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At least 595 records · Page 33Linked to original sources
PubMed2006

Imaging and sizing of diamond nanoparticles.

Typical disturbances of biological environment such as background scatter and refractive index variations have little effect on the size-dependent scattering property of highly refractive nanocrystals, which are potentially attractive optical labels. We report on what is to our knowledge the first investigation of these scattering optical labels, and their sizing, in particular, by imaging at subvideo frame rates and analyzing samples of diamond nanocrystals deposited on a glass substrate in air and in a matrix of weakly scattering polymer. The brightness of a diffraction-limited spot appears to serve as a reliable measure of the particle size in the Rayleigh scattering limit.

Algorithms↗
PubMed1985

Cobalt-induced bronchial asthma in diamond polishers.

Three diamond workers had occupational asthma attributed to the inhalation of cobalt powder. The exposure originated from high speed polishing disks with an abrasive consisting of microdiamonds cemented in extra fine cobalt not alloyed to tungsten carbide. The bronchoconstriction progressed towards the end of working-days; it was especially pronounced in the absence of an adequate exhaust ventilation; and it could be accompanied by rhinitis and chest tightness. Cobalt inhalation challenge tests were positive in all three patients, and exposure to cobalt temporarily increased nonspecific hyperreactivity.

Adult↗
PubMed2006

Defective ribosomal protein gene expression alters transcription, translation, apoptosis, and oncogenic pathways in Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) is a broad developmental disease characterized by anemia, bone marrow (BM) erythroblastopenia, and an increased incidence of malignancy. Mutations in ribosomal protein gene S19 (RPS19) are found in approximately 25% of DBA patients; however, the role of RPS19 in the pathogenesis of DBA remains unknown. Using global gene expression analysis, we compared highly purified multipotential, erythroid, and myeloid BM progenitors from RPS19 mutated and control individuals. We found several ribosomal protein genes downregulated in all DBA progenitors. Apoptosis genes, such as TNFRSF10B and FAS, transcriptional control genes, including the erythropoietic transcription factor MYB (encoding c-myb), and translational genes were greatly dysregulated, mostly in diseased erythroid cells. Cancer-related genes, including RAS family oncogenes and tumor suppressor genes, were significantly dysregulated in all diseased progenitors. In addition, our results provide evidence that RPS19 mutations lead to codownregulation of multiple ribosomal protein genes, as well as downregulation of genes involved in translation in DBA cells. In conclusion, the altered expression of cancer-related genes suggests a molecular basis for malignancy in DBA. Downregulation of c-myb expression, which causes complete failure of fetal liver erythropoiesis in knockout mice, suggests a link between RPS19 mutations and reduced erythropoiesis in DBA.

Adult↗
PubMed2006

Cost-effective flow cell for the determination of malachite green and leucomalachite green at a boron-doped diamond thin-film electrode.

An electrooxidation and a cost-effective flow-based analysis of malachite green (MG) and leucomalachite green (LMG) were investigated at a boron-doped diamond thin-film (BDD) electrode. Cyclic voltammetry as a function of the pH of the supporting electrolyte solution was studied. Comparison experiments were performed with a glassy carbon electrode. A well-defined cyclic voltammogram, providing the highest peak current, was obtained when using phosphate buffer at pH 2. The potential sweep-rate dependence of MG and LMG oxidation (peak currents for 1 mM MG and LMG linearly proportional to v 1/2, within the range of 0.01 to 0.3 V/s) indicates that the oxidation current is a diffusion-controlled process on the BDD surface. In addition, hydrodynamic voltammetry and amperometric detection using the BDD electrode combined with a flow injection analysis system was also studied. A homemade flow cell was used, and the results were compared with a commercial flow cell. A detection potential of 0.85 V was selected when using a commercial flow cell, at which MG and LMG exhibited the highest signal-to-background ratios. For the homemade flow cell, a detection potential of 1.1 V was chosen because MG and LMG exhibited a steady response. The flow analysis results showed linear concentration ranges of 1-100 microM and 4-80 microM for MG and LMG, respectively. The detection limit for both compounds was 50 nM.

