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At least 487 records · Page 27Linked to original sources
PubMed2003

Reduction of wear in total hip replacement prostheses by amorphous diamond coatings.

Wear-debris-induced periprosthetic bone loss and aseptic loosening is regarded as the main long-term problem of total hip replacements (THRs). In this study the amount of wear debris from articulating surfaces of THRs was reduced so as to be close to negligible by the use of high-quality amorphous diamond (AD) coatings deposited by pulsed plasma arc techniques. The wear rates determined in a commercial hip simulator for 15 million walking cycles (corresponding to about 15 years of clinical use) in serum lubrication were even 1,000,000 times lower than the clinical values for conventional THRs (polyethylene-metal or metal-metal pairs). Elimination of wear debris and good biomechanical performance should provide a substantial improvement of the clinical longevity of the THRs.

Biocompatible Materials↗
PubMed2003

Tantalum as a buffer layer in diamond-like carbon coated artificial hip joints.

The acid resistance of tantalum coated and uncoated human hip joint prostheses was studied with commercial CrCoMo acetabular cups. The samples were exposed to 10% HCl solution and the quantities of dissolved Cr, Co, and Mo were measured with proton-induced X-ray emission (PIXE). The absolute quantities were obtained with the use of Cr and Se solution standards. Tantalum coatings (thicknesses 4-6 microm) were prepared in vacuum with magnetron sputtering. Tantalum coating decreased the corrosion rate by a factor of 10(6). As a spinoff from recent wear tests on artificial hip joints it was shown that tantalum has excellent mechanical properties as an intermediate layer of diamond-like carbon (DLC) coatings. When tantalum was tested together with DLC on three metal-on-metal hip joint pairs in a hip simulator, no observable defects occurred during 15 million walking cycles with a periodic 50-300-kg load (Paul curve).

Acids↗
PubMed2005

Improvement of arthroscopic cartilage stiffness probe using amorphous diamond coating.

During arthroscopic evaluation of articular cartilage unstable contact and even slipping of the measurement instrument on the tissue surface may degrade the reproducibility of the measurement. The main aim of the present study was to achieve more stable contact by controlling the friction between articular cartilage surface and the arthroscopic cartilage stiffness probe (Artscan 200, Artscan Oy, Helsinki, Finland) using amorphous diamond (AD) coating. In order to obtain surfaces with different average roughnesses (R(a)), polished stainless steel disks were coated with AD by using the filtered pulsed arc-discharge (FPAD) method. Dynamic coefficient of friction (mu) between the articular cartilage (n = 8) and the coated plates along one non-coated plate was then determined. The friction between AD and cartilage could be controlled over a wide range (mu = 0.027-0.728, p < 0.05, Wilcoxon test) by altering the roughness. Possible deterioration of cartilage was investigated by measuring surface roughness after friction tests and comparing it with the roughness of the adjacent, untested samples (n = 8). Importantly, even testing with the roughest AD (R(a) = 1250 nm) did not damage articular surface. On the basis of the friction measurements, a proper AD coating was selected for the stiffness probe. The performance of coated and non-coated probe was compared by measuring bovine osteochondral samples (n = 22) with both instruments. The reproducibility of the stiffness measurements was significantly better with the AD-coated probe (CV% = 4.7) than with the uncoated probe (CV% = 8.2). To conclude, AD coating can be used to safely control dynamic friction with articular surface. Sufficient friction between articular surface and reference plate of the arthroscopic probe improves significantly reproducibility of the stiffness measurements.

Animals↗
PubMed2006

In vitro and in vivo evaluation of ultrananocrystalline diamond for coating of implantable retinal microchips.

In this work, ultrananocrystalline diamond (UNCD) thin films were evaluated for use as hermetic and bioinert coatings for a retinal microchip. These films were deposited on highly conductive Si substrates at different temperatures (from 400 to 800 degrees C), using microwave plasma enhanced chemical vapor deposition with argon-rich Ar/CH4 gas mixtures and different relative amounts of hydrogen (0-20%). Scanning electron microscopy studies showed that all the films are dense and continuous. Results of cyclic voltammetry test revealed that when there was <2% of hydrogen in the plasma, the film obtained renders the surface electrochemically inactive, with very low leakage currents ( approximately 4 x 10(-7) A/cm2 at +/-5 V). In addition, in vivo tests of the UNCD-coated Si samples were performed by implanting them in the eyes of rabbits for 4-6 months within the eye physiological environment. According to all these results, it was concluded that UNCD is a promising candidate for use as the encapsulating coatings for implantable retinal microelectronic devices.

Animals↗
PubMed2006

Examination of surface properties and in vitro biological performance of amorphous diamond-like carbon-coated polyurethane.

