged amino acid residues actually point toward and into the hole and overlap collagen spaces to provide putative binding sites for calcium and phosphate ions; and what phenomena may be responsible for mineralization beyond hole and overlap zones and into extracellular tissue regions between collagen structural units. These questions will be discussed to provide a broader understanding of collagen contributions to potential mechanisms of vertebrate mineralization. PMID:23543143

Landis, William J; Jacquet, Robin

2013-10-01

270

Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications.  

PubMed

A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6-12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration. PMID:24411353

Yang, Guangyong; Liu, Jianli; Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue; Xu, Huazi; Huang, Qing

2014-02-01

271

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

SciTech Connect

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.

Orme, C A; Giocondi, J L

2006-07-29

272

P-RoC- Phosphorus Recovery from Wastewater by Crystallisation of Calcium Phosphate Compounds  

E-print Network

The P-RoC process – the phosphorus recovery straight from the aqueous phase by crystallisation of calcium phosphate – was developed in order to simultaneously remove and recover phosphorus from municipal waste- and industrial process waters by applying calcium silicate hydrate (CSH) compounds or synthesised tobermorite pellets as crystallisation seed materials. At first, the experiments were performed in fixed bed reactors in laboratory- and in pilot scale. In continuation stirred reactor technique was developed and optimised in order to reduce operation and maintenance efforts of the process. Apart from the composition and grain size of the seed materials and the hydraulic retention time (HRT) in the reactor, the efficiency and longevity of the P-RoC process was mainly controlled by the initial P concentration of the wastewater. P-RoC proved to be feasible to treat also highly DOC- and P-enriched process waters. Total P (P-tot) contents in the generated crystallisation products of at least 10-11 % P-tot were achieved in long-term fixed bed experiments, which was promising for the substitution of natural phosphate rock in the phosphorus industry. Mineralogical investigations (FTIR-ATR, XRD) proved the formation of hydroxy-apatite-(HAP) like coatings onto the surface of the seed materials using municipal wastewater.

unknown authors

273

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

PubMed

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

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

274

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

PubMed

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. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1001-1010, 2015. PMID:24889783

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

2015-03-01

275

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

PubMed Central

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.

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

2015-01-01

276

Remineralization of early enamel lesions using casein phosphopeptide amorphous calcium Phosphate: An ex-vivo study  

PubMed Central

Objective: This study aimed at qualitatively evaluating the remineralization potential of casein phosphopeptide amorphous calcium phosphate on artificial early enamel lesions in an ex-vivo scenario by observing the treated tooth surface using a scanning electron microscope (SEM). Materials and Methods: This randomized study was conducted on 10 subjects undergoing orthodontic treatment with premolar extraction as part of their treatment. Artificial white lesions were created with the application of 37% phosphoric acid for 20 mins. Teeth were then divided into two groups: one experimental and the other control. Customised orthodontic band with a window was luted with intermediate restorative material in the experimental group whereas in the control group, band without a window was luted. The casein phosphopeptide amorphous calcium phosphate (GC TOOTH MOUSSE) paste was then applied on the window region of the experimental group for 3 mins thrice daily after meals for 14 days, whereas no paste was applied in the control group. After 14 days, teeth were extracted and viewed under an SEM. Results: The study groups showed remineralization of the lesions as compared with the control group in most of the samples. Conclusion: Casein phophopeptide could significantly remineralize the artificial enamel lesions in vivo. PMID:22114422

Vashisht, Ruchi; Kumar, Anil; Indira, R.; Srinivasan, M.R.; Ramachandran, S.

2010-01-01

277

Morphological modifications of electrodeposited calcium phosphate coatings under amino acids effect  

NASA Astrophysics Data System (ADS)

Calcium phosphate coatings are synthesized on titanium alloy (Ti6Al4V) substrates by pulsed electrodeposition. This work aims to observe the morphological modifications of the coating when an amino acid is added to the electrolytic solution used in the process. The effects of two amino acids (glutamic acid and aspartic acid) are studied at a low and a high concentration. The coating morphology is observed at a nanometer scale by field emission gun-scanning electron microscopy (FEG-SEM). The structural characterization of the coating is performed by Fourier transformed infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray diffraction (XRD). Moreover, corrosion measurements of the prosthetic surfaces are carried out by potentiodynamic polarization experiments in a physiological solution named Dulbecco's modified eagle medium (DMEM). The results show that the addition of an amino acid to the electrolytic solution leads to the decrease of the size of the crystallites which compose the prosthetic calcium phosphate coating that becomes denser and less porous than the coatings obtained without amino acid. Consequently, the corrosion behavior of the prosthetic material immersed in DMEM is improved.

Drevet, R.; Lemelle, A.; Untereiner, V.; Manfait, M.; Sockalingum, G. D.; Benhayoune, H.

2013-03-01

278

Calcium phosphate/octadecyl-quatemized carboxymethyl chitosan nanoparticles: an efficient and promising carrier for gene transfection.  

PubMed

Calcium phosphate (CaP) has been widely used as the vector for gene transfection in the past three decades. However, clinical application is still not popular due to the poor-controlling of DNA/CaP complexes preparation, cytotoxicity and its low transfection efficiency. In this study, a novel amphipathic octadecyl-quatemized carboxymethyl chitosan (OQCMC) derivative from chitosan was combined with calcium phosphate to synthesize CaP/OQCMC nanoparticles (CaP/OQCMC NPs). The nanoparticles were 122-177 nm in diameter exhibited neutral zeta potential (from -0.115 mV to 0.216 mV), and they were applied as DNA vectors for DNA loading and in vitro transfection. The results showed that CaP/OQCMC NPs displayed high DNA loading capacity and enhanced transfection efficiency with extremely low cytotoxicity. In addition, both CaP and OQCMC are biocompatible and biodegradable, thus the as-prepared CaP/OQCMC NPs are promising in gene delivery. PMID:23882752

Sun, Ying; Li, Xiaoyu; Liang, Xiaofei; Wan, Zhiyong; Duan, Yourong

2013-08-01

279

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

PubMed

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

Dingerkus, G; Séret, B; Guilbert, E

1991-01-15

280

Lysophosphatidic acid induces inositol phosphate and calcium signals in exocrine cells from the avian nasal salt gland  

Microsoft Academic Search

We tested lysophosphatidic acid (LPA), known to induce inositol phosphate generation and calcium signals as well as rearrangements of the cytoskeleton and mitogenic responses in fibroblasts, for its ability to activate phospholipase C in an exocrine cell system, the salt-secreting cells from the avian nasal salt gland. LPA (>10 nmol\\/l) caused the generation of inositol phosphates from membrane-bound phosphatidylinositides. The

J.-P. Hildebrandt

1995-01-01

281

Bio-inspired Resorbable Calcium Phosphate-Polymer Nanocomposites for Bone Healing Devices with Controlled Drug Release  

Microsoft Academic Search

\\u000a In orthopedic research, increasing attention is being paid to bioresorbable composite materials as an attractive alternative\\u000a to permanent metal bone healing devices. Typical composites consist of a biodegradable polyester matrix loaded with bioactive\\u000a calcium phosphate ceramic particles (tricalcium phosphate, TCP or hydroxyapatite, HA) added to improve the biological response\\u000a and mechanical properties of the neat polymer. The mechanical behavior of

Irena Gotman; Sabine Fuchs

282

Hierarchically microporous/macroporous scaffold of magnesium-calcium phosphate for bone tissue regeneration.  

PubMed

Hierarchically 3D microporous/macroporous magnesium-calcium phosphate (micro/ma-MCP) scaffolds containing magnesium ammonium phosphate hexahydrate [NH(4)MgPO(4).6H(2)O] and hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)] were fabricated from cement utilizing leaching method in the presence of sodium chloride (NaCl) particles and NaCl saturated water solution. NaCl particles produced macroporosity, and NaCl solution acted as both cement liquid and porogens, inducing the formation of microporosity. The micro/ma-MCP scaffolds with porosities varied from 52 to 78% showed well interconnected and open macropores with the sizes of 400-500 microm, and degradation of the scaffolds was significantly enhanced in Tris-HCl solution compared with macroporous MCP (ma-MCP) and corresponding calcium phosphate cement (CPC) scaffolds. Cell attachment and proliferation of MG(63) on micro/ma-MCP were significantly better than ma-MCP and CPC scaffolds because of the presence of microporosity, which enhanced the surface area of the scaffolds. Moreover, the alkaline phosphatase (ALP) activity of the MG(63) cells on micro/ma-MCP was significantly higher than ma-MCP and CPC scaffolds at 7 days, and the MG(63) cells with normal phenotype spread well and formed confluent layers across the macroporous walls of the micro/ma-MCP scaffolds. Histological evaluation confirmed that the micro/ma-MCP scaffolds improved the efficiency of new bone regeneration, and exhibited excellent biocompatibility, biodegradability and faster and more effective osteogenesis in vivo. PMID:19931903

Wei, Jie; Jia, Junfeng; Wu, Fan; Wei, Shicheng; Zhou, Huanjun; Zhang, Hongbo; Shin, Jung-Woog; Liu, Changsheng

2010-02-01

283

Long-chain base phosphates modulate pollen tube growth via channel-mediated influx of calcium.  

PubMed

Long-chain base phosphates (LCBPs) have been correlated with amounts of crucial biological processes ranging from cell proliferation to apoptosis in animals. However, their functions in plants remain largely unknown. Here, we report that LCBPs, sphingosine-1-phosphate (S1P) and phytosphingosine-1-phosphate (Phyto-S1P), modulate pollen tube growth in a concentration-dependent bi-phasic manner. The pollen tube growth in the stylar transmitting tissue was promoted by SPHK1 overexpression (SPHK1-OE) but dampened by SPHK1 knockdown (SPHK1-KD) compared with wild-type of Arabidopsis; however, there was no detectable effect on in vitro pollen tube growth caused by misexpression of SPHK1. Interestingly, exogenous S1P or Phyto-S1P applications could increase the pollen tube growth rate in SPHK1-OE, SPHK1-KD and wild-type of Arabidopsis. Calcium ion (Ca(2+) )-imaging analysis showed that S1P triggered a remarkable increase in cytosolic Ca(2+) concentration in pollen. Extracellular S1P induced hyperpolarization-activated Ca(2+) currents in the pollen plasma membrane, and the Ca(2+) current activation was mediated by heterotrimeric G proteins. Moreover, the S1P-induced increase of cytosolic free Ca(2+) inhibited the influx of potassium ions in pollen tubes. Our findings suggest that LCBPs functions in a signaling cascade that facilitates Ca(2+) influx and modulates pollen tube growth. PMID:24905418

Wu, Juyou; Qin, Xiaoya; Tao, Shutian; Jiang, Xueting; Liang, Yun-Kuan; Zhang, Shaoling

2014-08-01

284

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

PubMed

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

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

2011-09-01

285

A New Type of Biphasic Calcium Phosphate Cement as a Gentamicin Carrier for Osteomyelitis  

PubMed Central

Osteomyelitis therapy is a long-term and inconvenient procedure for a patient. Antibiotic-loaded bone cements are both a complementary and alternative treatment option to intravenous antibiotic therapy for the treatment of osteomyelitis. In the current study, the biphasic calcium phosphate cement (CPC), called ?-TCP/HAP (?-tricalcium phosphate/hydroxyapatite) biphasic cement, was prepared as an antibiotics carrier for osteomyelitis. The developed biphasic cement with a microstructure of ?-TCP surrounding the HAP has a fast setting time which will fulfill the clinical demand. The X-ray diffraction and Fourier transform infrared spectrometry analyses showed the final phase to be HAP, the basic bone mineral, after setting for a period of time. Scanning electron microscopy revealed a porous structure with particle sizes of a few micrometers. The addition of gentamicin in ?-TCP/HAP would delay the transition of ?-TCP but would not change the final-phase HAP. The gentamicin-loaded ?-TCP/HAP supplies high doses of the antibiotic during the initial 24 hours when they are soaked in phosphate buffer solution (PBS). Thereafter, a slower drug release is produced, supplying minimum inhibitory concentration until the end of the experiment (30 days). Studies of growth inhibition of Staphylococcus aureus and Pseudomonas aeruginosa in culture indicated that gentamicin released after 30 days from ?-TCP/HAP biphasic cement retained antibacterial activity. PMID:23662153

Chen, Yu-Chun; Lin, Feng-Huei

2013-01-01

286

The modulation of osteogenesis in vitro by calcium titanium phosphate coatings.  

PubMed

Calcium phosphate coated titanium and titanium alloy are widely used as dental and orthopaedic implants. This study examines the effect of novel calcium titanium and calcium titanium zirconium phosphates suitable for plasma-spraying onto titanium substrata on the expression of bone-related genes and proteins by human bone-derived cells (HBDC) and compares this behavior to that on native titanium and hydroxyapatite-coated titanium. Test materials were an acid etched and sand-blasted titanium surface (Ti-DPS), a plasma-sprayed hydroxyapatite coating (HA), and five materials which were created from CaTi(4)(PO(4))(6) (CTP) and CaZr(4)(PO(4))(6) (CZP): sintered CaTi(4)(PO(4))(6) (CTP-S1), sintered 46CaO.23TiO(2).31P(2)O(5) (CTP-S2), sintered CaTiZr(3)(PO(4))(6), (CTZP-S1), sintered 46CaO.23ZrO(2).31P(2)O(5) (CTZP-S2) and sintered 55CaO.20TiO(2).31P(2)O(5) (CTP-S3). HBDC were grown on the substrata for 3, 7, 14 and 21 d, counted and probed for various mRNAs and proteins (type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase and bone sialoprotein). All substrates significantly affected cellular growth and the temporal expression of an array of bone-related genes and proteins. At 14 and 21 d, cells on CTP-S3 displayed significantly enhanced expression of all osteogenic mRNAs. Surfaces of CTP-S1 and CTP-S3 had the most effect on osteoblastic differentiation inducing a greater expression of an array of osteogenic markers than recorded for cells grown on Ti-DPS and HA, suggesting that these novel materials may possess a higher potency to enhance osteogenesis. PMID:15109851

Knabe, C; Berger, G; Gildenhaar, R; Klar, F; Zreiqat, H

2004-09-01

287

Effect of cold-setting calcium- and magnesium phosphate matrices on protein expression in osteoblastic cells.  

PubMed

Bone loss due to accidents or tissue diseases requires replacement of the structure by either autografts, allografts, or artificial materials. Reactive cements, which are based on calcium phosphate chemistry, are commonly used in nonload bearing areas such as the craniofacial region. Some of these materials are resorbed by the host under physiological conditions and replaced by bone. The aim of this study was to test different calcium and magnesium cement composites in vitro for their use as bone substitution material. Phase composition of calcium deficient hydroxyapatite (Ca(9) (PO(4) )(5) HPO(4) OH), brushite (CaHPO(4) ·2H(2) O), and struvite (MgNH(4) PO(4) ·6H(2) O) specimens has been determined by means of X-ray diffraction, and compressive strength was measured. Cell growth and activity of osteoblastic cells (MG 63) on the different surfaces was determined, and the expression of bone marker proteins was analyzed by western blotting. Cell activity normalized to cell number revealed higher activity of the osteoblasts on brushite and struvite when compared to hydroxyapatite and also the expression of osteoblastic marker proteins was highest on brushite scaffolds. While brushite sets under acidic conditions, formation of struvite occurs under physiological pH, similar to hydroxyapatite cements, providing the possibility of additional modifications with proteins or other active components. PMID:21210513

Ewald, Andrea; Helmschrott, Kerstin; Knebl, Georg; Mehrban, Nazia; Grover, Liam M; Gbureck, Uwe

2011-02-01

288

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

PubMed Central

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

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

2013-01-01

289

High phosphate reduces host ability to develop arbuscular mycorrhizal symbiosis without affecting root calcium spiking responses to the fungus  

PubMed Central

The arbuscular mycorrhizal symbiosis associates soil fungi with the roots of the majority of plants species and represents a major source of soil phosphorus acquisition. Mycorrhizal interactions begin with an exchange of molecular signals between the two partners. A root signaling pathway is recruited, for which the perception of fungal signals triggers oscillations of intracellular calcium concentration. High phosphate availability is known to inhibit the establishment and/or persistence of this symbiosis, thereby favoring the direct, non-symbiotic uptake of phosphorus by the root system. In this study, Medicago truncatula plants were used to investigate the effects of phosphate supply on the early stages of the interaction. When plants were supplied with high phosphate fungal attachment to the roots was drastically reduced. An experimental system was designed to individually study the effects of phosphate supply on the fungus, on the roots, and on root exudates. These experiments revealed that the most important effects of high phosphate supply were on the roots themselves, which became unable to host mycorrhizal fungi even when these had been appropriately stimulated. The ability of the roots to perceive their fungal partner was then investigated by monitoring nuclear calcium spiking in response to fungal signals. This response did not appear to be affected by high phosphate supply. In conclusion, high levels of phosphate predominantly impact the plant host, but apparently not in its ability to perceive the fungal partner. PMID:24194742

Balzergue, Coline; Chabaud, Mireille; Barker, David G.; Bécard, Guillaume; Rochange, Soizic F.

