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Magnesium and its alloys are potential candidate materials for use as absorbable implants due to their excellent biodegradability and biocompatibility. Reducing their rapid corrosion rate by alloying and surface modification has been the focus of many research programs. To improve the corrosion resistance and to impart coloration, pure Mg is modified by micro-arc oxidation (MAO) using electrolytes containing different concentrations of manganese (Mn). A porous and thick MAO coating layer consisting of MgO, Mg3(PO4)2 and Mg2SiO4 phases is deposited on Mg. The color of the MAO treated Mg is changed from light gray to brown with the addition of 0.015 M Mn to the base electrolyte. The MAO coatings prepared in this study offers an improved corrosion resistance for Mg.

The present study addresses the deposition of a duplex coating by microarc oxidation (MAO) treatment and polycaprolactone (PCL) coating to improve the corrosion resistance of Mg. A uniform PCL coating layer is formed by dip coating method on MAO treated Mg, and the corrosion resistance of MAO–PCL duplex coated Mg is evaluated by potentiodynamic polarization study and immersion test. The results reveal that the porous nature of MAO treated Mg fails to offer a better corrosion resistance in Hanks' balanced salt solution (HBSS). However, deposition of PCL coating (using 4 and 7 wt.% PCL) over MAO treated Mg significantly increased the corrosion resistance of Mg in HBSS for 7 days. The MAO–PCL duplex coating can be a good alternative method of protecting Mg from rapid corrosion for biodegradable implant applications.

Magnesium and its alloys have been suggested as potential absorbable implant materials due to their excellent biodegradability and biocompatibility. Current researchers focus on reducing the rapid corrosion rate of Mg and its alloys by alloying and surface modification. To improve the corrosion resistance, pure Mg is modified by micro-arc oxidation (MAO) in phosphate electrolyte containing sodium hydroxide and its properties are compared with those formed using only phosphate or sodium hydroxide as electrolytes. A uniform and stable coating layer is formed on Mg after MAO treatment in phosphate electrolyte containing sodium hydroxide. The corrosion resistance of MAO-coated Mg is evaluated by potentiodynamic polarization study and immersion test. The results reveal that MAO coating enables a good improvement in corrosion resistance, and among them, coatings treated using phosphate electrolyte containing sodium hydroxide offer the best performance. Copyright © 2013 John Wiley & Sons, Ltd.

Background Acquired resistance to 5-fluorouracil (5-FU) is one of the important reasons for failure in 5-FU-based chemotherapy. The upregulation of dihydropyrimidine dehydrogenase (DPD) in tumours was reported as an important factor for acquired 5-FU resistance. The aim of this study is to examine whether intra-hepatic DPD was involved in acquired 5-FU resistance. Methods HT-29 human colorectal xenograft tumours were established in nude mice. After long-term exposure to 5-FU, some of the tumour became “resistant” and the others remained “sensitive” to 5-FU. DPD expression levels in the livers and tumours of “resistant”, “sensitive” or untreated mice were examined, and pharmacokinetics of 5-FU in rats’ plasma were investigated. Gimeracil, a DPD inhibitor, was checked whether it could reverse the reduced bioavailability of 5-FU. Results DPD expression was upregulated obviously in tumours of “resistant” mice as reported previously. Importantly, DPD expression was also upregulated significantly in livers of “resistant” mice, compared with those of “sensitive” or untreated mice. Furthermore, the upregulation of DPD expression in livers led to accelerated metabolism of 5-FU. Gimeracil was found to reverse the reduced serum 5-FU concentration. The cultured tumour cells from 5-FU treated mice showed relative sensitivity to higher concentration of 5-FU, even the “resistant” tumour cells. Conclusion Our study suggested that the upregulation of DPD in liver may be involved in acquired resistance to 5-FU, and DPD inhibitors or increasing 5-FU dosage may have potential application in overcoming 5-FU acquired resistance.

