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Characteristics of Chinese patients with symptomatic Brugada syndrome in Taiwan.

Since 1992, the Brugada syndrome has been increasingly recognized worldwide, although its incidence and distribution remain unclear. In Asia, several cases have been reported in Japan, Thailand, Singapore, and Vietnam. However, little information is available from the Chinese population. Since June 1997, we have identified 10 patients with the diagnosis of the Brugada syndrome from six hospitals in Taiwan. All patients were male with the mean age of 46 +/- 7 years (range 36-61). They all had a normal chemistry profile, coronary angiography and echocardiography. Clinical presentations varied from seizure and syncope to sudden cardiac death. MRI and ultrafast CT of the heart did not show any abnormalities. Sustained ventricular tachycardia/ventricular fibrillation (VF) was induced in 7 of 8 patients who underwent an electrophysiologic study. The pharmacological provocation test was positive in 4 of 5 patients. One of the 4 patients who had a genetic study showed SCN5A gene mutation. An implantable cardioverter defibrillator (ICD) was implanted in 8 patients. During a mean follow-up of 29 +/- 17 months (range 2-54), 3 of 8 patients who had an ICD received appropriate ICD discharges after implantation. These 3 patients who were subsequently treated with antiarrhythmic agents have had no further recurrent ICD discharges. Two patients who refused ICD implantation are alive and well without taking antiarrhythmic agents. Our study showed that the clinical characteristics of our patients are similar to those described in the literature and that ICD is an effective treatment modality for patients with recurrent VF. However, antiarrhythmic agents may be beneficial for suppressing arrhythmia recurrences in selected patients.

Adult↗

Corneal topography after cataract surgery using a clear corneal incision closed with one radial suture.

BACKGROUND AND OBJECTIVE: To determine whether corneal topography and visual recovery are affected by suturing a temporal, clear corneal incision for cataract surgery. PATIENTS AND METHODS: Forty-one consecutive phacoemulsification patients (39 eyes) had a 3.2-mm incision sutured with one 10-0 nylon, radial suture removed after 1 postoperative week. Visual acuity (VA) and corneal topography, including best fit sphere (BFS), best fit cylinder (BFC), principle meridian, topographic irregularity (TI), and vector-corrected astigmatism (VCA), were measured preoperatively and 1 day, 1 week, and 1 month postoperatively. Two-tailed t tests and Pearson correlations were calculated. RESULTS: From the preoperative measurement to 1 week postoperatively, VA improved, BFS (P = .005) and TI (P = .033) increased, and VCA shifted with-the-rule. From 1 week to 1 month postoperatively, BFS (P = .012) and TI (P = .002) decreased. BFC and its direction did not change. Almost all measures were significantly correlated. CONCLUSION: The benefits of sutureless surgery on corneal topography and visual recovery are not degraded by using a suture to prevent wound leakage.

Aged↗

Human osteoblast-like cells (MG63) proliferate on a bioactive glass surface.

Bioglass, a resorbable glass, previously has been evaluated as a bone graft substitute using cells of animal origin. Limited information is available on its effect on human cells. The objective of this study was to test the hypothesis that Bioglass supports viability and proliferation of human bone cells. As a prototype of human bone cells, the osteoblast cell line MG63 was used and propagated on Bioglass disks. MG63 cells also were seeded onto disks made of titanium (Ti-6Al-4V) and of cobalt chrome (Co-Cr-Mo) alloys. The number of viable cells recovered was similar for Bioglass, titanium, and polystyrene control surfaces. Significantly fewer cells were recovered from CoCr (P < 0.05) compared to Bioglass, Ti-6 Al-4v, and polystyrene surfaces. The proportion of cells undergoing DNA synthesis, estimated by thymidine uptake, was significantly greater on Bioglass and titanium surfaces (P < 0.05) than on the CoCr surface. There were detectable differences in cell morphology on these biomaterials. Functional capacity was tested by assay of osteocalcin production and no differences were detectable among the different biomaterials. This study supports the hypothesis that 45S5 Bioglass provides a favorable environment for human osteoblast proliferation and function. Bioglass may have clinical potential as a bone graft substitute, a bioactive grout, or an implant coating for promoting bony ingrowth in uncemented prostheses.