Aniline Compounds↗
PubMed2005

Machining accuracy of CAD/CAM ceramic crowns fabricated with repeated machining using the same diamond bur.

The purpose of this study was to investigate the effect of repeated machining up to 51 times using the same diamond bur on machining accuracy of inner and outer surfaces of CAD/CAM (computer-aided designing and computer-aided manufacturing) machined ceramic crowns. The surface topography of machined crowns was examined using photographs. It was found that machining accuracy was not affected by the number of machining times. In all measuring points, the inner surface was machined to a dimension larger than the die model (i.e., increased gap), whereas the outer surface was machined to a dimension smaller than the crown model (i.e., smaller crown). Photo observation showed that cervical contour was machined in a clear, rounded form from 1st to 11th crowns.

Analysis of Variance↗
PubMed2002

[Influence of occupational dusts load on state of antioxidant system in miners engaged in diamond extraction industry].

Miners of diamond extraction industry in Yakutia demonstrated higher intensity of lipid peroxidation. Longstanding compensatory adaptive response to increased free radical oxidation and to unfavorable climate factors is higher superoxide dismutase and catalase and changes in protein metabolism. Lack of C and E vitamins in miners results from increased utilization due to strain of antioxidant defence mechanisms.

Adult↗
PubMed2002

Electrochemical oxidation of phenol at boron-doped diamond electrode. Application to electro-organic synthesis and wastewater treatment.

The electrochemical behaviour of a synthetic boron-doped diamond thin film electrode (BDD) has been studied in acid media containing phenol using cyclic voltammetry and bulk electrolysis. The results have shown that in the potential region of water stability direct electron transfers can occur on BDD surface resulting in electrode fouling due to the formation of a polymeric film on its surface. During electrolysis in the potential region of oxygen evolution, complex oxidation reactions can take place due to electrogenerated hydroxyl radicals. Electrode fouling is inhibited under these conditions. Depending on the experimental conditions, the electrogenerated hydroxyl radicals can lead to the combustion of phenol or to the selective oxidation of phenol to benzoquinone. The experimental results have also been compared to a theoretical model that permits the prediction of the evolution with time of phenol concentration, during its combustion, or during its selective oxidation to benzoquinone.

Benzoquinones↗
PubMed2002

In vitro cytocompatibility studies of Diamond Like Carbon coatings on titanium.

Diamond like carbon (DLC) films were deposited on to titanium (Ti) substrates by Plasma Enhanced Chemical Vapour Deposition (PECVD) process. The quality of the films were checked by Raman spectra and nano-hardness tests. The cytocompatibility of titanium and DLC coated titanium were studied using continuous cell lines of mouse fibroblast cells ( L-929), Human Osteoblast cells (HOS) and primary human umbilical cord vein endothelial cells (HUVEC). The cellular responses to the materials were assessed both quantitatively and qualitatively. The adhesion and spreading of cells on materials were compared using Ti as a control. Present study indicates an improved cytocompatibility of DLC coated Ti in comparison to bare Ti.

Animals↗
PubMed2003

Mining disasters in South Africa: the Rovic Diamond Mine disaster and the criminal liability of the mine authorities.

The South African economy depends heavily on the mining industry. Deep level mining--which is a very common occurrence in the South African Mining Industry, is fraught with dangers. It is therefore inevitable that these dangers will be a constant source of medico-legal involvement. At the end of November 1996, a mining disaster occurred at the Rovic Diamond Mine between Boshof and Dealsville. At about 1000 metres underground, a mudslide occurred and trapped 20 miners. Rescue workers could only retrieve four bodies. Due to the dangers of additional mudslides and collapse of the entire slope, the rescue workers were withdrawn. The 16 miners were later declared dead by a Court Order after a full investigation into the disaster was completed. In this discussion focus will be placed on the Rovic Mine Disaster Investigation, the post mortem examination of the four victims, the legal declaration of death of the other victims not found and the legal accountability of the mine authority.