Despite the emerging use of diamond-like carbon (DLC) as a coating for medical devices, few studies have examined the resistance of DLC coatings onto medical polymers to both microbial adherence and encrustation. In this study, amorphous DLC of a range of refractive indexes (1.7-1.9) and thicknesses (100-600 nm) was deposited onto polyurethane, a model polymer, and the resistance to microbial adherence (Escherichia coli; clinical isolate) and encrustation examined using in vitro models. In comparison to the native polymer, the advancing and receding contact angles of DLC-coated polyurethane were lower, indicating greater hydrophilic properties. No relationship was observed between refractive index, thickness, and advancing contact angle, as determined using multiple correlation analysis. The resistances of the various DLC-coated polyurethane films to encrustation and microbial adherence were significantly greater than that to polyurethane; however, there were individual differences between the resistances of the various DLC coatings. In general, increasing the refractive index of the coatings (100 nm thickness) decreased the resistance of the films to both hydroxyapatite and struvite encrustation and to microbial adherence. Films of lower thicknesses (100 and 200 nm; of defined refractive index, 1.8), exhibited the greatest resistance to encrustation and to microbial adherence. In conclusion, this study has uniquely illustrated both the microbial antiadherence properties and resistance to urinary encrustation of DLC-coated polyurethane. The resistances to encrustation and microbial adherence were substantial, and in light of this, it is suggested that DLC coatings of low thickness and refractive index show particular promise as coatings of polymeric medical devices.

Bacterial Adhesion↗
PubMed1995

Ultramicrotomy of diamond films for TEM cross-section analysis.

Ultramicrotomy has been used to prepare TEM cross-sections of typical hard dielectric, semiconductor, and metal coatings, providing a critical capability in the study of structure-property relationships of thin films. Ultramicrotomy of thin film coatings requires meticulous attention to technique and handling. The sample to be microtomed must be very small, well bonded to the epoxy embedding medium, and precisely oriented. In this article we report the ability to microtome TEM cross-sections of diamond and cubic boron-nitride (cBN) coatings.

Diamond↗
PubMed2004

Growth hormone therapy for short stature in Diamond Blackfan anemia.

BACKGROUND: We report a 13-year-old male with Diamond Blackfan anemia and short stature. He had a normal biochemical response to growth hormone (GH) stimulation, but his bone age was delayed, his insulin-like growth factor 1 (IGF-1) was low, and he had a poor growth velocity. He was started on daily GH injections. METHODS: From the patient's medical record the following data were collected: serial heights, serial weights, hemoglobin, hematocrit, bone age, IGF-1, and steroid dose. RESULTS: This patient had an increase in growth velocity up to 8.2 cm/year. CONCLUSIONS: Growth hormone therapy should be considered in children with DBA, short stature and poor growth velocity.

Adolescent↗
PubMed2006

Central venous catheter thrombosis as a cause of SVC obstruction and cardiac tamponade in a patient with Diamond-Blackfan anemia and iron overload.

Cardiac tamponade is an infrequent but potentially lethal complication related to use of central venous catheters (CVC). We present the case of a 16-year-old female with Diamond-Blackfan anemia (DBA) who developed pericardial tamponade secondary to superior venous caval obstruction caused by CVC thrombosis. The patient presented 3 months after line placement with vomiting, abdominal pain, and cardiomegaly on chest X-ray (CXR). Her condition quickly decompensated with cardiac arrest and subsequent death despite immediate pericardiocentesis. As a result of this case, our center has developed a protocol for the management of CVC problems as a means of facilitating rapid recognition of central line clots.

Adolescent↗
PubMed1990

Ventilatory function of workers exposed to cobalt and diamond containing dust.

The ventilatory function of 48 workers occupied on the average for six years in a plant producing diamond-cobalt circular saws was compared with that of 23 control subjects. The geometric mean airborne cobalt concentrations in the two main work areas amounted to 15.2 and 135.5 micrograms/m3 respectively. The spirometric changes found in the exposed workers were compatible with a moderate restrictive syndrome and were correlated with duration of exposure.

