PubMed · 5045195
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
M A Gomaa, M Abdel-Razek. 1972. Neutron dosimetry using multi-sphere spectrometer.. https://doi.org/10.1097/00004032-197204000-00006
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
The health consequences of beryllium (Be2+) exposure can be severe. Beryllium is responsible for a debilitating and potentially fatal lung disease, chronic beryllium disease (CBD) resulting from inhalation of beryllium particles. The US Code of Federal Register (CFR), 10 CFR 850, has established a limit of 0.2 microg beryllium/100 cm(2) as the maximum amount of beryllium allowable on surfaces to be released from beryllium work areas in Department of Energy (DOE) facilities. The analytical technique described herein reduces the time and cost of detecting beryllium on laboratory working surfaces substantially. The technique provides a positive colorimetric response to the presence of beryllium on a 30.5 cm x 30.5 cm (1 ft(2)) surface at a minimum detection of 0.2 microg/100 cm(2). The method has been validated to provide positive results for beryllium in the presence of excess iron, calcium, magnesium, copper, nickel, chromium and lead at concentrations 100 times that of beryllium and aluminum and uranium (UO2(2+)) at lesser concentrations. The colorimetric detection technique has also been validated to effectively detect solid forms of beryllium including Be(OH)2, BeCl2, BeSO4, beryllium metal and BeO.
Nickel-based alloys have been in use since the 1930s; however, there are concerns regarding the release of metal ions (Be(+2), Cr(+6), Cr(+3), Ni(+2), Mo(+6)) from these alloys into surrounding tissues. Therefore, the objective of this study was to determine the cellular location and accumulation of ions using atomic absorption spectroscopy and correlate location with the cytotoxic, morphologic, and ultrastructural evaluations reported previously. Human gingival fibroblasts were exposed to the metal ions for 72 h. Controlled atomic absorption spectroscopy studies were used to determine the intracellular location of these ions reported as parts per million metal ions per milligram protein. Enzymatic markers were shown to correspond to the appropriate fraction indicating success in fractionation of the gingival fibroblasts. These results correspond with the cytotoxic, morphologic, and ultrastructural alterations reported previously for fibroblasts exposed to these ions. The highest concentration of beryllium ions occurred in the low-density molecule fraction, where lipofuscin granules were found, which has been shown to contain metal ions. The highest concentrations of hexavalent chromium ions occurred in the plasma membrane and nuclear fractions followed by the mitochondria fraction, which is supported by the ions' ability to oxidize to trivalent chromium accumulating at the membrane as well as the alterations in nuclear and mitochondrial function. For trivalent chromium, the highest concentrations occurred in the low-density molecule and the plasma membrane fractions, which correlates with the ions' inability to readily cross membranes. The highest concentration of molybdenum ions occurred in the plasma membrane fraction correlating with alterations in membrane morphology and increased numbers of myelin figures. The highest concentration of nickel ions was associated with the cytosol fraction where lipid droplets seen in the transmission electron micrographs were located. The current study demonstrates that a successful subcellular fractionation was obtained on gingival fibroblasts and that the location of metallic ions within the fractions correlated with cellular alterations reported previously.
OBJECTIVES: This study examined dental material degradation product toxicity using the Microtox bacterial bioluminescence assay as well as the effects on toxicity of selective leaching, chelation with protein, the physical form of the products, and synergistic/antagonistic interactions among released ions. METHODS: Polarization was used to produce ionically dissolved (ID) and precipitated corrosion products from Litecast B alloy specimens, which were then chemically analyzed to determine their composition and to identify metal valence states. Corrosion product toxicity, as well as that of the individual alloying elements, alone and in the presence of mucin, was analyzed using Microtox. A mathematical approach identified synergistic/antagonistic interactions and determined element contribution to product toxicity. The mechanism by which the Microtox test bacterium interacts with solid products was explored. The toxicity of methyl methacrylate (MMA) monomer was also examined. RESULTS: Precipitated corrosion products were found to be more toxic than ID products. The metals in the precipitate have been shown to be available to the test bacterium. Be and Ni were the most toxic elements in the products and contributed significantly to their toxicity. Synergistic and slightly antagonistic interactions were observed in the ID and precipitated products, respectively. Mucin decreased toxicity of all elements except Be. MMA monomer toxicity was found to be low compared to metal toxicity. SIGNIFICANCE: Microtox is useful for evaluating dental degradation product biocompatibility and has significant promise for use in other types of studies, such as determining the effectiveness of antimicrobial treatments.