Purpose: The liver is the organ to which colorectal carcinomas (CRCs) most commonly metastasize, and surgical resection has been established as the most effective and potentially curative treatment for CRC with liver metastasis (LM). Therefore, surveillance of LM is vital for improvement of prognosis of CRC patients. In this study, we aimed to explore the potential value of carbohydrate antigen 19-9 (CA 19-9), carcinoembryonic antigen (CEA), and marker enzymes in indicating LM with CRC. Methods: Three groups of eligible patients with metastatic cancers were retrospectively included: CRC patients with LM (CRC-LM) or without LM (CRC- NLM), and non-CRC patients with LM (NCRC-LM). All metastatic lesions were identified by CT or MRI. Data on characteristics of the patients, the primary site, the locations of metastasis, CA 19-9, CEA, and biochemical parameters were collected for analysis. Results: A total of 493 patients were retrospectively included. More alcohol consumption was found in CRC-LM than CRC-NLM. Some biochemical enzymes were found to be significantly higher in groups with LM than without (CRC-LM or NCRC-LM v.s CRC-NLM). Both CEA and CA 19-9 were much higher in CRC-LM than CRC-NLM or NCRC-LM. For CRC patients, CA 19-9, γ-glutamyl transpeptidase, CEA and alcohol consumption were identified as independent factors associated with LM. Conclusion: Our analysis suggested the CA 19-9 might be a potential valuable indicator for LM of CRC in the clinic.

Purpose: Chemotherapy-induced anemia (CIA) is one of the most important causes of anemia in cancer patients. This study was conducted to describe the prevalence and characteristics of CIA in solid cancer patients in the Chinese population, and to explore the relationship of white blood cell (WBC) or platelet decrease with CIA. Methods: Data on age, gender, tumor diagnosis, anti-cancer treatment and blood cell analyses were available from 220 untreated non-anemic cancer patients who received at least 2 cycles of chemotherapy, and the data were analyzed to assess their relationship with CIA or its severity. Results: 139 patients (63.2%) presented anemia, most being Grade 1 or 2. Esophageal and lung cancers were associated with a high prevalence. G3/4 leucopenia and decrease of platelets were identified as independent risk factors for the occurrence of CIA. Moreover, G3/4 leucopenia, decrease of platelet and G3/4 thrombocytopenia were found to be also associated with the severity of CIA. Cisplatin-containing regimens were a main potential factor in causing CIA, although significant association was only found on univariate analysis. Conclusion: Anemia or decrease in hematoglobin are common in Chinese cancer patients receiving chemotherapy. Cisplatin-containing regimens might be an important factor influencing the occurrence of CIA. Our analysis firstly described some risk factors, such as decrease of platelets or WBCs, severity of leucopenia or thrombocytopenia, associated with the occurrence and severity of CIA.

Sunitinib, a novel oral multi-targeted tyrosine kinase inhibitor for patients with metastatic renal cell carcinoma (mRCC) and advanced gastrointestinal stromal tumor, has a good prospect for clinical application and is being investigated for the potential therapy of other tumors. We observed the phenomenon that drinking tea interfered with symptom control in an mRCC patient treated with sunitinib and speculated that green tea or its components might interact with sunitinib. This study was performed to investigate whether epigallocatechin-3-gallate (EGCG), the major constituent of green tea, interacted with sunitinib. The interaction between EGCG and sunitinib was examined in vitro and in vivo. 1H nuclear magnetic resonance (1H-NMR) spectroscopy and mass spectrometry (MS) were used to analyze the interaction between these two molecules and whether a new compound was formed. Solutions of sunitinib and EGCG were intragastrically administered to rats to investigate whether the plasma concentrations of sunitinib were affected by EGCG. In this study, we noticed that a precipitate was formed when the solutions of sunitinib and EGCG were mixed under both neutral and acidic conditions. 1H-NMR spectra indicated an interaction between EGCG and sunitinib, but no new compound was observed by MS. Sticky semisolid contents were found in the stomachs of sunitinib and EGCG co-administrated mice. The \( {\text{AUC}}_{{0 - \infty }} \) and Cmax of plasma sunitinib were markedly reduced by co-administration of EGCG to rats. Our study firstly showed that EGCG interacted with sunitinib and reduced the bioavailability of sunitinib. This finding has significant practical implications for tea-drinking habit during sunitinib administration.

