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PubMed1990

Bactericidal properties of a titanium-peroxy gel obtained from metallic titanium and hydrogen peroxide.

A stable titanium-peroxy-radical complex is formed when metallic titanium interacts with hydrogen peroxide. The radical appears as one component in an aqueous gel formed when excess peroxides have been (catalytically) decomposed. The interaction between titanium and hydrogen peroxide may be of importance also in vivo during an inflammatory response at the implant. We report in this paper on the bactericidal effects of the titanium gel in the lacto- and myeloperoxidase-halogen systems. Escherichia coli viable count was used to evaluate the bactericidal properties of the gel and of H2O2 for comparison. The gel had only small or no toxic properties at high dilutions. Higher concentrations of the gel had bactericidal properties similar to those of H2O2. The results indicate that at physiological pH, the decomposition products of the gel ae titanium hydroxide (Ti(IV)(OH-)4) and hydrogen peroxide (H2O2). It was found that the gel probably oxidizes glutathione directly in contrast to H2O2, which needs a peroxidase to do so. A model for the interaction between titanium and hydrogen peroxide is suggested. Its consequences for the properties of titanium in vivo are also discussed.

Chlorine↗

PubMed2002

A technique to immobilize bioactive proteins, including bone morphogenetic protein-4 (BMP-4), on titanium alloy.

Immobilization of biomolecules on surfaces enables both localization and retention of molecules at the cell-biomaterial interface. Since metallic biomaterials used for orthopedic and dental implants possess a paucity of reactive functional groups, biomolecular modification of these materials is challenging. In the present work, we investigated the use of a plasma surface modification strategy to enable immobilization of bioactive molecules on a "bioinert" metal. Conditions during plasma polymerization of allyl amine on Ti-6Al-4V were varied to yield 5 ("low")- and 12 ("high")-NH2/nm2. One- and two-step carbodiimide schemes were used to immobilize lysozyme, a model biomolecule, and bone morphogenetic protein-4 (BMP-4) on the aminated surfaces. Both schemes could be varied to control the amount of protein bound, but the one-step method destroyed the activity of immobilized lysozyme because of crosslinking. BMP-4 was then immobilized using the two-step scheme. Although BMP bound to both low- and high-NH2 surfaces was initially able to induce alkaline phosphatase activity in pluripotent C3H10T1/2 cells, only high amino group surfaces were effective following removal of weakly bound protein by incubation in cell culture medium.

Adsorption↗

PubMed1995

Nitric acid passivation of Ti6Al4V reduces thickness of surface oxide layer and increases trace element release.

Passivation of Ti6Al4V and cpTi implants using methods based on the ASTM-F86 nitric acid protocol are used with the intention of reducing their surface reactivity, and consequently the corrosion potential, in the highly corrosive biologic milieu. The ASTM-F86 passivation protocol was originally developed for surgical implants made of stainless steel and chrome cobalt alloy. Using X-ray photoelectron spectroscopy (XPS) to examine the effect of nitric acid passivation on the surface oxide layer of mill-annealed Ti6Al4V and cpTi, we have found that such treatment actually reduced the oxide thickness on the alloy while having no significant effect on the pure metal. These results correlated with observations obtained using graphite furnace atomic absorption spectrophotometry (GFAAS) to detect trace element release from solid, mill-annealed, Ti6Al4V and cpTi into serum-containing culture medium. We detected significantly greater levels of Ti, Al, and V in the presence of passivated compared to nonpassivated Ti6Al4V. In contrast, nitric acid passivation did not influence Ti release from mill-annealed cpTi. These results, derived from two mill-annealed Ti-based metals, would indicate that re-examination of ASTM-F86-based passivation protocols with respect to Ti6Al4V should be considered in view of the widespread use of this alloy for biomedical devices.

Alloys↗

PubMed2005

Effects of hydrothermal treatment with CaCl(2) solution on surface property and cell response of titanium implants.

