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McNabb P, Selwood AI, Holland PT, Aasen J, Aune T, Eaglesham G, Hess P, Igarishi M, Quilliam M, Slattery D, Van de Riet; J, Van Egmond H, Van den Top H, Yasumoto T. Multiresidue Method for Determination of Algal Toxins in Shellfish: Single-Laboratory Validation and Interlaboratory Study. J AOAC Int 2019. [DOI: 10.1093/jaoac/88.3.761] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
A method that uses liquid chromatography with tandem mass spectrometry (LC/MS/MS) has been developed for the highly sensitive and specific determination of amnesic shellfish poisoning toxins, diarrhetic shellfish poisoning toxins, and other lipophilic algal toxins and metabolites in shellfish. The method was subjected to a full single-laboratory validation and a limited interlaboratory study. Tissue homogenates are blended with methanol-water (9 + 1), and the centrifuged extract is cleaned up with a hexane wash. LC/MS/MS (triple quadrupole) is used for quantitative analysis with reversed-phase gradient elution (acidic buffer), electrospray ionization (positive and negative ion switching), and multiple-reaction monitoring. Ester forms of dinophysis toxins are detected as the parent toxins after hydrolysis of the methanolic extract. The method is quantitative for 6 key toxins when reference standards are available: azaspiracid-1 (AZA1), domoic acid (DA), gymnodimine (GYM), okadaic acid (OA), pectenotoxin-2 (PTX2), and yessotoxin (YTX). Relative response factors are used to estimate the concentrations of other toxins: azaspiracid-2 and -3 (AZA2 and AZA3), dinophysis toxin-1 and -2 (DTX1 and DTX2), other pectenotoxins (PTX1, PTX6, and PTX11), pectenotoxin secoacid metabolites (PTX2-SA and PTX11-SA) and their 7-epimers, spirolides, and homoYTX and YTX metabolites (45-OHYTX and carboxyYTX). Validation data have been gathered for Greenshell mussel, Pacific oyster, cockle, and scallop roe via fortification and natural contamination. For the 6 key toxins at fortification levels of 0.05–0.20 mg/kg, recoveries were 71–99% and single laboratory reproducibilities, relative standard deviations (RSDs), were 10–24%. Limits of detection were <0.02 mg/kg. Extractability data were also obtained for several toxins by using successive extractions of naturally contaminated mussel samples. A preliminary interlaboratory study was conducted with a set of toxin standards and 4 mussel extracts. The data sets from 8 laboratories for the 6 key toxins plus DTX1 and DTX2 gave within-laboratories repeatability (RSDr) of 8–12%, except for PTX-2. Between-laboratories reproducibility (RSDR) values were compared with the Horwitz criterion and ranged from good to adequate for 7 key toxins (HorRat values of 0.8–2.0).
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Aasen J, MacKinnon SL, LeBlanc P, Walter JA, Hovgaard P, Aune T, Quilliam MA. Detection and identification of spirolides in norwegian shellfish and plankton. Chem Res Toxicol 2005; 18:509-15. [PMID: 15777091 DOI: 10.1021/tx049706n] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mussels sampled in the spring of 2002 and 2003 from Skjer, a location in Sognefjord, Norway, tested positive in the mouse bioassay for lipophilic toxins. The symptoms, which included cramps, jumping, and short survival times (as low as 4 min), were not characteristic of toxins previously observed in Norway. A survey of the algae present at the aquaculture sites showed that the toxicity correlated with blooms of Alexandrium ostenfeldii. Up to 2200 cells/L were found at the peak of one bloom. In Canadian waters, this alga is known to be a producer of the cyclic imine toxins, spirolides. Analysis of mussel extracts from Skjer in the spring of 2002 and 2003, using liquid chromatography tandem mass spectrometry, revealed the presence of several new spirolides. The same compounds were also found in algal samples dominated by A. ostenfeldii, which had been sampled from Skjer in February 2003. A large-scale extraction of mussel digestive glands and chromatographic fractionation of the extracts allowed the isolation and structure elucidation of the main spirolide, 20-methyl spirolide G, with a molecular weight of 705.5. This is the first confirmed occurrence of spirolides in mussels and plankton from Norway.