Technical development for an efficient coating of bioactive materials improves the characteristics of a fully functional implant. The aim of this study was to investigate the osteoinductive effect of a newly developed hydroxyapatite (HA)-coating technique using aerosol deposition without post-heat treatment [room temperature (RT) group] on the titanium (Ti) dental implant in vitro and in vivo, compared with that of HA coating with post-heat treatment (HT-400 group) or machined surface (control group). Cell proliferation or attachment on the HA-coated Ti surface was assessed using tetrazolium salt, WST-8 or scanning electron microscopy (SEM). Human osteoblasts (HOB) on RT group were well attached and grew alike in the control or HT-400 group. The alkaline phosphatase activity of HOB cultured on RT and HT-400 group was significantly higher than the control group (p < 0.05). Evaluation by SEM, TEM, and XRD demonstrated that aerosol deposition facilitated HA particles to form a dense and uniform HA layer in the RT group despite no post-heating. In a rabbit tibia model (n = 3), the ratios of bone implant contact and bone area in the RT group (49.88%, 86.05%) were greater than in the HT-400 group (38.82%, 77.34%) or the control (28.31%, 73.86%). The finding of this study showed that the HA coating using aerosol deposition without post-heat treatment has a good biocompatibility, and provide a promoting strategy to enhance osseointegration in the application of the dental implant.

BACKGROUND The aim of this study was to analyze the prognostic implications of pretreatment circulating endothelial cells (CECs) and circulating endothelial progenitor cells (CEPCs) for the survival of patients with lung cancer. MATERIALS AND METHODS Relevant literature was identified using Medline and EMBASE. Patient clinical characteristics, overall survival (OS) and progression-free survival (PFS) together with CEC and CEPC positive rates before treatment were extracted. STATA 12.0 was used for our analysis and assessment of publication bias. RESULTS A total of 13 articles (8 for CEC and 5 for CEPC, n=595 and n=244) were pooled for the global meta-analysis. The odds ratio (OR) for OS predicted by pretreatment CECs was 1.641 [0.967, 2.786], while the OR for PFS was 1.168 [0.649, 2.100]. The OR for OS predicted by pretreatment CEPCs was 12.673 [5.274, 30.450], while the OR for PFS was 4.930 [0.931, 26.096]. Subgroup analyses were conducted according to clinical staging. Odds ratio (OR) showed the high level of pretreatment CECs only correlated with the OS of patients with advanced lung cancer (stage III-IV). CONCLUSIONS High counts of CECs seem to be associated only with worse 1-year OS in patients with lung cancer, while high level of pretreatment CEPCs correlate with both worse PFS and OS.

The room-temperature freeze-casting method was used to fabricate porous bioactive glass-ceramics. In this method, a glass/ camphene slurry prepared at 60°C was cast into a mold at 20°C, resulting in the production of a rigid green body that was comprised of three-dimensional dendritic camphene networks surrounded by highly concentrated glass powder walls. After the sublimation of camphene, the samples were sintered for 3 h at elevated temperatures ranging from 700° to 1100°C. As the sintering temperature was increased to 1000°C, the densification of the glass-ceramic wall was remarkably enhanced, while its highly porous structure was preserved. The sample sintered at 1000°C showed a high porosity of 53% and pore channels with a size of several tens of micrometers, as well as dense glass-ceramic walls. In addition, the fabricated samples effectively induced the deposition of apatite on their surfaces when immersed in simulated body fluid, implying that they are very bioactive.