Carbon↗
PubMed2002

The effect of thrombopoietin on erythroid progenitors in Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) is a rare congenital red blood cell aplasia. Usually, erythropoiesis in vitro is defective, and decreased numbers of erythroid progenitors are found in colony assays performed with bone marrow cells. Recently, some investigators showed that thrombopoietin (TPO) also works on common multipotent progenitor cells and stimulates erythropoiesis. We examined the effect of TPO together with erythropoietin (EPO), stem cell factor (SCF), and/or interleukin-3 (IL-3) on erythroid burst-forming units (BFU-E) of bone marrow nonadherent mononuclear cells from 2 patients with DBA using a serum-free culture system. Very few BFU-E appeared in cultures containing EPO alone. Adding IL-3, SCF, or both to cultures containing EPO induced an increase in the number of BFU-E. When TPO was added to cultures containing EPO and IL-3, SCF, or both, the number of BFU-E further increased. Especially in patient 2, BFU-E formation was grossly equal to that in normal controls. We conclude that TPO enhances bone marrow erythropoiesis in patients with DBA in the presence of EPO and SCF and/or IL-3. The data raise the possibility of the combination of TPO and SCF as a therapeutic agent in DBA.

Anemia, Diamond-Blackfan↗
PubMed2004

Diamond-Blackfan anemia in Japan: clinical outcomes of prednisolone therapy and hematopoietic stem cell transplantation.

The epidemiology and treatment outcomes for Diamond-Blackfan anemia (DBA) were surveyed in a cohort of 54 children (M/F = 26:28) registered in Japan from 1988 to 1998. The annual incidence was 4.02 cases per million births, the median age at diagnosis was 60 days, and 59% of the cases presented by 3 months of age. Three patients had a familial occurrence. All patients received prednisolone (PSL), and cyclosporin A (CsA) was added to the therapy in 17 patients. Forty-seven patients received transfusions, and 13 underwent hematopoietic stem cell transplantation (HSCT). The cumulative probabilities of a medication-free or a transfusion-free state prior to HSCT were 36% and 69%, respectively, at more than 5 years after diagnosis. Thirteen patients were weaned from PSL therapy without HSCT, and CsA was not associated with weaning from therapy. Transfusion and medication were stopped at 249 days and 933 days after diagnosis in 34 and 13 patients, respectively, who achieved a state of independence. No initial findings predicted the treatment dependence. More than 20% of patients experienced sustained hemosiderosis and/or adverse effects of PSL. The ages and reticulocyte counts at diagnosis of the patients who underwent HSCT were lower than in the patients who did not. HSCT led to the highest success (85%) of all previous reports, even though 5 alternative donors were included in our study. Two cord blood transplants from unrelated donors failed. These findings suggest the need for developing an integral treatment strategy including selective HSCT for refractory DBA.

Abnormalities, Multiple↗
PubMed2002

Diamond-like carbon coatings with Ca-O-incorporation for improved biological acceptance.

Diamond-like carbon (DLC) coatings were modified by doping the thin films with Ca-O compounds. Raman spectroscopy indicates growth of sp(2)-hybridised, ordered regions in size and/or number within the amorphous carbon-hydrogen network as a result of the Ca-O-incorporation. CaCO(3) was identified by X-ray induced photoelectron spectroscopy. Proliferation and morphology of L929 mouse fibroblasts reveal improved biocompatibility of Ca-O-modified DLC.

Animals↗
PubMed2003

High-performance liquid chromatography with diamond ATR-FTIR detection for the determination of carbohydrates, alcohols and organic acids in red wine.

A horizontal diamond attenuated total reflection (ATR) element has been incorporated in a flow-through cell with low dead volume and used for on-line mid-IR detection in high-performance liquid chromatography. The chemical inertness of the ATR element permitted the use of a strongly acidic mobile phase in the isocratic separation. The hyphenation was used for the analysis of organic acids, sugars and alcohols in red wine. In the case of co-eluting analytes multivariate curve resolution-alternating least squares (MCR-ALS) was successfully employed for quantitative analysis.

Alcohols↗
PubMed2006

Mediator-free amperometric determination of glucose based on direct electron transfer between glucose oxidase and an oxidized boron-doped diamond electrode.

A mediator-free glucose biosensor, termed a "third-generation biosensor," was fabricated by immobilizing glucose oxidase (GOD) directly onto an oxidized boron-doped diamond (BDD) electrode. The surface of the oxidized BDD electrode possesses carboxyl groups (as shown by Raman spectra) which covalently cross-link with GOD through glutaraldehyde. Glucose was determined in the absence of a mediator used to transfer electrons between the electrode and enzyme. O2 has no effect on the electron transfer. The effects of experimental variables (applied potential, pH and cross-link time) were investigated in order to optimize the analytical performance of the amperometric detection method. The resulting biosensor exhibited fast amperometric response (less than 5 s) to glucose. The biosensor provided a linear response to glucose over the range 6.67x10(-5) to 2x10(-3) mol/L, with a detection limit of 2.31x10(-5) mol/L. The lifetime, reproducibility and measurement repeatability were evaluated and satisfactory results were obtained.

