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PubMedDate not supplied

Pneumocystis carinii pneumonia in patients with Diamond-Blackfan anemia receiving high-dose corticosteroids.

The authors describe three infants with Diamond-Blackfan anemia receiving corticosteroids who were diagnosed with Pneumocystis carinii pneumonia. Two patients exhibited intermittent neutropenia as well. Each child had been receiving relatively high doses of corticosteroids for at least 2 months, and two were having prednisone tapered when pneumonia developed. One child responded to trimethoprim/sulfamethoxazole and pentamidine, but the other two patients died. Infants with Diamond-Blackfan anemia receiving prolonged corticosteroid therapy should receive P. carinii pneumonia prophylaxis, such as trimethoprim/sulfamethoxazole, and prophylaxis should continue during corticosteroid tapering.

Anemia, Diamond-Blackfan↗
PubMed1999

Ultrasonic root-end preparation with smooth and diamond-coated tips.

The purpose of this study was to compare the effects of smooth and diamond-coated ultrasonic retrotips on the external and internal surfaces of root-end preparations with the aid of a scanning electron microscope (SEM). Forty-four mesial roots of human mandibular molars were selected. The canals were cleaned, shaped and obturated using gutta-percha and sealer. The apical portions were resected at a 45 degrees-angle bevel exposing both mesial canals and the isthmus area. The roots were then divided into two groups according to the type of root-end preparation: Group A--performed with smooth retrotips (S) and Group B--performed with diamond-coated retrotips (DC). The specimens were coded and prepared for SEM evaluation. Observations of the external surface preparation showed that the S and DC retrotips produced very well-centered cavities involving both canals and isthmus area with minimal deviations and no perforative defects. When the internal surface of the root-end preparations was evaluated, it was evident that the use of S retrotips resulted in clean canal walls with little superficial debris and smear layer. Internal canal surfaces done with DC retrotips were irregular showing patent grooves, in contrast with the more uniform, regular and smoother surfaces when S retrotips were employed.

Apicoectomy↗
PubMed2002

An investigation of the operating characteristics of two PTW diamond detectors in photon and electron beams.

The dosimetric properties of two PTW Riga diamond detectors type 60003 were studied in high-energy photon and electron therapy beam. Properties under study were current-voltage characteristic, polarization effect, time stability of response, dose response, dose-rate dependence, temperature stability, and beam quality dependence of the sensitivity factor. Differences were shown between the two detectors for most of the previous properties. Also, the observed behavior was, to some extent, different from what was reported in the PTW technical specifications. The necessity to characterize each diamond detector individually was addressed.

Calibration↗
PubMed2005

A preliminary dosimetric characterization of chemical vapor deposition diamond detector prototypes in photon and electron radiotherapy beams.

Three radiation detectors based on polycrystalline diamond films with different thickness and resistivity, obtained by microwave chemical vapor deposition, were tested to assess their suitability for relative dosimetry of photon and electron beams supplied by clinical linear accelerators. All samples showed a linear response as a function of the absorbed dose. The sensitivity per unit of detector sensitive volume spanned between 7 and 43 nC Gy(-1) mm(-3) with an applied electric field of 40 kV/cm. The dose rate dependence was evaluated following the Fowler theory and delta coefficient values between 0.95 and 1.00 were found for the three samples when polarized at 40 kV/cm. Percentage depth dose curves, output factors, and normalized dose profiles were determined for 6 and 10 MV photon beams and for 6 and 15 MeV electron beams. The results obtained with the diamond detectors were in good agreement with those obtained by reference detector measurements [all the data were within the experimental uncertainty of 1% (1sigma)].

Crystallization↗
PubMedDate not supplied

Synthetic diamonds as in vivo radiation detectors.