Collagen, as a major constituent of human connective tissues, has been regarded as one of the most important biomaterials. As a coating moiety on Ti hard-tissue implants, the collagen has recently attracted a great deal of attention. This article reports the effects of fibrillar assembly and crosslinking of collagen on its chemical stability and the subsequent osteoblastic responses. The fibrillar self-assembly of collagen was carried out by incubating acid-dissolved collagen in an ionic-buffered medium at 37°C. The degree of assembly was varied with the incubation time and monitored by the turbidity change. The differently assembled collagen was coated on the Ti and crosslinked with a carbodiimide derivative. The partially assembled collagen contained fibrils with varying diameters as well as nonfibrillar aggregates. On the other hand, the fully assembled collagen showed the complete formation of fibrils with uniform diameters of ∼100–200 nm with periodic stain patterns within the fibrils, which are typical of native collagen fibers. Through this fibrillar assembly, the collagen coating had significantly improved chemical stability in both the saline and collagenase media. The subsequent crosslinking step also improved the stability of the collagen coating, particularly in the unassembled collagen. The fibrillar assembly and the crosslinking of collagen significantly influenced the osteoblastic cell responses. Without the assembly, the collagen layer on Ti adversely affected the cell attachment and proliferation. However, those cellular responses were improved significantly when the collagen was assembled to fibrils and the assembly degree was increased. After crosslinking the collagen coating, these cellular responses were significantly enhanced in the case of the unassembled collagen but were not altered much in the assembled collagen. Based on these observations, it is suggested that the fibrillar assembly and the crosslinking of collagen require careful considerations in the collagen administration as a coating moiety. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005

Hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) powders were synthesized by a sol-gel method for usage as bone filler and drug carrier. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water-based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of FHA powders. With heat treatment above 400degreesC, a characteristic apatite phase was observed for all the sol-gel powders. However, the crystallization temperature decreased with increasing fluoride addition. The tricalcium phosphate (TCP) phase formed in the pure HA powder above 800degreesC was attenuated in the FHA powders, confirming an enhanced phase stability of the FHA powders. Increasing the F- addition improved crystallinity and increased the crystallite size, as was determined from X-ray diffraction (XRD) analyses. The lattice parameters of the heat-treated powders varied corresponding to the fluoride addition, i.e., a gradual decrease in the a-axis, while little change in the c-axis was observed with increasing fluoride addition, indicating a nearly complete substitution of fluoride within the apatite lattice. However, little difference was observed with heat-treatment temperatures (400degrees-1000degreesC). The powders substituted with fluoride exhibited reduced dissolution rates in an in vitro solution as compared with the pure HA powder, suggesting the possibility of tailoring bioactivity with fluoride substitution.

The surface of a titanium (Ti) implant was modified by micro-arc oxidation (MAO) treatment. A porous layer was formed on the Ti surface after the oxidation treatment. The phase and morphology of the oxide layer were dependent on the voltage applied during the oxidation treatment. With increasing voltage, the roughness and thickness of the film increased and the TiO(2) phase changed from anatase to rutile. During the MAO treatment, Ca and P ions were incorporated into the oxide layer. The in vitro cell responses of the specimen were also dependant on the oxidation conditions. With increasing voltage, the ALP activity increased, while the cell proliferation rate decreased. Preliminary in vivo tests of the MAO-treated specimens on rabbits showed a considerable improvement in their osseointegration capability as compared to the pure titanium implant.

No standard chemotherapy regimen has been established for metastatic colorectal cancer (mCRC) after progression on 5-fluorouracil, oxaliplatin, and irinotecan. Here, we report the combination of raltitrexed and bevacizumab as a salvage regimen for the treatment of three heavily pretreated patients with KRAS mutant mCRC. All three patients had stable disease (SD) according to response evaluation criteria in solid tumors (RECIST) criteria, progression free survival (PFS) were 3.0, 3.2 months for the first two patients and have not been reached for over 5 months for the third patient and no severe adverse effect was observed. The combination of raltitrexed plus bevacizumab in mCRC seems worthy of further investigation.

The dielectric behavior of Pb(Zn1/3Nb2/3)O3-BaTiO3-PbTiO3 under various dc bias conditions was measured and analyzed over a broad temperature range. The dc bias field reduced the dielectric constant, increased the temperature of the dielectric constant maximum, and suppressed frequency dispersion. The coherence of the characteristic temperatures was clearly observed between the dielectric constant and the dielectric loss, which is considered to be associated viscous movement of domain walls. It is suggested that the dc bias field significantly influences the freezing process of polar microregions and changes the density of domain walls.

Both the electrostrictive strain and electric polarization of Pb(Zn1/3Nb2/3)O3-BaTiO3-PbTiO3 ceramics near MPB were carefully measured as a function of electric field strength, and temperature. The longitudinal strain versus the polarization squared with varying compositions was also analyzed. In terms of their domain structure and x-ray diffraction pattern under different dc bias, the field-induced domain switching and polarization mechanism of ferroelectric ceramics is discussed. It should be stressed that microdomains and macrodomains each provide a different contribution to the field-induced strain.