In order to obtain early and good osteointegration after implantation of a titanium implant in the human body, the surface modified treatments using NaOH or H(2)O(2) etc. were reported. In this study, titanium was hydrothermally treated with CaCl(2) solutions at 200 degrees C for 24hr (CaCl(2)-HT). Scanning electron microscope (SEM) observation clearly showed apatite deposition on the surface of CaCl(2) HT treated titanium faster than other chemical treated titanium immersion in simulated body fluid. X-ray photoelectron spectroscopy (XPS) analysis demonstrated that Ti--O--Ca bonding was formed on titanium surface by hydrothermal treatment with CaCl(2) solution. And it was revealed that thickness of TiO(2), which was known to play important roles for the formation of bone-like apatite, became approximately three times thicker than as-polished titanium. The amount of initial attached MC3T3-E1 cells on as-polished and NaOH, H(2)O(2) and this CaCl(2) HT treated titanium were almost the same values. After 5 days incubation, the growth rate of MC3T3-E1 cells on CaCl(2)-HT treated titanium was significantly higher than that on other chemical treated titanium. The hydrothermal treatment with 10-20 mmol/L CaCl(2) solution at 200 degrees C was an effective method for the fabrication of titanium implant with good bioactivity and osteoconductivity.

3T3 Cells↗

PubMed2002

Strategies to optimize reproductive efficiency by regulation of ovarian function.

Pregnancy rate to the Ovsynch protocol can be improved if cows are presynchronized (i.e., two PGF(2alpha) injections given 14 days apart and the second injection of PGF(2alpha) given 12 days prior to the first GnRH of the Ovsynch program) so that a greater proportion of cows during the Ovsynch protocol ovulate to the first GnRH injection and have a CL at PGF(2alpha) injection. Pregnancy rates were normal in anestrous cows (39.6%) if they ovulated to both injections of GnRH. Estradiol cypionate (ECP) can be used to replace GnRH to induce ovulation as a modification of the Presync-Ovsynch program (i.e., Presync-Heatsynch). Pregnancy rates after TI were 37.1+/-5.8% for Presync-Ovsynch compared to 35.1+5.0% for Presync-Heatsynch. Use of ECP to induce ovulation was an alternative to GnRH in which greater uterine tone, ease of insemination and occurrence of estrus, improved acceptance by inseminators. A GnRH agonist (Deslorelin; 750 microg) implant inserted at 48 h after injection of PGF(2alpha), as a component of the Ovsynch protocol, induced ovulation, development of a normal CL and delayed follicular growth until 24 d after implant insertion. Utilization of Deslorelin implants (450 microg and 750 microg) to induce ovulation compared to GnRH (100 microg) within the Ovsynch protocol resulted in 27 d pregnancy rates (GnRH 100 microg, 39%; Deslorelin implants 450 microg, 40% and 750 microg, 27.5%) with 12.7%, 5.0% and 9.5% embryonic losses by 41 d of pregnancy, respectively. Induction of an accessory CL with injection of hCG on day 5 after insemination improved conception rates by 7.1%. Bovine somatotrophin injected at first insemination following a Presync-Ovsynch program in cycling-lactating dairy cows increased 74 days pregnancy rates (57.1%>42.6%).

Animals↗

PubMed2006

Corrosion evaluation of Ti-48Al-2Cr-2Nb (at.%) in Ringer's solution.

The corrosion behavior of Ti-48Al-2Cr-2Nb (at.%) in Ringer's solution was studied to evaluate its potential as a biocompatible material. Corrosion properties of Ti-6Al-4V were determined under the same conditions for comparison. Two electrochemical techniques, potentiodynamic anodic polarization and electrochemical impedance spectroscopy, were employed to test Ti-48Al-2Cr-2Nb and Ti-6Al-4V. Surface modifications to the samples were made by autoclaving and by oxidation in air at 500 degrees C and 800 degrees C. The results show excellent corrosion resistance for unmodified Ti-48Al-2Cr-2Nb, corroborated by the high values of polarization resistance and corrosion potential and low values of corrosion current and corrosion rate. Ti-48Al-2Cr-2Nb appears to possess corrosion characteristics similar to Ti-6Al-4V. Surface modification rendered the Ti-48Al-2Cr-2Nb material extremely corrosion resistant.

Alloys↗

PubMed2004

Alterations in gene expression in cadaveric vs. live donor kidneys suggest impaired tubular counterbalance of oxidative stress at implantation.