Alloys↗

The adhesion of thin carbon films to metallic substrates.

As part of the development of carbon-coated prosthetic devices, the adhesion of thin carbon films to metallic substrates has been studied. The bond strength of carbon films about 5000 A thick on Ti-6A1-4V and stainless steel was measured in a pull test and found to be greater than 4700 psi. Auger electron spectroscopy showed a reactive film/substrate interface. The ultimate bond strength was found to be dependent on the substrate and the deposition parameters.

Adhesiveness↗

Analysis of integrin expression in U2OS cells cultured on various calcium phosphate ceramic substrates.

Earlier we observed that calcium phosphate (Ca-P)-coated implant substrates stimulated the differentiation of osteoblast-like cells compared to uncoated substrates. This suggests that this difference in osteogenic induction is due to the chemical composition of the substratum. We hypothesized that Ca-P coatings modulate integrin expression patterns, because those receptors are the sensors of the cell. Therefore, in the present study we quantitatively analyzed integrin expression of osteosarcoma cells and their proliferation behavior on various well-defined Ca-P substrates. For this study we used the osteosarcoma cell line U2OS. Five groups of substrates were used: thermanox (Th), uncoated titanium (Ti), dense sintered hydroxyapatite (HA), and two Ca-P-coated titanium discs (TiHA-O% and TiHA-5%). At day 5, cell numbers were significantly lower (p < 0.05) for both types of Ca-P-coated titanium substrates compared to the other substrates. There were no significant differences between HA and uncoated titanium. From day 5 to 8, accumulated cell number was ranking highest to lowest HA > Th = Ti > TiHA-0% > TiHA-5%. Integrin expression at day 5 and day 8 of incubation was analyzed by flow cytometry for integrin subunits beta 1, alpha 3, alpha 4, alpha 5, alpha 6, and alpha v. Fluorescence-activated cell sorting (FACS) analysis showed that the cells express high levels of beta 1, low levels of alpha 4, alpha 5, and alpha 6, and moderate levels of alpha 3 and alpha v integrin subunits on the various biomaterial substrates. Minor differences in integrin expression between the various substrates were seen. Therefore, the observed differences in proliferation between the coatings may reside in modulating the functional properties of integrins.

Alkaline Phosphatase↗

In vitro periodontal ligament fibroblast attachment to plasma-cleaned titanium surfaces.

The objective of this research was to characterize the in vitro cellular behavior of fibroblast-like cells derived from rat periodontal ligament on commercially pure titanium surfaces which were sterilized by a variety of treatments. Following standard surface preparation protocols, the Ti specimens were sterilized by either steam autoclaving, exposure to ethylene oxide gas, exposure to ultraviolet light, or plasma-cleaning in argon for either one min or five min. Fibroblast-like cells in serum-supplemented media were incubated on the various Ti specimens for up to two h. In general, the levels of cell attachment for plasma-cleaned surfaces were significantly higher than those for steam-sterilized surfaces, but were significantly lower than the attachment levels for both the ultraviolet-treated surfaces and the tissue culture plastic control. The duration of plasma cleaning itself did not have a significant effect on the percentage of cell attachment at any time period. SEM evaluations indicated that by two h, the cellular morphology was different on the variously treated specimens. These studies indicate that the method of sterilization following implant surface preparation can affect the initial in vitro biological events of cell attachment and spreading.

Animals↗

Corrosion resistance, mechanical properties, corrosion fatigue strength and cytocompatibility of new Ti alloys without Al and V.