Adult↗
PubMed2003

[Raman spectra and XPS analyses of the diamond-like carbon film deposited by surface wave plasma].

Raman spectrum and X-ray photoelectron spectroscopy (XPS) were used for the structural analysis of diamond-like carbon (DLC) film deposited by surface wave plasma. Decomposition methods were used respectively to achieve the quantitative measurement of sp3 content of the films deposited under different working times. We obtained the result that the sp3 bonding of the films was in the range of 20%-40% and increased with the depositing time by using both analysis methods.

Carbon↗
PubMed2003

Molecular basis of Diamond-Blackfan anaemia: what have we learnt so far? Review article.

A considerable progress has been made in the last three years in the uncovering of the molecular basis of Diamond-Blackfan anaemia (DBA). Two genetic loci on 19q13.2 and 8p23 chromosomes have been associated with the DBA phenotype, and the ribosomal protein S19 (RP S19) located at 19q has been found mutated in 25% of DBA patients. In this review we will outline possible mechanisms of how mutations in RP S19 might lead to the DBA phenotype, we will discuss candidate genes on 8p23 chromosome, and finally, a complex molecular model of DBA development will be proposed.

Anemia, Diamond-Blackfan↗
PubMed2004

Molecular basis of Diamond-Blackfan anemia: new findings from the Italian registry and a review of the literature.

BACKGROUND AND OBJECTIVES: Diamond-Blackfan anemia (DBA) is a rare, pure red blood cell aplasia of childhood caused by an intrinsic defect in erythropoietic progenitors. Malformations occur in about 40% of patients. More than half of patients respond to steroids; non-responders need chronic transfusions or stem cell transplantation (SCT). Mutations in the gene encoding ribosomal protein S19 are found in 25% of patients, but the link with erythropoiesis is unclear. A second DBA locus has been found on chromosome 8p22-p23; analysis of genes of the region is in progress. METHODS AND INFORMATION SOURCES: We present clinical and molecular data from 97 Italian DBA patients and a review of the literature. RESULTS AND STATE OF THE ART: We describe five new RPS19 gene mutations: four point mutations and one unbalanced chromosomal translocation. Hematologic findings, malformations and outcome are similar in the RPS19 mutated and the non-mutated groups. No genotype-phenotype correlation has been found so far in RPS19 mutated patients. Our data, however, and a thorough review of literature show a worse outcome (expressed as transfusion dependence) in patients with mutations that completely abolish one allele, i.e. gross chromosomal rearrangements and mutations at the initiation codon. The association of mental retardation with large deletions at the 19q locus points to a contiguous gene syndrome. A recurrent missense mutation (Arg62Trp) is associated with transfusion dependence in eight of the nine reported cases. PERSPECTIVES: Nationwide collaboration and population-based registries recording molecular data are essential for the further dissection of this rare heterogeneous disease and the definition of new therapeutic trials.

Anemia, Diamond-Blackfan↗
PubMed2004

Elevated thrombopoietin levels and alterations in the sequence of its receptor, c-Mpl, in patients with Diamond-Blackfan anemia.

In the study of the possible thrombopoietin (TPO)-c-Mpl pathway involvement in the pathogenesis of Diamond-Blackfan anemia, repeatedly increased serum TPO levels were identified in 7/14 patients and changes in c-mpl sequence in 3/14 patients. While elevated TPO levels can represent a compensatory mechanism for impaired erythropoiesis, c-Mpl mutations could influence the disease severity.