Synthetic diamonds with controlled amounts of impurity atoms can be manufactured so that, as thermoluminescent dosimeters, they can be made to have sensitivities at least as good as presently available commercial thermoluminescent dosimeters. They also exhibit, for radiations normally found in therapy situations, a linearity of response that extends from less than 0.01 Gy (1 rad) to over 10 Gy (1000 rad). Their physical size and form, crystals which can have volumes of less than 1 mm3, make them ideal candidates for in vivo monitoring of radiation fields, particularly electron fields where high-resolution measurements are essential for accurate isodose line determinations. Aspects of dose response from gamma-ray beams in relation to the type and concentrations of the impurity atoms within the diamond are discussed, and some experimental values for gamma, x-ray, and electron beams are presented.

Carbon↗
PubMed2003

Theoretical analysis of a carbon-carbon dimer placement tool for diamond mechanosynthesis.

Density functional theory is used with Gaussian 98 to analyze a new family of proposed mechanosynthetic tools that could be employed for the placement of two carbon atoms--a carbon-carbon (CC) dimer--on a growing diamond surface at a specific site. The analysis focuses on specific group IV-substituted biadamantane tool tip structures and evaluates their stability and the strength of the bond they make with the CC dimer. These tools should be stable in a vacuum and should be able to hold and position a CC dimer in a manner suitable for positionally controlled diamond mechanosynthesis at room temperature.

Adamantane↗
PubMed1998

Dental cutting: the historical development of diamond burs.

This brief history of the dental diamond bur is intended to provide both a historical perspective and an evaluation of the current state of bur technology. An understanding of the origins of dental diamonds and the issues facing manufacturers transforms the dentist from a simple user into an informed consumer. The author contends that this can improve dental care and enable the dentist to collaborate with manufacturers in developing improved dental burs.

Dental High-Speed Equipment↗
PubMed2002

Study of 22 Egyptian patients with Diamond-Blackfan anemia, corticosteroids, and cyclosporin therapy results.

OBJECTIVE: Diamond-Blackfan anemia is a rare congenital hypoproliferative anemia of infancy and early childhood. Treatment with corticosteroids is commonly used, but with limited success. Trials with cyclosporin-A (CSA) are not frequently reported. Therefore, in this study we analyzed our results in the management of this rare disease by different medical treatments. DESIGN: The results of 22 patients diagnosed at our Hematology Center in the New Cairo University Children's Hospital during the period 1991-2001 were retrospectively analyzed. Our patients first received prednisolone (2 mg/kg/d) for different courses according to their response. Since the year 2000, the steroid nonresponders received CSA (3-12 mg/kg/d) for 6 months unless treatment complications developed. RESULTS: The age at the onset of the disease ranged from 1 to 24 months (median: 2.5 months). The mean values of the hemoglobin, the reticulocyte count, and the myeloid/erythroid ratio at the onset of the disease were 4.75 +/- 1.79 g/dL, 0.14 +/- 0.16, and 39.4 +/- 27.08, respectively. Patients received prednisolone from 0.25 to 10 years (median: 2 years). Ten patients were nonresponders (45.5%), and 5 patients (22.7%) responded to corticosteroid therapy. Two of 5 responders are off treatment with a hemoglobin level of >9 g/dL, and 3 of 5 are currently corticosteroid-dependent. Of 10 patients not responding to steroids, 8 received CSA for 6 months. Four patients (50%) responded to CSA therapy. A significant positive association was found between CSA dose and response. CONCLUSION: CSA therapy should be tried in steroid-resistant Diamond-Blackfan anemia patients before blood transfusion or corticosteroid therapy complications are instituted.

Age of Onset↗
PubMed2007

Calculus removal with diamond-coated ultrasonic inserts in vitro.