The effects of various metallic ions using various metallic powders on the relative growth ratio of fibroblasts L929 and osteoblasts MC3T3-E1 cells were carried out. Ti, Zr, Sn, Nb and Ta had evidently no effect on the relative growth ratios of cells. Otherwise, Al and V ions exhibit cytotoxicity from a concentration of > or = 0.2 ppm. This Al effect on cells tend to be stronger in medium containing small quantity of V ions (< or = 0.03 ppm). The new Ti-15%Zr-4%Nb-4%Ta-0.2%Pd alloy exhibited a higher corrosion resistance in physiological saline solution. The addition of 0.02%O and 0.05%N to Ti-Zr alloy improved the mechanical properties at room temperature and corrosion fatigue strength. The relative growth ratios for the new Ti alloy plate and the alloy block extraction were unity. Further, the relative growth ratios were almost unity for the new Ti alloy against apatite ceramic pins up to 10(5) wear cycles in Eagle's MEM solution. However, there was a sharp decrease for Ti-6%Al-4%V ELI alloy from 3 x 10(4) wear cycles as V ion was released during wear into the wear test solution since the pH of the Eagle's MEM increases with increasing wear cycles.

3T3 Cells↗

Osteoblast precursor cell attachment on heat-treated calcium phosphate coatings.

The influence of properties of calcium phosphate (CaP) coatings on bone cell activity and bone-implant osseointegration is not well-established. This study investigated the effects of characterized CaP coatings of various heat treatments on osteoblast response. It was hypothesized that heat treatments of CaP coatings alter the initial osteoblast attachment. The 400 degrees C heat-treated coatings were observed to exhibit poor crystallinity and significantly greater phosphate or apatite species compared with as-sputtered and 600 degrees C heat-treated coatings. Similarly, human embryonic palatal mesenchyme (HEPM) cells, an osteoblast precursor cell line, seeded on 400 degrees C heat-treated coatings, exhibited significantly greater cell attachment compared with Ti surfaces, as-sputtered coatings, and 600 degrees C heat-treated coatings. The HEPM cells on Ti surfaces and heat-treated coatings were observed to attach through filopodia, and underwent cell division, whereas the cells on as-sputtered coatings displayed fewer filopodia extensions and cell damage. Analysis of the data suggested that heat treatment of CaP coatings affects cell attachment.

Apatites↗

On the formation of fibrous capsule and fluid space around machined and porous blood plasma clot coated titanium.

Machined and machined submicron porous titanium, with and without a thin blood plasma coating (100 nm), were implanted for 7 or 28 days in subcutaneous pockets on the back of the rat. After explantation the specimens were analyzed by light microscopy with respect to thickness of the fibrous capsule, the fluid space width between implants and fibrous capsule, and formation of blood vessels. The results at 7 days indicate a thinnest fluid space for the plasma clot coated porous titanium surface, and the spaces vanished at the light microscopic level after 28 days outside all the analyzed surfaces. The thickness of the fibrous capsule increased outside the different surfaces at 7-28 days, and in this respect no significant differences were observed between the different surfaces at any time. Analysis of neovascularization showed that the number of vessels and proportion of vessels in the fibrous capsule increased with time at all surfaces, except machined Ti where the number instead decreased from 7 to 28 days. The average distance between the blood vessels and the fluid space increased with time for all types of surfaces. The results in the present study indicate that the healing process around titanium can be modulated by porosity and thin pre-prepared plasma coatings.

Journal Article↗

Adsorption of glycosaminoglycans to commercially pure titanium.

Aqueous solutions of the glycosaminoglycans (GAG), chondroitin-4-sulphate (C4S), chondroitin-6-sulphate (C6S), heparan sulphate (HS) and hyaluronan (HY) were reacted with 5 g samples of both native and calcium-treated titanium powder (99.5% pure) for 0-48 h in 10 ml volume at 37 degrees C. Residual GAG was detected in the supernatant following recovery of the TiO2-GAG complex by centrifugation (5000 g for 1 min) as hexuronic acid using the carbazole tetraborate method of Bitter and Muir. No adsorption on to native TiO2 was evident. In contrast, prior treatment of TiO2 with calcium produced a significant adsorption of C4S to a maximum of 60 micrograms of GAG per gram Ti. Only trace amounts of C6S, HS and hyaluronan interacted in the same way. Further evidence of interaction was obtained following the liberation of bound GAG from the TiO2-Ca-GAG complex with EDTA and identification using cellulose acetate electrophoresis. These findings suggest that calcium ions are required for adsorption of GAG to TiO2 which is mediated through the anionic determinants of the GAG surface and that the special configuration of C4S, the predominant chondroitin sulphate isomer found in alveolar bone, is important in the adsorption process. The implication of these findings in relation to the interaction between bone and titanium implants is discussed.

