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De Alwis GK Needham LL Barr DB 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2006,843(1):34-41
Organophosphorus (OP) pesticides are among the most widely used pesticides in the United States. Human exposure to these pesticides may occur from their use on crops in agriculture and for pest control in residential settings. Most of the OP pesticides used in the United States are metabolized to up to three of six common urinary dialkyl phosphate metabolites. Quantification of these metabolites provides information on cumulative exposure to most OP pesticides. To accurately quantify OP pesticide metabolites in human urine, we developed a simple, highly sensitive, analytic method involving automated solid-phase extraction (SPE) of human urine, followed by post-extraction derivatization of the organophosphorus metabolites with 1-chloro-3-iodopropane, and analysis by isotope dilution gas-chromatography-tandem mass spectrometry. The styrene-divinyl benzene polymer-based SPE cartridges yielded good SPE recoveries of the metabolites because of their enhanced non-polar interactions. This method is less labor-intensive, more time-efficient, and reproducible than previously reported methods. Automation of the SPE allowed unattended extraction of urine samples, and hence, increased the sample throughput and reduced the inter- and intra-day variations. The method limits of detection were excellent for all analytes ranging from 50 pg/ml to 170 pg/ml. Relative standard deviations ranged from 2% to 12%. 相似文献
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D K Milton K U Alwis L Fisette M Muilenberg 《Applied and environmental microbiology》2001,67(12):5420-5424
(1-->3)-beta-D-Glucans have been recognized as a potential causative agent responsible for bioaerosol-induced respiratory symptoms observed in both indoor and occupational environments. A specific enzyme immunoassay was developed to quantify (1-->6) branched, (1-->3)-beta-D-glucans in environmental samples. The assay was based on the use of a high-affinity receptor (galactosyl ceramide) specific for (1-->3)-beta-D-glucans as a capture reagent and a monoclonal antibody specific for fungal cell wall beta-D-glucans as a detector reagent. The assay was highly specific for (1-->6) branched, (1-->3)-beta-D-glucans (such as that from Saccharomyces cerevisiae) and did not show any response at 200 ng/ml to curdlan, laminarin, pustulan, dextran, mannan, carboxymethyl cellulose, and endotoxins. The detection level was 0.8 ng/ml for baker's yeast glucan and Betafectin. A coefficient of variation of 7.8% was obtained for (1-->3)-beta-D-glucans in house dust samples. Metal working fluids spiked with (1-->3)-beta-D-glucans inhibited the glucan assay. Because the assay is specific for (1-->6) branched, (1-->3)-beta-D-glucans and is sensitive and reproducible, it will be useful for the investigation of health effects from exposure to this class of biologically active molecules. 相似文献
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Malathi De Alwis 《Medical anthropology quarterly》2004,18(1):104-107
Masking Terror: How Women Contain Violence in Southern Sri Lanka. Alex Argenti-Pillen. Philadelphia: University of Pennsylvania Press, 2003. xv. 235 pp.
Scarred Minds: The Psychological Impact of War on Sri Lankan Tamils. Daya Somasunderam New Delhi: Sage, 1998. 353 pp.
The Ocean of Stories: Children's Imagination, Creativity, and Reconciliation in Eastern Sri Lanka. Patricia Lawrence. Colombo, Sri Lanka: International Centre for Ethnic Studies, 2003.94 pp. 相似文献
Scarred Minds: The Psychological Impact of War on Sri Lankan Tamils. Daya Somasunderam New Delhi: Sage, 1998. 353 pp.
The Ocean of Stories: Children's Imagination, Creativity, and Reconciliation in Eastern Sri Lanka. Patricia Lawrence. Colombo, Sri Lanka: International Centre for Ethnic Studies, 2003.94 pp. 相似文献
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Scott A. Smith A. Ruklanthi de Alwis Nurgun Kose Ramesh S. Jadi Aravinda M. de Silva James E. Crowe Jr. 《Journal of virology》2014,88(21):12233-12241
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Andrew J.P. Francis Chandi de Alwis Les Peach Jennifer R. Redman 《Biological Rhythm Research》2013,44(1):91-103
The Australian platypus, Ornithorhynchus anatinus, is one of three extant genera of the order monotremata. Given the divergent evolutionary lineage of monotremes in relation to more commonly studied animals, it was of interest to determine first, whether platypuses possess endogenous biological pacemakers and, second, general parameters of aquatic activity rhythms under artificial and natural light–dark (LD) cycles. Using a novel recording device, aquatic activity rhythms were measured in three platypuses: a paired male and female studied together, and a single female studied in isolation from other platypuses. Under a constant photic environment, some evidence was found for persistent and free-running rhythmicity, indicating the presence of an endogenous circadian pacemaker in the platypus. Under artificial LD cycles the paired animals exhibited a nocturnal pattern of entrainment, although in the single female considerable variability in entrained phase-relations was found under natural LD cycles. Evidence for a circadian pacemaker in the hypothalamic region of platypuses is also discussed. 相似文献
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Sascha C. Hughan Christopher M. Spring Simone M. Schoenwaelder Sharelle Sturgeon Imala Alwis Yuping Yuan James D. McFadyen Erik Westein Duncan Goddard Akiko Ono Yuji Yamanashi Warwick S. Nesbitt Shaun P. Jackson 《The Journal of biological chemistry》2014,289(8):5051-5060
The Dok proteins are a family of adaptor molecules that have a well defined role in regulating cellular migration, immune responses, and tumor progression. Previous studies have demonstrated that Doks-1 to 3 are expressed in platelets and that Dok-2 is tyrosine-phosphorylated downstream of integrin αIIbβ3, raising the possibility that it participates in integrin αIIbβ3 outside-in signaling. We demonstrate that Dok-2 in platelets is primarily phosphorylated by Lyn kinase. Moreover, deficiency of Dok-2 leads to dysregulated integrin αIIbβ3-dependent cytosolic calcium flux and phosphatidylinositol(3,4)P2 accumulation. Although agonist-induced integrin αIIbβ3 affinity regulation was unaltered in Dok-2−/− platelets, Dok-2 deficiency was associated with a shear-dependent increase in integrin αIIbβ3 adhesive function, resulting in enhanced platelet-fibrinogen and platelet-platelet adhesive interactions under flow. This increase in adhesion was restricted to discoid platelets and involved the shear-dependent regulation of membrane tethers. Dok-2 deficiency was associated with an increased rate of platelet aggregate formation on thrombogenic surfaces, leading to accelerated thrombus growth in vivo. Overall, this study defines an important role for Dok-2 in regulating biomechanical adhesive function of discoid platelets. Moreover, they define a previously unrecognized prothrombotic mechanism that is not detected by conventional platelet function assays. 相似文献