2013-01-01

290

Novel tea polyphenol-modified calcium phosphate nanoparticle and its remineralization potential.  

PubMed

Tea polyphenols (TP) are not only potent antimicrobial and antioxidant agents but also effective modifiers in the formation of nanosized crystals. Since nano-hydroxyapatite (n-HA) is known to enhance remineralization of dental hard tissue, our aims were to synthesize nanosized calcium phosphate particles incorporating TP and to test their potential as caries preventive agent. An ammonia water diffusion method was used to synthesize nanosized calcium phosphate particles (TP-CaP) in the presence of various amounts of TP. The resultant products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The remineralization potential of the nano TP-CaP was then investigated in a 12-day pH-cycling model. Nano TP-CaP slurries, at pH 7.0 and pH 5.5, were applied onto preformed enamel lesions 4 × 3 min per day. n-HA slurries at pH 7.0 and pH 5.5 were used as positive controls, and deionized water was served as a negative control. SEM showed nanosized particles were only formed at 27 mg/mL of TP. Further characterization of the nanosized particles revealed the components were amorphous calcium phosphate, HA, and TP. Both surface microhardness and transverse microradiography analyses showed that nano TP-CaP at pH 5.5, but not at pH 7.0, significantly enhanced remineralization, to the same extent as the n-HA controls. Furthermore, significantly higher amount of TP was found in the supernatant of TP-CaP at pH 5.5 than those at pH 7.0. Since TP can inhibit bacterial growth and enzyme activities, the novel nanosized TP-CaP particle, at low pH, is a potential dual-functional-remineralization and antibacteria-product. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014. PMID:25470574

He, Libang; Deng, Dongmei; Zhou, Xuedong; Cheng, Lei; Ten Cate, Jacob M; Li, Jiyao; Li, Xudong; Crielaard, Wim

2014-12-01

291

The Calcium Phosphate Matrix of FGF-2-Apatite Composite Layers Contributes to Their Biological Effects  

PubMed Central

The purpose of the present study was to fabricate fibroblast growth factor (FGF)-2-apatite composite layers on titanium (Ti) pins in one step at 25 °C using a supersaturated calcium phosphate (CaP) solution, and to evaluate the physicochemical characteristics and biological effects of the coated Ti pins compared with coated Ti pins fabricated at 37 °C. Ti pins were immersed in a supersaturated CaP solution containing 0.5, 1.0, or 2.0 µg/mL FGF-2 at 25 °C for 24 h (25F0.5, 25F1.0, and 25F2.0) or containing 4.0 µg/mL FGF-2 at 37 °C for 48 h (37F4.0). Except for the 25F0.5, the chemical compositions and the mitogenic activity levels of FGF-2 of the composite layers formed by these two methods were similar, except for the Ca/P molar ratio, which was markedly smaller at 25 °C (1.55–1.56 ± 0.01–0.02, p = 0.0008–0.0045) than at 37 °C (1.67 ± 0.11). Thus, either the apatite was less mature or the amount of amorphous calcium phosphate was higher in the composite layer formed at 25 °C. In vivo, the pin tract infection rate by visual inspection for 37F4.0 (45%) was lower than that for 25F1.0 (80%, p = 0.0213), and the rate of osteomyelitis for 37F4.0 (35%) was lower than that for 25F0.5 (75%, p = 0.0341). The extraction torque for 37F4.0 (0.276 ± 0.117 Nm) was higher than that for 25F0.5 (0.192 ± 0.117 Nm, p = 0.0142) and that for 25F1.0 (0.176 ± 0.133 Nm, p = 0.0079). The invasion rate of S. aureus for 37F4.0 (35%) was lower than that for 25F0.5 (75%, p = 0.0110). On the whole, the FGF-2-apatite composite layer formed at 25 °C tended to be less effective at improving fixation strength in the bone-pin interface and resisting pin tract infections. These results suggest that the chemistry of the calcium phosphate matrix that embeds FGF-2, in addition to FGF-2 content and activity, has a significant impact on composite infection resistance and fixation strength. PMID:24918287

Mutsuzaki, Hirotaka; Ito, Atsuo; Sogo, Yu; Sakane, Masataka; Oyane, Ayako; Yamazaki, Masashi

2014-01-01

292

Targeting and activation of antigen-specific B-cells by calcium phosphate nanoparticles loaded with protein antigen.  

PubMed

Cross-linking of the B-cell receptors of an antigen-specific B-cell is the initial signal for B-cell activation, proliferation, and differentiation into antibody secreting plasma cells. Since multivalent particulate structures are efficient activators of antigen-specific B-cells, we developed biodegradable calcium phosphate nanoparticles displaying protein antigens on their surface and explored the efficacy of the B-cell activation after exposure to these nanoparticles. The calcium phosphate nanoparticles were functionalized with the model antigen Hen Egg Lysozyme (HEL) to take advantage of a HEL-specific B-cell receptor transgenic mouse model. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. The functionalized calcium phosphate nanoparticles were preferentially bound and internalized by HEL-specific B-cells. Co-cultivation of HEL-specific B-cells with the functionalized nanoparticles also increased surface expression of B-cell activation markers. Functionalized nanoparticles were able to effectively cross-link B-cell receptors at the surface of antigen-matched B-cells and were 100-fold more efficient in the activation of B-cells than soluble HEL. Thus, calcium phosphate nanoparticles coated with protein antigens are promising vaccine candidates for induction humoral immunity. PMID:24776487

Temchura, Vladimir V; Kozlova, Diana; Sokolova, Viktoriya; Uberla, Klaus; Epple, Matthias

2014-07-01

293

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

E-print Network

in the human body [1-3]. For these reasons, apatite and whitlockite have been widely used as biocompatible in the body is confined in bone [1]. The total amount of Sr in human skeleton is small but not insignificant) and Tri Calcium Phosphate (-TCP). Doping with Sr2+ ions has a clear effect on the proportions

Paris-Sud XI, Université de

294

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

Microsoft Academic Search

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

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

2007-01-01

295

Comparison of the adjuvant activity of aluminum hydroxide and calcium phosphate on the antibody response towards Bothrops asper snake venom.  

PubMed

The adjuvanticity of aluminum hydroxide and calcium phosphate on the antibody response in mice towards the venom of the snake Bothrops asper was studied. It was found that, in vitro, most of the venom proteins are similarly adsorbed by both mineral salts, with the exception of some basic phospholipases A2, which are better adsorbed by calcium phosphate. After injection, the adjuvants promoted a slow release of the venom, as judged by the lack of acute toxicity when lethal doses of venom were administered to mice. Leukocyte recruitment induced by the venom was enhanced when it was adsorbed on both mineral salts; however, venom adsorbed on calcium phosphate induced a higher antibody response towards all tested HPLC fractions of the venom. On the other hand, co-precipitation of venom with calcium phosphate was the best strategy for increasing: (1) the capacity of the salt to couple venom proteins in vitro; (2) the venom ability to induce leukocyte recruitment; (3) phagocytosis by macrophages; and (4) a host antibody response. These findings suggest that the chemical nature is not the only one determining factor of the adjuvant activity of mineral salts. PMID:23506358

Olmedo, Hidekel; Herrera, María; Rojas, Leonardo; Villalta, Mauren; Vargas, Mariángela; Leiguez, Elbio; Teixeira, Catarina; Estrada, Ricardo; Gutiérrez, José María; León, Guillermo; Montero, Mavis L

2014-01-01

296

Self-healing hybrid nanocomposites consisting of bisphosphonated hyaluronan and calcium phosphate nanoparticles.  

PubMed

Non-covalent interactions are often regarded as insufficient to construct macroscopic materials of substantial integrity and cohesion. However, the low binding energy of such reversible interactions can be compensated by increasing their number to work in concert to create strong materials. Here we present the successful development of an injectable, cohesive nanocomposite hydrogel based on reversible bonds between calcium phosphate nanoparticles and bisphosphonate-functionalized hyaluronic acid. These nanocomposites display a capacity for self-healing as well as adhesiveness to mineral surfaces such as enamel and hydroxyapatite. Most importantly, these non-covalently cross-linked composites are surprisingly robust yet biodegradable upon extensive in vitro and in vivo testing and show bone interactive capacity evidenced by bone ingrowth into material remnants. The herein presented method provides a new methodology for constructing nanoscale composites for biomedical applications, which owe their integrity to reversible bonds. PMID:24862440

Nejadnik, M Reza; Yang, Xia; Bongio, Matilde; Alghamdi, Hamdan S; van den Beucken, Jeroen J J P; Huysmans, Marie C; Jansen, John A; Hilborn, Jöns; Ossipov, Dmitri; Leeuwenburgh, Sander C G

2014-08-01

297

[The characteristics and properties of calcium phosphates in biomaterial formulations used in dentistry. 1].  

PubMed

In this work we present the features and the properties of natural and synthetic apatites, which we use in an experimental study of various commercial products composed by calcium phosphate. After having considered the general concepts of biomaterials and biocompatibility, we describe non biological tests used for the characterization of these products. Biomaterials used in this study are: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable thin Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2 Osprogel, Bio-oss, Biostite, Osprovit, Merck Hydroxiapatite. Tests used are: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and thermodifferential analysis (TG, DTG, DTA), scanner-ing electron microscopy (SEM) morphological analysis. Last but not least, we underline the particular features of these tests whose interpretation allows a more precise definition of the bioactivity of a biocompatible material. PMID:7783709

Mongiorgi, R; Valdrè, G; Bertocchi, G; Minguzzi, V; Prati, C; Corvo, G; D'Amato, S

1995-01-01

298

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

PubMed Central

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

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

2013-01-01

299

Adjuvant effects of chitosan and calcium phosphate particles in an inactivated Newcastle disease vaccine.  

PubMed

The adjuvant activity of chitosan (CS) and calcium phosphate (CAP) particles was studied following intranasal (mucosal) administration to commercial chickens with inactivated Newcastle disease virus (NDV) vaccine. After three vaccinations with inactivated NDV in combination with CS or CAP an increase in antibody titers in blood and mucosal samples in chickens was observed when compared with the administration of NDV antigen only. A lower level of humoral immunity was observed in broiler chickens compared to layer-type birds. The CS-based vaccine demonstrated higher antigenic and protective activity following lethal challenge than the vaccine containing CAP. Because CS particles efficiently changed mucosal and humoral immunity and protective activity, CS may in the future be considered for use as a potential adjuvant for production of vaccines for poultry. PMID:24758112

Volkova, Marina A; Irza, Anna V; Chvala, Irina A; Frolov, Sergy F; Drygin, Vladimir V; Kapczynski, Darrell R

2014-03-01

300

Preparation, characterization, biological activity, and transport study of polystyrene based calcium-barium phosphate composite membrane.  

PubMed

Calcium-barium phosphate (CBP) composite membrane with 25% polystyrene was prepared by co-precipitation method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), and Thermogravimetric analysis (TGA) were used to characterize the membrane. The membrane was found to be crystalline in nature with consistent arrangement of particles and no indication of visible cracks. The electrical potentials measured across the composite membrane in contact with univalent electrolytes (KCl, NaCl and LiCl), have been found to increase with decrease in concentrations. Thus the membrane was found to be cation-selective. Transport properties of developed membranes may be utilized for the efficient desalination of saline water and more importantly demineralization process. The antibacterial study of this composite membrane shows good results for killing the disease causing bacteria along with waste water treatment. PMID:23910337

Khan, Mohammad Mujahid Ali; Rafiuddin

2013-10-01

301

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

PubMed

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

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

2014-07-01

302

Enzyme-assisted calcium phosphate biomineralization on an inert alumina surface.  

PubMed

In this study a bioinspired approach to induce self-mineralization of bone-like material on alumina surfaces is presented. The mineralizing enzyme alkaline phosphatase (ALP) is covalently immobilized by a carbodiimide-mediated chemoligation method. The enzymatic activity of immobilized ALP and its mineralization capability are investigated under acellular conditions as well as in the presence of human bone cells. Analytical, biochemical and immunohistochemical characterization show that ALP is efficiently immobilized, retains its activity and can trigger calcium phosphate mineralization on alumina at acellular conditions. In vitro cell tests demonstrate that ALP-functionalized alumina clearly boosts and enhances bone cell mineralization. Our results underpin the great potential of ALP-functionalized alumina for the development of bioactive surfaces for applications such as orthopaedic and dental implants, enabling a fast and firm implant osseointegration. PMID:25462843

Aminian, Alieh; Pardun, Karoline; Volkmann, Eike; Li Destri, Giovanni; Marletta, Giovanni; Treccani, Laura; Rezwan, Kurosch

2015-02-01

303

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

NASA Astrophysics Data System (ADS)

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.

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

304

Calcitriol pulse therapy for severe hyperparathyroidism or calcium salts as phosphate binders in renal dialysis patients?  

PubMed

The concurrent use of calcitriol (CAL) pulse therapy to reduce parathyroid hormone (PTH) secretion and of calcium (Ca) salts as the most appropriate phosphate binders was evaluated for over 1 year in a group of 14 patients with good divalent ion control on CaCO3 therapy but with increasing levels of serum intact PTH. CAL pulse therapy was effective and safe in only 2 patients; in the remaining subjects it resulted in hypercalcemia and/or hyperphosphatemia, not reversed by adjusting the dialysate Ca concentration and or CaCO3 dose, and had to be stopped. Therefore, CAL pulse therapy does not seem to be compatible with Ca salts which, in our opinion, deserve priority in the therapy of renal dialysis patients. PMID:8569985

Gonella, M; Calabrese, G; Aleo, A G; Vagelli, G; Deambrogio, P

1995-01-01

305

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

SciTech Connect

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.

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

306

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

PubMed

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

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

2014-12-01

307

Effects of calcium phosphate composition in sputter coatings on in vitro and in vivo performance.  

PubMed

Calcium phosphate (CaP) ceramic coatings have been used to enhance the biocompatibility and osteoconductive properties of metallic implants. The chemical composition of these ceramic coatings is an important parameter, which can influence the final bone performance of the implant. In this study, the effect of phase composition of CaP-sputtered coatings was investigated on in vitro dissolution behavior and in vivo bone response. Coatings were prepared by a radio frequency (RF) magnetron sputtering technique; three types of CaP target materials were used to obtain coatings with different stoichiometry and calcium to phosphate ratios (hydroxyapatite (HA), ?-tricalciumphosphate (?-TCP), and tetracalciumphosphate (TTCP)) were compared with non-coated titanium controls. The applied ceramic coatings were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy. The in vitro dissolution/precipitation of the CaP coatings was evaluated using immersion tests in simulated body fluid (SBF). To mimic the in vivo situation, identical CaP coatings were also evaluated in a femoral condyle rabbit model. TCPH and TTCPH showed morphological changes during 4-week immersion in SBF. The results of bone implant contact (BIC) and peri-implant bone volume (BV) showed a similar response for all experimental coatings. An apparent increase in tartrate resistant acid phosphatase (TRAP) positive staining was observed in the peri-implant region with decreasing coating stability. In conclusion, the experimental groups showed different coating properties when tested in vitro and an apparent increase in bone remodeling with increasing coating dissolution in vivo. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 300-310, 2015. PMID:24659523

Urquia Edreira, Eva R; Wolke, Joop G C; Aldosari, Abdullah AlFarraj; Al-Johany, Sulieman S; Anil, Sukumaran; Jansen, John A; van den Beucken, Jeroen J J P

2015-01-01

308

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

PubMed Central

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

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

2010-01-01

309

The functional expression of human bone-derived cells grown on rapidly resorbable calcium phosphate ceramics.  

PubMed

The use of biodegradable bone substitutes is advantageous for alveolar ridge augmentation, since it avoids second-site surgery for autograft harvesting. This study examines the effect of novel, rapidly resorbable calcium phosphates on the expression of bone-related genes and proteins by human bone-derived cells (HBDC) and compares this behavior to that of tricalciumphosphate (TCP). Test materials were alpha-TCP, and four materials which were created from beta-Rhenanite and its derivatives: R1-beta-Rhenanite (CaNaPO(4)); R1/M2 composed of CaNaPO(4) and MgNaPO(4); R1+SiO(2) composed of CaNaPO(4) and 9% SiO(2) (wt%); and R17-Ca(2)KNa(PO(4))(2). HBDC were grown on the substrata for 3, 5, 7, 14 and 21 days, counted and probed for various mRNAs and proteins (Type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase and bone sialoprotein). All substrata supported continuous cellular growth for 21 days. At day 21, surfaces of R1+SiO(2) and R17 had the highest number of HBDC. At 14 and 21 days, cells on R1 and on R1+SiO(2) displayed significantly enhanced expression of all osteogenic proteins. Since all novel calcium phosphates supported cellular proliferation together with expression of bone-related proteins at least as much as TCP, these ceramics can be regarded as potential bone substitutes. R1 and R1+SiO(2) had the most effect on osteoblastic differentiation, thus suggesting that these materials may possess a higher potency to enhance osteogenesis than TCP. PMID:14585721

Knabe, C; Berger, G; Gildenhaar, R; Howlett, C R; Markovic, B; Zreiqat, H

2004-01-01

310

In vitro testing of Nd:YAG laser processed calcium phosphate coatings.  

