| 1. |
- Quétel, C. R., et al.
(författare)
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Methylmercury in tuna: demonstrating measurement capabilities and evaluating comparability of results worldwide from the CCQM P-39 comparison
- 2005
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 20, s. 1058-66
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Tidskriftsartikel (refereegranskat)abstract
- Six metrology institutes (NMIs) representing at the Comité International des Poids et Mesures (CIPM) 4 Member States of the Metre Convention and 2 international organisations, and 8 expert laboratories selected outside CIPM have compared their capabilities to quantitatively measure methylmercury (MeHg) in a prepared tuna material containing approximately 4.3 mg kg–1 Hg. This comparison was the object of the CIPM–Comité Consultatif pour la Quantité de Matière (CCQM) Pilot Study 39, organised by the Institute for Reference Materials and Measurements (IRMM), from the European Commission—Joint Research Centre. Beside the test material itself, a bottle of the BCR-464 tuna Certified Reference Material (CRM) and an ampoule of IRMM-670, a 202Hg isotope enriched MeHg candidate isotopic CRM, were distributed to all participants, who were free to apply the measurement strategy of their choice. Four, including 1 NMI, relied on external calibration or the method of standard additions, whereas the other 10 implemented an isotope dilution mass spectrometry (IDMS) approach and chose to use the IRMM-670 for their measurements. Alkaline digestion at room temperature (with manual shaking) or high temperature (under sonication, oven or hot plate conditions) was employed by most participants, with hydrochloric acid leaching the second most popular choice. Alkylation (4 phenylations, 4 ethylations and 3 propylations) in the aqueous phase was preferred by a large majority over butylation by the Grignard reaction. All participants were requested to estimate the uncertainty associated with their results and 9 out of 14 stated relative combined uncertainties below 6%(k= 2). Despite this apparent consensus, the perception of which factor caused the largest contribution to this estimation differed among participants because of the differences in the analytical methodologies deployed but also because of wide differences of the concepts of uncertainty estimation. The mixture mode(MM) median, calculated also from the measurement uncertainties stated by the participants, was 1.967 ± 0.204 × 10–5 mol kg–1(95% confidence). Twelve of the results were re-grouped within a range of less than 0.3 × 10–5 mol kg–1(MM median = 1.967 ± 0.162 × 10–5 mol kg–1, 95% confidence): they nearly all (1 exception) overlapped with each other within k= 2 stated uncertainties. For the other 2 results the uncertainty seemed to have been particularly underestimated as they lay, respectively, at more than 20% above and less than –40% below the overall average. The relative standard deviation of the results of 9 laboratories out of the 10 that applied IDMS was about 2.6%. It can be assumed from the degree of equivalence shown by 12 out of 14 study participants that, at present, laboratories worldwide are potentially able to supply accurate results for MeHg in fish-type matrices (containing about 2 × 10–5 mol kg–1) within ±10% uncertainty. This encouraging outcome permitted scheduling of a follow-up CCQM-K43 key comparison for a lower MeHg content level in salmon tissues.
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| 2. |
- Wester, Elisabet Sjöberg, et al.
(författare)
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A simple screening assay for the most common JK*0 alleles revealed compound heterozygosity in Jk(a-b-) probands from Guam
- 2009
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Ingår i: Immunohematology. - 0894-203X. ; 25:4, s. 165-169
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Tidskriftsartikel (refereegranskat)abstract
- The Jk(a-b-) phenotype results from alterations in the JK gene and is characterized by absence of the RBC urea transporter in the cell membrane. The frequency of Jk(a-b-) varies among populations, but this phenotype is most commonly found in people of Polynesian and Finnish descent. Although rare, Jk(a-b-) individuals present a clinical challenge because anti-Jk3 is produced readily in response to transfusion and pregnancy, and Jk(a-b-) blood is not routinely available. Identification of Jk(a-b-) patients and donors is most often performed serologically. However, ten JK*o alleles have been identified, and this information can be used in DNA-based typing. We selected five JK*o alleles that had been encountered by our reference laboratory in two or more samples from unrelated individuals and designed an allele-specific primer PCR assay for use as an initial screening tool. After in-house validation, we tested genomic DNA from a family: a mother and her two sons referred to us for genetic investigation of their Jk(a-b-) phenotypes. Two different nucleotide substitutions, -1g>a in intron 5 (IVS5) and 956C>T in exon 10, originally associated with Polynesian and Indian/African populations respectively, were identified in the family. The mother and one son were compound heterozygotes, and the second son was homozygous for IVS5-1g>a. We conclude that the effort to design and validate such a screening assay was cost-efficient when compared with DNA sequencing costs. Furthermore, selection of the more common JK*o mutations was a practical approach that resulted in rapid identification of the genetic bases behind the Jk(a-b-) phenotypes in this unusual family. Although an obvious target for eventual inclusion into high-throughput genotyping platforms for clinical diagnostic services, current systems are very limited. Our approach provides a simple and inexpensive method for the identification of these rare alleles.
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| 3. |
- Wurst, FM, et al.
(författare)
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World Health Organization/International Society for Biomedical Research on Alcoholism study on state and trait markers of alcohol use and dependence: Back to the future
- 2005
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Ingår i: Alcoholism: Clinical and Experimental Research. - 0145-6008. ; 29:7, s. 1268-1275
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Tidskriftsartikel (refereegranskat)abstract
- This article summarizes content proceedings of a symposium held at the 2004 International Society for Biomedical Research on Alcoholism Congress in Mannheim, Germany. The chairs were Boris Tabakoff and Friedrich M. Wurst. The presentations were (1) Genetic associations with alcoholism and affective disorders, by Paula Hoffman; (2) Proteomic analysis of blood constituents in alcoholism, by Boris Tabakoff; (3) Contrasts between the responses of GGT and CDT to high alcohol intake, and a test of their combined use, by John Whitfield; (4) Direct ethanol metabolites such as ethyl glucuronide, fatty acid ethyl esters, phosphatidylethanol and ethyl sulfate: a new line of sensitive and specific biomarkers, by Friedrich Martin Wurst; and (5) Genetic studies of alcoholism subtypes in a Han Taiwanese population, by Ru-Band Lu.
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