Adolescent↗
PubMed2004

Postmortem diagnosis of Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) is a rare etiology for congenital anemia, but this diagnosis should be considered when aregenerative hypoplastic anemia occurs in infancy. A term infant girl received a red blood cell transfusion at birth for neonatal anemia (hemoglobin 75 g/L) initially attributed to abruptio placentae. There were no additional investigations. Hemoglobin gradually decreased during the first 4 weeks of life, leading to severe anemia and death despite transfusions. A postmortem diagnosis of DBA was made by extraction of DNA collected on blood filter paper showing a deletion in RPS19 gene. Neonatal anemias should be carefully investigated and close follow-up should be performed during the first months of life, even if there is an obvious hemorrhagic etiology.

Anemia, Diamond-Blackfan↗
PubMed2005

[Congenital hypoplastic anemia (Diamond-Blackfan anemia)].

We report two cases of very rare congenital hypoplastic anemia (Diamond-Blackfan anemia) in children. Both patients were boys admitted to our Clinic as severe anemia of unknown etiology, and had been previously treated in their Cantonal hospitals. Diagnose of congenital hypoplastic anemia was set up according: anamnesis, clinical picture with dominant features of anemia, cytomorphologic finding of peripheral blood picture, according blood marrow aspirate finding and according erithropoetin level level in blood.

Anemia, Diamond-Blackfan↗
PubMed2005

Occupational asthma caused by cobalt chloride in a diamond polisher after cessation of occupational exposure: a case report.

OBJECTIVES: The inspiration of cobalt containing dust leads to various respiratory symptoms, including asthma and interstitial lung disease. Occupational asthma caused by cobalt chloride has been diagnosed in a 35-year-old patient, who worked as a diamond polishing disc former. The patient presented a 2-year history of dyspnea, cough and symptoms of rhinitis. MATERIALS AND METHODS: The patient underwent a medical history interview, skin prick tests with common and occupational allergens (cobalt and nickel chloride), and pulmonary function testing both before and after the nasal provocation with 0.05% cobalt chloride. Additionally, the authors analyzed morphological and biochemical changes before and after the specific nasal challenge test. Cell proliferation analysis was also carried out. RESULTS: Skin prick tests (SPTs) with common environmental allergens were found to be negative, while SPTs with cobalt chloride were positive for all applied solutions. The provocation with cobalt chloride caused a significant increase in the proportion of eosinophils, basophils and albumin during the late allergic reaction. The positive lymphocyte transformation caused by cobalt was also observed. CONCLUSIONS: Cobalt salts may induce occupational asthma. The mechanism of this asthma may be IgE-mediated. The cobalt-sensitized lymphocytes may play an important role in this disease.

Adult↗
PubMed2005

Interactions between RPS19, mutated in Diamond-Blackfan anemia, and the PIM-1 oncoprotein.

BACKGROUND AND OBJECTIVES: Diamond Blackfan anemia (DBA) is a congenital disease characterized by defective erythroid progenitor maturation. Patients' bone marrow progenitor cells do not respond to erythropoietic growth factors, such as erythropoietin. Mutations in the gene encoding for ribosomal protein (RP) S19 account for 25% of cases of DBA. The link between defective erythropoiesis and RPS19 is still unclear. Two not mutually exclusive hypotheses have been proposed: altered protein synthesis and loss of unknown extraribosomal functions. DESIGN AND METHODS: We used yeast two-hybrid screening and a human liver cDNA library obtained at 19-24 weeks of gestation, when hepatic erythropoiesis is efficient, to search for proteins interacting with RPS19. RESULTS: We found that RPS19 binds PIM-1, an ubiquitous serine-threonine kinase whose expression can be induced in erythropoietic cells by several growth factors, such as erythropoietin. The PIM-1/RPS19 interaction was demonstrated both in vitro and in living cells and led to phosphorylation of RPS19 in an in vitro kinase assay. We also showed that in human 293T cells PIM-1 interacts with ribosomes and may be involved in translational control. Three DBA-associated RPS19 mutations alter the binding between RPS19 and PIM-1. INTERPRETATION AND CONCLUSIONS: A link between erythropoietic growth factor signaling and RPS19 has been identified for the first time.

Amino Acid Sequence↗