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Research Support, Non-U.S. Gov't |
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Van De Riet J, Gibbs RS, Muggah PM, Rourke WA, MacNeil JD, Quilliam MA, Aasen J, Amzil; B. Ben Gigirey Z, Burdaspal P, Burrell SW, Brazeau J, Carter SJ, Ceredi A, Duffy C, Eaglesham G, Hatfeld R, Hillyard T, Jensen MKH, Lacaze JP, Langlois D, Legarda TM, Marcos E, Milandri A, Mulder PPJ, Murphy C, Ouellette S, Panganiban C, Pante L, Paulsrud MS, Pooley BP, Reeves K, Riccardi E, Rodríguez Velasco ML, Sacrey TZ, Savar V, Selwood A, Sizoo EA, Turner AD, van Ginkel R, Wotherspoon ATL. Liquid Chromatography Post-Column Oxidation (PCOX) Method for the Determination of Paralytic Shellfish Toxins in Mussels, Clams, Oysters, and Scallops: Collaborative Study. J AOAC Int 2019. [DOI: 10.1093/jaoac/94.4.1154] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Sixteen laboratories participated in a collaborative study to evaluate method performance parameters of a liquid chromatographic method of analysis for paralytic shellfsh toxins (PST) in blue mussels (Mytilus edulis), soft shell clams (Mya arenaria), sea scallops (Placopectin magellanicus), and American oysters (Crassostrea virginicus). The specifc analogs tested included saxitoxin, neosaxitoxin, gonyautoxins-1 to -5, decarbamoyl-gonyautoxins-2 and -3, decarbamoyl-saxitoxin, and N-sulfocarbamoylgonyautoxin-2 and -3. This instrumental technique has been developed as a replacement for the current AOAC biological method (AOAC Offcial MethodSM 959.08) and an alternative to the pre-column oxidation LC method (AOAC Offcial MethodSM 2005.06). The method is based on reversed-phase liquid chromatography with post-column oxidation and fluorescence detection (excitation 330 nm and emission 390 nm). The shellfsh samples used in the study were prepared from the edible tissues of clams, mussels, oysters, and scallops to contain concentrations of PST representative of low, medium, and high toxicities and with varying profles of individual toxins. These concentrations are approximately equivalent to ½ maximum level (ML), ML, or 2×ML established by regulatory authorities (0.40, 0.80, and 1.60 mg STX·diHCl eq/kg, respectively). Recovery for the individual toxins ranged from 104 to 127%, and recovery of total toxin averaged 116%. Horwitz Ratio (HorRat) values for individual toxins in the materials included in the study were generally within the desired range of 0.3 to 2.0. For the estimation of total toxicity in the test materials, the reproducibility relative standard deviation ranged from 4.6 to 20%. A bridging study comparing the results from the study participants using the post-column oxidation (PCOX) method with the results obtained in the study director’s laboratory on the same test materials using the accepted reference method, the mouse bioassay (MBA; AOAC Offcial MethodSM 959.08), showed that the average ratio of results obtained from the two methods was 1.0. A good match of values was also achieved with a new certifed reference material. The results from this study demonstrated that the PCOX method is a suitable method of analysis for PST in shellfsh tissue and provides both an estimate of total toxicity, equivalent to that determined using the MBA AOAC Offcial MethodSM 959.08, and a detailed profle of the individual toxin present in the sample.
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Aasen J, Samdal IA, Miles CO, Dahl E, Briggs LR, Aune T. Yessotoxins in Norwegian blue mussels (Mytilus edulis): uptake from Protoceratium reticulatum, metabolism and depuration. Toxicon 2005; 45:265-72. [PMID: 15683864 DOI: 10.1016/j.toxicon.2004.10.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Revised: 10/13/2004] [Accepted: 10/18/2004] [Indexed: 11/19/2022]
Abstract
The Protoceratium reticulatum cell density at Flodevigen reached a maximum of 2200 cells/L on 16 May 2001. The levels of yessotoxins (YTXs) in blue mussels (Mytilus edulis) at the same site increased sharply by 14 May and peaked on 28 May, after which they steadily declined. No other algal species present showed a similar pattern of correspondence. Together with the recent finding that Norwegian strains of P. reticulatum produce YTXs, these results indicate that P. reticulatum causes yessotoxin (YTX) contamination of shellfish in Norway, and that only relatively low cell densities are necessary for this to occur. The mussels from Flodevigen were analyzed by LC-MS for YTX, 45-hydroxyYTX, carboxyYTX, and a new yessotoxin believed to be 45-hydroxycarboxyYTX, and by ELISA for YTXs. The seasonal variations in toxin content versus time measured by the two methods were qualitatively very similar, although the response in the ELISA was 3-9 times higher due to the antibodies detecting other YTXs that were not detected by the LC-MS method. Changes in the LC-MS profile for YTXs, and in the ratio of YTXs by LC-MS to YTXs by ELISA with time, were consistent with extensive metabolism of YTX in the mussels. Kinetic analysis of the LC-MS data showed an initial half-life of 20 days for YTX, and for YTX+45-hydroxyYTX, in the mussels. Similar analysis of the ELISA data gave a half-life of 24 days for YTXs. The depuration rate remained consistent over a 3-month period during which the temperature remained at 13-16 degrees C.