Recipients of live donor transplant kidneys (LIV) exhibit a significantly longer allograft half-life compared with cadaveric donor organs (CADs). The reasons are incompletely understood. Therefore this study sought to elucidate the genome-wide gene expression profiles in microdissected transplant kidney biopsies obtained from five cadaveric and five matched live donors before transplantation. cDNA microarrays were used to determine the transcripts in isolated glomeruli (G) and the tubulointerstitial (TI) compartment. Data were subjected to hierarchical clustering, maxT adjustment and a jackknife procedure to ensure robustness of reported findings; validation was performed by independent analysis of split biopsies and TaqMan-PCR. One hundred and thirteen sequences representing 62 unique genes (17 redundant features), and 34 ESTs separated G from TI. No difference in gene expression was found in G between LIV and CAD kidneys, but nine genes (two represented twice) and three ESTs were abundantly expressed in the CAD TI compared with LIV. The main biological function of these genes is counter regulation of oxidative stress. Promoter analysis of significant features suggested coregulated gene groups. These data suggest that CAD kidneys exhibit a distinctly different set of transcripts in the TI compartment but not in the G compartment when compared with LIV kidneys.

Cadaver↗

PubMed2004

Characterization of apatite formed on alkaline-heat-treated Ti.

Alkaline-heat-treated titanium self-forms an apatite surface layer in vivo. The aim of the present study was to materialistically characterize the surface of alkaline-heat-treated titanium immersed in simulated body fluid (AHS-TI) and to examine the differentiation behavior of osteoblasts on AHS-TI. SEM, thin-film XRD, FTIR, and XPS analyses revealed that AHS-TI contained a 1.0- micro m-thick, low-crystalline, and [002] direction-oriented carbonate apatite surface. Human osteoblast-like SaOS-2 cells were cultured on polystyrene, titanium, and AHS-TI, and RT-PCR analyses of osteogenic differentiation-related mRNAs were conducted. On AHS-TI, the expression of bone sialoprotein mRNA was up-regulated as compared with that on polystyrene and titanium (p < 0.05). On AHS-TI, the expression of osteopontin and osteocalcin mRNAs was up-regulated as compared with that on polystyrene (p<0.05). The results indicate that the apatite was bone-like and accelerated the osteogenic differentiation of SaOS-2, suggesting that alkaline-heat treatment might facilitate better integration of titanium implants with bone.

Alkalies↗

PubMed2007

Titanate biomaterials with enhanced antiinflammatory properties.

While titanium implants are generally recognized as having excellent biocompatibility, the mechanistic basis for this has yet to be established. We previously demonstrated that TiO2, found on surfaces of titanium, has antioxidant properties that degrade the reactive oxygen species (ROS) which mediate the inflammatory response. We hypothesized that the antioxidant mechanism was similar to that known to mediate photocatalysis by titanium oxides. Specifically, we investigated whether the electronic or valence state of the surface titanium atoms mediates the catalytic degradation of ROS. Surface Ti(IV) atoms in TiO2 and SrTiO3 single crystal substrates were converted into Ti(III) while maintaining the bulk crystalline structure by vacuum annealing or Niobium doping. The degradation of both chemically-induced and neutrophil-derived ROS were significantly increased by changing the valence state of surface titanium. These results suggest that titanium-mediated degradation of ROS is through a catalytic mechanism. Furthermore, we describe a series of novel biomaterials that have antioxidant properties superior to those of titanium.

Anti-Inflammatory Agents↗

PubMed2004

Leptin-induced increase in leukemia inhibitory factor and its receptor by human endometrium is partially mediated by interleukin 1 receptor signaling.

Leptin and leukemia inhibitory factor (LIF) have been implicated as important mediators of implantation. The present study was designed to investigate whether leptin can directly regulate the expression of LIF and its receptor (LIF-R) in human endometrial cells and/or whether leptin-induced effects are linked to, or regulated in part by IL-1 signaling. Primary endometrial cells and endometrial epithelial cell lines (HES and Ishikawa cells) were cultured for 24-48 h in a medium containing insulin (5 microg/ml) and leptin (3, 10, and 62 nm) or IL-1beta (0.6, 3, and 10 nm) in the presence or absence of cytokines and/or receptor antagonists. The endpoints included phosphorylation of signal transducer and activator of transcription 3 (STAT3) and the relative levels of LIF, LIF-R, IL-1beta, IL-1 receptor antagonist (IL-1Ra) and IL-1 receptor type I (IL-1R tI) as determined by ELISA or Western blotting techniques. Leptin treatment increases the level of phosphorylated STAT3, LIF-R, and LIF. Leptin also increases the levels of IL-1 ligand, receptor, and antagonist as was previously reported. Blockade of OB-R with antibodies or with a specific OB-R inhibitor (leptin peptide antagonist-2) abrogated leptin-induced effects, suggesting that leptin binding to its receptor activates Janus kinase 2/STAT3 signaling. Treatment of endometrial cells with IL-1beta also results in elevated levels of LIF-R. Interestingly, the inhibition of IL-1R tI with a specific antibody or with IL-1Ra negatively affects both leptin-induced and IL-1-induced effects on LIF-R levels. Abnormal endometrial LIF expression has been associated with human infertility and leptin has profound effects on the levels of LIF, IL-1, and their cognate receptors in vitro. Thus, it is tempting to speculate that leptin's role in vivo could include the regulation of other key cytokines to be fundamental to endometrial receptivity during implantation (i.e. LIF and IL-1).