To investigate the expression of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) in penile cancer.A total of 96 patients with penile cancer were included, the expression of TS and DPD in tumor tissues were examined by immunohistochemistry method, the relationship of TS and DPD expressions with the clinical characters were also analyzed.The expression of TS and DPD in penile cancer tissue were 41. 67% (40/96) and 33. 33% (32/96) respectively. There was a positive correlation between TS and DPD expression (Pearson C= 0. 362, P0. 01). DPD was found to be more expressed in non-smoking patients (P = 0. 040).TS and DPD were moderately expressed in penile cancer and their expressions were positively correlated. This could be helpful for the application of fluorouracil in chemotherapy for the patients with penile cancer.

We identified clinical characteristics of 30 pulmonary metastasis (PM) patients and 29 second primary lung cancer (SPLC) patients with feature of solitary pulmonary mass (SPM) after radical treatment of prior cancers. 6.7% and 44.8% patients presented with centrally located SPM and the median event-free durations were 33 and 72 months in PM and SPLC groups, respectively. PM was more likely to be found in prior cancers with stage III. In conclusion, the location of SPM, the event-free duration and the prior tumor staging were important features for differentiating SPLC from PM among patients with SPM after prior cancers.

Background. The RAS-association domain family 1 A (RASSF1A) is a classical member of RAS effectors regulating cell proliferation and apoptosis. Loss of RASSF1A expression may shift the balance towards a growth-promoting effect without the necessity of activating K-ras mutations. Its potential association with K-ras mutations in colorectal cancer (CRC) is unclear. Methods. RASSF1A expression was examined in normal mucosa, adenoma, and tumor tissues of colon and rectum, respectively. We examined the association of RASSF1A expression, mutations of K-ras, and EGFR status in 76 primary CRCs. The relationship between clinicopathological characteristics and RASSF1A expression was also analyzed. Results. RASSF1A expression level decreased progressively in normal mucosa, adenoma and, tumor tissues, and the loss of RASSF1A expression occurred more frequently in tumor tissues. Of 76 primary CRCs, loss of RASSF1A expression and/or K-ras mutations were detected in 77% cases. Loss of RASSF1A expression was more frequent in K-ras wild-type than in mutation cases (63% versus 32%, P = 0.011). Conclusions. Our study indicates that loss of RASSF1A may be involved in pathogenesis of CRC, its expression was found predominantly in K-ras wild-type CRCs, suggesting that it may be another way of affecting RAS signaling, in addition to K-ras mutations.

Penile Squamous Cell Carcinoma (SCC) is a rare cancer with poor prognosis and limited response to conventional chemotherapy. The genetic and epigenetic alterations of Epidermal Growth Factor Receptor (EGFR)-RAS-RAF signaling in penile SCC are unclear. This study aims to investigate four key members of this pathway in penile SCC. We examined the expression of EGFR and RAS-association domain family 1 A (RASSF1A) as well as the mutation status of K-RAS and BRAF in 150 cases of penile SCC. EGFR and RASSF1A expression was evaluated by immunohistochemistry. KRAS mutations at codons 12 and 13, and the BRAF mutation at codon 600 were analyzed on DNA isolated from formalin fixed paraffin embedded tissues by direct genomic sequencing. EGFR expression was positive in all specimens, and its over-expression rate was 92%. RASSF1A expression rate was only 3.42%. Significant correlation was not found between the expression of EGFR or RASSF1A and tumor grade, pT stage or lymph node metastases. The detection of KRAS and BRAF mutations analysis was performed in 94 and 83 tumor tissues, respectively. We found KRAS mutation in only one sample and found no BRAF V600E point mutation. In summary, we found over-expression of EGFR in the majority cases of penile SCC, but only rare expression of RASSF1A, rare KRAS mutation, and no BRAF mutation in penile SCC. These data suggest that anti-EGFR agents may be potentially considered as therapeutic options in penile SCC.