BACKGROUND: Efficient calculus removal is a primary goal in periodontal therapy. Diamond-coated ultrasonic inserts (DIs) offer promise for improved scaling and were evaluated in vitro. METHODS: Extracted human teeth with moderate to severe calculus had areas of calculus ( approximately 5 x 5 mm) delineated with small burs. Each calculus area was treated under 2.5x magnification to the point of visible root cleanliness with sharp Gracey curets (hand instruments [HIs]), plain ultrasonic inserts (PIs), or ultrasonic inserts with fine-grit diamond coating; the latter two were used in a magnetostrictive ultrasonic instrument at a medium power setting. Each curet or insert was used for four teeth and then replaced by a new instrument. The time needed to clean each tooth/surface was recorded. The total area treated and the area of the residual calculus were calculated using an imaging analysis program. RESULTS: The mean time required for clinical calculus removal was 29.7 seconds for DIs, 91.9 seconds for PIs, and 49.8 seconds for HIs (all P <0.0001 from each other). Overall, the mean percentage of residual calculus was 6.3% for DIs, 5.4% for PIs, and 3.1% for HIs (significant differences between HIs and the other treatments). CONCLUSIONS: In vitro calculus removal was faster with DIs, followed by HIs and PIs. More residual calculus was found with the DIs; however, the 1% to 3% difference (93.7% clean versus 94.6% clean versus 96.9% clean with DIs, PIs, and HIs, respectively) does not seem to be clinically significant.

Coated Materials, Biocompatible↗
PubMed1999

Improved efficacy of calculus removal in furcations using ultrasonic diamond-coated inserts.

Dentsply Cavitron Diamond Inserts provide improved efficacy in removing calculus from furcations. A total of 60 extracted human mandibular molar teeth had artificial calculus applied to the furcations, then were randomly treated with either sharp universal Gracey curettes (HAND), a plain ultrasonic TFI-10 tip in a cavitron instrument (CAV), or one of 2 diamond-coated cavitron instruments (TFI-10 fine-grit (FIN) and TFI-10 medium-grit (MED)) When the time needed to completely clean the furcations was evaluated, MED was the fastest, followed by FIN, CAV, and HAND, respectively. All of the powered instruments were faster than hand curettes with regard to effective in vitro calculus removal in furcations. The use of these types of instruments would reduce the time required to perform periodontal surgery and might improve regenerative therapy.

Dental Calculus↗
PubMed2003

Diamond-Blackfan anemia: report of 6 cases.

Diamond-Blackfan anemia is a rare congenital hypoplastic anemia. We report 6 children diagnosed as Diamond-Blackfan anemia at our clinic. All had severe pallor at presentation, with mild hepatomegaly and just palpable spleen in one child. Thumb anomaly was present in one of them. All of them had macrocytic or normocytic anemia with reticulocytopenia, and bone marrow examination revealed marked erythroid hypoplasia. All of them were treated with oral steroids with a good response.

Anemia, Diamond-Blackfan↗
PubMed2004

Nomimmune hydrops fetalis due to Diamond-Blackfan anemia.

We describe case report of a baby with Diamond-Blackfan anemia, who presented as non-immune hydrops fetalis. The diagnosis was confirmed by measurement of red cell adenosine deaminase activity which is increased in Diamond-Blackfan anemia. At 2 years of age he is dependent on small dose of alternate day steroid to maintain his hemoglobin.

Anemia, Diamond-Blackfan↗
PubMed2005

[Atomic hydrogen emission line and the high quality diamond film].

The process of atomic hydrogen emission in CH4/H2 gas mixture in EACVD is simulated by Monte Carlo method. In the simulation two basic types of collision between electron and H2 molecule are considered: elastic collision and inelastic collision. Four types of inelastic processes have been considered, namely vibrational excitation, dissociation, electron excitation (contains Halpha, Hbeta and Hgamma) and ionization. For e-CH4 collision, elastic momentum transfer, vibrational excitation, dissociation, dissociative excitation (contains Halpha, Hbeta and Hgamma), ionization and dissociative ionization are considered. The relationship between the number of H, CH3 and the ratio of atomic hydrogen emission line intensity under different experimental conditions is investigated. A method to obtain the optimum experimental condition for diamond deposition by the atomic hydrogen emission line is given. The result is of great importance to depositing high quality diamond films by controlling the conditions of technology efficiently.

Diamond↗
PubMed2006

Ultra-smooth nanostructured diamond films deposited from He/H2/CH4/N2 microwave plasmas.

