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In 1989, it was discovered that the recycled insulation oil in pole transformers for electric power supply was contaminated with trace amounts of polychlorinated biphenyls (PCBs; maximum 50 mg-PCB/kg-insulation oil). In order to remove the PCBs from transformer components using n-hexane as a solvent, we investigated the relationship between progressive stages of dismantling and cleaning results. The results are summarized as follows: (1) Based on the cleaning test results, we made an estimate of the residual PCB amount on iron and copper components. By dismantling the test pole transformers into the "iron core and coil portion" and cleaning the components, we achieved a residual PCB amount that was below the limit of detection (0.05 mg-PCB/kg-material). To achieve a residual PCB amount below the limit of detection for the transformer paper component, it was necessary to cut the paper into pieces smaller than 5 mm. We were unable to achieve a residual PCB amount below the limit of detection for the wood component. (2) Compared to Japan's stipulated limited concentration standard values for PCBs, the results of the cleaning test show that cleaning iron or copper components with PCBs only on their surface with the solvent n-hexane will satisfy the limited concentration standard values when care is taken to ensure the component surfaces have adequate contact with the cleaning solvent.

Diffuse reflectance spectroscopy can be successfully used for the quantitative determination of small amounts of pollutants like metals. The remission function was found to be linearly proportional to the concentration, when we applied the Kubelka-Munk equation. The color reactions of Cu(II), Co(II), and Ni(II) with dithiooxamide, were realised on filter paper. Reaction between Fe(III) and ammonium thiocyanate was realized on filter paper and gelatine matrix. All measurements were accomplished with a laboratory-constructed reflectometer. We have obtained a calibration curve by plotting the optical density of reflectance A(R) vs log of the mol l(-1) concentration. Limits of detection at the 10(-4) M level were estimated for all the compounds. Linear dynamic range extend over one order of magnitude and shows the potential of device for the quantitative analysis of environmental pollutants.

Efforts to reduce the high global prevalence of nutritional anemia require the use of both reliable laboratory assays to distinguish iron deficiency from other causes of anemia and cost-effective methods for collection of blood specimens under field conditions. The suitability of using small plasma samples spotted and dried on filter paper for measurements of plasma ferritin and transferrin receptor was evaluated in the present study.Blood specimens obtained from 73 male and 83 female subjects (19-40 years) representing a wide range of iron status were used to perform parallel measurements of plasma ferritin and transferrin receptor on whole plasma and spotted plasma samples.Ratio plots, evaluating the acceptability and precision of the spot method in ferritin and transferrin receptor assays, showed the expected proportion of data points within the 95% prediction interval. In the composite group of 156 subjects, both the whole plasma and plasma spot methods gave a geometric mean transferrin receptor/ferritin ratio of 18. The regression equation for the ratio was logy = 1.045 logx - 0.05126; r = 0.986; P0.0001. The ratio of transferrin receptor/ferritin determined from plasma spots correctly identified all 12 subjects with iron deficiency anemia compared with 11 of the 12 for whole plasma measurements.Measurements of ferritin and transferrin receptor on plasma spotted and dried on filter paper are comparable to whole plasma values for the identification of iron deficiency anemia. The use of dried plasma spots will facilitate the collection, storage, and transport of samples in epidemiological studies of anemia prevalence.

Amplification of DNA from whole blood collected on Guthrie card filter paper presents considerable technical obstacles due to the presence of natural PCR inhibitors (protein, heavy metals, heme, and heme degradation products) and low copy number of genomic material. For this purpose we evaluated guanidine thiocyanate‐impregnated filter paper (GT‐903), a DNA collection device designed specifically to bind PCR inhibitors and preserve DNA in an aqueous extractable form. Compared to standard 903, which retains DNA and elutes inhibitors during aqueous extraction, we found GT‐903 retained 90% of protein, hemoglobin, and iron. SDS‐PAGE analysis indicated that the majority of the protein released from standard 903 corresponded to albumin (70‐) and globin (15‐kDa); negligible levels of these proteins were eluted from GT‐903. To evaluate PCR efficiency, we amplified the 491 bp region encoding the cystic fibrosis ΔF508 mutation. Using comparable template, we found GT‐903 amplification more efficient than standard 903 following qualitative (TBE‐PAGE) and quantitative (anti‐dsDNA EIA) determination. We conclude that GT‐903 provides a good DNA collection device and addresses the complications associated with natural PCR inhibitors. J. Clin. Lab. Anal. 11:87–93. © 1997 Wiley‐Liss, Inc.

The aim of this study was to investigate a possible relationship between exposure to sulfides and disturbances of the synthesis of heme and the erythrocytes. Eighteen workers exposed to sulfides at a pulp and paper plant were examined and compared with individually matched referents from a thermomechanical pulp plant without such exposure. The exposure levels of methylmercaptan, dimethylsulfide, and dimethyldisulfide were low. However, five subjects were exposed to high levels of short duration, and their data were analyzed separately. The activity of the enzymes delta-aminolevulinic acid synthase and heme synthase in reticulocytes, characteristics of the erythrocytes, and the iron status were analyzed. A minor decrease, not statistically significant, was observed for the enzymes among the five highly exposed subjects. However, the concentrations of iron and transferrin were elevated and the concentration of ferritin was low in comparison to the corresponding levels of the referents. This combination will not occur spontaneously. A previous study indicated that sulfides may inhibit heme synthesis, and the present study suggests that they may also disturb iron metabolism.

Mutants of Escherichia coli K-12 blocked in each of the three enzymatic reactions between chorismate and 2,3-dihydroxybenzoate, in the pathway leading to the iron-sequestering compound enterochelin, have been isolated and biochemically characterized. The three genes concerned (designated entA, entB and entC ) have been shown to be clustered on the chromosome between purE and gal and to be located near minute 14 by cotransduction with the purE, lip , and fep genes. entA, entB , and entC were shown to be the structural genes for 2,3-dihydro-2,3-dihydroxybenzoate dehydrogenase, 2,3-dihydro-2,3-dihydroxybenzoate synthetase, and isochorismate synthetase, respectively.