PubMed

Nd:YAG laser cladding is a new method for deposition of a calcium phosphate onto metallic surfaces of interest in implantology. The aim of this study was to compare the biologic response of MG-63 human osteoblast-like cells grown on Ti-6Al-4V substrates coated with a calcium phosphate layer applied using different methods: plasma spraying as reference material and Nd:YAG laser cladding as test material. Tissue culture polystyrene was used as negative control. The Nd:YAG laser clad material showed a behaviour similar to the reference material, plasma spray, respective to cell morphology (SEM observations), cell proliferation (AlamarBlue assay) and cytotoxicity of extracts (MTT assay). Proliferation, as measured by the AlamarBlue assay, showed little difference in the metabolic activity of the cells on the materials over an 18 day culture period. There were no significant differences in the cellular growth response on the test material when compared to the ones exhibited by the reference material. In the solvent extraction test all the extracts had some detrimental effect on cellular activity at 100% concentration, although cells incubated in the test material extract showed a proliferation rate similar to that of the reference material. To better understand the scope of these results it should be taken into account that the Nd:YAG clad coating has recently been developed. The fact that its in vitro performance is comparable to that produced by plasma spray, a material commercially available for more than ten years, indicates that this new laser based method could be of commercial interest in the near future. PMID:17122931

De Carlos, A; Lusquiños, F; Pou, J; León, B; Pérez-Amor, M; Driessens, F C M; Hing, K; Best, S; Bonfield, W

2006-11-01

311

The use of physiological solutions or media in calcium phosphate synthesis and processing.  

PubMed

This review examined the literature to spot uses, if any, of physiological solutions/media for the in situ synthesis of calcium phosphates (CaP) under processing conditions (i.e. temperature, pH, concentration of inorganic ions present in media) mimicking those prevalent in the human hard tissue environments. There happens to be a variety of aqueous solutions or media developed for different purposes; sometimes they have been named as physiological saline, isotonic solution, cell culture solution, metastable CaP solution, supersaturated calcification solution, simulated body fluid or even dialysate solution (for dialysis patients). Most of the time such solutions were not used as the aqueous medium to perform the biomimetic synthesis of calcium phosphates, and their use was usually limited to the in vitro testing of synthetic biomaterials. This review illustrates that only a limited number of research studies used physiological solutions or media such as Earle's balanced salt solution, Bachra et al. solutions or Tris-buffered simulated body fluid solution containing 27mM HCO3(-) for synthesizing CaP, and these studies have consistently reported the formation of X-ray-amorphous CaP nanopowders instead of Ap-CaP or stoichiometric hydroxyapatite (HA, Ca10(PO4)6(OH)2) at 37°C and pH 7.4. By relying on the published articles, this review highlights the significance of the use of aqueous solutions containing 0.8-1.5 mMMg(2+), 22-27mM HCO3(-), 142-145mM Na(+), 5-5.8mM K(+), 103-133mM Cl(-), 1.8-3.75mM Ca(2+), and 0.8-1.67mM HPO4(2-), which essentially mimic the composition and the overall ionic strength of the human extracellular fluid (ECF), in forming the nanospheres of X-ray-amorphous CaP. PMID:24389317

Tas, A Cuneyt

2014-05-01

312

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

PubMed Central

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

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

2009-01-01

313

Study of Biomimetic and electrolytic calcium phosphate coating on titanium alloy by laser induced breakdown spectroscopy depth profiling  

NASA Astrophysics Data System (ADS)

Depth profile analysis by means of laser induced breakdown spectroscopy (LIBS) was investigated with respect to its potential to measure the thickness of different types of thin calcium phosphate used as biomimetic coatings on Ti6Al4V alloy. The coating thickness is determined from the ratio of the intensities of a calcium line and a titanium line measured at burst energy high enough to penetrate the coating with a single burst. To achieve an ablation depth in the range of the coating thickness of about 10 ?m a Nd: YAG laser at 532 nm in single shot mode was used. The achieved thickness resolution is estimated to about 500 nm for coating thicknesses of electrolytically deposited calcium phosphate in the range of 1.0 to 10.0 ?m.

Estupiñán, Hugo; Peña, Dario Y.; Cabanzo, Rafael; Mejía-Ospino, Enrique

2008-04-01

314

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

PubMed Central

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

Yanamadala, Vijay

2010-01-01

315

Effects of environmental calcium and phosphate on wear and strength of glass ionomers exposed to acidic conditions.  

PubMed

This study evaluated the effects of environmental calcium and phosphate on wear resistance, strength, and surface morphology of highly viscous glass-ionomers (HVGICs) (Fuji IX Fast [FN] and KetacMolar [KM]) when exposed to acidic conditions. Fabricated specimens were randomly divided into five groups and kept in acidic solutions (pH 3) with varied levels of calcium and phosphate ranging from 0 to 2.4 mM. After 4 weeks of conditioning, the specimens were subjected to wear testing, shear punch, and surface roughness testing as well as SEM evaluation. Multiple comparisons of wear depth (microm), shear strength (MPa), and surface roughness (Ra) between acidic conditions were performed using ANOVA/post-hoc Scheffe's test (p < 0.05). Results showed that FN and KM exposed to acidic conditions had varied wear resistance, shear strength, surface roughness, and structure depending on environmental phosphate level. Increased level of environmental phosphate led to rougher surface, greater wear resistance, and strength of FN and KM than the controls (acid of pH 3). Under SEM, the surface of both FN and KM specimens were covered by numerous small particles when environmental phosphate was high. Results suggest that environmental phosphate may improve wear resistance and shear strength of HVGICs when challenged by acids. PMID:18506830

Wang, X Y; Yap, Adrian U J

2009-02-01

316

Postprandial effects of calcium phosphate supplementation on plasma concentration-double-blind, placebo-controlled cross-over human study  

PubMed Central

Background The aim of the present study was to examine the postprandial calcium and phosphate concentrations after supplementation with pentacalcium hydroxy-triphosphate (CaP). Methods Ten men participated in this double-blind, placebo-controlled, cross-over study. The participants were divided into two groups. One group consumed bread enriched with CaP (plus 1 g calcium/d) and the other group a placebo product for three weeks. After a two week wash-out, the intervention was switched between the groups for another three weeks. Blood samples were drawn at the beginning (single administration) and at the end (repeated administration) of the intervention periods at 0, 30, 60, 120, 180 and 240 min. Between 0 and 30 min, a test meal, with or without CaP was consumed. The plasma concentrations of calcium and phosphate were examined. One participant dropped out due to personal reasons. Results CaP supplementation resulted in a significantly higher plasma calcium concentration after 240 min compared to placebo. After repeated CaP administration, the AUC for the increment in plasma calcium concentration was significantly higher compared to placebo. After single and repeated CaP supplementation, plasma phosphate concentration significantly decreased after 30, 60, 120 and 180 min compared to 0 min. The placebo administration resulted in significant decreases after 30, 60 and 120 min compared to 0 min. Conclusion Our results show that CaP contributes to an adequate calcium supply, but without increasing the plasma concentration of phosphate. Trial registration http://www.clinicaltrials.gov; NCT01296997 PMID:23510513

2013-01-01

317

Phosphorus removal and recovery from wastewater by tobermorite-seeded crystallisation of calcium phosphate.  

PubMed

Investigations were focused on the development of a technology for phosphorus (P) recovery straight from wastewater. Facing the finiteness of the natural resources of this essential nutrient, the declared goal must be the sustainable use of available phosphorus sinks such as wastewater treatment plants (WWTP) for the generation of P rock substitutes. A feasible method for simultaneous elimination and recovery of phosphorus from wastewater proved to be the P-RoC process - the phosphorus recovery from wastewater by induced crystallisation of calcium phosphate, applying tobermorite-rich waste compounds of the construction industry. The experiments were performed in fixed bed-, stirred- and expanded bed reactors in laboratory--as well as in pilot-scale experiments. The efficiency and longevity of the P-RoC process was determined by the supply of Ca ions and the initial P concentration. Total P (P-tot) contents in the generated crystallisation products of up to 13% P-tot (30% P2O5) were achieved. Mineralogical investigations proved the formation of a hydroxy-apatite-(HAP)-like coating onto the seed material's surface. Reuse options for the generated crystallisation products, such as substitute for phosphate rock or as new fertiliser, were assessed. PMID:16605025

Berg, U; Donnert, D; Weidler, P G; Kaschka, E; Knoll, G; Nüesch, R

2006-01-01

318

Human bone marrow stem cell-encapsulating calcium phosphate scaffolds for bone repair  

PubMed Central

Due to its injectability and excellent osteoconductivity, calcium phosphate cement (CPC) is highly promising for orthopedic applications. However, a literature search revealed no report on human bone marrow mesenchymal stem cell (hBMSC) encapsulation in CPC for bone tissue engineering. The aim of this study was to encapsulate hBMSCs in alginate hydrogel beads and then incorporate them into CPC, CPC–chitosan and CPC–chitosan–fiber scaffolds. Chitosan and degradable fibers were used to mechanically reinforce the scaffolds. After 21 days, that the percentage of live cells and the cell density of hBMSCs inside CPC-based constructs matched those in alginate without CPC, indicating that the CPC setting reaction did not harm the hBMSCs. Alkaline phosphate activity increased by 8-fold after 14 days. Mineral staining, scanning electron microscopy and X-ray diffraction confirmed that apatitic mineral was deposited by the cells. The amount of hBMSC-synthesized mineral in CPC–chitosan–fiber matched that in CPC without chitosan and fibers. Hence, adding chitosan and fibers, which reinforced the CPC, did not compromise hBMSC osteodifferentiation and mineral synthesis. In conclusion, hBMSCs were encapsulated in CPC and CPC–chitosan–fiber scaffolds for the first time. The encapsulated cells remained viable, osteodifferentiated and synthesized bone minerals. These self-setting, hBMSC-encapsulating CPC-based constructs may be promising for bone tissue engineering applications. PMID:20451676

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

2010-01-01

319

An Alternative Reaction Scheme for Calcium Phosphate Nucleation on Silica Glass Ceramics: Molecular Dynamics Simulations  

NASA Astrophysics Data System (ADS)

The silica mineral ?-wollastonite exposed to physiological aqueous solutions induces the nucleation of calcium phosphate (CaP) on its surface. The nucleation is the initial step of the formation of biological-like CaP layers which finally provide an ideal environment for a strong bonding to biological tissues and mature bone. However,the mechanism of nucleation and the molecular structure of the first inorganic precipitates is still under investigation. We have performed density functional molecular dynamics simulations on model systems and propose a nucleophilic substitution reaction type which includes the formation of covalent Si--O--P linkages. Initially, oxygen atoms of phosphate ions attach to silicon atoms of the solvated silica species at the surface of the mineral. Subsequently, a Si--O bond is formed and the silicon atom has a penta-oxo coordination. Finally, another Si--O bond of the penta- coordinated silicon is broken.The calculated change of the Helmholtz free energy is negative. That is, the reaction ends with CaP strongly bonded to the mineral. The reaction barriers along this pathway remain fairly low, as the pentacoordinated Si is part of a metastable intermediate state.

Delley, Bernard

2005-03-01

320

Adsorption on apatitic calcium phosphates for drug delivery: interaction with bisphosphonate molecules.  

PubMed

Bisphosphonates (BPs) are well established as an important class of drugs for the treatment and prevention of several bone disorders including osteoporosis. This work investigated the interaction of two bisphosphonates, risedronate and tiludronate, with several apatitic supports, a well-crystallised hydroxyapatite (HA) and nanocrystalline apatites with varying maturation times, chemical composition and surface characteristics. The purpose was to fully understand the adsorption mechanism and desorption process, by the evaluation of the effect of several physicochemical parameters (temperature, pH and concentration of calcium and phosphate ions). Whatever the nature of the BP and the structure and composition of the apatite, the adsorption of such anti-resorptive agents can be well described as an ion exchange-reaction between phosphates species on the apatitic surface and BP molecules in solution. However, the parameters of adsorption can vary depending on the physicochemical conditions of the adsorption reaction. In addition, the structure and composition of the apatitic surface also influence the adsorption properties. Finally, BPs molecules are slowly released from apatitic supports, because most of the adsorbed molecules are irreversibly bound and not spontaneously released by dilution or simple washing. Moreover, similar to their adsorption, the release of bisphosphonates is strongly affected not only by the chemical properties of the molecule, but also by the chemical and structural characteristics of the apatitic substrates. The understanding of the adsorption and release processes provides fundamental tools for the development of drug delivery systems using apatite materials. PMID:24789452

Pascaud, P; Errassifi, F; Brouillet, F; Sarda, S; Barroug, A; Legrouri, A; Rey, C

2014-10-01

321

Effect of silicon on the formation of silk fibroin/calcium phosphate composite.  

PubMed

The silk fibroin/calcium phosphate composites were prepared by adding the different amount of Na(2)SiO(3) to assess the effect of silicon on the HA (hydroxyapatite) formation in the composites. FTIR and XRD results suggested that the inorganic phase was constituted mainly by the amorphous DCPD (dicalcium phosphate dehydrate), a precursor of HA in the bone mineral, when the composites were prepared at the final Na(2)SiO(3) concentration lower than 0.008%. Otherwise, HA was formed as the predominant one in the as-prepared composite, accompanied with a conformational transition in the organic phase of silk fibroin protein from silk I (alpha-helix and/or polyglycine II (3(1)-helix) conformations) to silk II (antiparallel beta-sheet conformation). SEM images showed the different morphologies with the samples, i.e., sheet-like crystals in the composites prepared at a low Na(2)SiO(3) concentration and rod-like bundles in other composites. The rod-like bundles were connected together to form the porous network, due to the fact that the HA crystals grew with the aggregation of silk fibroin, and further accreted onto the silk fibroin fibrils. TG curves indicated that the composites prepared with a certain amount of additional SiO (3) (2-) had the higher thermal stability because of its high molecular orientation and crystallinity, and high water-holding capacity due to the porous microstructure. PMID:17619986

Li, Li; Wei, Ke-Min; Lin, Feng; Kong, Xiang-Dong; Yao, Ju-Ming

2008-02-01

322

Development of dual-setting calcium phosphate cement using absorbable polymer.  

PubMed

Calcium phosphate cements used as bone substitutes generally have low mechanical strength compared with the bones of the human body. To solve these needs, we have incorporated hydrogels in the manufacture of samples made of alpha-tricalcium phosphate (?-TCP) cement, developing a system of dual-setting cement. This study aimed to produce composite materials by combining ?-TCP powder and hydrogels. The composites were prepared using the synthesized powder and four different formulations of hydrogels, using either poly(N-vinyl-2-pyrrolidone) or poly(N-vinyl-2-pyrrolidone-co-acrylic acid), with either azobisisobutyronitrile or ammonium persulfate as initiator. The properties of all composites were evaluated through measuring compressive strength and apparent density and through X-ray diffraction and scanning electron microscopy. The composites showed compressive strengths of around 24 MPa. Soaking the samples in simulated body fluid formed a layer of hydroxyapatite-like crystals on the surface of some samples, showing the bioactivity of the newly developed cements and their potential use as biomaterial. PMID:24236442

Thürmer, Mônica Beatriz; Diehl, Carlos Eduardo; Brum, Fábio José Bento; dos Santos, Luís Alberto

2013-11-01

323

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

PubMed Central

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

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

324

Effects of polymer concentration on the morphology of calcium phosphate crystals formed in polyacrylamide hydrogels  

NASA Astrophysics Data System (ADS)

Growing crystals in hydrogels is an attractive method to form inorganic solids with designed morphology under ambient conditions. Precipitation of the inorganic solids in a hydrogel matrix can be regarded as mimicking the process of biomineralization. In the construction of biominerals, an organic template composed of insoluble macromolecules is used to control the crystal growth of the inorganic compounds. The morphological control in biomineralization can be applied to artificial reaction systems. In this study, the morphology of calcium phosphate crystals formed in polymeric hydrogels of various polymer concentrations was investigated. Spherical octacalcium phosphate (OCP) precipitated in the polyacrylamide (PAAm) hydrogels. Fibrous crystals gradually covered the surface of the spherical crystals as the polymer concentration of the gel increased. The morphology of the OCP crystals changed from sea urchin shapes to wool-ball shapes with increasing PAAm concentration. The morphological change is generated by the template effect of the polymer wall, which is made up of stacked PAAm sheets, surrounding the spherical OCP crystals.

Yokoi, Taishi; Kawashita, Masakazu; Ohtsuki, Chikara

2013-11-01

325

In situ synthesis of silicon-substituted biphasic calcium phosphate and their performance in vitro  

NASA Astrophysics Data System (ADS)

In situ preparation of silicon (Si) substituted biphasic calcium phosphate (BCP) of hydroxyapatite (HAp)/ ?-tricalcium phosphate (?-TCP) were carried out through aqueous co-precipitation method. The concentrations of added silicon were varied with the phosphor in order to obtain constant Ca/(P+Si) ratios of 1.602. X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy were used to characterize the structure of synthesized silicon substituted BCP powders. The characterization revealed that the formation of biphasic mixtures of different HAp/ ?-TCP ratios was dependent on the content of silicon. After immersing in Hanks' balanced salt solution (HBSS) for 1 week, 3 wt% silicon 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. In the case of 1 wt% silicon substituted BCP powders, the degradation behavior was detected after immersion in HBSS for 3 weeks. On the other hand, silicon unsubtituted BCP powders were not degraded even after that duration. On the basis of these results, silicon substituted BCP is able to develop a new apatite phase on the surface in contact with physiological fluids faster than BCP does. This enhanced reactivity resulted in reduction for the stability of the ?-TCP structure due to SiO4 tetrahedral distortion and disorder at the hydroxyl site when silicon incorporates into BCP.