Addition of He to a high CH4 content (10.7 vol%) H2/CH4/N2 feedgas mixture for microwave plasma chemical vapor deposition produced hard (58-72 GPa), ultra-smooth nanostructured diamond films on Ti-6AI-4V alloy substrates. Upon increase in He content up to 71 vol%, root mean squared (RMS) surface roughness of the film decreased to 9-10 nm and average diamond grain size to 5-6 nm. Our studies show that increased nanocrystallinity with He addition in plasma is related to plasma dilution, enhanced fragmentation of carbon containing species, and enhanced formation of CN radical.

Diamond↗
PubMed1990

A comparison of the effects of urate, hydroxyapatite and diamond crystals on polymorphonuclear cells: relationship of mediator release to the surface area and adsorptive capacity of different particles.

The ability of monosodium urate monohydrate (MSUM), hydroxyapatite and diamond crystals to stimulate phagocytosis, degranulation and secretion of cell movement factors (CMF) from polymorphonuclear leukocytes (PMN) was determined. The ability of each crystal to adsorb PMN derived enzymes and CMF was also compared. MSUM crystals stimulated greater enzyme release and generation of CMF than hydroxyapatite; in contrast, hydroxyapatite crystals exhibited greater adsorption of PMN products. This was partly due to the greater surface area (at a given concentration) of hydroxyapatite crystals. Diamond crystals clearly interacted with PMN, but they did not stimulate degranulation or CMF production.

Adsorption↗
PubMed1989

[The cobalt lung in diamond cutters: a new disease].

Although for forty years already broncho-pulmonary pathology has been described in workers exposed to hard-metal (i.e. alloys of tungsten carbide and cobalt) and although cobalt is considered the offending agent of this hazard, these abnormalities have almost not been found after exposure to cobalt alone except in animal experiments. Recently we detected clearcut broncho-pulmonary pathology in 48 diamond polishers (i.e. nearly 1% of those exposed) attributable to the ultrafine cobalt dust from the cutting surface of polishing disks, in which it was used as a cementing matrix for microdiamonds without any tungsten carbide. Nineteen of these patients presented with a fibrosing alveolitis documented in 6 by lung biopsy and in 12 by broncho-alveolar lavage, both of which revealed characteristic multinucleated giant cells. Thirteen suffered from asthma of occupational origin, in 9 proven by cobalt-inhalation tests, and in 5 by peak flow measurements at the workplace. Sixteen had mixed bronchial and alveolar pathology or were incompletely documented. A cross-sectional study in about 200 diamond polishers showed a significant correlation between exposure to cobalt and decrease in lung function. The strikingly harmful effects of cobalt can be explained by the chronic exposure to very small particles with markedly increased solubility. The pathogenesis of the broncho-pulmonary pathology may be attributed to the cytotoxic as well as to the sensitising (i.e. allergic and/or idiosyncratic) actions of cobalt.

Asthma↗
PubMedDate not supplied

[Characteristics of diamond detectors of ionizing radiation].

The article describes a device for detecting ionizing irradiation on the basis of a diamond detector and gives its characteristics. It has been shown that the diamond detector device by its parameters is superior to a similar device based on the silicon detector and in a number of cases to the ionizing chamber device. It can therefore be used successfully in the systems measuring the dose-radiation field.

Carbon↗
PubMed1997

The diamond-coated sonic scaler tip. Part I: Oscillation pattern of different sonic scaler inserts.

The authors have developed a set of four modified sonic scaler inserts with variously shaped shafts and diamond-coated budded inserts. The inserts are specially designed for the furcation area since instruments used hitherto have not been successful in completely preventing slow continuous periodontal breakdown in multirooted teeth. To test their clinical effectiveness, the displacement amplitude of the different sonic scalers was measured under varying load applications. Each scaler insert generated different and characteristic displacement amplitudes from rest position. The conventional insert was continuously dampened under increasing load application, whereas the diamond-coated inserts showed only minor variations of oscillation pattern. In a clinical situation, both insert types should be used, with the least possible application load to maintain effectiveness and minimize removal of hard tissue.

Dental Scaling↗