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Torgersen T, Aasen J, Aune T. Diarrhetic shellfish poisoning by okadaic acid esters from Brown crabs (Cancer pagurus) in Norway. Toxicon 2005; 46:572-8. [PMID: 16153454 DOI: 10.1016/j.toxicon.2005.06.024] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 06/29/2005] [Accepted: 06/30/2005] [Indexed: 11/24/2022]
Abstract
In 2002 several hundred people were taken ill after eating self-harvested brown crabs (Cancer pagurus) in the southern part of Norway. The symptoms were similar to diarrhetic shellfish poisoning (DSP) although with a somewhat delayed onset. This happened at the same time as an unusual early bloom of Dinophysis acuta had lead to high amounts of DSP toxins in blue mussels (Mytilus edulis) in the same area. The proposed cause of the intoxication was that crabs had accumulated toxins by eating blue mussels. Analyses of crab material from the area revealed very little free toxin in the form of okadaic acid (OA). However, after alkaline hydrolysis of the material, the amounts of OA found in the crabs were above the toxic level. MS/MS analysis of a sample from one intoxication episode indicated presence of the 14:0, 16:1, 16:0 and 18:1 fatty acid esters of okadaic acid. Esterified OA constituted more than 90% of total identified DSP toxins in crabs, indicating that not only esterified toxin from mussels was accumulated, but also that appreciable transfer of OA to OA-esters occurred in the crabs.
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Hess P, Nguyen L, Aasen J, Keogh M, Kilcoyne J, McCarron P, Aune T. Tissue distribution, effects of cooking and parameters affecting the extraction of azaspiracids from mussels, Mytilus edulis, prior to analysis by liquid chromatography coupled to mass spectrometry. Toxicon 2005; 46:62-71. [PMID: 15922391 DOI: 10.1016/j.toxicon.2005.03.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2004] [Revised: 03/18/2005] [Accepted: 03/21/2005] [Indexed: 10/25/2022]
Abstract
This study used liquid chromatography coupled to mass spectrometry to identify some parameters important in the analysis of azaspiracids. The first aspect was the distribution of azaspiracids within mussels, in particular the content in the digestive gland as compared to the remaining tissues. In our study, azaspiracids accumulated in the digestive gland, similar to other lipophilic toxins. The ratio of toxin in the digestive gland compared to the whole mussel was on average circa 5, both for a bulk sample collected in Norway in 2004 and for 28 samples from Ireland collected over 3 years (2001-2003). These results may justify the practise to only analyse the digestive gland, a step considered necessary to achieve adequate detection limits for azaspiracids both in the mouse bioassay and other analytical techniques. Steaming of mussels as a sample pre-treatment was found to be another parameter affecting the result. Azaspiracids concentrated indirectly, i.e. through the loss of water or juice from the matrix. The cooked shellfish tissues had a concentration of azaspiracids 2-fold higher than the uncooked shellfish, both for whole flesh and for digestive gland tissue. This finding is of particular importance since it may affect the maximum guidance level at which shellfish may be allowed for human consumption. Finally, parameters affecting the extraction efficiency were studied, including the nature of the extraction solvent, the sample-to-solvent ratio and replicate extraction. The largest differences were observed between different solvents and between different sample-to-solvent ratios, while the effect of replicate extraction was minimal if large sample-to-solvent ratios were used. Duplicate extraction using 100% methanol was found to be the best combination of parameters.