Adsorption↗

Effects of Ca and H2O2 added to RPMI on the fretting corrosion of Ti6Al4V.

Titanium and its alloys have demonstrated considerable success in various surgical procedures including orthopedic, dental, and cardiovascular surgery. However, particulate debris from corrosion and wear is present in a considerable quantity in tissue local to the implant. This study evaluated the effect of Ca, since it is present in both serum and bone, and H2O2, since it is produced through local inflammation, on the amount of titanium release. Four sets of Ti6Al4V plates and Ti6Al4V screws were used. Each set was designated to one of four solutions: RPMI (cell culture growth media), RPMI with CaCl2, RPMI with CaCO3, and RPMI with H2O2. A fretter was used to cause corrosion by creating micromotion between two screws and a two-hole plate of Ti6Al4V. After fretting for 72 h, weight loss of the plate and screws and the amount of Ti and vanadium (V) in solution was used to assess the amount of fretting corrosion which had occurred. Results of weight loss and Ti in solution indicated that the presence of H2O2 increased the amount of particulate debris produced in RPMI as compared with RPMI alone. The addition of CaCl2 to RPMI also increased both weight loss and Ti in solution compared with RPMI alone. The addition of CaCO2, however, did not give values significantly different from RPMI alone. Comparison of weight loss and Ti in solution indicated that the increase in fretting corrosion was not different between RPMI with CaCl2 and RPMI with H2O2. The particulate wear debris from the four solutions was black in color and the size of the particulate produced was compared using a Coulter Multisizer. The results indicated that particles produced in the four solutions were not different, with mean values between 1.324 and 1.100 microns, and they were similar in size to the particulate found in tissues surrounding failed total hip replacements. In order to better understand the role of Ca in the fretting corrosion of Ti6Al4V, energy dispersive x-ray analysis (EDXA) using SEM was used to determine elemental composition of one countersink surface of a plate which had been run four times in RPMI with CaCl2. The presence of Ca in the bulk was not significant (% composition < 0.5%). However, Ca was present in two surface particles which were examined at a magnification of 55,000, with a Ca% composition of 63.2% and 19.2%. While results from this study indicate that both soluble Ca(CaCl2) and H2O2 increase the fretting corrosion of Ti6Al4V, the insoluble form of Ca, which would be found in bone and hydroxyapatite, has no effect. These data indicate that it is important to specify the media used in corrosion, dissolution, and elution experiments.

Alloys↗

Biomimetic apatite formation on chemically treated titanium.

Titanium treated in NaOH can form hydroxycarbonated apatite (HCA) after exposition in simulated body fluid (SBF). Generally, titanium is covered with a passive oxide layer. In NaOH this passive film dissolves and an amorphous layer containing alkali ions is formed on the surface. When exposed to SBF, the alkali ions are released from the amorphous layer and hydronium ions enter into the surface layer, resulting in the formation of Ti-OH groups in the surface. The released Na(+) ions increase the degree of supersaturation of the soaking solution with respect to apatite by increasing pH, and Ti-OH groups induce apatite nucleation on the titanium surface. The acid etching of titanium in HCl under inert atmosphere was examined as a pretreatment to obtain a uniform initial titanium surface before alkali treatment. Acid etching in HCl leads to the formation of a micro-roughened surface, which remains after alkali treatment in NaOH. It was shown by SEM, gravimetric and solution analysis that the apatite nucleation was uniform and the thickness of precipitated HCA layer increased continuously with time. The treatment of titanium by acid etching in HCl and subsequently in NaOH is a suitable method for providing the metal implant with bone-bonding ability.