Biosensing Techniques↗
PubMed2006

Adhesion of slime producing Staphylococcus epidermidis strains to PVC and diamond-like carbon/silver/fluorinated coatings.

Staphylococcus epidermidis has emerged as a pathogen associated with infections of implanted medical devices. Bacterial adhesion is a crucial step in infection on biomaterial surfaces. To quantitatively determine the relationship between poly (vinyl chloride) (PVC) surface properties and bacterial adhesion, we have compared attachment of slime-producing S. epidermidis strains on PVC and various coatings under flow conditions. Bacterial adhesion and colonization was quantified by counting the viable organisms on the adherent surface as well as by scanning electron microscopy, epifluorescence microscopy and atomic force microscopy. Fluorination of the PVC surface encourages S. epidermidis adhesion whereas; diamond-like carbon (DLC) and especially silver (Ag) coatings seem to inhibit its adhesion. In most materials, the number of adherent bacteria decreased with the increase of shear rate. These results indicate that bacterial adhesion is influenced by the chemical properties of the polymeric surfaces, the surface roughness and the associated flow conditions.

Bacterial Adhesion↗
PubMed1992

Efficacy of a porcelain refinishing system in restoring surface finish after grinding with fine and extra-fine diamond burs.

Commercial porcelain refinishing kits are claimed to restore the surface finish on porcelain after adjustments in circumstances that preclude reglazing. This study investigates the efficacy of one such kit in restoring a Vitadur N porcelain surface finish after grinding with fine (30 microns grit-red band) and extra-fine (15 microns grit-yellow band) high-speed diamond burs. The production of the porcelain test samples, the refinishing procedures, and the refinishing times were standardized throughout. Techniques were selected to simulate clinical practice. Randomly selected examples of surfaces created during refinishing were subjected to scanning electron microscopy, using standard kV and tilt angle settings, and to surface profilometry tracings. Roughness average (Ra) readings were recorded for each test specimen for every surface finish. Ra readings were analyzed statistically using a two-way unbalanced model for analysis of variance. Although refinishing after grinding with a 15 microns grit bur produced surfaces significantly smoother than on specimens previously ground with the 30 microns grit burs, the surfaces remained significantly rougher than when originally glazed. It is concluded that, using the type of kit tested, burs of a grade finer than the existing 15 microns grit yellow band types would be appropriate for porcelain adjustments to permit subsequent refinishing to a surface smoothness comparable to the original glaze.

Aluminum Oxide↗
PubMed1994

Cobalt powdersintering industry (stone cutting diamond wheels): a study of environmental-biological monitoring, workplace improvement and health surveillance.

This communication deals with an aspect of occupational hygiene in a factory producing granite cutting diamond wheels by sintering, in moulds, of fine cobalt powder. The factory has been studied between 1988 and 1991; the Department of Preventive and Occupational Medicine of the Local Sanitary Unit of Reggio Emilia has followed the evolution of the local exhaust ventilation equipment supplied by the employer in that period. At the same time, the following measurements and observations were carried out: (a) cobalt exposure by personal sampling, (b) airborne cobalt measurements by area sampling, (c) biological monitoring of cobalt in urine, (d) health surveillance.

Adult↗
PubMed2005

Bone marrow transplantation for diamond-blackfan anemia.

Patients with Diamond-Blackfan anemia (DBA) who are unresponsive to or intolerant of corticosteroids, experience treatment failure with other treatments, develop additional cytopenias or clonal disease, or opt for curative therapy are often treated with allogeneic bone marrow transplantation. We studied the transplantation outcomes of 61 DBA patients whose data were reported to the International Bone Marrow Transplant Registry between 1984 and 2000. The median age was 7 years (range, 1-32 years). Among 55 patients with available transfusion information, 35 (64%) had received > or =20 units of blood before transplantation. Most patients (67%) received their bone marrow grafts from an HLA-matched related donor. The median time to neutrophil recovery was 17 days (range, 10-119 days) and to platelet recovery was 23 days (range, 9-119 days). Five patients did not achieve neutrophil engraftment. The 100-day mortality was 18% (95% confidence interval, 10%-29%). Grade II to IV acute graft-versus-host disease occurred in 28% (range, 17%-39%) and chronic graft-versus-host disease in 26% (range, 15%-39%). The 3-year probability of overall survival was 64% (range, 50%-74%). In univariate analysis, a Karnofsky score > or =90 and transplantation from an HLA-identical sibling donor were associated with better survival. These data suggest that allogeneic bone marrow transplantation is effective for the treatment of DBA. Transplantation before deterioration of the performance status and from an HLA-identical sibling donor may improve survival.

Adolescent↗