Cells, Cultured↗

PubMed2005

[Corrosion study of anodically and thermically surface-treated osteosynthesis plates].

For the fixation of mandibular fractures, at the Department of Oral Surgery and Dentistry at Semmelweis University, anodically and thermically treated TiO2/Ti osteosynthesis plates are used. The corrosion studies were performed in a generally-applied 3-electrode electrochemical measurement cell, with a calomel electrode as reference electrode, and a Pt net as conducting electrode. The cyclic voltammetric measurements demonstrated that the pore-free surface TiO2 layer forms a highly protective barrier on the surface of Ti. The electrochemical impedance spectrum reflected a decrease in inhomogeneity of the sample because of a decrease in the number of pinholes. Such a change is indicative of passivation. The reported techniques appear to comprise a reliable method of study for an evaluation of the long-term corrosion behaviour of implants.

Bone Plates↗

PubMed1997

Radiological and survival comparison of four methods of fixation of a proximal femoral stem.

We compared the radiological appearances and survival of four methods of fixation of a femoral stem in 538 hips after follow-up for five or ten years. The fixation groups were: 1) press-fit shot-blasted smooth Ti-A1-V stem; 2) press-fit shot-blasted proximally ridged stem; 3) proximal hydroxyapatite (HA) coating; and 4) cementing. Survival analysis at five to ten years showed better results in the HA-coated (100% at five to six years) and cemented stems (100% at 5 to 6 years) than in the two press-fit groups. There was a higher mean rate of migration in the smooth and ridged Ti-A1-V shot-blasted press-fit groups (0.8 mm/year and 0.6 mm/year, respectively) when compared with the HA-coated and cemented prostheses (both 0.3 mm/year). More radiolucent lines and osteolytic lesions were seen in the press-fit groups than in either the HA-coated or cemented implants, with a trend for a lower incidence of both in the HA compared with the cemented group. Proximal osteopenia increased in the press-fit and cemented prostheses with time, but did not do so in the HA group. There was a higher incidence of resorption of the femoral neck with time in the cemented group than in the other three. We conclude that the HA and the cemented interfaces both provide secure fixation with a trend in favour of HA. The cemented prosthesis meets the suggested National Institutes of Health definition of 'efficacious' at ten years.

Adult↗

PubMed1994

Composition and morphology of wear debris in failed uncemented total hip replacement.

Interfacial membranes collected at revision from 11 failed uncemented Ti-alloy total hip replacements were examined. Particles in the membranes were characterised by electron microscopy, microchemical spectroscopy and particle size analysis. Most were polyethylene and had a mean size of 0.53 micron +/- 0.3. They were similar to the particles seen in the base resin used in the manufacture of the acetabular implants. Relatively few titanium particles were seen. Fragments of bone, stainless steel and silicate were found in small amounts. Most of the polyethylene particles were too small to be seen by light microscopy. Electron microscopy and spectroscopic techniques are required to provide an accurate description of this debris.

Aged↗

PubMed1995

Cellular response to well-characterized calcium phosphate coatings and titanium surfaces in vitro.

The cellular response to well-characterized Ca-P and Ti surfaces was analyzed. This study indicated that the ion-beam sputtering process could produce a hydroxyapatite-type coating. However, structural alterations such as the incorporation of CO3 and the loss of the OH groups were observed. The Ti surfaces were shown to be predominantly amorphous TiO2. The in vitro cell culture study showed no significant differences in cell number for the Ti and Ca-P surfaces throughout the 12-day study. Furthermore, the initial percentage of protein within the cell layers was significantly lower for cells on Ca-P surfaces compared with the cell layer on Ti surfaces. However, after 3 h incubation, no significant difference in the percentage of protein was observed for the Ti and Ca-P surfaces.