Apatites↗

Characterization and protein-adsorption behavior of deposited organic thin film onto titanium by plasma polymerization with hexamethyldisiloxane.

Plasma polymerized hexamethyldisiloxane (HMDSO) thin film was deposited onto titanium using a radio-frequency apparatus for the surface modification of titanium. A titanium disk was first polished using colloidal silica at pH=9.8. Plasma-polymerized HMDSO films were firmly attached to the titanium by heating the titanium to a temperature of approximately 250 degrees C. The thickness of the deposited film was 0.07-0.35mum after 10-60min of plasma polymerization. The contact angle with respect to double distilled water significantly increased after HMDSO coating. X-ray photoelectron spectroscopy revealed that the deposited thin film consisted of Si, C, and O atoms. No Ti peaks were observed on the deposited surface. The deposited HMDSO film was stable during 2-weeks immersion in phosphate buffer saline solution. Fourier transform reflection-absorption spectroscopy showed the formation of Si-H, Si-C, C-H, and Cz.dbnd6;O bonds in addition to Si-O-Si bonds. Quartz crystal microbalance-dissipation measurement demonstrated that the deposition of HMDSO thin films on titanium has a benefit for fibronectin adsorption at the early stage. In conclusion, plasma polymerization is a promising technique for the surface modification of titanium. HMDSO-coated titanium has potential application as a dental implant material.

Adsorption↗

Topographical characterization and microstructural interface analysis of vacuum-plasma-sprayed titanium and hydroxyapatite coatings on carbon fibre-reinforced poly(etheretherketone).

In the present study, topographical characterization and microstructural interface analysis of vacuum-plasma-sprayed titanium and hydroxyapatite (HA) coatings on carbon fibre-reinforced polyetheretherketone (CF/PEEK) was performed. VPS-Ti coatings with high roughness values (Ra=28.29+/-3.07 microm, Rz=145.35+/-9.88 microm) were obtained. On this titanium, intermediate layer HA coatings of various thicknesses were produced. With increasing coating thickness, roughness values of the HA coatings decreased. A high increase of profile length ratio, Lr, of the VPS-Ti coatings (Lr=1.45) compared to the grit-blasted CF/PEEK substrate (Lr=1.08) was observed. Increasing the HA coating thickness resulted in a reduction of the Lr values similar to the roughness values. Fractal analysis of the obtained roughness profiles revealed that the VPS-Ti coatings showed the highest fractal dimension of D=1.34+/-0.02. Fractal dimension dropped to a value of 1.23-1.25 for all HA coatings. No physical deterioration of the CF/PEEK substrate was observed, indicating that substrate drying and the used VPS process parameter led to the desired coatings on the composite material. Cross-section analysis revealed a good interlocking between the titanium intermediate layer and the PEEK substrate. It is therefore assumed that this interlocking results in suitable mechanical adhesive strength. From the results obtained in this study it is concluded that VPS is a suitable method for manufacturing HA coatings on carbon fibre-reinforced PEEK implant materials.

Journal Article↗

A study of the abrasive resistance of metal alloys with applications in dental prosthetic fixators.

Wear is one of the main surface failure mechanisms in materials and it will play a leading role in substitutive dental biomaterials. The aim of the present study is to compare the abrasive wear of different metallic materials used in dental applications. The results show that the abrasive wear of alloys based on precious metals such as Pt, Pd, Au and Ag is higher than for Ti and Ti based alloys. The alloy with the highest wear resistance is the Co-Cr which exhibits as well the highest hardness and Young's modulus. Since the method corresponds to a well-established abrasive wear standard, the behaviour of the different materials can be easily compared.

Alloys↗

Improvement in the morphology of Ti-based surfaces: a new process to increase in vitro human osteoblast response.