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Miles CO, Wilkins AL, Hawkes AD, Selwood A, Jensen DJ, Aasen J, Munday R, Samdal IA, Briggs LR, Beuzenberg V, MacKenzie AL. Isolation of a 1,3-enone isomer of heptanor-41-oxoyessotoxin from Protoceratium reticulatum cultures. Toxicon 2004; 44:325-36. [PMID: 15321705 DOI: 10.1016/j.toxicon.2004.06.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2004] [Revised: 06/11/2004] [Accepted: 06/12/2004] [Indexed: 11/24/2022]
Abstract
The 1,3-enone isomer (1) of heptanor-41-oxoyessotoxin (2) was isolated from extracts of Protoceratium reticulatum during large-scale production of yessotoxin (4). We found that 2 readily isomerizes to 1 in the presence of dilute ammonia and present evidence for the existence of 40-epi-2 (3) that also isomerizes to 1. 1-3 were detected by LC-MS methods both in extracts of P. reticulatum cultures and in mussels contaminated with yessotoxins. The isomerization of 2 and 3 into 1 occurs so readily that purification on basic alumina needs to be conducted carefully. No toxic effects were recorded in mice injected intraperitoneally with 1 at a dose of 5,000 microg/kg.
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Miles CO, Wilkins AL, Jensen DJ, Cooney JM, Quilliam MA, Aasen J, MacKenzie AL. Isolation of 41a-Homoyessotoxin and the Identification of 9-Methyl-41a-homoyessotoxin and Nor-ring A-yessotoxin from Protoceratium reticulatum. Chem Res Toxicol 2004; 17:1414-22. [PMID: 15540939 DOI: 10.1021/tx049832r] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
41a-homoyessotoxin (1), a new analogue of yessotoxin (7), was isolated from extracts of Protoceratium reticulatum grown in culture. In addition, 9-methyl-41a-homoyessotoxin (2) and a nor-ring A-yessotoxin (3) were identified as the major components of a mixed fraction. The structural information was initially obtained from LC-UV and LC-MS3 chromatograms, with subsequent definitive structure determination by NMR, LC-MS/MS, and high-resolution MS. Full 1H and indirectly detected 13C NMR assignments for all but two carbon atoms were obtained from ca. 100 microg of 1. Full 1H NMR assignments for 2 and 3 and identification of three new heptanor-41-oxo-analogues of 3 (4-6) during LC-MS3 analysis of a fraction containing 1-3 and 7 are also reported.
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Finch SC, Wilkins AL, Hawkes AD, Jensen DJ, MacKenzie AL, Beuzenberg V, Quilliam MA, Olseng CD, Samdal IA, Aasen J, Selwood AI, Cooney JM, Sandvik M, Miles CO. Isolation and identification of (44-R,S)-44,55-dihydroxyyessotoxin from Protoceratium reticulatum, and its occurrence in extracts of shellfish from New Zealand, Norway and Canada. Toxicon 2005; 46:160-70. [PMID: 15975615 DOI: 10.1016/j.toxicon.2005.03.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 03/08/2005] [Accepted: 03/08/2005] [Indexed: 10/25/2022]
Abstract
44,55-Dihydroxyyessotoxin (1) was isolated from extracts of Protoceratium reticulatum and identified by analysis of its one- and two-dimensional NMR and mass spectra. In addition, LC-MS methods revealed the presence of compounds tentatively identified as (44-R,S)-44,55-dihydroxy-41a-homoyessotoxin (2) and (44-R,S)-44,55-dihydroxy-9-methyl-41a-homoyessotoxin (3). LC-MS analyses indicate that 1 is a constituent of P. reticulatum in New Zealand and Norway, and it was present in three species of mussels from New Zealand, Norway, and Canada.
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Aasen J, Kerty E, Russell D, Bakke SJ, Nyberg-Hansen R. Amaurosis fugax: clinical, Doppler and angiographic findings. Acta Neurol Scand 1988; 77:450-5. [PMID: 3043995 DOI: 10.1111/j.1600-0404.1988.tb05939.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Clinical, Doppler and angiographic findings are described in 53 consecutive patients who presented with amaurosis fugax (AF) in a total of 57 eyes; 4 had non-simultaneous attacks in both eyes. Atherosclerotic lesions were detected on Doppler or angiographic (conventional arteriography and/or intravenous digital subtraction angiography) examination in 36 (63%) of the relevant precerebral internal carotid arteries (ICA) in 34 patients. Nineteen (53%) of these lesions caused a diameter reduction of more than 75%. Patient age was the most important factor in predicting the presence of relevant carotid occlusive disease, all 36 lesions being found in patients over 50 years of age. Two unusual cases of AF are described; in one AF was caused by stenosis of the ipsilateral ophthalmic artery, and in another by occlusion of the brachiocephalic artery with a steal syndrome from the right common carotid artery (CCA) to the right subclavian artery.