Song, Chang-Weon; Kim, Tae-Wan; Kim, Dong-Hyun; Jin, Hyeong-Ho; Hwang, Kyu-Hong; Lee, Jong Kook; Park, Hong-Chae; Yoon, Seog-Young

2012-01-01

326

Investigation of silicon complexes in Si-doped calcium phosphate bioceramics  

NASA Astrophysics Data System (ADS)

Silicon doped calcium phosphate materials have drawn great interest as bioceramics for bone repair due to their enhanced bioactivity. However, the low level of doping in these materials, generally ˜1 wt.%, makes it difficult to determine the effects the silicon has on the structure of these materials. In this study, silicon substituted hydroxyapatite (Si-HA), silicon stabilized alpha tricalcium phosphate (Si-TCP), and a multi-phase mixture consisting of approximately 75% Si-TCP with the remainder being mainly Si-HA have been synthesized using isotopically enriched silica containing ^29Si. ^29Si magic-angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) has been used to examine the silicon complexes within these materials resulting from the substitution of SiO4^4- for PO4^3- and the required charge compensation mechanism needed to achieve this. Previous ab initio studies on these materials have investigated charge compensation mechanisms to suggest possible silicon complexes and these serve as a basis for interpreting the NMR results.

Gillespie, P.; Stott, M. J.; Sayer, M.; Wu, G.

2007-03-01

327

Calcium phosphate ceramic systems in growth factor and drug delivery for bone tissue engineering: A review  

PubMed Central

Calcium phosphates (CaPs) are the most widely used bone substitutes in bone tissue engineering due to their compositional similarities to bone mineral and excellent biocompatibility. In recent years, CaPs, especially hydroxyapatite and tricalcium phosphate, have attracted significant interest in simultaneous use as bone substitute and drug delivery vehicle, adding a new dimension to their application. CaPs are more biocompatible than many other ceramic and inorganic nanoparticles. Their biocompatibility and variable stoichiometry, thus surface charge density, functionality, and dissolution properties, make them suitable for both drug and growth factor delivery. CaP matrices and scaffolds have been reported to act as delivery vehicles for growth factors and drugs in bone tissue engineering. Local drug delivery in musculoskeletal disorder treatments can address some of the critical issues more effectively and efficiently than the systemic delivery. CaPs are used as coatings on metallic implants, CaP cements, and custom designed scaffolds to treat musculoskeletal disorders. This review highlights some of the current drug and growth factor delivery approaches and critical issues using CaP particles, coatings, cements, and scaffolds towards orthopedic and dental applications. PMID:22127225

Bose, Susmita; Tarafder, Solaiman

2012-01-01

328

Thermal spraying of functionally graded calcium phosphate coatings for biomedical implants  

NASA Astrophysics Data System (ADS)

Biomedical requirements in a prosthesis are often complex and diverse in nature. Biomaterials for implants have to display a wide range of adaptability to suit the various stages of the bio-integration process of any foreign material into the human body. Often, a combination of materials is needed. The preparation of a functionally graded bioceramic coating composed of essentially calcium phosphate compounds is explored. The coating is graded in accordance to adhesive strength, bioactivity, and bioresorbability. The bond coat on the Ti-6Al-4V stub is deposited with a particle range of the hydroxyapatite (HA) that will provide a high adhesive strength and bioactivity but have poor bioresorption properties. The top coat, however, is composed of predominantly ?-tricalcium phosphate (?-TCP) that is highly bioresorbable. This arrangement has the propensity of allowing accelerated bio-integration of the coating by the body tissues as the top layer is rapidly resorbed, leaving the more bioactive intermediate layer to facilitate the much needed bioactive properties for proper osteoconduction. The processing steps and problems are highlighted, as well as the results of post-spray heat treatment.

Wang, Y.; Khor, K. A.; Cheang, P.

1998-03-01

329

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

PubMed Central

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

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

2013-01-01

330

Mullite microsphere-filled lightweight calcium phosphate cement slurries for geothermal wells: Setting and properties  

SciTech Connect

The chemical factors affecting the setting properties of microsphere-filled lightweight calcium phosphate cement (LCPC) slurries, ranging in density from 1.32 to 1.12 g/cc, at high hydrothermal temperature were investigated. The LCPC slurries consisted of calcium aluminate cement (CAC) as the base reactant, a {single_bond}({single_bond}NaPO{sub 3}{single_bond}){single_bond}{sub n} solution as the acid reactant, and mullite-shelled hollow microspheres as the lightweight additive. Two major aspects were studied; one was the importance of the chemical constituents of CAC, and the other was the rate of the hydrothermal reaction between the mullite shell and the Na ions dissociated from {single_bond}({single_bond}NaPO{sub 3}{single_bond}){single_bond}{sub n}. For the former, the use of CAC having C{sub 2}AS and CA phases as the major chemical components shortened the thickening time of LCPC slurries, whereas CACs with CA, CA{sub 2}, and {alpha}-Al{sub 2}O{sub 3} phase components extended the thickening time. For the hydrothermal reaction, an excess of zeolite X type formed by the uptake of Na by mullite microspheres reduced the thickening time.

Sugama, T.; Carciello, N.R. [Brookhaven National Lab., Upton, NY (United States)] [Brookhaven National Lab., Upton, NY (United States); Nayberg, T.M. [UNOCAL, Brea, CA (United States)] [UNOCAL, Brea, CA (United States); Brothers, L.E. [Halliburton Energy Services Technology Center, Duncan, OK (United States)] [Halliburton Energy Services Technology Center, Duncan, OK (United States)

1995-08-01

331

In Vitro Properties of Orthodontic Adhesives with Fluoride or Amorphous Calcium Phosphate  

PubMed Central

This in vitro study evaluated the efficacy of orthodontic adhesives with fluoride or amorphous calcium phosphate (ACP) in reducing bacterial adhesion and enamel demineralization. Forty human premolars each sectioned buccolingually into three parts were bracketed with control resin (Transbond XT) or adhesives containing ACP (Aegis Ortho) or fluoride (QuickCure). Artificial lesions induced by pH cycling were examined by X-ray photoelectron spectrophotometry (XPS) and polarized light microscopy (PLM). After 28 days, Aegis Ortho demonstrated the lowest calcium and phosphorous content by XPS analysis. After 42 days, reductions in lesion depth areas were 23.6% for Quick Cure and 20.3% for Aegis Ortho (P < 0.05). In the presence of 1% sucrose, adhesion of Streptococcus mutans to Aegis Ortho and Quick Cure was reduced by 41.8% and 37.7% (P < 0.05) as compared to Transbond XT. Composites containing ACP or fluoride reduced bacterial adherence and lesion formation as compared to a composite without ACP or fluoride. PMID:21912546

Chow, Clara Ka Wai; Wu, Christine D.; Evans, Carla A.

2011-01-01

332

Odontogenic Differentiation of Human Dental Pulp Stem Cells Stimulated by the Calcium Phosphate Porous Granules  

PubMed Central

Effects of three-dimensional (3D) calcium phosphate (CaP) porous granules on the growth and odontogenic differentiation of human dental pulp stem cells (hDPSCs) were examined for dental tissue engineering. hDPSCs isolated from adult human dental pulps were cultured for 3-4 passages, and populated on porous granules. Cell growth on the culture dish showed an ongoing increase for up to 21 days, whereas the growth on the 3D granules decreased after 14 days. This reduction in proliferative potential on the 3D granules was more conspicuous under the osteogenic medium conditions, indicating that the 3D granules may induce the odontogenic differentiation of hDPSCs. Differentiation behavior on the 3D granules was confirmed by the increased alkaline phosphatase activity, up-regulation of odontoblast-specific genes, including dentin sialophosphoprotein (DSPP) and dentin matrix protein 1 (DMP1) by quantitative polymerase chain reaction, and greater level of dentin sialoprotein synthesis by western blot. Moreover, the cellular mineralization, as assessed by Alizarin red S and calcium quantification, was significantly higher in the 3D CaP granules than in the culture dish. Taken all, the 3D CaP porous granules should be useful for dental tissue engineering in combination with hDPSCs by providing favorable 3D substrate conditions for cell growth and odontogenic development. PMID:21772958

Nam, Sunyoung; Won, Jong-Eun; Kim, Cheol-Hwan; Kim, Hae-Won

2011-01-01

333

Injectable Calcium Phosphate Cement: Effects of Powder-to-Liquid Ratio and Needle Size  

PubMed Central

Calcium phosphate cement (CPC) sets in situ and forms apatite with excellent osteoconductivity and bone-replacement capability. The objectives of this study were to formulate an injectable tetracalcium phosphate-dicalcium phosphate cement (CPCD), and investigate the powder/liquid ratio and needle-size effects. The injection force (mean ± SD; n = 4) to extrude the paste increased from (8 ± 2) N using a 10-gauge needle to (144 ± 17) N using a 21-gauge needle (p < 0.05). With the 10-gauge needle, the mass percentage of extruded paste was (95 ± 4)% at a powder/liquid ratio of 3; it decreased to (70 ± 12)% at powder/liquid = 3.5 (p < 0.05). A relationship was established between injection force, F, and needle lumen cross-sectional area, A: F = 5.0 + 38.7/A0.8. Flexural strength, S, (mean ± SD; n = 5) increased from (5.3 ± 0.8) MPa at powder/liquid = 2 to (11.0 ± 0.8) MPa at powder/liquid = 3.5 (p < 0.05). Pore volume fraction, P, ranged from 62.4% to 47.9%. A relationship was established: S = 47.7 × (1 - P)2.3. The strength of the injectable CPCD matched/exceeded the reported strengths of sintered porous hydroxyapatite implants that required machining. The novel injectable CPCD with a relatively high strength may be useful in filling defects with limited accessibility such as periodontal repair and tooth root-canal fillings, and in minimally-invasive techniques such as percutaneous vertebroplasty to fill the lesions and to strengthen the osteoporotic bone. PMID:17635038

Burguera, Elena F.; Sun, Limin

2009-01-01

334

Passive and active in vitro resorption of calcium and magnesium phosphate cements by osteoclastic cells.  

PubMed

Biocements are clinically applied materials for bone replacement in non-load-bearing defects. Depending on their final composition, cements can be either resorbed or remain stable at the implantation site. Degradation can occur by two different mechanisms, by simple dissolution (passive) or after osteoclastic bone remodeling (active). This study investigated both the passive and active in vitro resorption behavior of brushite (CaHPO??· 2H?O), monetite (CaHPO?), calcium-deficient hydroxyapatite (CDHA; Ca?(PO?)?HPO?OH), and struvite (MgNH?PO??·?6H?O) cements. Passive resorption was measured by incubating the cement samples in a cell culture medium, whereas active resorption was determined during the surface culture of multinuclear osteoclastic cells derived from RAW 264.7 macrophages. Osteoclast formation was confirmed by showing tartrate resistant acid phosphatase (TRAP) activity on CDHA, brushite, and monetite surfaces, as well as by measuring calcitonin receptor (CT-R) expression as an osteoclast-specific protein by Western blot analysis for struvite ceramics. An absence of passive degradation and only marginally active degradation of <0.01% were found for CDHA matrices. For the secondary calcium phosphates brushite and monetite, active degradation was predominant with a cumulative Ca²+ release of 2.02 (1.20) ?mol during 13 days, whereas passive degradation released only 0.788 (0.04) ?mol calcium ions into the medium. The struvite cement was the most degradable with a passive (active) release of 9.26 (2.92) Mg²+ ions and a total weight loss of 4.7% over 13 days of the study. PMID:20673025

Grossardt, Christian; Ewald, Andrea; Grover, Liam M; Barralet, Jake E; Gbureck, Uwe

2010-12-01

335

Preparation of amorphous calcium-magnesium phosphates at pH 7 and characterization by x-ray absorption and fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Amorphous calcium-magnesium phosphates were prepared by precipitation from moderately supersaturated aqueous solutions at pH 7. Chemical analysis of the samples by ion chromatography showed that up to about 50% of the phosphate ions were protonated, the proportion increasing with the magnesium to calcium ion activity ratio in the solution. When left it contact with the supernatant, the amorphous precipitates matured to form the crystalline calcium phosphate brushite (CaHPO 4·2H 2O). The amorphous phases were characterized by X-ray absorption spectroscopy and by Fourier transform infrared spectroscopy and their properties compared with those of a basic amorphous tricalcium phosphate precipitated at pH 10. The X-ray absorption spectra near the K edge of calcium were very similar for all samples but there were differences in the infrared spectra between the basic and the more acidic salts. In the phosphate stretching region, the main band of the more acidic materials occured at higher wavenumber and was broader. Also there was a broad band of medium intensity at about 890 cm -1 whereas there was virtually no absorption band in this region in the spectrum of the amorphous tricalcium phosphate. The acidic amorphous calcium phosphates may be useful as model compounds in describing some complex biological calcium phosphates that form near neutral pH.

Holt, C.; van Kemenade, M. J. J. M.; Harries, J. E.; Nelson, L. S.; Bailey, R. T.; Hukins, D. W. L.; Hasnain, S. S.; De Bruyn, P. L.

1988-10-01

336

Calcium phosphate granules in the hepatopancreas of the blue crab Callinectes sapidus.  

PubMed

The hepatopancreas of the adult male blue crab Callinectes sapidus in intermolt was found to contain substantial amounts of calcium, magnesium, and inorganic phosphorus, averaging about 260, 20, and 250 microg-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 electron densities suggestive of high mineral content. After fractionation of the tissue using centrifugal techniques, almost 95% of the total mineral was found to reside in a heavy, nonmitochondrial particulate fraction(s). The bulk of the low-speed pellet consisted of relatively dense, roughly spherical granules 1-5 microm in diameter, which could be considerably purified by repeated suspension in water and low-speed sedimentation. In the electron microscope the isolated granules appeared basically similar to one of the three characteristic types of electron-dense granules seen in the intact tissue. Although the freshly isolated granules lost approximately 50% of their wet weight when dried at 105 degrees C, only 10% more was lost upon dry ashing at 450 degrees C, suggesting a fairly low content of organic material. Chemical analysis revealed calcium, magnesium, and inorganic phosphate at 5.7, 2.1, and 4.4 microg-atoms per mg dried granules, respectively, accounting for 69% of the dry weight of the fraction. By specific enzymatic assays, the freshly isolated granules were found to contain ATP, ADP, and AMP at levels of 0.13, 0.03, and 0.01 micromol/mg, or 8% of their total dry weight. The remainder of the total phosphorus contributed an additional 3%, whereas carbonate, citrate, oxalate, and protein each constituted no more than 1%. The mineral granules of the crab hepatopancreas appear to function as storage forms of calcium and phosphate during the intermolt period. This tissue appears promising as a model for study of the cellular events associated with biological calcification, since conventional biochemical techniques can be employed. Furthermore, the major mineralized component of the tissue can be obtained in large amounts for direct study by a simple fractionation procedure. PMID:4827907

Becker, G L; Chen, C H; Greenawalt, J W; Lehninger, A L

1974-05-01

337

CALCIUM PHOSPHATE GRANULES IN THE HEPATOPANCREAS OF THE BLUE CRAB CALLINECTES SAPIDUS  

PubMed Central

The hepatopancreas of the adult male blue crab Callinectes sapidus in 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 electron densities suggestive of high mineral content. After fractionation of the tissue using centrifugal techniques, almost 95% of the total mineral was found to reside in a heavy, nonmitochondrial particulate fraction(s). The bulk of the low-speed pellet consisted of relatively dense, roughly spherical granules 1–5 µm in diameter, which could be considerably purified by repeated suspension in water and low-speed sedimentation. In the electron microscope the isolated granules appeared basically similar to one of the three characteristic types of electron-dense granules seen in the intact tissue. Although the freshly isolated granules lost approximately 50% of their wet weight when dried at 105°C, only 10% more was lost upon dry ashing at 450°C, suggesting a fairly low content of organic material. Chemical analysis revealed calcium, magnesium, and inorganic phosphate at 5.7, 2.1, and 4.4 µg-atoms per mg dried granules, respectively, accounting for 69% of the dry weight of the fraction. By specific enzymatic assays, the freshly isolated granules were found to contain ATP, ADP, and AMP at levels of 0.13, 0.03, and 0.01 µmol/mg, or 8% of their total dry weight. The remainder of the total phosphorus contributed an additional 3%, whereas carbonate, citrate, oxalate, and protein each constituted no more than 1%. The mineral granules of the crab hepatopancreas appear to function as storage forms of calcium and phosphate during the intermolt period. This tissue appears promising as a model for study of the cellular events associated with biological calcification, since conventional biochemical techniques can be employed. Furthermore, the major mineralized component of the tissue can be obtained in large amounts for direct study by a simple fractionation procedure. PMID:4827907

Becker, Gerald L.; Chen, Chung-Ho; Greenawalt, John W.; Lehninger, Albert L.