Animals↗

PubMed2001

[Study on the pitting corrosion-resistant of Ti-75 alloys with different from oxidize temperatures in vacuum in oral cavity].

OBJECTIVE: To study the property of pitting corrosion-resistant of Ti-75 alloys with different from oxidize temperatures in vacuum in oral. METHODS: Ti-75 alloys were prepared 30 mm x 10 mm x 1 mm specimens and annealed at 200 degrees C, 300 degrees C, 400 degrees C, 500 degrees C oxidize temperatures in vacuum. The open-circuit potential (Ecoor) and the breakdown potential (Eb) were measured, and the cyclic anodic polarization curves was drawn. RESULTS: The Ecoor of Ti-75 alloys annealed at 200 degrees C oxidize temperatures in vacuum is -49.0 mV. At 300 degrees C, 400 degrees C, 500 degrees C oxidize temperatures in vacuum, the different Ecoor is -75.3 mV, -51.3 mV and -60 mV respectively. The Eb of Ti-75 alloys annealed at 200 degrees C oxidize temperature for 5 minutes in vacuum is the highest (+180 mV). CONCLUSION: It is better for Ti-75 alloys being annealed at 200 degrees C for 5 minutes in vacuum to release the stress of machine duplication and to resistant pitting corrosion.

Alloys↗

PubMed1995

Contigen Bard Collagen implant: the Japanese experience.

This was an open trial to evaluate the efficacy and safety of Contigen Bard Collagen Implant for the treatment of urinary incontinence in patients with either stress incontinence or true incontinence (intrinsic sphincter deficiency). Contigen was injected at two opposing sites in the submucosal tissues of the bladder neck or posterior urethra; this was repeated after 7 days if needed. Patients were evaluated in terms of the frequency and degree of incontinence, the number of pads used, quality of life and the pad weighing test. A global evaluation of the efficacy, safety, and usefulness of the procedure also was performed. Ninety-seven patients were enrolled, and 73 completed one-year of follow-up. At baseline, 66 patients, all females, had genuine stress incontinence (GSI), and 14 patients, 10 male and 4 female, had true incontinence (TI). Improvements in the degree of incontinence were observed in 61% of patients in the GSI group and 8% of patients in the TI group. The frequency of incontinence, number of pads used, and pad test (weight) were significantly (p < 0.0001) decreased in the GSI group. A global evaluation of efficacy found that 68% of patients in the GSI group were cured or improved, and 21% of patients in the TI group were cured or improved. Overall, 88% of the GSI group and 43% of the TI group found the procedure to be useful or slightly. Fifty adverse events were reported in 36 patients, but no patients discontinued treatment for adverse events. The most common adverse events were urinary retention in 24 patients, and difficulty voiding in 10 patients, although both side effects were transient.

Adult↗

PubMed2004

Controlled nucleation and growth of thin hydroxyapatite layers on titanium implants by using induction heating technique.

This paper reports the results obtained by the development of a new wet method of hydroxyapatite (HA) thin layer deposition. The method is based on the localized precipitation of HA on metallic substrates activated by induction heating. The technique developed has been shown to allow for the complete coating of substrates with micrometric thin films of HA within a low processing time. The method has been successfully applied to coat Ti plaques and Ti-6A1-4V cylinders.

Durapatite↗

PubMed2006

Synthesis and characterization of biocompatible polymer interlayers on titanium implant materials.

A bifunctional copolymer series of (4-vinylbenzyl)phosphonic acid diethylester and N-acryloxysuccinimide was developed as an interlayer with the aim of immobilizing proteins on titanium surfaces. Copolymers with varying compositions were synthesized, and an alternating copolymerization of the two monomers was found. The copolymers form ultrathin films of about 2-8 nm on titanium surfaces in a simple dipping process, as estimated from the attenuation of the titanium X-ray photoelectron spectroscopy (Ti-XPS) signal. The films were characterized by infrared spectroscopy, XPS, and time-of-flight secondary ion mass spectrometry. The results indicate that the immobilization is due to phosphonate groups, and thus the phosphonate content of the copolymers is decisive for the final film thickness. These polymer films were examined for their potential protein binding capacity by using trifluoroethylamine derivatization and subsequent XPS analysis as a reactivity assay.

Biocompatible Materials↗