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Case Reports |
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Castberg T, Torgersen T, Aasen J, Aune T, Naustvoll LJ. Diarrhoetic shellfish poisoning toxins in Cancer pagurus Linnaeus, 1758 (Brachyura, Cancridae) in Norwegian waters. ACTA ACUST UNITED AC 2010. [DOI: 10.1080/00364820410002550] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ward JF, Johansen I, Aasen J. Radiosensitization by N-ethyl maleimide--a model chemical system. INTERNATIONAL JOURNAL OF RADIATION BIOLOGY AND RELATED STUDIES IN PHYSICS, CHEMISTRY, AND MEDICINE 1969; 15:163-70. [PMID: 5305666 DOI: 10.1080/09553006914550241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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56 |
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13
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Grov A, Oeding P, Myklestad B, Aasen J. Reactions of staphylococcal antigens with normal sera, gamma G-globulins, and gamma G-globulin fragments of various species origin. ACTA PATHOLOGICA ET MICROBIOLOGICA SCANDINAVICA. SECTION B: MICROBIOLOGY AND IMMUNOLOGY 2009; 78:106-11. [PMID: 4192776 DOI: 10.1111/j.1699-0463.1970.tb04275.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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14
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Haukenes G, Aasen J. Rubella haemagglutination inhibitors: their separation from antibodies. ACTA PATHOLOGICA ET MICROBIOLOGICA SCANDINAVICA. SECTION B: MICROBIOLOGY AND IMMUNOLOGY 2009; 79:679-85. [PMID: 5286216 DOI: 10.1111/j.1699-0463.1971.tb00096.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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15
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Aasen J, Oeding P. Antigenic studies on Staphylococcus epidermidis. ACTA PATHOLOGICA ET MICROBIOLOGICA SCANDINAVICA. SECTION B: MICROBIOLOGY AND IMMUNOLOGY 2009; 79:827-34. [PMID: 5003328 DOI: 10.1111/j.1699-0463.1971.tb00118.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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16
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Haukenes G, Aasen J. Heterogeneity in the reactivity of antibodies with kaolin. ACTA PATHOLOGICA ET MICROBIOLOGICA SCANDINAVICA. SECTION B: MICROBIOLOGY AND IMMUNOLOGY 2009; 80:251-6. [PMID: 4624533 DOI: 10.1111/j.1699-0463.1972.tb00156.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Winnem M, Eskerud J, Monstad I, Kierulf H, Aasen J, Skovlund E. [Diagnosis of migraine in general practice]. NORDISK MEDICIN 1993; 108:280-282. [PMID: 8247716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
195 patients with headache were examined by general practitioners and neurologists, and their diagnoses were compared. The general practitioners diagnosed migraine in 116 cases, the neurologists in 144 cases, and in 104 cases their diagnoses agreed. Thus, migraine can be difficult to diagnose, and this study indicates underdiagnosis of this common condition by general practitioners. This may result in overuse of analgesics and alternative therapies, and too little prescription of specific migraine medication. Greater familiarity with the diagnostic criteria of the International Headache Society should make it easier to arrive at a correct migraine diagnosis.