1974-01-01

338

Dietary vitamin D intake is not associated with 25-hydroxyvitamin D3 or parathyroid hormone in elderly subjects, whereas the calcium-to-phosphate ratio affects parathyroid hormone.  

PubMed

This cross-sectional study investigates whether serum 25-hydroxyvitamin D3 [25(OH)D3] and intact parathyroid hormone (iPTH) are affected by vitamin D, calcium, or phosphate intake in 140 independently living elderly subjects from Germany (99 women and 41 men; age, 66-96 years). We hypothesized that habitual dietary intakes of vitamin D, calcium, and phosphate are not associated with 25(OH)D3 or iPTH and that body mass index confounds these associations. Serum 25(OH)D3 and iPTH were measured by an electrochemiluminescence immunoassay. Dietary intake was determined using a 3-day estimated dietary record. The median dietary intake levels of vitamin D, calcium, and phosphate were 3 ?g/d, 999 mg/d, and 1250 mg/d, respectively. Multiple regression analyses confirmed that dietary vitamin D and calcium did not affect 25(OH)D3 or iPTH; however, supplemental intakes of vitamin D and calcium were associated with 25(OH)D3 after adjustment for age, sex, body composition, sun exposure, physical activity, and smoking. In addition, phosphate intake and the calcium-to-phosphate ratio were associated with iPTH after multiple adjustments. In a subgroup analysis, calcium and vitamin D supplements, as well as phosphate intake, were associated with 25(OH)D3 and/or iPTH in normal-weight subjects only. Our results indicate that habitual dietary vitamin D and calcium intakes have no independent effects on 25(OH)D3 or iPTH in elderly subjects without vitamin D deficiency, whereas phosphate intake and the calcium-to-phosphate ratio affect iPTH. However, vitamin D and calcium supplements may increase 25(OH)D3 and decrease iPTH, even during the summer, but the impact of supplements may depend on body mass index. PMID:23890356

Jungert, Alexandra; Neuhäuser-Berthold, Monika

2013-08-01

339

Beta-type calcium phosphates with and without magnesium: From hydrolysis of brushite powder to robocasting of periodic scaffolds.  

PubMed

Several approaches have attempted to replace extensive bone loss, but each of them has their limitation. Nowadays, additive manufacture techniques have shown great potential for bone engineering. The objective of this study was to synthesize beta tricalcium phosphate (?-TCP), beta tricalcium phosphate substituted by magnesium (?-TCMP), and biphasic calcium phosphate substituted by magnesium (BCMP) via hydrolysis and produce scaffolds for bone regeneration using robocasting technology. Calcium deficient apatites, with and without magnesium were obtained by hydrolysis, calcined and physico-chemically characterized. Colorimetric cell viability assay, calcium nodule formation, and the expression of alkaline phosphatase, osteocalcin, transforming growth factor beta-1 and collagen were assessed using a mouse osteoblastic cell line (MC3T3-E1). Direct-write assembly of cylindrical periodic scaffolds was done via robotic deposition using ?-TCP, ?-TCMP, and BCMP colloidal inks. The sintered scaffolds were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, Archimede's method, and uniaxial compression test. According to the cell viability assay, the powders induced cell proliferation. Calcium nodule formation and bone markers activity suggested that the materials present potential value in bone tissue engineering. The scaffolds built by robocasting presented interconnected porous and exhibited mean compressive strength between 7.63 and 18.67 MPa, compatible with trabecular bone. PMID:24277559

Richard, Raquel C; Sader, Márcia S; Dai, Jisen; Thiré, Rossana M S M; Soares, Gloria D A

2014-10-01

340

Reconstruction of the immature craniofacial skeleton with a carbonated calcium phosphate bone cement: interaction with bioresorbable mesh.  

PubMed

Calcium phosphate cements have been recently introduced for use in craniofacial reconstruction. In the clinical setting, however, pulsations of the underlying brain and dura may interfere with the crystallization of these cements, thereby rendering their use in cranioplasty problematic. To circumvent such problems, many clinicians have interposed synthetic resorbable plates or mesh between the dura and the cement. At the present time, however, little is known about the influence of such materials or their breakdown products on the fate of calcium phosphate cements. The specific aim of this project was to evaluate the biocompatibility, osteoconductivity, and remodeling capacity of a calcium phosphate cement after implantation into experimental calvarial defects when combined with a resorbable mesh underlay. Four 10-mm diameter full-thickness calvarial defects (two frontal, two parietal) were created in each of six 3-week-old Yorkshire pigs. The defects were treated as follows: 1) empty control, 2) macroporous polylactic acid (70/30 L/DL polylactic acid [PLA]) mesh, 3) Norian CRS calcium phosphate cement, and 4) Norian CRS over PLA mesh underlay. Animals were divided into two groups. Half of the animals were killed 30 days after surgery, and half were killed 180 days after surgery, and the graft recipient sites were examined histologically. At 30 days, minimal bone ingrowth was observed in untreated calvarial defects or in those that were treated with PLA plates alone. Defects treated with the cement alone demonstrated a modest amount of new woven bone deposition, primarily at the periphery of the implants. Defects treated with calcium phosphate cement over PLA mesh underlays were characterized by remodeling and woven bone deposition at 30 days, with complete or near-complete osseous bridging of the ectocranial implant surfaces. Progressive bone ingrowth was noted in all defects at 180 days, with near-complete replacement of all Norian CRS implants by host bone. The PLA mesh remained incompletely resorbed at 180 days. No inflammatory response to the implants was observed at either time point. Calcium phosphate cement may be safely used for craniofacial reconstruction in the presence of PLA implants without compromise to its biocompatibility, osteoconductivity, or remodeling capacity. PMID:12544233

Losee, Joseph E; Karmacharya, Jagajan; Gannon, Francis H; Slemp, Alison E; Ong, Grace; Hunenko, Oksana; Gorden, Ashley D; Bartlett, Scott P; Kirschner, Richard E

2003-01-01

341

Prospective study of standalone balloon kyphoplasty with calcium phosphate cement augmentation in traumatic fractures  

PubMed Central

Prospective consecutive series cases study to investigate the clinical and radiological results of standalone balloon kyphoplasty and cement augmentation with calcium phosphate in traumatic fractures. Independent observer evaluation of radiological and computer tomography results, visual analogue scale (VAS), Roland–Morris score and complications with acute traumatic compression fractures type A, treated with a standalone balloon kyphoplasty and cement augmentation with calcium phosphate (Calcibon™); follow-up time at a mean of 30 months (24–37 months). From August 2002 to August 2003, consecutive patients with traumatic compression fractures (Magerl type A) without neurological deficit underwent standalone kyphoplasty with Calcibon. We report here the pre-, post-operative and the follow-up results, applying the VAS (0–10) for pain rating, the Roland–Morris (0–24) disability score, CT-scan examination, detailed radiographic evaluation of vertebral body (VB) deformity and segmental kyphosis measurement. The pre-operative X-ray measurements, VAS and the 7 days Roland–Morris scores are compared with the post-operative and the 30 months follow-up findings. Twenty-eight patients with 33 treated fracture levels were included in this study. The mean initial vertebral deformity (VB kyphosis) was 17°, corrected to a post-operative of 6°. We noted a loss of correction at the follow-up in comparison to the post-operative standing X-ray at 24 h of 3° vertebral deformity and 3° segmental kyphosis. The VAS score demonstrates a decrease over time from a mean of 8.7–3.1 at 7 days and to 0.8 at the last follow-up. The Roland–Morris disability score demonstrates a similar improvement. We noticed no major complications related to the procedure. The mean cement resorption after 1 year was 20.3% (0.3–35.3%) and is related to the individual biological resorption process and is not predictable. All patients with vertebral fractures as sole medical problem were discharged within 48 h. All active patients returned to the same work within 3 months with the same working ability as before the accident. Standalone balloon kyphoplasty is a potential alternative mini-invasive technique to reduce the fractures. However, due to the intrinsic characteristic of calcium phosphate cement (Calcibon) we recommend the application of this biological cement for standalone reduction and stabilisation only in fractures type A1 and A3.1 in young patient. In case of higher destruction levels of the VB, we propose the utilisation of Calcibon associated with posterior instrumentation. Having regard to the pointed out indications, our preliminary results demonstrate a new possibility to treat this kind of fractures, allowing a rapid handling of pain, early discharge and return to normal activities. PMID:17120071

Cremer, Claus; Otten, Philippe; Jakob, Roland Peter

2006-01-01

342

The effect of interfacial bonding of calcium phosphate cements containing bio-mineralized multi-walled carbon nanotube and bovine serum albumin on the mechanical properties of calcium phosphate cements  

Microsoft Academic Search

The aim of this study was to investigate the effect of adding bio-mineralized hydroxyl functionalized multi-walled carbon nanotubes (MWCNTs–OH) on the compressive strength of calcium phosphate cements (CPCs). Bovine serum albumin (BSA) was also incorporated as a protein which acts as promoter of hydroxyapatite (HA) crystal growth when bounded to CPC granules. The results show that the strong interfacial bonding

Kah Ling Low; Sharif Hussein Sharif Zein; Soon Huat Tan; David S. McPhail; Aldo R. Boccaccini

2011-01-01

343

Calcium phosphate cements loaded with basic fibroblast growth factor: delivery and in vitro cell response.  

PubMed

Combining calcium phosphate cements (CPCs) with bioactive molecules improves their bone regeneration potential. Although CPCs are highly osteoconductive, sometimes they have limited biological responses, especially in terms of cell proliferation. Here, we used basic fibroblast growth factor (bFGF) in an ?-tricalcium phosphate cement with different initial powder sizes (coarse vs. fine; designated as CPC-C and CPC-F, respectively) and investigated the behavior of bFGF loading and release, as well as the effects on osteoblast responses. bFGF was loaded at 10 ?g/ml or 25 ?g/ml onto the set form of two types of CPCs, aiming to allow penetration into the pore structure and adsorption onto the cement crystallites. The CPC formulated with fine powder (CPC-F) had higher specific surface area and smaller-sized pores and retained slightly higher amounts of bFGF within the structure. The bFGF release study performed for 3 weeks showed a sustained-release profile; after an initial rapid release over approximately 3 days, further release pattern was almost linear. Compared to CPC-F, CPC-C showed a much faster release pattern. The effects of the bFGF incorporation within CPCs on cellular responses were assessed in terms of cell proliferation using MC3T3-E1 pre-osteoblastic cells. Compared with bFGF-free CPCs (both CPC-C and CPC-F), those containing bFGF stimulated cell proliferation for up to 7 days. An inhibition study of bFGF receptor demonstrated that the improvement of cell proliferation resulted from the role of bFGF released from the CPCs. This study provides beneficial information on improving the biological properties of CPCs by combining them with specific therapeutic molecules, and particularly with bFGF, showing that the cell proliferative ability was significantly stimulated, which may have potential applications for further use in stem cell-based bone tissue engineering. PMID:22962037

Perez, Roman A; Kim, Tae-Hyun; Kim, Meeju; Jang, Jun-Hyeog; Ginebra, Maria-Pau; Kim, Hae-Won

2013-04-01

344

Short-term in vivo evaluation of zinc-containing calcium phosphate using a normalized procedure.  

PubMed

The effect of zinc-substituted calcium phosphate (CaP) on bone osteogenesis was evaluated using an in vivo normalized ISO 10993-6 protocol. Zinc-containing hydroxyapatite (ZnHA) powder with 0.3% by wt zinc (experimental group) and stoichiometric hydroxyapatite (control group) were shaped into cylindrical implants (2×6 mm) and were sintered at 1000 °C. Thermal treatment transformed the ZnHA cylinder into a biphasic implant that was composed of Zn-substituted HA and Zn-substituted ?-tricalcium phosphate (ZnHA/?ZnTCP); the hydroxyapatite cylinder was a highly crystalline and poorly soluble HA implant. In vivo tests were performed in New Zealand White rabbits by implanting two cylinders of ZnHA/?ZnTCP in the left tibia and two cylinders of HA in the right tibia for 7, 14 and 28 days. Incorporation of 0.3% by wt zinc into CaP increased the rate of Zn release to the biological medium. Microfluorescence analyses (?XRF-SR) using synchrotron radiation suggested that some of the Zn released from the biomaterial was incorporated into new bone near the implanted region. In contrast with previous studies, histomorphometric analysis did not show significant differences between the newly formed bone around ZnHA/?ZnTCP and HA due to the dissolution profile of Zn-doped CaP. Despite the great potential of Zn-containing CaP matrices for future use in bone regeneration, additional in vivo studies must be conducted to explain the mobility of zinc at the CaP surface and its interactions with a biological medium. PMID:24907765

Calasans-Maia, Monica; Calasans-Maia, José; Santos, Silvia; Mavropoulos, Elena; Farina, Marcos; Lima, Inayá; Lopes, Ricardo Tadeu; Rossi, Alexandre; Granjeiro, José Mauro

2014-08-01

345

The optimum zinc content in set calcium phosphate cement for promoting bone formation in vivo  

PubMed Central

The final aim of our study is to develop a novel calcium phosphate cement based on zinc-containing ?-tricalcium phosphate (?ZnTCP) and evaluate its potential as bonegraft material in vivo. In the present study, in vivo efficacy of zinc in hardened bodies of ?ZnTCP was explored. The hardened bodies prepared from ?ZnTCP with zinc content of 0.00, 0.04, 0.08, 0.11 and 0.19 wt % were prepared by mixing pure ?TCP or ?ZnTCP powder with 12 wt% sodium succinate solution at a solid-to-liquid ratio of 2.0. Due to the release of zinc ions into the physiological salt solution during curing, the zinc content in the hardened bodies was calculated to be 0.00, 0.03, 0.06, 0.10 and 0.18 wt%, respectively. The hardened bodies were implanted in the femora and tibia of white rabbits for 4 weeks. Histological and histomorphometric evaluation showed that the hardened body containing 0.03 wt% zinc, significantly promoted more new bone formation without evoking adverse tissue reactions than that without zinc. The hardened bodies containing 0.06 and 0.10 wt% zinc also resulted in the increase in numbers of active osteoblasts surrounding the new bone but caused inflammation at the implant sites. Results of this study indicate that the hardened body prepared with ?ZnTCP is superior to that prepared with ?TCP in promoting new bone formation due to the release of zinc ions. This study also indicates that the optimum amount of zinc in the hardened body is about 0.03 wt % to avoid inflammatory reaction. PMID:21461346

Li, Xia; Sogo, Yu; Ito, Atsuo; Mutsuzaki, Hirotaka; Ochiai, Naoyuki; Kobayashi, Takayuki; Nakamura, Satoshi; Yamashita, Kimihiro; LeGeros, Racquel Z.

2009-01-01

346

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

PubMed

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

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

2011-04-01

347

Bone regeneration using beta-tricalcium phosphate in a calcium sulfate matrix.  

PubMed

The aim of the study was the histomorphometric comparison of the osteogenic potential of beta-tricalcium phosphate (beta-TCP) alone or in a calcium sulfate matrix. Three round defects, 10 mm (diameter) x 5 mm (depth), were created on each iliac crest of 4 dogs. The defects were divided into 3 groups. Ten defects were filled with beta-TCP in a calcium sulfate (CS) matrix (Fortoss Vital; group A), 10 defects were filled with beta-TCP alone (Fortoss Resorb; group B), and 4 defects were left ungrafted to heal spontaneously (group C). All defects were left to heal for 4 months without the use of a barrier membrane. Histologic evaluation and morphometric analysis of undecalcified slides was performed using the areas of regenerated bone and graft remnants. All sites exhibited uneventful healing. In group A sites (beta-TCP/CS), complete bone formation was observed in all specimens, graft granules dominated the area, and a thin bridge of cortical bone was covering the defect. Group B (beta-TCP) defects were partially filled with new bone, the graft particles still dominated the area, while the outer cortex was not restored. In the ungrafted sites (group C), incomplete new bone formation was observed. The outer dense cortical layer was restored in a lower level, near the base of the defect. The statistical analysis revealed that the mean percentage of new bone regeneration in group A was higher than in group B (49.38% and 40.31%, respectively). A statistically significant difference existed between the 2 groups. The beta-TCP/CS group exhibited significantly higher new bone regeneration according to a marginal probability value (P = .004 < .05). The use of beta-TCP in a CS matrix produced significantly more vital new bone fill and preserved bone dimensions compared with the use of beta-TCP alone. PMID:19288885

Podaropoulos, Leonidas; Veis, Alexander A; Papadimitriou, Serafim; Alexandridis, Constantinos; Kalyvas, Demos

2009-01-01

348

Calcium/phosphate/vitamin D homeostasis and bone mass in patients after gastrectomy, vagotomy, and cholecystectomy.  