BACKGROUND: It has been reported that antidiabetic drugs affect the risk of cancer and the prognosis of patients with diabetes, but few studies have demonstrated the influence of different antidiabetic agents on outcomes after anticancer therapy among patients with cancer. The objective of this study was to evaluate the influence of the antidiabetic drugs metformin and insulin on the prognosis of patients with advanced nonsmall cell lung cancer (NSCLC) plus type 2 diabetes who received first-line chemotherapy. METHODS: Data on patients with NSCLC who had diabetes from 5 hospitals in China during January 2004 to March 2009 were reviewed retrospectively. Ninety-nine patients were included in the final analysis. The influence of metformin and insulin on chemotherapy response rates and survival in these patients was evaluated. RESULTS: Chemotherapy with metformin (Group A) produced superior results compared with insulin (Group B) and compared with drugs other than metformin and insulin (Group C) in terms of both progression-free survival (PFS) (8.4 months vs 4.7 months vs 6.4 months, respectively; P = .002) and overall survival (OS) (20.0 months vs 13.1 months vs 13.0 months, respectively; P = .007). Although no significant differences in the response rate (RR) were observed between these 3 groups, when groups B and C (ie, the nonmetformin group) were combined, there was a tendency for better disease control in Group A than that in nonmetformin group. No significant difference in survival was observed between chemotherapy with insulin (Group B) versus other drugs (Group C). CONCLUSIONS: The current data suggested that metformin may improve chemotherapy outcomes and survival for patients who have NSCLC with diabetes. Cancer 2011;. © 2011 American Cancer Society.

To increase the mechanical property of zirconia, we have investigated the phase change and the resulting hardness of zirconia ceramics by hydroxyapatite (HA) powder bed sintering. It was observed using X-ray diffraction that the cubic zirconia phase, which has a higher hardness value than that of the tetragonal phase, was obtained at the surface of 3 mol% Y2O3 doped tetragonal zirconia polycrystal (3Y-TZP) ceramics during the sintering process; in our experimental conditions, the phase change at the surface increased as the sintering time increased. We believe that the observed crystalline phase change originated from the decomposition of HA and the diffusion of CaO, as follows. CaO, which was derived from the decomposition of HA at high temperature (1400˚C), diffused into the surface of 3Y-TZP and acted as a stabilizer. As a result, the Vickers hardness value of the treated specimens was higher than that of the non-treated specimen due to the formation of the cubic phase on the surface of 3Y-TZP.

A hydroxyapatite (HA)-titania (TiO2) hybrid coating is developed to improve the biocompatibility of titanium (Ti) implants. The HA predeposited layer on Ti via electron beam (e-beam) evaporation is subsequently treated by micro-arc oxidation (MAO) to produce an HA-TiO2 hybrid layer on Ti. The e-beam-deposited HA layer has a thickness of ≈1 μm and was highly dense prior to MAO. By means of MAO treatment, a rough and porous TiO2 layer is formed beneath the HA layer with a simultaneous local dissolution of the HA layer. Due to the HA precoating, high concentrations of Ca and P are preserved on the coating surface. The osteoblast-like cells on the hybrid coating layer grow and spread favorably. The cell proliferation rate on the hybrid coatings is not much different from that on pure Ti or simple MAO-treated Ti. However, the alkaline phosphatase (ALP) activity of the cells is significantly higher ( p < 0.05) on the HA-TiO2 hybrid coatings than on either the pure Ti or the simple MAO-treated specimen, suggesting that the cellular activity on the hybrid coatings is improved.

A thin hydroxyapatite (HA) layer was coated on a microarc oxidized titanium (MAO-Ti) substrate by means of the sol-gel method. The microarc oxidation (anodizing) enhanced the biocompatibility of the Ti, and the bioactivity was improved further by the sol-gel HA coating on the anodized Ti. The HA sol was aged fully to obtain a stable and phase-pure HA, and the sol concentration was varied to alter the coating thickness. Through the sol-gel HA coating, the Ca and P concentrations in the coating layer increased significantly. However, the porous morphology and roughness of the MAO-Ti was altered very little by the sol-gel treatment. The proliferation and alkaline phosphatase (ALP) activity of the osteoblast-like cells on the MAO/HA sol-gel-treated Ti were significantly higher than those on the MAO-Ti without the HA sol-gel treatment.