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Comparative Study |
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Ward JF, Johansen I, Aasen J. Radiosensitization by N-ethyl maleimide--a model chemical system. UCLA 12-724. UCLA [REPORTS]. U.S. ATOMIC ENERGY COMMISSION 1969:77. [PMID: 5372498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Aasen J, Slaastad RA. [Acute dystonia caused by metoclopramide (Primperan)]. TIDSSKRIFT FOR DEN NORSKE LEGEFORENING 1982; 102:916-7. [PMID: 7164045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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Case Reports |
43 |
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20
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McNabb P, Selwood AI, Holland PT, Aasen J, Aune T, Eaglesham G, Hess P, Igarishi M, Quilliam M, Slattery D, Van de Riet J, Van Egmond H, Van den Top H, Yasumoto T. Multiresidue method for determination of algal toxins in shellfish: single-laboratory validation and interlaboratory study. J AOAC Int 2005; 88:761-72. [PMID: 16001850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
A method that uses liquid chromatography with tandem mass spectrometry (LC/MS/MS) has been developed for the highly sensitive and specific determination of amnesic shellfish poisoning toxins, diarrhetic shellfish poisoning toxins, and other lipophilic algal toxins and metabolites in shellfish. The method was subjected to a full single-laboratory validation and a limited interlaboratory study. Tissue homogenates are blended with methanol-water (9 + 1), and the centrifuged extract is cleaned up with a hexane wash. LC/MS/MS (triple quadrupole) is used for quantitative analysis with reversed-phase gradient elution (acidic buffer), electrospray ionization (positive and negative ion switching), and multiple-reaction monitoring. Ester forms of dinophysis toxins are detected as the parent toxins after hydrolysis of the methanolic extract. The method is quantitative for 6 key toxins when reference standards are available: azaspiracid-1 (AZA1), domoic acid (DA), gymnodimine (GYM), okadaic acid (OA), pectenotoxin-2 (PTX2), and yessotoxin (YTX). Relative response factors are used to estimate the concentrations of other toxins: azaspiracid-2 and -3 (AZA2 and AZA3), dinophysis toxin-1 and -2 (DTX1 and DTX2), other pectenotoxins (PTX1, PTX6, and PTX11), pectenotoxin secoacid metabolites (PTX2-SA and PTX11-SA) and their 7-epimers, spirolides, and homoYTX and YTX metabolites (45-OHYTX and carboxyYTX). Validation data have been gathered for Greenshell mussel, Pacific oyster, cockle, and scallop roe via fortification and natural contamination. For the 6 key toxins at fortification levels of 0.05-0.20 mg/kg, recoveries were 71-99% and single laboratory reproducibilities, relative standard deviations (RSDs), were 10-24%. Limits of detection were <0.02 mg/kg. Extractability data were also obtained for several toxins by using successive extractions of naturally contaminated mussel samples. A preliminary interlaboratory study was conducted with a set of toxin standards and 4 mussel extracts. The data sets from 8 laboratories for the 6 key toxins plus DTX1 and DTX2 gave within-laboratories repeatability (RSD(R)) of 8-12%, except for PTX-2. Between-laboratories reproducibility (RSDR) values were compared with the Horwitz criterion and ranged from good to adequate for 7 key toxins (HorRat values of 0.8-2.0).
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Aasen J, Fossberg E. [Adrenal cysts]. TIDSSKRIFT FOR DEN NORSKE LEGEFORENING 1980; 100:1139-42. [PMID: 7456003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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Case Reports |
45 |
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22
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Winnem M, Eskerud J, Monstad I, Kierulf H, Aasen J, Skovlund E. [Diagnosis of migraine in general practice]. TIDSSKRIFT FOR DEN NORSKE LEGEFORENING 1993; 113:2386-8. [PMID: 8378899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
195 patients with headache were examined by general practitioners and neurologists, and their diagnoses were compared. The general practitioners diagnosed migraine in 116 cases, the neurologists in 144 cases, and in 104 cases their diagnoses agreed. Thus, migraine can be difficult to diagnose, and this study indicates underdiagnosis of this common condition by general practitioners. This may result in overuse of analgesics and alternative therapies, and too little prescription of specific migraine medication. Greater familiarity with the diagnostic criteria of the International Headache Society should make it easier to arrive at a correct migraine diagnosis.
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Comparative Study |
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23
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Aasen J. [Basal cell carcinoma with metastases]. TIDSSKRIFT FOR DEN NORSKE LEGEFORENING 1980; 100:1848-9. [PMID: 7456043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
|
Case Reports |
45 |
|
24
|
Raknerud N, Aasen J, Smith E. [Lipohyperplasia of Bauhin's valve]. TIDSSKRIFT FOR DEN NORSKE LEGEFORENING 1984; 104:1138-40. [PMID: 6740608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Case Reports |
41 |
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25
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Aasen J, Nyberg-Hansen R, Seem K. [Uveomeningoencephalitic syndrome]. TIDSSKRIFT FOR DEN NORSKE LEGEFORENING 1985; 105:2300-1. [PMID: 4082142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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Case Reports |
40 |
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