PubMed

Sixty-two outpatients were assessed and divided into the following groups: 20 patients who had had partial gastrectomy (PG group), 22 patients who had had truncal vagotomy and pyloroplasty (TV group) or high selective vagotomy (HSV group), and 20 patients who had had cholecystectomy (CH group). The patients' age ranged from 35 to 64 years (mean 45 years), and the average postoperative period was 9 years. None of the patients evidenced clinical or biochemical symptoms of malnutrition or malabsorption or of diseases affecting vitamin D metabolism. The function of the kidneys and the liver was normal. An age-matched group of volunteers served as a control group. The calcium dietary intake was determined using a standardized questionnaire; and the levels of serum calcium (Cas), phosphate (Ps), alkaline phosphatase (AP), and 25-hydroxyvitamin D [25(OH)D] and the excretion of Ca in a sample of fasting urine corrected for concurrent creatine excretion (FuCa/cr) were assessed by means of standard laboratory techniques. The bone mineral density (BMD) of the lumbar spine (L2-4) and femoral neck (neck-L) was determined by means of dual energy x-ray absorptiometry (DXA). The daily Ca dietary intake was lower than recommended (RDA) in 80% of the patients, with most of them ingesting less than 300 mg daily. The mean values of Cas, Ps, AP, and FuCa/cr did not differ from those in the controls. Significantly reduced 25(OH)D levels were observed in the PG group (7.0 ng/ml) (p < 0.001) and CH group (12.5 ng/ml) (p < 0.01) compared with the values in the control group (20.0 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7676706

Marcinowska-Suchowierska, E B; Ta?a?aj, M J; W?odarcyzk, A W; Bielecki, K; Zawadzki, J J; Brzozowski, R

1995-01-01

349

Mesenchymal stem cell response to conformal sputter deposited calcium phosphate thin films on nanostructured titanium surfaces.  

PubMed

Biomaterial surfaces that can directly induce the osteogenic differentiation of mesenchymal stem cells (MSCs) present an exciting strategy for bone tissue engineering and offers significant benefits for improving the repair or replacement of damaged or lost bone tissue. In this study, titanium nanostructures with distinctive topographical features were produced by radio frequency magnetron sputtering. The response of MSCs to the nanostructured titanium (Ti) surfaces before and after augmentation by a sputter deposited calcium phosphate (CaP) coating has been investigated. The sputtered CaP has the characteristics of a calcium enriched hydroxyapatite surface layer, as determined by X-ray photoelectron spectroscopy and X-ray diffraction studies. The sputter deposited Ti has a polycrystalline surface morphology, as confirmed by atomic force microscopy, and CaP layers deposited thereon (TiCaP) conform to this topography. The effects of these surfaces on MSC focal adhesion formation, actin cytoskeleton organization and Runx2 gene expression were examined. The Ti and TiCaP surfaces were found to promote changes in MSC morphology and adhesion known to be associated with subsequent downstream osteogenic differentiation; however, the equivalent events were not as pronounced on the CaP surface. A significant increase in Runx2 expression was observed for CaP compared to Ti, but no such difference was seen between either Ti and TiCaP, nor CaP and TiCaP. Importantly, the Ti surface engendered the expected contribution of nanoscale features to the MSC response; moreover, the CaP layer when used in combination with this topography has been found to cause no adverse effects in respect of MSC behavior. PMID:24249697

McCafferty, Mura M; Burke, George A; Meenan, Brian J

2014-10-01

350

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

SciTech Connect

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.

SUGAMA,T.; BROTHERS, L.E.

2005-01-01

351

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

PubMed

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

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

2010-01-01

352

Amorphous calcium phosphate is a major component of the forming fin bones of zebrafish: Indications for an amorphous precursor phase.  

PubMed

A fundamental question in biomineralization is the nature of the first-formed mineral phase. In vertebrate bone formation, this issue has been the subject of a long-standing controversy. We address this key issue using the continuously growing fin bony rays of the Tuebingen long-fin zebrafish as a model for bone mineralization. Employing high-resolution scanning and transmission electron microscopy imaging, electron diffraction, and elemental analysis, we demonstrate the presence of an abundant amorphous calcium phosphate phase in the newly formed fin bones. The extracted amorphous mineral particles crystallize with time, and mineral crystallinity increases during bone maturation. Based on these findings, we propose that this amorphous calcium phosphate phase may be a precursor phase that later transforms into the mature crystalline mineral. PMID:18753619

Mahamid, Julia; Sharir, Amnon; Addadi, Lia; Weiner, Steve

2008-09-01

353

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

PubMed Central

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

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

2010-01-01

354

Remineralization of Enamel Subsurface Lesions by Sugar-free Chewing Gum Containing Casein Phosphopeptide-Amorphous Calcium Phosphate  

Microsoft Academic Search

Casein phosphopeptide-amorphous calcium phosphate nanocomplexes (CPP-ACP) exhibit anticariogenic potential in laboratory, animal, and human in situ experiments. The aim of this study was to determine the ability of CPP-ACP in sugar-free chewing gum to remineralize enamel subsurface lesions in a human in situ model. Thirty subjects in randomized, cross-over, double-blind studies wore removable palatal appliances with six human-enamel half-slabs inset

P. Shen; F. Cai; A. Nowicki; J. Vincent; E. C. Reynolds

2001-01-01

355

Urinary phosphate\\/creatinine, calcium\\/creatinine, and magnesium\\/creatinine ratios in a healthy pediatric population  

Microsoft Academic Search

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

Vera Matos; Guy van Melle; Olivier Boulat; Michèle Markert; Claude Bachmann; Jean-Pierre Guignard

1997-01-01

356

Transition points in steel fibre pull-out tests from magnesium phosphate and accelerated calcium aluminate binders  

Microsoft Academic Search

Results are reported on the pull-out characteristics of two distinct types of steel fibre from two different rapid strengthening matrices, magnesia phosphate and accelerated calcium aluminate. The procedure incorporated a novel method of identifying the force necessary to initiate whole fibre movement relative to the matrix, one of the key transition points in the force\\/displacement relationship. Significantly different force\\/displacement relationships

P. Frantzis; R. Baggott

2003-01-01

357

Influence of a protein on the crystallization of calcium phosphates and carbonates from solutions simulating human blood plasma  

Microsoft Academic Search

Experiments on the steady-state crystallization of calcium phosphates and carbonates from aqueous solutions simulating human blood plasma under typical physiological conditions (37.0 +\\/- 0.2degreesC and pH 7.35 +\\/- 0.05) were performed. The influence of a dissolved protein (bovine serum albumin) on the crystallization was studied. It was found that the amorphism of the precipitate increases with the concentration of the

S V Dorozhkin

2004-01-01

358

Effect of biphasic calcium phosphates on drug release and biological and mechanical properties of poly(?-caprolactone) composite membranes  

Microsoft Academic Search

Poly(-caprolactone) (PCL) and biphasic calcium phosphate (CaP) composite membranes were prepared for use in tissue regeneration by a novel solvent casting-press- ing method. An antibiotic drug, tetracycline hydrochloride (TCH), was entrapped within the membranes to investigate the efficacy of the material as a drug delivery system. The CaP powders were varied in amount (0 -50 wt %) and in powder

Hae-Won Kim; Jonathan C. Knowles; Hyoun-Ee Kim

2004-01-01

359

Bone regeneration using an injectable calcium phosphate\\/autologous iliac crest bone composites for segmental ulnar defects in rabbits  

Microsoft Academic Search

Background Treatment of segmental bone loss remains a challenge in skeletal repair. A major therapeutic goal is the development of implantable\\u000a materials that will promote bone regeneration. Objective We evaluate bone regeneration in grafts containing different concentrations autologous iliac crest bone (ACB) particles,\\u000a carried in a new injectable calcium phosphate cement (CPC), in ulnar bone defects in rabbits. Methods Large

Yao Weitao; Kong Kangmei; Wang Xinjia; Qi Weili

2008-01-01

360

Periodontal regeneration in experimentally-induced alveolar bone dehiscence by an improved porous biphasic calcium phosphate ceramic in beagle dogs  

Microsoft Academic Search

Regeneration of lost periodontium is the focus of periodontal therapy. To achieve the effective regeneration, a number of\\u000a bone graft substitute materials have been developed. This study aimed to investigate the histological response in alveolar\\u000a bone dehiscences which were filled with an improved biphasic calcium phosphate (BCP) ceramic with more reasonable pore diameter,\\u000a pore wall thickness and porosity. Twenty-four alveolar

Han Shi; Jia Ma; Ning Zhao; Yangxi Chen; Yunmao Liao

2008-01-01

361

nutrient Requirements and Interactions Cytotoxicity of Fecal Water Is Dependent on the Type of Dietary Fat and Is Reduced by Supplemental Calcium Phosphate in Rats1  

Microsoft Academic Search

The effects of the type of dietary fat (180 g\\/kg diet) and of calcium phosphate (CaHPCXi)sup plementation (25 vs. 225 mmol\\/kg diet) on luminal solubility of fatty acids and bile acids, cytotoxicity of fecal water and intestinal epitheliolysis were studied in rats. In rats fed the low and high calcium phosphate diets, fecal excretion of fatty acids diminished in the

JOHN A. LAPRÃ; HIELKE T. DE VRIES; ANDROELOF VAN DER MEER

362

Novel composites materials from functionalized polymers and silver coated titanium oxide capable for calcium phosphate induction, control of orthopedic biofilm infections: an “in vitro” study  

Microsoft Academic Search

Three copolymers containing the functional groups P=O, S=O and C=O were prepared, and upon the introduction in calcium phosphate\\u000a aqueous solutions at physiological conditions, “in vitro” were induced the precipitation of calcium phosphate crystals. The\\u000a investigation of the crystal growth process was done at constant supersaturation. It is suggested that the negative end of\\u000a the above functional groups acts as

M. Tyllianakis; E. Dalas; M. Christofidou; J. K. Kallitsis; A. Chrissanthopoulos; P. G. Koutsoukos; C. Bartzavali; N. Gourdoupi; K. Papadimitriou; E. K. Oikonomou; S. N. Yannopoulos; D. Sevastos

2010-01-01

363

In vivo bone regeneration with injectable calcium phosphate biomaterial: A three-dimensional micro-computed tomographic, biomechanical and SEM study  

Microsoft Academic Search

This in vivo study investigated the efficiency of an injectable calcium phosphate bone substitute (IBS) for bone regenerative procedures through non-destructive three-dimensional (3D) micro-tomographic (?CT) imaging, biomechanical testing with a non-destructive micro-indentation technique and 2D scanning electron microscopy (SEM) analysis. The injectable biomaterial was obtained by mixing a biphasic calcium phosphate (BCP) ceramic mineral phase and a cellulosic polymer. The

Olivier Gauthier; Ralph Müller; Dietrich von Stechow; Bernard Lamy; Pierre Weiss; Jean-Michel Bouler; Eric Aguado; Guy Daculsi

2005-01-01

364

Effects of paricalcitol on calcium and phosphate metabolism and markers of bone health in patients with diabetic nephropathy: results of the VITAL study  

PubMed Central

Background Chronic kidney disease (CKD) is associated with elevations in serum phosphate, calcium–phosphorus product and bone-specific alkaline phosphatase (BAP), with attendant risks of cardiovascular and bone disorders. Active vitamin D can suppress parathyroid hormone (PTH), but may raise serum calcium and phosphate concentrations. Paricalcitol, a selective vitamin D activator, suppressed PTH in CKD patients (stages 3 and 4) with secondary hyperparathyroidism (SHPT) with minimal changes in calcium and phosphate metabolism. Methods The VITAL study enrolled patients with CKD stages 2–4. We examined the effect and relationship of paricalcitol to calcium and phosphate metabolism and bone markers in a post hoc analysis of VITAL. The study comprised patients with diabetic nephropathy enrolled in a double-blind, placebo-controlled, randomized trial of paricalcitol (1 or 2 ?g/day). Urinary and serum calcium and phosphate, serum BAP, and intact PTH (iPTH) concentrations were measured throughout the study. Results Baseline demographics and calcium, phosphate, PTH (49% with iPTH <70 pg/mL), and BAP concentrations were similar between groups. A transient, modest yet significant increase in phosphate was observed for paricalcitol 2 ?g/day (+0.29 mg/dL; P < 0.001). Dose-dependent increases in serum and urinary calcium were observed; however, there were few cases of hypercalcemia: one in the 1-?g/day group (1.1%) and three in the 2-?g/day group (3.2%). Significant reductions in BAP were observed that persisted for 60 days after paricalcitol discontinuation (P < 0.001 for combined paricalcitol groups versus placebo). Paricalcitol dose-dependent reductions in iPTH were observed. Paricalcitol in CKD patients (±SHPT) was associated with modest increases in calcium and phosphate. Conclusion Paricalcitol reduces BAP levels, which may be beneficial for reducing vascular calcification. Trial registration Trial is registered with ClinicalTrials.gov, number NCT00421733. PMID:23787544

Coyne, Daniel W.; Andress, Dennis L.; Amdahl, Michael J.; Ritz, Eberhard; de Zeeuw, Dick

2013-01-01

365

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

PubMed Central

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

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

2013-01-01

366

Pegylated siRNA-loaded calcium phosphate nanoparticle-driven amplification of cancer cell internalization in vivo  

PubMed Central

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

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

367

Use of gastrointestinal proton pump inhibitors to regulate osteoclast-mediated resorption of calcium phosphate cements in vivo.  

PubMed

Osteoclasts degrade bone through the creation of an enclosed, acidic extracellular microenvironment adjacent to the bone surface. Membrane bound proton pumps in the osteoclast cell membrane function to create this acidified environment. Accordingly, this H(+) ion transport mechanism provides a potential target for a specific class of drugs, proton pump inhibitors (PPI), with a view to controlling osteoclast mediated bone resorption. Self setting calcium phosphate cements are common bone graft materials that are degraded by osteoclastic activity. We have already shown that incorporation of bafilomycin, a non-regulated PPI, within these cements prevents or delays osteoclast mediated resorption of the cement. We demonstrate here that two regulated proton pump inhibitors, Pantaprazole and Omeprazole, currently used clinically to treat gastroesophageal reflux disorders, are effective in inhibiting osteoclast mediated resorption in-vivo when delivered to a bony defect in self setting calcium phosphate cements. As determined by qualitative histology, Pantaprazole at a dose of 0.5mg/ml produced a delay in osteoclast resorption whilst this effect was not as evident using Omeprazole at an equivalent dose, but higher doses of Omeprazole (40mg/ml) did delay cement resorption. These data demonstrate, for the first time, the functional effect of blocking the H(+)/K(+) ATPase pump in-vivo on the capacity of osteoclasts to resorb bone and the potential of this strategy to modulate osteoclast mediated resorption of calcium phosphate biomaterials. PMID:19450226

Sheraly, A R; Lickorish, D; Sarraf, F; Davies, J E

2009-04-01

368

Potentiostatic pulse-deposition of calcium phosphate on magnesium alloy for temporary implant applications - An in vitro corrosion study.  

PubMed

In this study, a magnesium alloy (AZ91) was coated with calcium phosphate using potentiostatic pulse-potential and constant-potential methods and the in vitro corrosion behaviour of the coated samples was compared with the bare metal. In vitro corrosion studies were carried out using electrochemical impedance spectroscopy and potentiodynamic polarization in simulated body fluid (SBF) at 37°C. Calcium phosphate coatings enhanced the corrosion resistance of the alloy, however, the pulse-potential coating performed better than the constant-potential coating. The pulse-potential coating exhibited ~3 times higher polarization resistance than that of the constant-potential coating. The corrosion current density obtained from the potentiodynamic polarization curves was significantly less (~60%) for the pulse-deposition coating as compared to the constant-potential coating. Post-corrosion analysis revealed only slight corrosion on the pulse-potential coating, whereas the constant-potential coating exhibited a large number of corrosion particles attached to the coating. The better in vitro corrosion performance of the pulse-potential coating can be attributed to the closely packed calcium phosphate particles. PMID:25427473

Kannan, M Bobby; Wallipa, O

2013-03-01

369

Electrospun gelatin/poly(?-caprolactone) fibrous scaffold modified with calcium phosphate for bone tissue engineering.  

PubMed

In this study gelatin (Gel) modified with calcium phosphate nanoparticles (SG5) and polycaprolactone (PCL) were used to prepare a 3D bi-layer scaffold by collecting electrospun PCL and gelatin/SG5 fibers separately in the same collector. The objective of this study was to combine the desired properties of PCL and Gel/SG5 in the same scaffold in order to enhance mineralization, thus improving the ability of the scaffold to bond to the bone tissue. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the wide angle X-ray diffraction (WAXD) measurements confirmed that SG5 nanoparticles were successfully incorporated into the fibrous gelatin matrix. The composite Gel/SG5/PCL scaffold exhibited more enhanced mechanical properties than individual Gel and Gel/SG5 scaffolds. The presence of SG5 nanoparticles accelerated the nucleation and growth of apatite crystals on the surface of the composite Gel/SG5/PCL scaffold in simulated body fluid (SBF). The osteoblast response in vitro to developed electrospun scaffolds (PCL and Gel/SG5/PCL) was investigated by using normal human primary NHOst cell lines. NHOst cell culture studies showed that higher alkaline phosphatase (ALP) activity and better mineralization were obtained in the case of composite materials than in pure PCL scaffolds. The mechanically strong PCL scaffold served as a skeleton, while the Gel/SG5 fibers facilitated cell spreading and mineralization of the scaffold. PMID:25280695

Rajzer, Izabella; Menaszek, El?bieta; Kwiatkowski, Ryszard; Planell, Josep A; Castano, Oscar

2014-11-01

370

Zero Echo Time Magnetic Resonance Imaging of Contrast-Agent-Enhanced Calcium Phosphate Bone Defect Fillers  

PubMed Central

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

Sun, Yi; Ventura, Manuela; Oosterwijk, Egbert; Jansen, John A.; Walboomers, X. Frank

2013-01-01

371

The effect of discrete calcium phosphate nanocrystals on bone-bonding to titanium surfaces.  

