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  • 1
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Data sets on CB concentrations in fish-eating mammals from five laboratories were combined to test and refine a pharmacokinetic model. Clear differences in PCB patterns were observed between species. The ability to metabolize chlorobiphenyl (CB) congeners with vicinal H-atoms only in the ortho- and meta-positions and with one ortho-chlorine substituent generally increased in the order otter 〈 cetaceans (harbor porpoise, common dolphin) 〈 phocid seals (harbor and grey seal), but the metabolism of congeners with vicinal H-atoms in the meta- and para-positions and with two ortho-chlorines increased in the order cetaceans 〈 seals 〈 otter. Both categories of congeners are probably metabolized by different families of cytochrome P450 (1A and 2B) of which levels apparently differed between the cetaceans, the pinnipeds, and the otter. Within-species CB patterns differed in a concentration-dependent manner. The induction of cytochrome P450 enzymes offers the most likely explanation for this phenomenon, but starvation could have a similar effect on occasion.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Human genetics 〈Berlin〉 99 (1997), S. 612-615 
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Hereditary multiple exostoses (EXT) is a genetically heterogeneous bone disorder caused by genes segregating on human chromosomes 8, 11, and 19 and designated EXT1, EXT2 and EXT3, respectively. Recently, the EXT1 gene has been isolated and partially characterized and appears to encode a tumor suppressor gene. We have identified six mutations in the human EXT1 gene from six unrelated multiple exostoses families segregating for the EXT gene on chromosome 8. One of the mutations we detected is the same 1-bp deletion in exon 6 that was previously reported in two independent EXT families. The other five mutations, in exons 1, 6, 9, and the splice junction at the 3′ end of exon 2, are novel. In each case, the mutation is likely to result in a truncated or nonfunctional EXT1 protein. These results corroborate and extend the previous report of mutations in this gene in two EXT families, and provide additional support for the EXT1 gene as the cause of hereditary multiple exostoses in families showing linkage to chromosome 8.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0935-6304
    Keywords: Gas chromatography, GC ; Fused silica capillary columns ; Retention index ; Internal standards ; Environmental samples ; Dichlorobenzyl alkyl ethers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A homologous series of 2,4-dichlorobenzyl alkyl ethers (DCBEs) have been synthesized and purified for use as retention index calibrants and internal standards. They are stable, sensitive to ECD and FID and ideal for GC-MS, with base peaks at m/z 159/161. The retention index calibration against the n-alkanes for a linear temperature program (LTP) series is given and recommendations made for the most suitable members of the DCBE series for use as internal standards in organochlorine (OC) residue analysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0935-6304
    Keywords: Gas chromatrography, GC ; Capillary columns ; Splitless and on-column injection ; Interlaboratory study ; Chlorobiphenyl congeners ; Internal standards ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Community Bureau of Reference has organized a collaborative interlaboratory project to improve the analytical protocol for some specific chlorobiphenyls (CBs) within the European Community (EC). A series of test procedures were prescribed to optimize the gas chromatographic conditions for splitless and on-column injection, which substantially improved the quality of data. Important parameters included the initial column and injector temperatures and the choice of the polarity of the stationary phase. In a study with cleaned eel-fat extracts, coefficients of variation for reproducibility CV(R) ranging from 11 to 24% at the 0.04-0.3 mg/kg level per CB congener were obtained. No significant difference could be found between splitless- and on-column injection.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 332 (1988), S. 591-597 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper gives an account of the systematic, collaborative learning programme undertaken by a group of experienced analytical laboratories within the European Economic Community (EEC) to improve the state-of-the art in the determination of individual chlorobiphenyl congeners in different matrices in preparation for the certification exercises to produce two fish oils as certified reference materials (CRMs). The choice of individual CB congeners, the critical GC parameters necessary to optimise the chromatographic separation and quantification of the congener is given. An assessment is made of the methods of extraction, separation and clean-up of samples prior to gas chromatographic analysis.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 332 (1988), S. 583-590 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reference materials (RMs) available for organic trace analysis (OTA) and the development programmes of the RM producers are reviewed. The need for a wider range of determinants, matrices and classes of RMs, particularly the more widespread use of laboratory RMs (LRMs) is discussed. Additional certified RMs should include phenolic surfactant degradation products, chlorophenolics from the wood and paper industries, and organobromines from fire retardants. RMs as molecular markers of geogenic, pyrogenic and biogenic sources; chlorophylls and xanthophylls as a measure of marine productivity and natural shellfish toxins are proposed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 339 (1991), S. 173-180 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Six chlorinated biphenyls — CB IUPAC nos 28, 52, 101, 118, 153 and 180 — have been certified in a dried sewage sludge of a mainly residential area. After a thorough preparation the material has been studied for the “within-” and “between bottle” homogeneity as well as for its long term stability. The certification of the CBs in the dried sludge has been performed with 18 well trained laboratories, applying different methods of extraction, clean-up and chromatographic separation. ECD has been used as final detection and MS to verify the peak identities. All methods for the homogeneity and stability studies as well as those used for the certification campaign are described. CB 138 could not be certified as it co-eluted with CB 183. The major precautions followed by the participants to ensure traceability of the results to the basic units are also discussed. They highlight the level of quality control requested from certifying laboratories. The certified values were obtained after a technical discussion of the methods followed and of each of the individual results. They are given together with the indicative value for CB 138+CB 163.
    Type of Medium: Electronic Resource
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