A fluorine-substituted hydroxyapatite (FHA) and zirconia (ZrO2) dense composite (50:50 by volume) was fabricated, and its feasibility for hard tissue applications was investigated in terms of its mechanical properties and osteo- blast-like cell (MG63) responses in vitro. The incorporation of fluorine into the hydroxyapatite (HA) structure was highly effective in producing a completely dense apatite-ZrO2 composite through a pressureless sintering route, by pre- venting the thermal degradation of the apatite and ZrO2. The resultant FHA-ZrO2 dense composite had excellent me- chanical properties, such as flexural strength (310 MPa), fracture toughness (3.4 MPam 1/2 ), hardness (10 GPa), and elastic modulus (160 GPa). The flexural strength and fracture toughness of the composite showed a noticeable improve- ment by a factor of 4 with respect to the pure apatites (HA and FHA). The MG63 cellular responses to the composite were assessed in terms of the cell proliferation (cell number and ( 3 H)-thymidine incorporation) and differentiation (alka- line phosphatase activity, osteocalcin, and collagen produc- tion). The cells on the FHA-ZrO2 composite spread and grew well, and proliferated actively during the culture pe- riod. The expression of alkaline phosphatase, osteocalcin, and collagen by the cells on the composite showed a similar trend to that on the pure apatites, although slight down- regulations were observed, implying that the FHA-ZrO2 50:50 composite retains the osteoblastic functionality and traits of the pure HA ceramics to a high degree. This finding, in conjunction with the considerable improvements in me- chanical properties, supports the extended use of this com- posite for hard tissue applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 258 -268, 2005

Hydroxyapatite (HA) was coated onto a titanium (Ti) substrate with the insertion of a titania (TiO2) buffer layer by the sol-gel method. The HA layer was employed to enhance the bioactivity and osteoconductivity of the Ti substrate, and the TiO2 buffer layer was inserted to improve the bonding strength between the HA layer and Ti substrate, as well as to prevent the corrosion of the Ti substrate. The HA layer coated over the TiO2 showed a typical apatite phase at 400 degrees C and the phase intensity increased above 450 degrees C. The sol-gel derived HA and TiO2 films, with thicknesses of approximately 800 and 200 nm, respectively, adhered tightly to each other and to the Ti substrate. The bonding strength of the HA/TiO2 double layer coating on Ti was markedly improved when compared to that of the HA single coating on Ti. The highest strength of the double layer coating was 55 MPa after heat treatment at 500 degrees C. The improvement in bonding strength with the insertion of TiO2 was attributed to the resulting enhanced chemical affinity of TiO2 toward the HA layer, as well as toward the Ti substrate. Human osteoblast-like cells, cultured on the HA/TiO2 coating surface, proliferated in a similar manner to those on the TiO2 single coating and on the pure Ti surfaces. However, the alkaline phosphatase activity of the cells on the HA/TiO2 double layer was expressed to a higher degree than that on the TiO2 single coating and pure Ti surfaces. The corrosion resistance of Ti was improved by the presence of the TiO2 coating, as confirmed by a potentiodynamic polarization test.

With an electron-beam evaporation process, a calcium phosphate (Ca-P) thin film of approximately 500 nm thick was deposited on sand blasted with large grits and acid etched (SLA) Ti without changing the typical morphology of the SLA surface. Dissolution behavior was investigated by measuring the amount of dissolved phosphate ions with ion chromatography after immersing the SLA Ti sample coated with a Ca-P film in 1 ml de-ionized water maintained at 37 degrees C for different periods of soaking time, and the surface morphology was observed with field emission scanning electron microscopy. The amount of phosphate ions increased quickly right after immersion but began to decrease after 2 days of immersion by redeposition with Ca ions as apatite, and the amount of biomimetic apatite increased with the extended soaking time. The Saos-2 cell was more attached on the coated surface, and the in vivo evaluation was that the Ca-P deposited SLA implant greatly improved the new bone formation ability.