PubMed

We sought to address the question: Can metallic surfaces be rendered bone-bonding? We employed dual acid-etched (DAE) commercially pure titanium (cpTi) and titanium alloy (Ti6Al4V) custom-made rectangular coupons (1.3 mm x 2.5 mm x 4 mm) with, or without, further modification by the discrete crystalline deposition (DCD) of calcium phosphate (CAP) nanocrystals. A total of 48 implants comprising four groups were placed bilaterally in the distal femur of male Wistar rats for 9 days. After harvesting, the bone immediately proximal and distal to the implant was removed, resulting in a test sample comprising the implant with two attached cortical arches. The latter were distracted at 30 mm/min, in an Instron machine, and the disruption force was recorded. Results showed that alloy samples exhibited greater disruption forces than cpTi, and that DCD samples had statistically significantly greater average disruption forces than non-DCD samples. The bone-bonding phenomenon was visually evident by fracture of the cortical arches and an intact bone/implant interface. Field emission scanning electron microscopy showed the bone/implant interface was occupied by a bony cement line matrix that was interlocked with the surface topographical features of the implant. We conclude that titanium implant surfaces can be rendered bone-bonding by an increase in the complexity of the surface topography. PMID:17697709

Mendes, Vanessa C; Moineddin, Rahim; Davies, John E

2007-11-01

372

Effects of adding resorbable chitosan microspheres to calcium phosphate cements for bone regeneration.  

PubMed

Calcium phosphate cements (CPCs) have been widely used as bone graft substitutes. However, the undesirable osteoinductivity and slow degradability of CPCs greatly hamper their clinical application. The aim of this study was to synthesize a type of injectable, bioactive cement. This was accomplished by incorporating chitosan microspheres into CPC. CPC containing chitosan microspheres was analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD showed that the hardened chitosan microsphere/CPC with different proportions of microspheres contained diffraction peaks of hydroxyapatite and chitosan. Compressive strength and dissolution in simulated body fluid were measured. The chitosan microsphere/CPC containing 10% (w/w) chitosan microspheres had a compressive strength of 14.78 ± 0.67 MPa. Cavity defects were created in both femoral condylar regions of New Zealand White rabbits. Chitosan microsphere/CPC (composite group) and ?-TCP/CPC (control group) were implanted separately into the bone defects of both femurs. X-ray analysis was performed to observe the filling of these bone defects 3 days after surgery. The extent of bone substitute degradation and new bone formation were evaluated by SEM and histological examination at 8, 16, and 24 weeks after implantation. These results showed far more new bone formation and degradation of the chitosan microsphere/CPC composite in the bone defects. These data indicate that a chitosan microsphere/CPC composite might be considered as a promising injectable material for the generation of new bone tissue. PMID:25492197

Meng, Dan; Dong, Limin; Wen, Ying; Xie, Qiufei

2015-02-01

373

Fluorescent labeling analysis and electron probe microanalysis for alveolar ridge augmentation using calcium phosphate cement.  

PubMed

Our previous histopathological study showed that the augmentation block, prepared from a calcium phosphate cement (CPC) mixed with H2O at powder to liquid ratio of 5 g/mL, placed on the alveolar bone ridge, was gradually replaced by natural bone. In the present study, fluorescent labeling analysis (FLA) and electron probe microanalysis (EPMA) were performed on the same surgical site of the above histopathological study. Fluorescent labeling agents, that would be incorporated into newly formed mineralized tissues, were injected into dogs intramuscularly twice a week during the 3 week period that ended 1 week before sacrifice. The specimens obtained from the block were subjected to FLA for assessing the extent of new bone formation and to EPMA for measuring the elemental (Ca, P, Mg) distributions. FLA results showed the presence of newly formed bone at 1 month after surgery. EPMA results showed that the elemental distributions in the augmentation site were similar to those of the residual bone area at 6 months after surgery. FLA and EPMA examinations also indicated that the implants were surrounded and fixed by natural bone chronologically. A CPC augmentation block is clearly useful for alveolar ridge augmentation and osteointegrated implant fixation. PMID:12608419

Fujikawa, Kenji; Sugawara, Akiyoshi; Kusama, Kaoru; Nishiyama, Minoru; Murai, Seidai; Takagi, Shozo; Chow, Laurence C

2002-12-01

374

In vitro bioactivity and biocompatibility of calcium phosphate cements using Hydroxy-propyl-methyl-Cellulose (HPMC)  

NASA Astrophysics Data System (ADS)

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.

Jyoti, M. Anirban; Thai, Van Viet; Min, Young Ki; Lee, Byong-Taek; Song, Ho-Yeon

2010-12-01

375

Bioactivity and corrosion properties of gelatin-containing and strontium-doped calcium phosphate composite coating  

NASA Astrophysics Data System (ADS)

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.

Huang, Yong; Yan, Yajing; Pang, Xiaofeng; Ding, Qiongqiong; Han, Shuguang

2013-10-01

376

Biphasic calcium phosphate coating on cobalt-base surgical alloy during investment casting.  

PubMed

The biphasic calcium phosphate (BCP) yields higher bioactivity and efficiency than the Hydroxyapatite (HA) alone. The HA/?-TCP ratio significantly affects BCP bioactivity as well as the extent of BCP resorption. In this study, the BCP coating on ASTM F-75 cobalt base alloy during the investment casting process was investigated. For this purpose, molten metal was poured at 1,470°C into previously coated investment molds preheated to 750, 850, 950, 1,050°C in order to investigate the effect of mold preheating temperatures on coating phase transformations. For in vitro evaluation, samples were immersed in the simulated body fluid (SBF) at 37°C for 4 weeks and characterized by XRD, SEM, EDS, and optical microscopy. The weight percentages of HA and ?-TCP of the specimens were calculated to find that the HA/?-TCP ratio significantly depended on the mold preheating temperature as it caused changes in the dissolution behavior of BCP coating and the bone-like apatite precipitation on coating during in vitro evaluation. PMID:21894538

Minouei, H; Meratian, M; Fathi, M H; Ghazvinizadeh, H

2011-11-01

377

The Role of Carboxydothermus hydrogenoformans in the Conversion of Calcium Phosphate from Amorphous to Crystalline State  

PubMed Central

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

Haddad, Mathieu; Vali, Hojatollah; Paquette, Jeanne; Guiot, Serge R.

2014-01-01

378

Calcium-phosphate-hybridized tendon directly promotes regeneration of tendon-bone insertion.  

PubMed

We developed a novel technique to improve tendon-bone attachment by hybridizing calcium phosphate (CaP) with tendons using an alternate soaking process. We characterized the deposited CaP on or in tendons and determined the healing process of anterior cruciate ligament (ACL) grafts by implanting CaP-hybridized free tendons in bone tunnels intra-articularly. Tendons to be implanted were alternately soaked 10 times in a Ca-containing solution and a PO(4)-containing solution for 30 s each. Treated tendons had ash contents threefold that of untreated tendons. Low-crystallinity apatite was found on or in treated tendons. In animal experiments, the CaP-hybridized tendon exhibited osteoclasts at the tendon-bone interface at 5 days after operation. At 2 weeks after operation, there were more osteoclasts and osteoblasts around the tendon than at 5 days after operation. Directly bonded areas were partially found between the implanted tendon and newly formed bone. The formation of a cartilage layer was partially apparent at 3 weeks after operation. The newly formed bone was observed almost around the tendon. We conclude that CaP-hybridized tendons clearly enhance the healing process of ACL grafts at the tendon-bone interface and regenerate a direct insertion-like formation of tendons similar to a normal healthy ACL insertion within 3 weeks after operation. PMID:15227677

Mutsuzaki, Hirotaka; Sakane, Masataka; Nakajima, Hiromi; Ito, Atsuo; Hattori, Shinya; Miyanaga, Yutaka; Ochiai, Naoyuki; Tanaka, Junzo

2004-08-01

379

Solution growth of spherulitic rod and platelet calcium phosphate assemblies through polymer-assisted mesoscopic transformations.  

PubMed

Solution growth of apatite its precursors in the presence of urea commercial gelatin is found to lead, under appropriate conditions, to a rich spectrum of morphologies, among them high aspect ratio needles in uniform sturdy spherulitic assemblies resulting from a herein documented morphological 'Chrysalis Transformation'; the latter transformation involves the growth of parallel arrays of high aspect ratio needles within micron-scale tablets the formation of a radial needle arrangement upon disruption of tablet wrapping. A different level of gelatin leads to the formation of sturdy platelet-based spherulites through another morphological transformation. We also probe the role of four simple synthetic water-soluble polymers; we find that three of them (poly(vinyl alcohol), polyvinylpyrrolidone and polyacrylamide)) also affect substantially the assembly habits of apatite; the effect is similar to that of gelatin but the attained control is less perfect/complete. The case of poly(vinyl alcohol) provides, through variation of the degree of hydrolysis, insights as regards the chain architecture features that might favor morphological transformations. Morphological transformations of particle assemblies documented herein constitute novel ways of generating dense quasi-isotropic reinforcements with high aspect ratio ceramic particles; it becomes possible to tailor calcium phosphate phases at the structural level of crystal assembly. PMID:23498246

Kosma, Vassiliki A; Beltsios, Konstantinos G

2013-05-01

380

Characterization and properties of novel gallium-doped calcium phosphate ceramics.  

PubMed

Addition of a gallium (Ga) precursor in the typical reaction protocols used for the preparation of ?-tricalcium phosphate (?-TCP) led to novel Ga-doped ?-TCP ceramics with rhombohedral structures (R3c space group). From the refinement of their X-ray diffraction patterns, it was found that the incorporation of Ga in the ?-TCP network occurs by substitution of one of the five calcium (Ca) sites, while occupation of another Ca site decreases in inverse proportion to the Ga content in the structure. The Ga local environment and the modification of the phosphorus environments due to the Ga/Ca substitution in Ga-doped ?-TCP compounds are probed using (31)P and (71)Ga magic-angle spinning NMR. A decrease of the unit cell volume is observed with increasing Ga content, together with improved mechanical properties. Indeed, the compressive strength of these new bioceramics is enhanced in direct proportion of the Ga content, up to a 2.6-fold increase as compared to pure ?-TCP. PMID:21793526

Mellier, Charlotte; Fayon, Franck; Schnitzler, Verena; Deniard, Philippe; Allix, Mathieu; Quillard, Sophie; Massiot, Dominique; Bouler, Jean-Michel; Bujoli, Bruno; Janvier, Pascal

2011-09-01

381

Calcium phosphate coated Keratin-PCL scaffolds for potential bone tissue regeneration.  

PubMed

The incorporation of hydroxyapatite (HA) nanoparticles within or on the surface of electrospun polymeric scaffolds is a popular approach for bone tissue engineering. However, the fabrication of osteoconductive composite scaffolds via benign processing conditions still remains a major challenge to date. In this work, a new method was developed to achieve a uniform coating of calcium phosphate (CaP) onto electrospun keratin-polycaprolactone composites (Keratin-PCL). Keratin within PCL was crosslinked to decrease its solubility, before coating of CaP. A homogeneous coating was achieved within a short time frame (~10min) by immersing the scaffolds into Ca(2+) and (PO4)(3-) solutions separately. Results showed that the incorporation of keratin into PCL scaffolds not only provided nucleation sites for Ca(2+) adsorption and subsequent homogeneous CaP surface deposition, but also facilitated cell-matrix interactions. An improvement in the mechanical strength of the resultant composite scaffold, as compared to other conventional coating methods, was also observed. This approach of developing a biocompatible bone tissue engineering scaffold would be adopted for further in vitro osteogenic differentiation studies in the future. PMID:25687004

Zhao, Xinxin; Lui, Yuan Siang; Choo, Caleb Kai Chuen; Sow, Wan Ting; Huang, Charlotte Liwen; Ng, Kee Woei; Tan, Lay Poh; Loo, Joachim Say Chye

2015-04-01

382

Arterial Calcification in Chronic Kidney Disease: Key Roles for Calcium and Phosphate  

PubMed Central

Vascular calcification contributes to the high risk of cardiovascular mortality in chronic kidney disease (CKD) patients. Dysregulation of calcium (Ca) and phosphate (P) metabolism is common in CKD patients, and drives vascular calcification. In this article, we review the physiological regulatory mechanisms for Ca and P homeostasis and the basis for their dysregulation in CKD. In addition, we highlight recent findings indicating that elevated Ca and P have direct effects on vascular smooth muscle cells (VSMCs) that promote vascular calcification, including stimulation of osteo/chondrogenic differentiation, vesicle release, apoptosis, loss of inhibitors, and ECM matrix degradation. These studies suggest a major role for elevated P in promoting osteo/chondrogenic differentiation of VSMC, whereas elevated Ca has a predominant role in promoting VSMC apoptosis and vesicle release. Furthermore, the effects of elevated Ca and P are synergistic providing a major stimulus for vascular calcification in CKD. Unravelling the complex regulatory pathways that mediate the effects of both Ca and P on VSMCs will ultimately provide novel targets and therapies to limit the destructive effects of vascular calcification in CKD patients. PMID:21885837

Shanahan, Catherine M.; Crouthamel, Matthew H.; Kapustin, Alexander; Giachelli, Cecilia M.

2011-01-01

383

Mechanical testing and osteointegration of titanium implant with calcium phosphate bone cement and autograft alternatives.  

PubMed

The purpose of this study was to evaluate the osteointegration of a titanium (Ti) implant with the calcium phosphate cement (CPC) and autograft prostheses by pull-out test and histological examination. Stems of sixty Ti cylinders were bilaterally inserted into femoral medullary canals in 30 rabbits at the 1st, 4th, 12th, 26th and 70th postoperative weeks. The bone autograft and CPC were filled into the pre-trimmed bone marrow cavity with a polymethyl methacrylate retarder in the distal end, and then a Ti cylinder was inserted into femurs. The CPC group was significantly (p<0.05) associated with a larger pull-out force at 4th (37%) and 12th (62%) weeks compared to the autograft group. The bone area and the bone-to-implant contact ratios of the CPC groups were significantly higher than that of the autograft groups at early healing stage. The histological exams suggest that the CPC enhanced the earlier bone formation around the implant at a period not longer than 12 weeks postoperation. We conclude that CPC graft has the higher ability to facilitate the osteointegration and stabilize the Ti implant at a relatively early stage than the autograft in vivo. PMID:21783127

Lin, Dan-Jae; Ju, Chien-Ping; Huang, Shu-Huei; Tien, Yin-Chun; Yin, Hsiang-Shu; Chen, Wen-Cheng; Chern Lin, Jiin-Huey

2011-10-01

384

Effect of surface roughness and calcium phosphate coating on the implant/bone response.  

PubMed

The influence of surface roughness and calcium phosphate (Ca-P) coating on the bone response of titanium implants was investigated. Four types of titanium implants, i.e. as-machined, grit blasted, as-machined with Ca-P sputter coating, and grit blasted with Ca-P sputter coating, were prepared. The Ca-P sputter-coating, produced by using the RF magnetron sputter technique, was rapid heat-treated with infrared radiation at 600 degrees C. These implants were inserted into the left and right femoral condyles and the left and right tibial diaphyses of the rabbits. After implantation periods of 2 and 12 weeks, the bone-implant interface was evaluated histologically and histomorphometrically. Histological evaluation revealed no new bone formation around different implant materials after 2 weeks of implantation. After 12 weeks, bone healing was almost completed. For both tibial and femoral implants, Ca-P coated implants always showed a higher amount of bone contact than either of the non-coated implants. On the other hand, surface roughness improved only the response to implants inserted into the tibial diaphysis. On the basis of these findings, we concluded that 1) deposition of a sputtered Ca-P coating on an implant has a beneficial effect on the bone response to this implant during the healing phase, and 2) besides implant surface conditions the bone response is also determined by local implant site conditions. PMID:11168222

Hayakawa, T; Yoshinari, M; Nemoto, K; Wolke, J G; Jansen, J A

2000-08-01

385

Mixed zirconia calcium phosphate coatings for dental implants: Tailoring coating stability and bioactivity potential.  