Surface roughness has been shown to be an influencing parameter for cell response. In this experience we attempted to compare the effect of roughness organization of Ti6A14V or pure titanium substrates on human osteoblast (hOB) response (proliferation, adhesion). Surface roughness was extensively analyzed at scales above the cell size (macro-roughness) or below the cell size (micro-roughness) by calculation of relevant classic amplitude parameters (Ra, Rt) and original frequency parameters (Order, Delta). We developed a new process to prepare isotropic surfaces (electro-erosion), which were compared to isotropic surfaces obtained by polishing and anisotropic surfaces obtained by machine-tooling. The hOB response on electro-eroded (EE) Ti6A14V surfaces or pure titanium (Ti) surfaces was largely increased when compared to polished or machine-tooled surfaces after 21 days of culture. Moreover, the polygonal morphology of hOB on these EE surfaces was very close to the aspects of hOB in vivo on human bone trabeculae. By a complete description of the surface topography of EE surfaces, we concluded that when the topography was considered below the cell scale, hOB appreciated their isotropic smooth aspect, although when the topography was considered above the cell scale they appreciated their rough isotropic 'landscape' formed by many 'bowl-like nests' favouring cell adhesion and growth. Electro-erosion is a promising method for preparation of bone implant surfaces, as it could easily be applied to preparation of most biomaterials with complex geometries.

Algorithms↗

A novel test method for evaluation of the abrasive wear behaviour of total hip stems at the interface between implant surface and bone cement.

After total hip replacement, some cemented titanium stems show above-average early loosening rates. Increased release of wear particles and resulting reaction of the peri-prosthetic tissue were considered responsible. The objective was to develop a test method for analysing the abrasive wear behaviour of cemented stems and for generating wear particles at the interface with the bone cement. By means of the novel test device, cemented hip stems with different designs, surface topographies and material compositions using various bone cements could be investigated. Before testing, the cemented stems were disconnected from the cement mantle to simulate the situation of stem loosening (debonding). Subsequently, constant radial contact pressures were applied on to the stem surface by a force-controlled hydraulic cylinder. Oscillating micromotions of the stem (+/- 250 microm; 3 x 10(6)cycles; 5 Hz) were carried out at the cement interface initiating the wear process. The usability of the method was demonstrated by testing geometrically identical Ti-6A1-7Nb and Co-28Cr-6Mo hip stems (n= 12) with definite rough and smooth surfaces, combined with commercially available bone cement containing zirconium oxide particles. Under identical frictional conditions with the rough shot-blasted stems, clearly more wear particles were generated than with the smooth stems, whereas the material composition of the hip stems had less impact on the wear behaviour.

Biocompatible Materials↗

Results of IVF attempts in patients with unexplained infertility.

From January 1986 to July 1987, 143 patients with unexplained infertility (UI) following 217 IVF attempts were studied and randomly assigned for statistical analysis to be compared with 434 tubal infertility (TI) patients undergoing 748 IVF attempts. The age of patients, previous pregnancy history and stimulation protocols were identical in both groups. In comparison with tubal patients, IVF attempts on the UI group were characterized by the same rates of cycle failure, mean number of oocytes retrieved per cycle, a lower fertilization rate (45.7% UI/59.8% TI) (P less than 0.01) and no difference in cleavage and nidation rates. However, a decrease in the pregnancy rate/attempt (13.8% UI/19.5% TI) tended towards a significant value (P = 0.06). Although the semen parameters were found to be in the normal range during the previous fertility screening in both groups, the incidence of at least one abnormality (count less than 20 X 10(6)/ml, and/or total motility less than 30% and/or abnormal forms greater than 75%) on the day of insemination was found to be significantly higher in UI (20%) than in TI (11%) patients. Moreover, 25% of UI patients did not fertilize any oocytes inseminated, whatever the number of oocytes retrieved. This rate of failed fertilization was significantly lower (9%) in tubal patients. The oestrogen response profiles were similar in both groups, analyzed according to the stimulation protocols.(ABSTRACT TRUNCATED AT 250 WORDS)

Buserelin↗