PubMed

Enhanced coating stability and adhesion are essential for long-term success of orthopedic and dental implants. In this study, the effect of coating composition on mechanical, physico-chemical and biological properties of coated zirconia specimens is investigated. Zirconia discs and dental screw implants are coated using the wet powder spraying (WPS) technique. The coatings are obtained by mixing yttria-stabilized zirconia (TZ) and hydroxyapatite (HA) in various ratios while a pure HA coating served as reference material. Scanning electron microscopy (SEM) and optical profilometer analysis confirm a similar coating morphology and roughness for all studied coatings, whereas the coating stability can be tailored with composition and is probed by insertion and dissections experiments in bovine bone with coated zirconia screw implants. An increasing content of calcium phosphate (CP) resulted in a decrease of mechanical and chemical stability, while the bioactivity increased in simulated body fluid (SBF). In vitro experiments with human osteoblast cells (HOB) revealed that the cells grew well on all samples but are affected by dissolution behavior of the studied coatings. This work demonstrates the overall good mechanical strength, the excellent interfacial bonding and the bioactivity potential of coatings with higher TZ contents, which provide a highly interesting coating for dental implants. PMID:25579931

Pardun, Karoline; Treccani, Laura; Volkmann, Eike; Streckbein, Philipp; Heiss, Christian; Li Destri, Giovanni; Marletta, Giovanni; Rezwan, Kurosch

2015-03-01

386

Effect of methotrexate on the mechanical properties and microstructure of calcium phosphate cement.  

PubMed

Calcium phosphate cement (CPC) is widely used as an antitumor bone-filling material. Methotrexate (MTX) is recognized as an effective chemotherapy medicine. The current study examined the effects of MTX on the mechanical properties and microstructure of CPC. Methotrexate-loaded CPC at mass ratios of 0%, 0.1%, 0.2%, and 0.5% were designated as groups A, B, C, and D, respectively, and were pressed into precast cylindrical molds. Solidification time, axial compressive strength, transverse compressive strength, and rotational tensile strength were measured, and scanning electron microscopy images were captured before and after MTX-CPC microstructure changes occurred. Average initial and final setting times increased gradually with increasing drug concentration, but this increase was not significant among the groups. Average axial transverse compressive strength and rotational tensile strength of groups B and C were not significantly different from those of group A (P>.05); however, there was a significant difference in these properties between groups A and D (P<.05). Scanning electron microscopy observations showed a porous crystalline structure. The addition of MTX to CPC does not significantly affect the basic crystal structure and setting time of CPC. Adding MTX at mass ratios of 0.1% and 0.2% to CPC does not lead to a significant difference in mechanical strength and can therefore be applied in clinical practice. This study may shed some light on the future application of MTX-loaded CPC in the treatment of bone defects after tumor excision. PMID:25275979

Liao, Guangjun; Sun, Dongxiu; Han, Jian; Tan, Jiangwei

2014-10-01

387

Improving the packing density of calcium phosphate coating on a magnesium alloy for enhanced degradation resistance.  

PubMed

In this study, an attempt was made to improve the packing density of calcium phosphate (CaP) coating on a magnesium alloy by tailoring the coating solution for enhanced degradation resistance of the alloy for implant applications. An organic solvent, ethanol, was added to the coating solution to decrease the conductivity of the coating solution so that hydrogen bubble formation/bursting reduces during the CaP coating process. Experimental results confirmed that ethanol addition to the coating solution reduces the conductivity of the solution and also decreases the hydrogen evolution/bubble bursting. In vitro electrochemical experiments, that is, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization showed that CaP coating produced in 30% (v/v) ethanol containing coating solution (3E) exhibits significantly higher degradation resistance (i.e., ~50% higher polarization resistance and ~60% lower corrosion current) than the aqueous solution coating. Scanning electron microscope (SEM) analysis of the coatings revealed that the packing of 3E coating was denser than that of aqueous coating, which can be attributed to the lower hydrogen evolution in the former than in the latter. Further increase in the ethanol content in the coating solution was not beneficial; in fact, the coating produced in 70% (v/v) ethanol containing solution (7E) showed degradation resistance much inferior to that of the aqueous coating, which is due to low thickness of 7E coating. PMID:23008190

Kannan, M Bobby

2013-05-01

388

Macroporous calcium phosphate ceramic: a prospective study of 106 cases in lumbar spinal fusion.  

PubMed

Macroporous biphasic calcium phosphate (MBCP, Triosite) is well known for its safety, absence of allergenicity, and excellent bone-bonding capacity, and it has been widely used as a bone graft substitute in orthopaedic, ENT, and dental surgery. This study investigates the clinical performance of this synthetic porous ceramic in a series of 106 patients, mainly with degenerative spine aetiologies (95/106) and with a minimum follow-up of 2 years. All patients were treated with posterior correction involving the semi-rigid New Orleans instrumentation. Spinal fusion was always performed using MBCP granules mixed with autogenous bone chips and bone marrow obtained from the local spine. Fusion of the spine was confirmed for 100 patients, and 6 non-unions were observed (3 resulting from primary spondylolisthesis). This study shows that MBCP provides suitable results in spinal fusion involving a semi-rigid instrumentation. Because the indication of degenerative spine is not very favorable to fusion, this technique appears to be a good alternative to autografts and could decrease patient morbidity resulting from iliac bone grafting. PMID:10847976

Cavagna, R; Daculsi, G; Bouler, J M

1999-01-01

389

A facile approach to construct hybrid multi-shell calcium phosphate gene particles*  

PubMed Central

The calcium phosphate (CaP) particles have attracted much attention in gene therapy. How to construct stable gene particles was the determining factor. In this study, hybrid multi-shell CaP gene particles were successfully constructed. First, CaP nanoparticles served as a core and were coated with DNA for colloidal stabilization. The ?-potential of DNA-coated CaP nanoparticles was ?15 mV. Then polyethylenimine (PEI) was added and adsorbed outside of the DNA layer due to the electrostatic attraction. The ?-potential of hybrid multi-shell CaP particles was slightly positive. With addition of PEI, the hybrid multi-shell particles could condense DNA effectively, which was determined by ethidium bromide (EtBr) exclusion assay. The hybrid particles were spherical and uniform with diameters of about 150 nm at proper conditions. By simple modification of PEI, the hybrid multi-shell CaP gene particles were successfully constructed. They may have great potential in gene therapy. PMID:20349526

Xu, Zhi-xue; Zhang, Ran; Wang, You-xiang; Hu, Qiao-ling

2010-01-01

390

Phase development in the hardening process of two calcium phosphate bone cements: an energy dispersive X-ray diffraction study  

SciTech Connect

This work was aimed at the application of an energy dispersive X-ray diffraction technique to study the kinetics of phase development during the setting and hardening reactions in two calcium phosphate bone cements. The cements under study are based on either tricalcium phosphate or tetracalcium phosphate initial solid phase, and a magnesium carbonate-phosphoric acid liquid phase as the hardening liquid. The application of the energy dispersive X-ray diffraction method allowed to collect the diffraction patterns from the cement pastes in situ starting from 1 min of the setting and hardening process. The only crystallized phase in both cements was apatite-like phase, the primary crystallization process proceeds during a few seconds of the setting reaction. Both the compressive strength and the pH value changes during the hardening period can be attributed to the transformations occurring in the intergranular X-ray amorphous phase.

Generosi, A. [Istituto di Struttura della Materia, CNR, via del Fosso del Cavaliere, 100-00133 Rome (Italy); Smirnov, V.V. [Institute for Physical Chemistry of Ceramics, Russian Academy of Sciences, Ozernaya 48, Moscow 119361 (Russian Federation); Rau, J.V. [Istituto per lo Studio dei Materiali Nanostrutturati, CNR, Piazzale Aldo Moro, 5-00185 Rome (Italy); Albertini, V. Rossi [Istituto di Struttura della Materia, CNR, via del Fosso del Cavaliere, 100-00133 Rome (Italy); Ferro, D. [Istituto per lo Studio dei Materiali Nanostrutturati, CNR, Piazzale Aldo Moro, 5-00185 Rome (Italy); Barinov, S.M. [Institute for Physical Chemistry of Ceramics, Russian Academy of Sciences, Ozernaya 48, Moscow 119361 (Russian Federation)], E-mail: barinov_s@mail.ru

2008-03-04

391

Synthesis of bone-like micro-porous calcium phosphate/iota-carrageenan composites by gel diffusion.  

PubMed

Brushite and octacalcium phosphate (OCP) crystals are well-known precursors of hydroxylapatite (HAp), the main mineral found in bone. In this report, we present a new method for biomimicking brushite and OCP using single and double diffusion techniques. Brushite and OCP crystals were grown in an iota-carrageenan gel. The aggregates were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and thermal gravimetric analysis (TGA). SEM revealed different morphologies of brushite crystals from highly porous aggregates to plate-shaped forms. OCP crystals grown in iota-carrageenan showed a porous spherical shape different from brushite growth forms. The XRD method demonstrated that the single-diffusion method favors the formation of monoclinic brushite. In contrast, the double diffusion method was found to promote the formation of the triclinic octacalcium phosphate OCP phase. By combining the different parameters for crystal growth in carrageenan, such as ion concentration, gel pH and gel density, it is possible to modify the morphology of composite crystals, change the phase of calcium phosphate and modulate the amount of carrageenan inclusion in crystals. This study suggests that iota-carrageenan is a high-molecular-weight polysaccharide that is potentially applicable for controlling calcium phosphate crystallization. PMID:23759383

Gashti, Mazeyar Parvinzadeh; Stir, Manuela; Hulliger, Jürg

2013-10-01

392

Reciprocal regulation of calcium-/phosphate-regulating hormones in cyclists during the Giro d'Italia 3-week stage race.  

PubMed

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

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

393

A novel strategy for preparing nanoporous biphasic calcium phosphate of controlled composition via a modified nanoparticle-assembly method.  

PubMed

Biphasic calcium phosphate (BCP) consisting of hydroxyapatite (HAp) and ?-tricalcium phosphate is usually prepared by thermal decomposition of calcium-deficient HAp (CDHAp). However, the calcium deficiency and morphology of CDHAp are difficult to manipulate in parallel. In this study, we report a novel strategy for controlling the composition of nanoporous BCP by using only CDHAp nanoparticles with specific properties (Ca/P molar ratio, 1.61; particle size, 50 nm) as a building block and by adjusting the calcium deficiency of the nanoparticle-assembled CDHAp (Ca/P molar ratio, 1.50-1.67; pore size, 8 nm) with the addition of water-soluble Ca(NO3)2 or (NH4)2HPO4. After thermal treatment at 1000 °C, the composition of BCP could be predictably controlled by adjusting the Ca/P ratio of the nanoparticle-assembled CDHAp. Changes in the Ca/P ratio did not significantly affect the surface morphology of BCP, but the grain size (210-300 nm) and pore size (140-170 nm) tended to increase slightly as the Ca/P ratio decreased. The porosity significantly decreased upon the addition of Ca salts (porosity, 20%) or PO4 salts (porosity, 14%) compared with that of the sample without additives (porosity, 53%). In vitro tests demonstrated enhanced cell adhesion on nanoporous BCP compared with densely sintered pure HAp, and cell differentiation was promoted on the nanoporous pure HAp. PMID:24411377

Fujiwara, Keiko; Okada, Masahiro; Takeda, Shoji; Matsumoto, Naoyuki

2014-02-01

394

Evolution of the local calcium content around irradiated beta-tricalcium phosphate ceramic implants: in vivo study in the rabbit.  

PubMed

To evaluate whether dissolved calcium from tricalcium phosphate implants contributes to osseous wound healing in bone defects, the authors used nuclear radioactivated materials. Six months after irradiation, the calcium was still radioactive. Samples of the material were prepared and placed in rabbit condyles for 1, 3 and 9 months. Over time the condyles were retrieved and treated for histology or radiocounting. Measurements of the radioactivity of the slices and histomorphometry of the implants and surrounding tissues were performed. The authors observed that the radioactivity decreased regularly. Connective tissue had penetrated the pores and totally invaded the implants, first at the periphery of the implants, then inside the pores. Comparison of the results of radioactivity and histomorphometry suggest that part of the calcium from the implants was re-used specifically in the new osseous tissue. PMID:9663747

Le Huec, J C; Clément, D; Brouillaud, B; Barthe, N; Dupuy, B; Foliguet, B; Basse-Cathalinat, B

1998-01-01

395

Energy dispersive X-ray diffraction study of phase development during hardening of calcium phosphate bone cements with addition of chitosan  

Microsoft Academic Search

The aim of this work was to study the phase transformation during the setting reaction of two calcium phosphate bone cements based on either alpha tricalcium phosphate (?-TCP) or tetracalcium phosphate (TetCP) initial solid phase, and a magnesium carbonate–phosphoric acid solution as the hardening liquid. Low molecular weight (38.2kDa) chitosan was used to retard the cement’s setting reaction. To follow

J. V. Rau; A. Generosi; V. V. Smirnov; D. Ferro; V. Rossi Albertini; S. M. Barinov

2008-01-01

396

Engineering of pulsed laser deposited calcium phosphate biomaterials in controlled atmospheres  

NASA Astrophysics Data System (ADS)

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.

Drukteinis, Saulius E.

397

Calcium and phosphate ion releasing composite: Effect of pH on release and mechanical properties  

PubMed Central

Objectives Secondary caries and restoration fracture are the two main challenges facing tooth cavity restorations. The objective of this study was to develop a composite using tetracalcium phosphate (TTCP) fillers and whiskers to be stress-bearing, and to be “smart” to increase the calcium (Ca) and phosphate (PO4) ion release at cariogenic pH. Methods TTCP was ball-milled to obtain four different particle sizes: 16.2 ?m, 2.4 ?m, 1.3 ?m, and 0.97 ?m. Whiskers fused with nano-sized silica were combined with TTCP as fillers in a resin. Filler level mass fractions varied from 0% to 75%. Ca and PO4 ion release were measured vs. time at pH of 7.4, 6, and 4. Composite mechanical properties were measured via three-point flexure before and after immersion in solutions at the three pH. Results TTCP composite without whiskers had flexural strength similar to a resin-modified glass ionomer (Vitremer) and previous Ca-PO4 composites. With whiskers, the TTCP composite had a flexural strength (mean ± sd; n = 5) of (116 ± 9) MPa, similar to (112 ± 14) MPa of a stress-bearing, non-releasing hybrid composite (TPH) (p > 0.1). The Ca release was (1.22 ± 0.16) mmol/L at pH of 4, higher than (0.54 ± 0.09) at pH of 6, and (0.22 ± 0.06) at pH of 7.4 (p < 0.05). PO4 release was also dramatically increased at acidic pH. After immersion, the TTCP-whisker composite matched the strength of TPH at all three pH (p > 0.1); both TTCP-whisker composite and TPH had strengths about 3-fold that of a releasing control. Significance The new TTCP-whisker composite was “smart” and increased the Ca and PO4 release dramatically when the pH was reduced from neutral to a cariogenic pH of 4, when these ions are most needed to inhibit caries. Its strength was 2–3 fold higher than previously-known Ca-PO4 composites and resin-modified glass ionomer. This composite may have the potential to provide the necessary combination of load-bearing and caries-inhibiting capabilities. PMID:19101026

Xu, Hockin H. K.; Weir, Michael D.; Sun, Limin

2009-01-01

398

Novel non-rigid calcium phosphate scaffold seeded with umbilical cord stem cells for bone tissue engineering  

PubMed Central

The need for bone repair has increased as the population ages. Non-rigid calcium phosphate scaffolds could provide compliance for micro-motions within the tissues and yet have load-supporting strength. The objectives of this study were to (1) develop a non-rigid calcium phosphate cement (CPC) scaffold; and (2) investigate human umbilical cord mesenchymal stem cell (hUCMSC) proliferation, osteodifferentiation and mineralization on non-rigid CPC for the first time. Non-rigid CPC was fabricated by adding extra tetracalcium phosphate in the traditional CPC, and by incorporating chitosan, absorbable fibers, and hydrogel microbeads. The non-rigid CPCmicrobead scaffold possessed a strain-at-failure of 10.7%, much higher than the traditional CPC’s strain of 0.05% which is typical for brittle bioceramics. Flexural strength of non-rigid CPCmicrobead was 4-fold that of rigid CPC-mircobead scaffold, while work-of-fracture (toughness) was increased by 20-fold. The strength of non-rigid CPC-microbead-fiber scaffold matched that of cancellous bone. hUCMSCs on non-rigid CPC proliferated from 100 cells/mm2 at 1 day, to 600 cells/mm2 at 8 days. Alkaline phosphatase, osteocalcin, and collagen gene expressions of hUCMSCs were greatly increased, and the cells synthesized bone minerals. hUCMSCs on non-rigid CPC-microbead-fiber construct had higher bone markers and more mineralization than those on rigid CPC. In conclusion, this study developed the first non-rigid, in situ-setting calcium phosphate-microbead-fiber scaffold with a strain-at-failure exceeding 10%. hUCMSCs showed excellent proliferation, osteodifferentiation, and mineralization on non-rigid CPC scaffold. The novel non-rigid CPC-hUCMSC construct with good strength, high strain-at-failure and toughness, as well as superior cell proliferation, osteodifferentiation and mineralization is promising for load-bearing bone regeneration applications. PMID:22451091

Thein-Han, WahWah; Weir, Michael D.; Simon, Carl G.; Xu, Hockin H. K.

2013-01-01

399

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

NASA Astrophysics Data System (ADS)

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.

Gan, Lu

400

Development of collagen-hydroxyapatite nanostructured composites via a calcium phosphate precursor mechanism  

NASA Astrophysics Data System (ADS)

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.

Jee, Sang Soo